Academic literature on the topic 'DCAF12L2'

We genetically characterized the synaptic role of the Drosophila homologue of human DCAF12, a putative cofactor of Cullin4 (Cul4) ubiquitin ligase complexes. Deletion of Drosophila DCAF12 impairs larval locomotion and arrests development. At larval neuromuscular junctions (NMJs), DCAF12 is expressed presynaptically in synaptic boutons, axons, and nuclei of motor neurons. Postsynaptically, DCAF12 is expressed in muscle nuclei and facilitates Cul4-dependent ubiquitination. Genetic experiments identified several mechanistically independent functions of DCAF12 at larval NMJs. First, presynaptic DCAF12 promotes evoked neurotransmitter release. Second, postsynaptic DCAF12 negatively controls the synaptic levels of the glutamate receptor subunits GluRIIA, GluRIIC, and GluRIID. The down-regulation of synaptic GluRIIA subunits by nuclear DCAF12 requires Cul4. Third, presynaptic DCAF12 is required for the expression of synaptic homeostatic potentiation. We suggest that DCAF12 and Cul4 are critical for normal synaptic function and plasticity at larval NMJs.

Multisubunit cullin-RING ubiquitin ligase 4 (CRL4)-DCAF12 recognizes the C-terminal degron containing acidic amino acid residues. However, its physiological roles and substrates are largely unknown. Purification of CRL4-DCAF12 complexes revealed a wide range of potential substrates, including MOV10, an “ancient” RNA-induced silencing complex (RISC) complex RNA helicase. We show that DCAF12 controls the MOV10 protein level via its C-terminal motif in a proteasome- and CRL-dependent manner. Next, we generated Dcaf12 knockout mice and demonstrated that the DCAF12-mediated degradation of MOV10 is conserved in mice and humans. Detailed analysis of Dcaf12-deficient mice revealed that their testes produce fewer mature sperms, phenotype accompanied by elevated MOV10 and imbalance in meiotic markers SCP3 and γ-H2AX. Additionally, the percentages of splenic CD4+ T and natural killer T (NKT) cell populations were significantly altered. In vitro, activated Dcaf12-deficient T cells displayed inappropriately stabilized MOV10 and increased levels of activated caspases. In summary, we identified MOV10 as a novel substrate of CRL4-DCAF12 and demonstrated the biological relevance of the DCAF12-MOV10 pathway in spermatogenesis and T cell activation.

Background. Myasthenia gravis (MG) is an autoimmune disease that severely affects the life quality of patients. This study explores the differences in immune cell types between MG and healthy control and the role of immune-related genes in the diagnosis of MG. Methods. The GSE85452 dataset was downloaded from the Gene Expression Omnibus (GEO) database and analyzed using the limma package to determine differentially expressed genes (DEGs) between patients with MG and the control group. Differentially expressed immune cells were analyzed using single-sample gene set enrichment analysis (GSEA), while immune cell-associated modules were identified by weighted gene coexpression network analysis (WGCNA). Then, the expression of the identified hub genes was confirmed by RT-PCR in peripheral blood mononuclear cells (PBMCs) of MG patients. The R package pROC was used to plot the receiver operating characteristics (ROC) curves. Results. The modules related to CD56bright natural killer cells were identified by GSEA and WGCNA. The proportion of CD56bright natural killer cells in the peripheral blood of MG patients is low. The results of RT-PCR showed that the levels of DDB1- and CUL4-associated factor 12 (DCAF12) and heat shock protein family A member 1A (HSPA1A) were significantly decreased in peripheral blood mononuclear cells of MG patients compared with healthy controls. The ROC curve results of DCAF12 and HSPA1A mRNA in MG diagnosis were 0.780 and 0.830, respectively. Conclusions. CD56bright NK cell is lower in MG patients and may affect MG occurrence. DCAF12 and HSPA1A are lowly expressed in PBMCs of MG patients and may serve as the diagnostic biomarkers of MG.

BackgroundDespite advances in immune suppression, kidney allograft rejection and other injuries remain a significant clinical concern, particularly with regards to long-term allograft survival. Evaluation of immune activity can provide information about rejection status and help guide interventions to extend allograft life. Here, we describe the validation of a blood gene expression classifier developed to differentiate immune quiescence from both T cell–mediated rejection (TCMR) and antibody-mediated rejection (ABMR).MethodsA five-gene classifier (DCAF12, MARCH8, FLT3, IL1R2, and PDCD1) was developed on 56 peripheral blood samples and validated on two sample sets independent of the training cohort. The primary validation set comprised 98 quiescence samples and 18 rejection samples: seven TCMR, ten ABMR, and one mixed rejection. The second validation set included eight quiescence and 11 rejection samples: seven TCMR, two ABMR, and two mixed rejection. AlloSure donor-derived cell-free DNA (dd-cfDNA) was also evaluated.ResultsAlloMap Kidney classifier scores in the primary validation set differed significantly between quiescence (median, 9.49; IQR, 7.68–11.53) and rejection (median, 13.09; IQR, 11.25–15.28), with P<0.001. In the second validation set, the cohorts were statistically different (P=0.03) and the medians were similar to the primary validation set. The AUC for discriminating rejection from quiescence was 0.786 for the primary validation and 0.800 for the second validation. AlloMap Kidney results were not significantly correlated with AlloSure, although both were elevated in rejection. The ability to discriminate rejection from quiescence was improved when AlloSure and AlloMap Kidney were used together (AUC, 0.894).ConclusionValidation of AlloMap Kidney demonstrated the ability to differentiate between rejection and immune quiescence using a range of scores. The diagnostic performance suggests that assessment of the mechanisms of immunologic activity is complementary to allograft injury information derived from AlloSure dd-cfDNA. Together, these biomarkers offer a more comprehensive assessment of allograft health and immune quiescence.

Abstract Abstract 1765 Hypoxia may cause pulmonary and brain edema, pulmonary hypertension, aberrant metabolism and early mortality. To better understand pathological processes associated with hypoxia, we examined gene expression in Chuvash polycythemia blood mononuclear cells. Chuvash polycythemia is a congenital disorder of up-regulated hypoxic response at normoxia wherein VHLR200W homozygosity leads to elevated hypoxia inducible factor (HIF)-1 and HIF-2 levels, thromboses, pulmonary hypertension, lower systemic blood pressure (SBP) and increased mortality. VHLR200W homozygotes are often treated by phlebotomy resulting in iron deficiency, allowing us to evaluate an interaction of augmented hypoxia sensing with iron deficiency. Expression profiling of 8 VHLR200W homozygotes and 17 VHL wildtype individuals, matched for normal iron status as reflected in serum ferritin concentration, revealed altered regulation of 3069 genes at false discovery rate <0.05, with 847 up-regulated and 2222 down-regulated in VHLR200W homozygotes. Genes induced by homozygous VHLR200W were enriched in immune response pathways; those repressed in RNA transcription and protein synthesis pathways. Forty-two genes showed a >1.5-fold change in expression level, mostly (74%) an increase. Seven showed a >2-fold increase: CA1 (carbonic anhydrase), SELENBP1 (selenium binding protein 1), IL1B (interleukin 1 beta), SLC4A1 (solute carrier family 4 member 1), HBB (hemoglobin beta), and AHSP (alpha hemoglobin stabilizing protein). Additional studies including 16 VHLR200W homozygotes with low ferritin indicated that iron deficiency enhanced the induction effect of VHLR200W for 51 of the 847 upregulated genes and suppressed the induction effect for 108 of the upregulated genes. Genes further upregulated by iron deficiency included CA1, CSDA (cold shock domain protein A), BCL2L1 (BCL-2 like 1), BPGM (2,3-bisphosphoglycerate mutase), DCAF12 (DDB1 and CUL4 associated factor 12), FECH (ferrochelatase), SELENBP1 and SLC4A1. Genes for which iron deficiency suppressed the induction included inflammatory and immune pathway genes such as CASP5, CXCL16, IFI30, IFI35, IRF5, LILRB1, NOD2, RELT, TCIRG1 and TNFAIP2. A number of the genes with altered regulation in VHLR200W homozygotes might modify risk of thrombosis (upregulated: F3, SERPINE1, SERPINB2, SERPING1, PLAUR, THBD; down regulated: SERBP1), elevated systolic pulmonary artery pressure (upregulated: HTR1B, THBS1; downregulated: S1PR1, STIM2), or benign hemangioma (downregulated: CCM2). However, expression of these genes tended not to be influenced by iron status. VEGF was induced in VHLR200W homozygotes and surprisingly this induction was suppressed by iron deficiency. Expression relationships suggested a broad effect of VHLR200W in reducing systolic blood pressure through inducing VEGF. We demonstrate that many genes have commensurate changes of their expression by both iron deficiency and VHLR200W associated normoxic up-regulation of HIFs, as expected. However, there are genes that are regulated asynchronously. Further research is needed to define the molecular bases of separate regulation of genes by HIFs and iron status and to define relative risks and benefits of therapeutic phlebotomy for polycythemia. The resulting elucidation of the genomic pathways affecting predisposition to thromboses, pulmonary hypertension, lower systolic blood pressure and the interaction of augmented hypoxia sensing with iron deficiency should have broad implications leading to a better understanding of the pathophysiology of many diseases and the development of targeted therapies. Disclosures: No relevant conflicts of interest to declare.

Abstract Abstract 3245 Sickle cell disease (SCD) and Chuvash polycythemia (CP) are both monogenic hematologic disorders, the first resulting in hemolytic anemia and the second in polycythemia related to an upregulated hypoxic response at normoxia. Specifically, homozygosity for the VHLR200W mutation leads to increased levels of the transcription factors hypoxia inducible factor (HIF)-1 and HIF-2 at normoxia and altered transcription of many genes. Much attention in the pathophysiology of SCD has focused on the adverse effects of chronic inflammation, enhanced cellular adhesion pathways and hemolytic rate. However, the chronic anemia of SCD is associated with an upregulation of the hypoxic response as evidenced by high erythropoietin concentrations. In this prospective study, we compared gene expression alterations in peripheral blood mononuclear cells in SCD and CP. Our pre-specified hypothesis was that we could identify hypoxia-mediated gene expression alterations in SCD through a comparison with altered gene expression in CP and reveal molecular pathways that are potentially shared by these two conditions. We prospectively compared gene expression profiles in two independent cohorts, an SCD cohort comprised of 22 SCD patients and 19 African American controls and a CP cohort comprised of 8 VHLR200W homozygotes and 17 Chuvash controls with wildtype VHL. Because iron deficiency can influence the hypoxic response, we excluded iron-deficient subjects from each cohort. We used the identical Affymetrix exon array platform for both cohorts. Differential gene expression was highly correlated between the two conditions, with Spearman correlation ρ = 0.75 between their expression profiles across 16,642 genes, suggesting that 56% of expression variation triggered by beta hemoglobin mutation in SCD may be explained by hypoxic transcriptional responses. A small portion of differential genes were highly induced in both conditions. Among 54 genes up-regulated >1.5-fold in SCD patients, 24 (44%) overlapped with the 31 genes up-regulated >1.5-fold in VHLR200W homozygotes. The genes highly induced in both conditions included FAM46C (family with sequence similarity 46 member C), SELENBP1 (selenium binding protein 1), IL1B (interleukin 1, beta), MOP-1, SNCA (synuclein, alpha), GMPR (guanosine monophosphate reductase), BPGM (2,3-bisphosphoglycerate mutase), SLC25A37 (solute carrier family 25 member 37), CA1 (carbonic anhydrase I), DCAF12 (DDB1 and CUL4 associated factor 12), EPB42 (erythrocyte membrane protein band 4.2), AHSP (alpha hemoglobin stabilizing protein), SLC4A1 (solute carrier family 4 member 1), HBB (hemoglobin, beta), HBD (hemoglobin, delta), CSDA (cold shock domain protein A), FECH (ferrochelatase), BCL2L1 (BCL2-like 1), OSBP2 (oxysterol binding protein 2), APOBEC3A (apolipoprotein B mRNA editing enzyme catalytic polypeptide-like 3A), IFIT1 (interferon-induced protein with tetratricopeptide repeats 1), IFIT3 (interferon-induced protein with tetratricopeptide repeats 3), IFI44L (interferon-induced protein 44-like), and IFI27 (interferon, alpha-inducible protein 27). Three genes were down-regulated >1.5-fold in SCD patients. One of these, GIMAP7 (GTPase, IMAP family member 7), was among the 11 genes down-regulated >1.5-fold in VHLR200Whomozygotes. These results suggest that there is a broad upregulation of the hypoxic response in SCD and that the hypoxic response may underlie or interact with an important proportion of the clinical and pathophysiologic manifestations of SCD. Disclosures: No relevant conflicts of interest to declare.

Abstract Background Osteoarthritis (OA) is a chronic degenerative joint disease and the most frequent type of arthritis. This study aimed to identify the key miRNAs and genes associated with OA progression. Methods The GSE105027 (microRNA [miRNA/miR] expression profile; 12 OA samples and 12 normal samples) and GSE48556 (messenger RNA [mRNA] expression profile; 106 OA samples and 33 normal samples) datasets were selected from the Gene Expression Omnibus database. Differentially expressed genes (DEGs) and miRNAs (DEMs) were analyzed using the limma and ROCR packages in R, respectively. The target genes that negatively correlated with the DEMs were predicted, followed by functional enrichment analysis and construction of the miRNA-gene and miRNA-transcription factor (TF)-gene regulatory networks. Additionally, key miRNAs and genes were screened, and their expression levels were verified by real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR). Results A total of 1696 DEGs (739 upregulated and 957 downregulated) and 108 DEMs (56 upregulated and 52 downregulated) were identified in the OA samples. Furthermore, 56 target genes that negatively correlated with the DEMs were predicted and found to be enriched in three functional terms (e.g., positive regulation of intracellular protein transport) and three pathways (e.g., human cytomegalovirus infection). In addition, three key miRNAs (miR-98-5p, miR-7-5p, and miR-182-5p) and six key genes (murine double minute 2, MDM2; glycogen synthase kinase 3-beta, GSK3B; transmembrane P24-trafficking protein 10, TMED10; DDB1 and CUL4-associated factor 12, DCAF12; caspase 3, CASP3; and ring finger protein 44, RNF44) were screened, among which the miR-7-5p → TMED10/DCAF12, miR-98-5p → CASP3/RNF44, and miR-182-5p → GSK3B pairs were observed in the regulatory network. Moreover, the expression levels of TMED10, miR-7-5p, CASP3, miR-98-5p, GSK3B, and miR-182-5p showed a negative correlation with qRT-PCR verification. Conclusion MiR-98-5p, miR-7-5p, miR-182-5p, MDM2, GSK3B, TMED10, DCAF12, CASP3, and RNF44 may play critical roles in OA progression.

We employed imaging, electrophysiological, and molecular techniques with the genetically tractable model organism Drosophila melanogaster to unravel fundamental biological and genetic underpinnings regulating synaptic function and plasticity. Using a forward genetic screen, we identified mutations in the Drosophila ortholog of a human WD40 repeat-containing protein termed DDB1 and CUL4 associated factor 12 (DCAF12). We show that DCAF12 likely serves as an adaptor protein for the DDB1-Cul4 E3 ubiquitin ligase complex by recruiting specific target proteins for ubiquitination. DCAF12 is expressed in neurons, muscles, and glia. In mitotically active cells such as muscles, DCAF12 is localized to nuclei and co-localizes in distinct foci with CUL4, suggesting that DCAF12 mediates a nuclear role for the CUL4 E3 ubiquitin ligase complex. In neurons, DCAF12 is localized to both cytoplasmic and nuclear compartments of motor neuron cell bodies, where it colocalizes with Cul4 in nuclei. DCAF12 is also expressed at the periactive zone of presynaptic terminals, but does not distinctly associate with DDB1 or Cul4 at this region. Evoked neurotransmitter release at larval NMJs is significantly reduced in DCAF12 mutants. These defects are rescued by presynaptic expression of wild-type DCAF12, demonstrating that DCAF12 is required presynaptically and serves as an important component of the machinery that facilitates evoked release. In addition, our studies show that DCAF12 is required for the differential expression of glutamate receptor subunits at the larval NMJ through transcriptional and post-translational mechanisms. GluRIID subunit mRNA levels and GluRIIA/C/D subunit protein levels are increased at DCAF12 mutant NMJs. Normal GluRIIA subunit levels can be restored by postsynaptic expression of wild-type DCAF12, but not with a truncated DCAF12 protein lacking a nuclear localization signal (∆NLS-DCAF12). Furthermore, DCAF12 overexpression in muscle nuclei reduces synaptic GluRIIA levels, an effect that can be suppressed by removing a copy of Cul4. These data strongly indicate that DCAF12 in muscle nuclei is required for GluRIIA expression and/or function in a Cul4-dependent manner. Moreover, homozygous DCAF12-GluRIIA double mutants show a strong synthetic lethality phenotype, providing further support for the hypothesis that GluRIIA directly or indirectly requires DCAF12. Mutations in glutamate receptors at larval NMJs trigger a retrograde trans-synaptic signal that leads to a compensatory increase in presynaptic release, which precisely restores the normal efficacy of synaptic transmission and muscle excitation. Reducing the gene dosage of DCAF12 by one gene copy suppresses the initiation and maintenance of GluRIIA-mediated synaptic homeostatic potentiation. This block of synaptic homeostatic potentiation can be rescued by presynaptic expression of DCAF12. In our studies, we determined that DCAF12 is critical for 3 distinct synaptic mechanisms: evoked neurotransmitter release, neurotransmitter reception by regulation of GluR subunit composition, and retrograde synaptic homeostatic signaling. Future research will strive to identify presynaptic and postsynaptic protein targets of DCAF12 and the Cul4 E3 ubiquitin ligase complex and the role of ubiquitination in regulating these synaptic processes.