Academic literature on the topic 'LHCSR'

Non-photochemical quenching of excess excitation energy is an important photoprotective mechanism in photosynthetic organisms. In Arabidopsis thaliana, a high quenching capacity is constitutively present and depends on the PsbS protein. In the green alga Chlamydomonas reinhardtii, non-photochemical quenching becomes activated upon high light acclimation and requires the accumulation of light harvesting complex stress-related (LHCSR) proteins. Expression of the PsbS protein in C. reinhardtii has not been reported yet. Here, we show that PsbS is a light-induced protein in C. reinhardtii, whose accumulation under high light is further controlled by CO2 availability. PsbS accumulated after several hours of high light illumination at low CO2. At high CO2, however, PsbS was only transiently expressed under high light and was degraded after 1 h of high light exposure. PsbS accumulation correlated with an enhanced non-photochemical quenching capacity in high light-acclimated cells grown at low CO2. However, PsbS could not compensate for the function of LHCSR in an LHCSR-deficient mutant. Knockdown of PsbS accumulation led to reduction of both non-photochemical quenching capacity and LHCSR3 accumulation. Our data suggest that PsbS is essential for the activation of non-photochemical quenching in C. reinhardtii, possibly by promoting conformational changes required for activation of LHCSR3-dependent quenching in the antenna of photosystem II.

Sunlight drives photosynthesis but can also cause photodamage. To protect themselves, photosynthetic organisms dissipate the excess absorbed energy as heat, in a process known as nonphotochemical quenching (NPQ). In green algae, diatoms, and mosses, NPQ depends on the light-harvesting complex stress-related (LHCSR) proteins. Here we investigated NPQ inChlamydomonas reinhardtiiusing an approach that maintains the cells in a stable quenched state. We show that in the presence of LHCSR3, all of the photosystem (PS) II complexes are quenched and the LHCs are the site of quenching, which occurs at a rate of ∼150 ps−1and is not induced by LHCII aggregation. The effective light-harvesting capacity of PSII decreases upon NPQ, and the NPQ rate is independent of the redox state of the reaction center. Finally, we could measure the pH dependence of NPQ, showing that the luminal pH is always above 5.5 in vivo and highlighting the role of LHCSR3 as an ultrasensitive pH sensor.

Photosynthetic organisms use nonphotochemical quenching (NPQ) mechanisms to dissipate excess absorbed light energy and protect themselves from photooxidation. In the model green alga Chlamydomonas reinhardtii, the capacity for rapidly reversible NPQ (qE) is induced by high light, blue light, and UV light via increased expression of LHCSR and PSBS genes that are necessary for qE. Here, we used a forward genetics approach to identify SPA1 and CUL4, components of a putative green algal E3 ubiquitin ligase complex, as critical factors in a signaling pathway that controls light-regulated expression of the LHCSR and PSBS genes in C. reinhardtii. The spa1 and cul4 mutants accumulate increased levels of LHCSR1 and PSBS proteins in high light, and unlike the wild type, they express LHCSR1 and exhibit qE capacity even when grown in low light. The spa1-1 mutation resulted in constitutively high expression of LHCSR and PSBS RNAs in both low light and high light. The qE and gene expression phenotypes of spa1-1 are blocked by mutation of CrCO, a B-box Zn-finger transcription factor that is a homolog of CONSTANS, which controls flowering time in plants. CONSTANS-like cis-regulatory sequences were identified proximal to the qE genes, consistent with CrCO acting as a direct activator of qE gene expression. We conclude that SPA1 and CUL4 are components of a conserved E3 ubiquitin ligase that acts upstream of CrCO, whose regulatory function is wired differently in C. reinhardtii to control qE capacity via cis-regulatory CrCO-binding sites at key photoprotection genes.

This review on the evolution of quenching mechanisms for excess energy dissipation focuses on the role of Light-Harvesting Complex Stress-Related (LHCSR) proteins versus Photosystem II Subunit S (PSBS) protein, and the reasons for the redundancy of LHCSR in vascular plants as PSBS became established.

Photosynthetic organisms require rapid and reversible down-regulation of light harvesting to avoid photodamage. Response to unpredictable light fluctuations is achieved by inducing energy-dependent quenching, qE, which is the major component of the process known as non-photochemical quenching (NPQ) of chlorophyll fluorescence. qE is controlled by the operation of the xanthophyll cycle and accumulation of specific types of proteins, upon thylakoid lumen acidification. The protein cofactors so far identified to modulate qE in photosynthetic eukaryotes are the photosystem II subunit S (PsbS) and light-harvesting complex stress-related (LHCSR/LHCX) proteins. A transition from LHCSR- to PsbS-dependent qE took place during the evolution of the Viridiplantae (also known as ‘green lineage’ organisms), such as green algae, mosses and vascular plants. Multiple studies showed that LHCSR and PsbS proteins have distinct functions in the mechanism of qE. LHCX(-like) proteins are closely related to LHCSR proteins and found in ‘red lineage’ organisms that contain secondary red plastids, such as diatoms. Although LHCX proteins appear to control qE in diatoms, their role in the mechanism remains poorly understood. Here, we present the current knowledge on the functions and evolution of these crucial proteins, which evolved in photosynthetic eukaryotes to optimise light harvesting.

Photosynthetic organisms prevent oxidative stress from light energy absorbed in excess through several photoprotective mechanisms. A major component is thermal dissipation of chlorophyll singlet excited states and is called nonphotochemical quenching (NPQ). NPQ is catalyzed in green algae by protein subunits called LHCSRs (Light Harvesting Complex Stress Related), homologous to the Light Harvesting Complexes (LHC), constituting the antenna system of both photosystem I (PSI) and PSII. We investigated the role of LHCSR1 and LHCSR3 in NPQ activation to verify whether these proteins are involved in thermal dissipation of PSI excitation energy, in addition to their well-known effect on PSII. To this aim, we measured the fluorescence emitted at 77 K by whole cells in a quenched or unquenched state, using green fluorescence protein as the internal standard. We show that NPQ activation by high light treatment inChlamydomonas reinhardtiileads to energy quenching in both PSI and PSII antenna systems. By analyzing quenching properties of mutants affected on the expression of LHCSR1 or LHCSR3 gene products and/or state 1–state 2 transitions or zeaxanthin accumulation, namely,npq4,stt7,stt7 npq4,npq4 lhcsr1,lhcsr3-complementednpq4 lhcsr1andnpq1, we showed that PSI undergoes NPQ through quenching of the associated LHCII antenna. This quenching event is fast-reversible on switching the light off, is mainly related to LHCSR3 activity, and is dependent on thylakoid luminal pH. Moreover, PSI quenching could also be observed in the absence of zeaxanthin or STT7 kinase activity.

The emergence of chlorophyll-containing light-harvesting complexes (LHCs) was a crucial milestone in the evolution of photosynthetic eukaryotic organisms. Light-harvesting chlorophyll-binding proteins form complexes in proximity to the reaction centres of photosystems I and II and serve as an antenna, funnelling the harvested light energy towards the reaction centres, facilitating photochemical quenching, thereby optimizing photosynthesis. It is now generally accepted that the LHC proteins evolved from LHC-like proteins, a diverse family of proteins containing up to four transmembrane helices. Interestingly, LHC-like proteins do not participate in light harvesting to elevate photosynthesis activity under low light. Instead, they protect the photosystems by dissipating excess energy and taking part in non-photochemical quenching processes. Although there is evidence that LHC-like proteins are crucial factors of photoprotection, the roles of only a few of them, mainly the stress-related psbS and lhcSR, are well described. Here, we summarize the knowledge gained regarding the evolution and function of the various LHC-like proteins, with emphasis on those strongly related to photoprotection. We further suggest LHC-like proteins as candidates for improving photosynthesis in significant food crops and discuss future directions in their research.

Photosystem I (PSI) is one of the two photosystems present in oxygenic photosynthetic organisms and functions to harvest and convert light energy into chemical energy in photosynthesis. In eukaryotic algae and higher plants, PSI consists of a core surrounded by variable species and numbers of light-harvesting complex (LHC)I proteins, forming a PSI-LHCI supercomplex. Here, we report cryo-EM structures of PSI-LHCR from the red alga Cyanidioschyzon merolae in two forms, one with three Lhcr subunits attached to the side, similar to that of higher plants, and the other with two additional Lhcr subunits attached to the opposite side, indicating an ancient form of PSI-LHCI. Furthermore, the red algal PSI core showed features of both cyanobacterial and higher plant PSI, suggesting an intermediate type during evolution from prokaryotes to eukaryotes. The structure of PsaO, existing in eukaryotic organisms, was identified in the PSI core and binds three chlorophylls a and may be important in harvesting energy and in mediating energy transfer from LHCII to the PSI core under state-2 conditions. Individual attaching sites of LHCRs with the core subunits were identified, and each Lhcr was found to contain 11 to 13 chlorophylls a and 5 zeaxanthins, which are apparently different from those of LHCs in plant PSI-LHCI. Together, our results reveal unique energy transfer pathways different from those of higher plant PSI-LHCI, its adaptation to the changing environment, and the possible changes of PSI-LHCI during evolution from prokaryotes to eukaryotes.

La sfingosina-1 fosfato (S1P) è un lisosfingolipide presente nel liquido follicolare ovarico insieme alle gonadotropine glicoproteiche. L'ormone luteinizzante (LH) e l'ormone follicolo-stimolante (FSH) sono necessari per garantire la steroidogenesi, la gametogenesi e la riproduzione. La gonadotropina corionica umana (hCG) agisce durante la gravidanza sullo stesso recettore di LH, LHCGR, per stimolare la produzione di progesterone da parte del corpo luteo e mantenere la gravidanza. Inoltre, le gonadotropine sono fattori di crescita e differenziazione, che modulano la proliferazione cellulare, la sopravvivenza e l'apoptosi. Sia S1P che le gonadotropine esercitano le loro funzioni fisiologiche legandosi a recettori accoppiati a proteine G (GPCR). S1P si lega e attiva cinque recettori specifici, S1P1-5, modulando diverse vie di segnalazione. S1P1 e S1P3 sono altamente espressi nelle cellule primarie della granulosa luteina umana (hGLC). Questo studio mira a caratterizzare il ruolo della segnalazione intracellulare indotto da S1P e gonadotropine nel determinare lo sviluppo del follicolo ovarico in vitro. A questo scopo sono state utilizzate granulose umane e linee cellulari che esprimono stabilmente FSHR e LHCGR sotto il controllo di un promotore inducibile. Sono state valutate l’eterodimerizzazione di S1PR1 con LHCGR/FSHR e GPER e la cinetica delle proteine G e il reclutamento della β-arrestina 2 con LHCGR mediate da LH e hCG, così come l'attivazione di secondi messaggeri e l’internalizzazione di LHCGR in vitro. hGLC e hGL5 sono state trattate con dose fissa (0,1 μM) di S1P e con specifici agonisti di S1P1 e S1P3, SEW2871 e CYM5541. Nelle cellule della granulosa, S1P e, in maniera minore, SEW2871 e CYM5541, hanno indotto pCREB. Non è stata rilevata alcuna produzione di cAMP e l'attivazione di pCREB è avvenuta anche in presenza dell'inibitore della PKA H-89. Inoltre, pCREB S1P-dipendente è stata attenuata dall'inibitore di MEK U0126 e da un bloccante dei canali Ca2+ di tipo L, il verapamil. La completa inibizione di pCREB si è verificata bloccando S1P2 o S1P3 con specifici antagonisti. pCREB S1P-dipendente ha indotto l’espressione di FOXO1 ed EREG, confermando il ruolo esclusivo delle gonadotropine e delle interleuchine in questo processo, ma non ha influenzato la steroidogenesi. hCG induce l'accoppiamento Gαs-, Gq e β-arrestin 2 con LHCGR in modo più efficace rispetto a LH. In presenza di Dynasore, un inibitore dell'internalizzazione, hCG mantiene una cinetica simile, ma non LH, che necessita dell'endocitosi di LHCGR per indurre l'accoppiamento del recettore. Questi dati riflettono la cinetica ormone-specifica dell'attivazione dell'effettore a valle correlata alle proteine G e alla β -arrestina 2. LH ha indotto un rapido aumento di cAMP ed è più potente di hCG nell'attivazione di pERK1/2. È interessante notare che la cinetica dell'aumento di Ca2+ intracellulare indotto da hCG dipende dall'internalizzazione di LHCGR rispetto a LH che non riesce a indurre un aumento di Ca2+ intracellulare. È stata valutata l'interazione tra LHCGR e specifici marcatori degli endosomi per studiare l'internalizzazione di LHCGR mediata dalle gonadotropine. LH è più potente di hCG nel promuovere il riciclaggio di LHCGR. Questo studio ha dimostrato che S1P può indurre un'attivazione di pCREB indipendente da cAMP nelle cellule della granulosa, sebbene ciò non sia sufficiente per indurre la sintesi del progesterone. L'espressione genica di FOXO1 ed EREG indotta da S1P suggerisce che l'attivazione dell'asse S1P-S1PR può cooperare con le gonadotropine nel modulare lo sviluppo del follicolo. L'internalizzazione di LHCGR è fondamentale per modulare i segnali specifici di LH e hCG che influenzano le proteine G e l'accoppiamento β -arrestina 2 e le cascate di segnalazione a valle.
Sphingosine-1 phosphate (S1P) is a lysosphingolipid present in the ovarian follicular fluid together with glycoprotein hormone gonadotropins. Luteinizing hormone (LH) and follicle-stimulating hormone (FSH) are necessary to ensure steroidogenesis, gametogenesis and reproduction. Human chorionic gonadotropin (hCG) acts during pregnancy via the same receptor for LH, the LHCGR, to stimulate progesterone production by the corpus luteum and maintaining pregnancy. In addition, gonadotropins are growth and differentiation factors, modulating cell proliferation, survival and apoptosis. Both S1P and gonadotropins exert their physiological functions by binding cognate G protein-coupled receptors (GPCRs). At nanomolar concentrations, S1P binds and activates five specific receptors, known as S1P1-5, modulating different signaling pathways. S1P1 and S1P3 are highly expressed in human primary granulosa lutein cells (hGLC). This study aims to characterize the role of S1P- and gonadotropins-induced signaling in determining ovarian follicle development in vitro. To this purpose were used human granulosa, cell lines stably expressing FSHR and LHCGR under the control of an inducible promoter, treated with gonadotropins and S1P. S1PR1 heterodimerization to LHCGR/FSHR and GPER and the kinetics of LH- and hCG-mediated G proteins and β-arrestin 2 coupling to LHCGR were evaluated, such as the activation of related second messengers and kinases, and the role of gonadotropins-induced LHCGR internalization in vitro. hGLC and hGL5 cells were treated with a fixed dose (0.1 μM) of S1P, or by S1P1- and S1P3-specific agonists SEW2871 and CYM5541. In granulosa cells, S1P and, at a lesser extent, SEW2871 and CYM5541, potently induced pCREB. No cAMP production was detected and pCREB activation occurred even in the presence of the PKA inhibitor H-89. Moreover, S1P-dependent pCREB was dampened by MEK inhibitor U0126 and by the L-type Ca2+ channel blocker verapamil. The complete inhibition of pCREB occurred by blocking either S1P2 or S1P3 with the specific receptor antagonists, or under PLC/PI3K depletion. S1P-dependent pCREB induced FOXO1 and EREG, confirming the exclusive role of gonadotropins and interleukins in this process, but did not affect steroidogenesis. The kinetics of LH and hCG-mediated G proteins and β-arrestin 2 coupling to their receptor, and the activation of related second messengers and kinases were evaluated by BRET. hCG induces Gαs-, Gq and β-arrestin 2 coupling to LHCGR more effectively than LH. Under receptor internalization blockade by Dynasore, hCG maintains similar kinetics, but not LH, which needs LHCGR endocytosis for inducing receptor coupling. These data reflect hormone-specific kinetics of downstream effector activation related to G proteins and β-arrestin 2. LH induced a rapid cAMP increase and is more potent than hCG in activating pERK1/2. Interestingly, the kinetic of hCG-induced intracellular Ca2+ increase depends on LHCGR internalization than LH that fails in inducing intracellular Ca2+ increase, consistently with weak Gq recruitment. The interaction between LHCGR and specific markers of endosomes were evaluated to estimate LHCGR internalization mediated by gonadotropins. Indeed, LH is more potent than hCG in promoting LHCGR recycling. This study demonstrated that S1P may induce a cAMP-independent activation of pCREB in granulosa cells, although this is not sufficient to induce progesterone synthesis. S1P-induced FOXO1 and EREG gene expression suggests that the activation of S1P-S1PR axis may cooperate with gonadotropins in modulating follicle development. LHCGR internalization is fundamental for modulating LH- and hCG-specific signals impacting G proteins and β-arrestin 2 coupling, and the downstream signaling cascades.

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Steroids and gonadotrophins are essential for the regulation of antral follicular development and the late stages of preantral development. Although the luteinizing hormone receptor (LHR) has been detected in the preantral follicles of rats, rabbits, and pigs, the expression of this receptor in bovine fetal ovary has not been demonstrated. The present study aimed to quantify the expression of the LHR and the mRNA abundance of the genes LHR binding protein (LRBP), STAR, HSD3B1, CYP17A1, and CYP19A1 during the development of bovine fetal ovary. In addition, we aimed to identify and quantify the expression of bta-miR-222 (a regulatory microRNA of the LHCGR gene). In summary, LHR expression was observed in the preantral follicle in bovine fetal ovary, from oogonias to primordial, primary and secondary stages, and the mRNA abundance was lower on day 150 than day 60. However, the mRNA abundance of LRBP followed the opposite pattern. The LHR protein was detected in oogonia, primordial, primary, and secondary follicles. Moreover, both oocytes and granulosa cells showed positive immunostaining for LHR. Similar to LRBP, the abundance of bta-miR-222 was higher on day 150 than day 60 or 90 of gestation. With regard to the gene expression of steroidogenic enzymes; only the mRNA abundance of STAR was higher on day 150 than on day 60. In conclusion, these results suggested the involvement of LHCGR/LRBP regulation with mechanisms related to the development of preantral follicles, especially during the establishment of secondary follicles. Furthermore, the present data reinforced that the reduced expression of LHR mRNA in bovine fetal ovaries on day 150 was related to the higher expression of LRBP and bta-miR-222.
Esteroides e gonadotrofinas são essenciais para a regulação do desenvolvimento folicular antral e os estágios finais do desenvolvimento pré-antral. Embora o receptor do hormônio luteinizante (LHR) tenha sido detectado nos folículos pré-antrais de ratos, coelhos e porcos, a expressão deste receptor no ovário fetal bovino não foi demonstrada. O presente estudo teve como objetivo quantificar a expressão do LHR e a abundância de mRNA da proteína de ligação LHR (LRBP), STAR, HSD3B1, CYP17A1 e CYP19A1 durante o desenvolvimento do ovário fetal bovino. Além disso, objetivamos identificar e quantificar a expressão de bta-miR-222 (microRNA regulador do gene LHCGR). Em resumo, a expressão de LHR foi observada no folículo pré-antral no ovário fetal de bovino e a abundância de mRNA foi menor no dia 150 do que no dia 60. No entanto, a abundância de mRNA da LRBP seguiu o padrão oposto. Semelhante a LRBP, a abundância de bta-miR-222 foi maior no dia 150 do que no dia 60 ou 90. Com relação à expressão gênica de enzimas esteroidogênicas; apenas a abundância de mRNA de STAR foi maior no dia 150 do que no dia 60. A proteína LHR foi detectada em oogônia, folículos primordiais, primários e secundários. Além disso, ambos os oócitos e células da granulosa apresentaram imunolocalização positiva para LHR. Em conclusão, estes resultados sugeriram o envolvimento da regulação do LHCGR / LBPB com mecanismos relacionados ao desenvolvimento de folículos pré-antrais, especialmente durante o estabelecimento de folículos secundários. Além disso, os presentes dados reforçaram que a expressão reduzida de mRNA de LHR em ovários fetais bovinos no dia 150 estava relacionada à maior expressão de LRBP e bta-miR-222.

Classicamente, la segnalazione dipendente dall’attivazione del cAMP mediata dal recettore dell'ormone follicolo-stimolante (FSHR) e dal recettore dell'ormone luteinizzante (LH) (LHCGR) favorisce la crescita del follicolo ovarico umano e la maturazione degli ovociti. Tuttavia, esistono dati in vitro contraddittori che suggeriscono un diverso significato fisiologico della segnalazione di cAMP mediata da FSHR, mostrando allo stesso tempo l'attivazione di eventi steroidogenici e pro-apoptotici. Questi segnali possono essere alterati dagli estrogeni che inducono eventi anti-apoptotici attraverso i loro recettori nucleari e all'azione non genomica di un recettore degli estrogeni accoppiato a proteine G (GPER). Lo scopo del progetto è chiarire il ruolo degli estrogeni/gonadotropine e dei loro recettori di membrana nella regolazione della fisiologia ovarica e nella selezione del follicolo dominante. In questo studio è stato dimostrato che GPER forma dimeri sia con FSHR che con LHCGR sulla superficie cellulare di cellule HEK293 che sovraesprimono i due recettori e di cellule primarie della granulosa luteina umana (hGLC). Gli eteromeri FSHR/GPER riprogrammano i segnali del cAMP e di morte, in stimoli proliferativi fondamentali per sostenere la sopravvivenza degli ovociti. Nelle cellule della granulosa umana, i segnali di sopravvivenza mancano quando è presente un rapporto FSHR:GPER elevato, che influisce negativamente sulla maturazione del follicolo e si correla con l'accoppiamento preferenziale alla proteina Gαs, l’attivazione della via cAMP/PKA e la capacità di risposta ad FSH dei pazienti sottoposti a stimolazione ovarica controllata. Gli eteromeri FSHR/GPER, invece, mediano segnali anti-apoptotici e proliferativi dipendenti da FSH tramite il dimero Gβγ e la compromissione della formazione degli eteromeri o il knockdown GPER aumenta la morte cellulare e la steroidogenesi FSH-dipendenti. Al contrario, il complesso GPER/LHCGR non influenza la produzione di cAMP indotta da LH e hCG e non compromette l'attivazione della via cAMP/PKA. Ciò si evince dalla simile fosforilazione di CREB ed ERK1/2 e dalla stessa produzione di progesterone in hGLC trattate con siRNA contro GPER e quelle trattato con mock. È interessante notare che GPER riduce l’accoppiamento LHCGR/Gαq e di conseguenza impedisce il rilascio intracellulare di Ca2+ e l'accumulo di IP1, dopo stimolazione con LH e hCG, in cellule HEK293 che co-esprimono LHCGR e GPER rispetto alle cellule che esprimono solo LHCGR. Inoltre, è stato dimostrato che in presenza di GPER la cinetica dell'internalizzazione di FSHR attraverso endosomi precoci e tardivi è ridotta, suggerendo la sua capacità di bloccare FSHR a livello intracellulare e riducendo il riciclaggio di FSHR sulla membrana. Infatti, l'internalizzazione di FSHR è necessaria affinché GPER inibisca la risposta del cAMP indotta da FSH. Secondo i nostri risultati, gli estrogeni sono selettivamente coinvolti nella regolazione dei segnali pro e anti-apoptotici, nell'internalizzazione dei recettori attraverso i complessi FSHR/GPER e nella modulazione della cascata di segnali mediata da LHCGR. I nostri risultati indicano come la maturazione degli ovociti dipenda dalla capacità del GPER di modulare i segnali selettivi di FSHR e LHCGR, indicando che gli eteromeri dei recettori delle gonadotropine possono essere un marker della proliferazione cellulare.
Classically, follicle-stimulating hormone receptor (FSHR) and luteinizing hormone (LH) receptor (LHCGR) -driven cAMP-mediated signaling boosts human ovarian follicle growth and oocyte maturation. However, contradicting in vitro data suggest a different view on physiological significance of FSHR-mediated cAMP signalling, showing at the same time the activation of steroidogenic and pro-apoptotic events. These signals can be impaired by estrogens inducing anti-apoptotic events via nuclear receptors and non-genomic action of a G protein-coupled estrogen receptor (GPER). The aim of the project is to better understand the role of estrogens/gonadotropins and their membrane receptors in regulating ovarian physiology and the selection of the dominant follicle. In this study it was demonstrated that GPER heteromerizes both with FSHR and LHCGR at the cell surface of HEK293 cells overexpressing the two receptors as well as human primary granulosa lutein cells (hGLC). FSHR/GPER heteromers reprogram cAMP/death signals into proliferative stimuli fundamental for sustaining oocyte survival. In human granulosa cells, survival signals are missing at high FSHR:GPER ratio, which negatively impacts follicle maturation and strongly correlates with preferential Gαs protein/cAMP-pathway coupling and FSH responsiveness of patients undergoing controlled ovarian stimulation. In contrast, FSHR/GPER heteromers triggered anti-apoptotic/proliferative FSH signaling delivered via the Gβγ dimer, whereas impairment of heteromer formation or GPER knockdown enhanced the FSH-dependent cell death and steroidogenesis. On the other hand, GPER/LHCGR complex does not affect the LH and hCG-induced cAMP production and do not compromise the activation of the cAMP/PKA pathway, as it is indicated by similar CREB and ERK1/2 phosphorylation and same progesterone production in hGLC treated with siRNA against GPER, and the mock-treated one. Interestingly, GPER displace the LHCGR/Gαq coupling and consequently impedes the intracellular Ca2+ release and IP1 accumulation in LHCGR-GPER co-expressing HEK293 cells upon LH and hCG treatment compared to LHCGR-expressing cells. Also, it was demonstrated that in presence of GPER the kinetic of FSHR internalization through early and late endosomes is reduced, suggesting its ability to blockade FSHR at the intracellular level and reduce FSHR recycling on cell membrane. Indeed, FSHR internalization is necessary for GPER to inhibit FSH-induced cAMP response. According to our results, estrogens are selectively involved in the regulation of pro- and anti-apoptotic signals and receptor internalization through FSHR/GPER complexes and in modulation of LHCGR-mediated signaling cascade. Our findings indicate how oocyte maturation depends on the capability of GPER to shape FSHR and LHCGR selective signals, indicating hormone receptor heteromers may be a marker of cell proliferation.

Orientador: Anthony César de Souza Castilho
Resumo: A superestimulação ovariana é uma biotecnologia amplamente empregada na espécie bovina para a obtenção de múltiplas ovulações. Com este objetivo diversos protocolos superestimulatórios surgiram, dentre eles o protocolo P-36 e sua variação, o protocolo P-36/eCG. Ambos os tratamentos utilizam o hormônio folículo estimulante (FSH) na indução do crescimento folicular. Como é acreditado que no último dia do tratamento, as células da granulosa folicular possuam receptores do hormônio luteinizante (LH; LHR), duas últimas doses de FSH foram substituídas pela administração de gonadotrifina coriónica equina (eCG; P-36/eCG). A molécula de eCG possui atividade tanto LH quanto FSH por se ligar a ambos receptores, aumentando a resposta ovulatória. Os dois tratamentos têm demonstrado eficácia quanto ao desenvolvimento de oócitos competentes para a produção embrionária, no entanto pouco se sabe sobre seus efeitos na diferenciação celular no folículo ovariano. Por isso, o presente estudo investigou os efeitos da superestimulação ovariana com FSH (P-36) ou FSH combinado com eCG (P-36/eCG) sobre aspectos bioquímicos e a produção de hormônios esteroides. Adicionalmente, quantificou-se a abundância de miRNAs reguladores da expressão do mRNA do LHR e outros miRNAs relacionados com o desenvolvimento folicular ovariano. Os resultados obtidos mostram que os tratamentos superestimulatórios alteram o perfil bioquímico intrafolicular e a concentração de estradiol no plasma. Aliado a isso, também alteram... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: Ovarian overstimulation is a biotechnology widely used in the bovine species to obtain multiple ovulations. With this objective, several protocols were introduced, including the P-36 protocol and its variation, the P-36/eCG protocol. Both treatments use follicle stimulating hormone (FSH) to induce the follicular growth. As it is believed that on the last day of treatment, follicular granulosa cells have luteinizing hormone (LHR) receptors, two last doses of FSH have been replaced by administration of equine chorionic gonadotrifine (eCG; P-36/eCG). The eCG molecule has LH and FSH activity by binding to both receptors, increasing the ovulatory response. Both treatments has demonstrated efficacy in the development of oocytes competent for embryo production, however little is known about their effects on cell differentiation in the ovarian follicle. Therefore, the present study investigated the effects of ovarian superstimulation using FSH (P-36) or FSH combined with eCG (P-36/eCG) on biochemical aspects and production of steroid hormones. In addition, the abundance of miRNAs regulating the expression of LHR mRNA and other miRNAs related to ovarian follicular development. Results demonstrated that superstimulatory treatments alter the intrafollicular biochemical profile and the plasma estradiol concentration. In addition, they also alter the expression of LHR and miRNAs regulating LHR mRNA expression, possibly modulating ovulatory capacity in superstimulated ovarian follicles.
Mestre

Polycystic ovary syndrome (PCOS) is the leading cause of anovulatory infertility and the most common endocrinopathy of women of reproductive age. Genome-wide association studies (GWAS) identified a number of loci associated PCOS in different ethnic populations, including women with Asian and European ancestry. Replication studies have confirmed some of these associations. Among the loci identified are those located near the LH receptor gene (LHCGR), a clathrin-binding protein gene (DENND1A) that also functions as a guanine nucleotide exchange factor, and the gene encoding RAB5B, a GTPase and protein involved in vesicular trafficking. The functional significance of one of these GWAS candidates (DENND1A) was supported by our discovery that a truncated protein splice variant of DENND1A termed DENND1A.V2, is elevated in PCOS theca cells, and that forced expression of DENND1A.V2 in normal theca cells increased CYP11A1 and CYP17A1 expression and androgen synthesis, a hallmark of PCOS. We previously proposed that the PCOS GWAS loci could be assembled into a functional network that contributes to altered gene expression in ovarian theca cells, resulting in increased androgen synthesis. Here we demonstrate the localization of LHCGR, DENND1AV.2 and RAB5B proteins in various cellular compartments in normal and PCOS theca cells. hCG and forskolin stimulation affects the distribution and co-localization of DENND1A.V2 and RAB5B in various cellular compartments This cytological evidence supports our PCOS gene network concept, and raises the intriguing possibility that LHCGR activation, via a cAMP-mediated process, promotes the translocation of DENND1A.V2 and RAB5B-containing vesicles from the PCOS theca cell cytoplasm into the nucleus, resulting in increased transcription of genes involved in androgen synthesis.

BPS/IC (Bladder Pain Syndrome/Interstitial Cystitis) ist ein sehr schweres und noch weitgehend unverstandenes Krankheitsbild in der Urologie. Viele Frauen sind im Alltag durch den ständigen Harndrang und die Schmerzen stark eingeschränkt und von Depressionen betroffen. Die Aufklärung der Pathogenese ist deshalb sehr wichtig, um eine adäquate Therapie für die Betroffenen zu entwickeln und die Krankheit möglichst frühzeitig diagnostizieren zu können. Das Schwangerschaftshormon hCG (humanes Choriongonadotropin) besitzt differenzierende und wachstumsfördernde Eigenschaften und eine Rolle in der Urothelregeneration und – stabilisierung scheint möglich. Daher ist das Ziel dieser Arbeit seinen Rezeptor, den LHCGR (Luteinizing-Hormone/Choriogonadotropin Rezeptor), in der Harnblase nachzuweisen und die urothelialen und muskulären Charakteristika zwischen gesunden und an BPS/IC erkrankten Harnblasen zu vergleichen. Die Darstellung des LHCGR erfolgte auf Proteinebene mittels indirekter Immunfluoreszenz und auf mRNA-Ebene durch Standard-PCR. Es zeigten sich im Urothel von Harnblase und Ureter 5 unterschiedliche Verteilungsmuster des Rezeptors hinsichtlich seiner Expression in verschiedenen Zellschichten und seiner subzellulären Lokalisation. Je nach Urothelzustand und zwischen den Entitäten Kontroll- bzw. BPS/IC-Harnblase variierten diese Muster in ihrer Häufigkeit. In anderen Epithelien, wie dem Vaginalepithel, änderte sich die zelluläre Verteilung des LHCGR in Abhängigkeit vom Differenzierungsgrad der Zellen. Es scheint möglich, dass auch die Rezeptorexpression in Urothelzellen deren verschiedene Differenzierungszustände widerspiegelt. Dies unterstützt den für hCG vermuteten Einfluss auf die Epithelregeneration. Ein Vergleich der urothelialen Fluoreszenzintensitäten zwischen weiblichen Kontroll – und BPS/IC-Harnblasen zeigte eine signifikant stärkere Expression des Rezeptors bei erkrankten Patienten. Dem gegenüber war kein Unterschied im Detrusor, weder zwischen Kontroll – und BPS/IC-Harnblasen noch im geschlechtsspezifischen Vergleich, festzustellen. Damit scheint der Rezeptor seine Hauptaufgabe vorrangig im Urothel zu entfalten. Die Korrelationsanalysen ergaben keinen signifikanten Zusammenhang zwischen dem Erkrankungsalter (Zeitpunkt der Diagnosestellung und Biopsieentnahme) und der LHCGR-Immunfluoreszenz. Ein endokrinologischer Einfluss auf die Rezeptorexpression wurde dadurch unwahrscheinlich und unterstützt die immer akzeptiertere Auffassung, dass BPS/IC nicht mehr mit der Menopause assoziiert ist. Neben dem Urothel und Detrusor zeigten auch Lamina propria und Gefäße von Harnblase und Ureter die Expression des LHCGR in der Immunhistochemie. Unterschiedliche Clustermuster des Rezeptors im Detrusor ließen auf die Oligomerisierung des Rezeptors schließen. Die Bedeutung dieser Zusammenschlüsse ist jedoch noch unklar, wobei unterschiedliche funktionelle Zustände des Rezeptors vermutet werden. Orientierung bieten andere Rezeptoren, die durch Dimerisierung verschiedener Rezeptorvarianten ihre Funktionalität verbessern oder verschlechtern konnten. Obwohl für keine bisher entdeckte Variante des LHCGR eine definitive Aufgabe ermittelt werden konnte, scheinen doch viele Varianten auch unterschiedliche Funktionen wahrnehmen zu können. Besonders auf der Regulierbarkeit des Rezeptors mittels interagierender Splicevarianten sollte das Augenmerk zukünftiger Studien liegen. Ob durch Komplexbildung verschiedener Varianten oder Bildung nichtfunktioneller trunkierter Rezeptoren, die Kontrollmöglichkeiten sind vielfältig und können auch auf Liganden wirken. Letztlich ließ der Nachweis des LHCGR in allen Schichten von Harnblase und Ureter eher eine globale Rolle des Rezeptors im Harntrakt des Menschen vermuten. Dazu passten auch die bereits nachgewiesenen Einflüsse seiner Liganden auf die Blasenfunktion von Hunden. Die hier vorgelegte Arbeit untersuchte zum ersten Mal die Expression des LHCGR mittels PCR und Immunhistochemie in humanen Harnblasen und Ureteren. Dabei löste sie sich von den sonst üblichen Vorstellungen einer Beziehung des Rezeptors zu Blasentumoren, Schwangerschaft oder Inkontinenz. Diagnose und Therapie von BPS/IC sind zur Zeit noch ständigen Wandlungen unterworfen und dabei entgehen viele Patienten der (frühen) Diagnosestellung und einer adäquaten Behandlung. Diese Studie sollte dazu beitragen neue Einblicke in die Pathophysiologie der Erkrankung zu erlangen, um eine kausale Therapie entwickeln zu können. Zukünftig könnten diese Ergebnisse dabei helfen die Anwendung einer sensitiven und vor allem spezifischen Diagnostik auf molekularer Ebene (mRNA - oder Proteinnachweis) zu ermöglichen.

Introdução: Os receptores do peptídeo insulinotrópico dependente de glicose (GIPR) e do hormônio luteinizante (LHCGR) são receptores acoplados à proteína G com amplo padrão de expressão tecidual. A expressão anômala destes receptores tem sido descrita em casos de hiperplasia adrenal macronodular independente de ACTH (AIMAH) e em alguns adenomas, resultando em aumento da secreção hormonal (cortisol, andrógenos e aldosterona) pelo cortex adrenal. O papel destes receptores em outras formas de hiperplasia, como a doença adrenocortical nodular pigmentosa primária (PPNAD), aumento da adrenal associado à neoplasia endócrina múltipla tipo 1 (MEN1), e em carcinoma do córtex adrenal tem sido pouco investigado; sendo assim, considera-se relevante estudar a expressão destes receptores nos pacientes com tumores adrenocorticais esporádicos, nos pacientes com AIMAH, PPNAD e aumento adrenal associado à MEN1. Objetivos: 1) Caracterização molecular dos casos de neoplasia endócrina múltipla tipo 1 e PPNAD: pesquisa de mutações dos genes MEN1 e PRKAR1A e análise da perda de heterozigose (LOH) destes genes no tecido adrenal destes pacientes. 2) Quantificar a expressão do GIPR e do LHCGR em tecido adrenocortical normal, tumoral, hiperplásico e correlacionar a expressão destes com a classificação histológica dos tumores adrenocorticais. Pacientes: 55 pacientes (30 adultos) com tumores adrenocorticais (37 adenomas e 18 carcinomas); 7 pacientes com AIMAH, 4 com MEN1, 1 com PPNAD e tecidos controles (adrenal; testículo e pâncreas). Métodos: extração de DNA genômico, RNA e síntese de DNA complementar (cDNA); amplificação por PCR das regiões codificadoras dos genes MEN1 e PRKAR1A seguida por seqüenciamento automático. Pesquisa de LOH pela amplificação de microssatélites por PCR e análise pelo programa GeneScan. Quantificação da expressão do GIPR e do LHCGR por PCR em tempo real pelo método TaqMan e estudo de imunohistoquímica para GIPR nos tumores adrenocorticais. Resultados: identificação de 3 mutações (893+ 1G>A, W183X e A68fsX118) e dois polimorfirmos (S145S e D418D) no gene MEN1 e uma mutação (Y21X) no PRKAR1A. Ausência de LOH nos tecidos adrenais estudados. A expressão do GIPR e do LHCGR foi identificada em tecidos adrenais normais, tumorais e hiperplásicos. O nível de expressão do GIPR foi mais elevado nos tumores adrenocorticais malignos que nos benignos tanto no grupo pediátrico (mediana= 18,1 e 4,6, respectivamente; p <0,05), quanto no grupo adulto (mediana = 4,8 e 1,3 respectivamente; p <0,001). O nível de expressão do LHCGR, no grupo pediátrico, foi elevado tanto nos tumores benignos quanto nos malignos (mediana= 6,4 e 4,3, respectivamente). No grupo adulto os níveis de expressão deste receptor foram extremamente baixos nos tumores malignos em relação aos benignos (mediana= 0,06 e 2,3, respectivamente; p <0,001). A imunohistoquímica para o GIPR foi variável e não correlacionada à expressão do gene GIPR. Não houve diferença nos níveis de expressão do GIPR e do LHCGR nas hiperplasias do córtex adrenal. Conclusões: a presença de LOH e mutação em heterozigose composta do gene MEN1 e do PRKAR1A foram afastadas como mecanismos responsáveis pelo aumento adrenal tanto nos pacientes com MEN1 como no paciente com PPNAD. A hiperexpressão de GIPR está associada a malignidade nos tumores adrenocorticais nos grupos adulto e pediátrico e a baixa expressão de LHCGR está associada a malignidade nos tumores adrenocorticais somente no grupo adulto.
Introduction: The glucose- dependent insulinotropic peptide receptor (GIPR) and luteinizing hormone receptor (LHCGR) are G-protein coupled receptors with a wide tissue expression pattern. The aberrant expression of these receptors has been described in cases of ACTH-independent macronodular adrenal hyperplasia (AIMAH) and in some adenomas, resulting in the increase of adrenal cortex hormonal secretion (cortisol, androgens and aldosterone). The role of these receptors in other forms of adrenocortical hyperplasia, such as primary pigmented nodular adrenocortical disease (PPNAD), adrenal enlargement associated with multiple endocrine neoplasia type 1 (MEN1), and adrenocortical carcinoma has been scarcely investigated. Thus, the study of the expression of these receptors in patients with sporadical adrenocortical tumors, AIMAH, PPNAD and adrenal enlargement associated to MEN1 was considered important. Objectives: 1) Molecular study in patients with multiple endocrine neoplasia type 1 and PPNAD: mutation screening of MEN1 and PRKAR1A genes and analysis of the loss of heterozygosis (LOH) of these genes in the adrenal lesions of these patients. 2) To quantify the GIPR and LHCGR expression, in normal, tumor and hyperplasic tissue and to correlate the expression of these receptors with the adrenocortical tumor histology. Patients: 55 patients (30 adults) with adrenocortical tumors (37 adenomas and 18 carcinomas); 7 patients with AIMAH, 4 with MEN1, 1 with PPNAD and control tissue (adrenal, testis and pancreas). Methods: Extraction of genomic DNA, RNA and synthesis of complementary DNA (cDNA); PCR-amplification of the coding regions of MEN1 and PRKAR1A, followed by direct sequencing. LOH study using polymorphic marker amplification by PCR and GeneScan software analysis. Quantification of GIPR and LHCGR expression using realtime PCR -TaqMan method and GIPR immunohistochemistry study in adrenocortical tumors. Results: Identification of 3 mutations (893+ 1G>A, W183X and A68fsX118) and two polymorphic alterations (S145S and D418D) in MEN1 and a mutation (Y21X) in the PRKAR1A gene; LOH was not identified in adrenal tissue. The GIPR and LHCGR expression was identified in normal, tumor and hyperplasic adrenal tissues; the GIPR expression level was more elevated in malignant tumors compared to benign tumors in pediatric (median = 18.1 and 4.6, respectively; p <0.05) and adult patients (median = 4.8 and 1.3 respectively; p <0.001). The LHCGR expression in pediatric patients was elevated in benign as well as in malignant tumors (median = 6.4 and 4.3, respectively). In the adult group, the expression level of these receptors was extremely low in malignant tumors in relation to benign ones (median = 0.06 and 2.3, respectively; p <0.001). The GIPR immunohistochemistry was variable and did not correlate with GIPR gene expression. No difference between GIPR and LHCGR expression levels was observed in the different forms of hyperplasia. Conclusions: The presence of LOH and mutations in compound heterozygosis of MEN1 and PRKAR1A genes were ruled out as the mechanisms responsible for the adrenal enlargement in patients with multiple endocrine neoplasia type 1. GIPR overexpression is associated with malignant adrenocortical tumors in the adult and pediatric patients and low LHCGR expression is associated with malignant adrenocortical tumors only in the adult patients.

L’endométriose est une pathologie chronique, bénigne, caractérisée par la présence de tissu endométrial (glande et stroma) en dehors de l’utérus. La forte prévalence de cette maladie, sa symptomatologie invalidante et son coût annuel considérable en font un véritable enjeu de santé publique. Le traitement de l’endométriose comprend un volet chirurgical, potentiellement délabrant, et un volet médical, basé sur des produits anti-gonadotropes en première intention. L’endométriose est d’origine multifactorielle. Sa physiopathologie demeure mal connue. Alors que le reflux menstruel via les trompes semble être le primum movens, plusieurs étapes sont nécessaires à la formation des lésions d’endométriose : l’adhésion et l’implantation des cellules endométriales au mésothélium péritonéal, la prolifération cellulaire soutenue par un phénomène d’angiogenèse et enfin, la réaction inflammatoire. Ces étapes sont dépendantes de facteurs génétiques, immunologiques et environnementaux. L’inflammation joue un rôle clef dans la pathogénie de l’endométriose. Nous avons montré dans un premier temps, à l’aide d’une double approche de PCR quantitative et d’immunohistochimie, la surexpression du récepteur de la LH (LHCGR) dans les tissus endometriosiques ectopiques. A l’aide d’un modèle in vitro, nous avons démontré que la stimulation du LHCGR par l’hCG activait les MAPK (avec une augmentation du rapport pERK/ERK), exerçait une effet prolifératif et enfin, induisait la surexpression de nombreux gènes cibles : CYP19A1, NR5A1, INSL3, VEGFA et PTGS2. Ensuite, nous avons étudié les principaux acteurs de la voie des prostaglandines. Nous avons montré une nette perturbation de cette voie en faveur d’une augmentation de l’inflammation avec une surexpression de la PTGS2 ainsi que des récepteurs des prostaglandines PTGER2, 3 et 4 dans l’endomètre des patientes endométriosiques. Nous avons ensuite étudié la voie des sphingosines en analysant l’expression de ses acteurs clef (SPHK1-2, SGPP1-2, SGPL1, SPHAKAP, S1PR1-5). Nous avons mis en évidence pour la première fois l’existence d’une profonde dérégulation de l’expression des enzymes et des récepteurs de cette voie en faveur d’une diminution du catabolisme du Sphingosine-1phosphate. Cette perturbation est à l’origine de la réaction inflammatoire qui participe à l’entretien de la prolifération et de la croissance des cellules endométriosiques. Dans un deuxième temps, nous avons exploré le retentissement systémique de l’endométriose à l’aide du modèle d’une interleukine pro-inflammatoire et fibrosante, l’IL-33, et de deux interleukines anti-inflammatoires l’IL-19 et l’IL-22. L’IL-33 est significativement plus élevée dans le sérum des patientes endométriosiques en particulier en cas d’endométriose profonde. Nous avons également mis en évidence l’existence d’une corrélation significative avec le nombre et la sévérité des lésions profondes. En opposition, les interleukines anti-inflammatoires IL-19 et IL-22 sont significativement diminuées dans le sérum des patientes endométriosiques. En conclusion, nous avons montré l’existence d’une perturbation des voies inflammatoires : la voie de la PTGS2 et de celle des sphingosines ainsi que le rôle pro-inflammatoire du LCGHR. Nous avons également mis en évidence le déséquilibre de la balance des cytokines systémiques inflammatoires et anti-inflammatoires dans l’endométriose. Ainsi, ces médiateurs de l’inflammation pourraient être considérés comme de potentiels marqueurs évolutifs de l’endométriose. Leur utilisation pourrait permettre d’effectuer un diagnostic plus précoce, et d’envisager de nouvelles thérapeutiques ciblées
Pas de résumé en anglais