Academic literature on the topic 'Protein micropatterning'

Protein micropatterning is a powerful tool for spatial arrangement of transmembrane and intracellular proteins in living cells. The restriction of one interaction partner (the bait, e.g., the receptor) in regular micropatterns within the plasma membrane and the monitoring of the lateral distribution of the bait’s interaction partner (the prey, e.g., the cytosolic downstream molecule) enables the in-depth examination of protein-protein interactions in a live cell context. This study reports on potential pitfalls and difficulties in data interpretation based on the enrichment of clathrin, which is a protein essential for clathrin-mediated receptor endocytosis. Using a highly modular micropatterning approach based on large-area micro-contact printing and streptavidin-biotin-mediated surface functionalization, clathrin was found to form internalization hotspots within the patterned areas, which, potentially, leads to unspecific bait/prey protein co-recruitment. We discuss the consequences of clathrin-coated pit formation on the quantitative analysis of relevant protein-protein interactions, describe controls and strategies to prevent the misinterpretation of data, and show that the use of DNA-based linker systems can lead to the improvement of the technical platform.

Depositing biomolecule micropatterns on solid substrates via microcontact printing (µCP) usually requires complex chemical substrate modifications to initially create reactive surface groups. Here, we present a simplified activation procedure for untreated solid substrates based on a commercial polymer metal ion coating (AnteoBindTM Biosensor reagent) that allows for direct µCP and the strong attachment of proteins via avidity binding. In proof-of-concept experiments, we identified the optimum working concentrations of the surface coating, characterized the specificity of protein binding and demonstrated the suitability of this approach by subcellular micropatterning experiments in living cells. Altogether, this method represents a significant enhancement and simplification of existing µCP procedures and further increases the accessibility of protein micropatterning for cell biological research questions.

S-palmitoylation describes the reversible attachment of fatty acids (predominantly palmitate) onto cysteine residues via a labile thioester bond. This posttranslational modification impacts protein functionality by regulating membrane interactions, intracellular sorting, stability, and membrane micropatterning. Several recent findings have provided a tantalizing insight into the regulation and spatiotemporal dynamics of protein palmitoylation. In mammalian cells, the Golgi has emerged as a possible super-reaction center for the palmitoylation of peripheral membrane proteins, whereas palmitoylation reactions on post-Golgi compartments contribute to the regulation of specific substrates. In addition to palmitoylating and depalmitoylating enzymes, intracellular palmitoylation dynamics may also be controlled through interplay with distinct posttranslational modifications, such as phosphorylation and nitrosylation.

Micropatterning techniques have been widely used in biology, particularly in studies involving cell adhesion and proliferation on different substrates. Cell micropatterning approaches are also increasingly employed as in vitro tools to investigate intracellular mechanotransduction processes. In this report, we examined how modulating cellular shapes on two-dimensional rectangular fibronectin micropatterns of different widths influences nuclear mechanotransduction mediated by emerin, a nuclear envelope protein implicated in Emery–Dreifuss muscular dystrophy (EDMD). Fibronectin microcontact printing was tested onto glass coverslips functionalized with three different silane reagents (hexamethyldisilazane (HMDS), (3-Aminopropyl)triethoxysilane (APTES) and (3-Glycidyloxypropyl)trimethoxysilane (GPTMS)) using a vapor-phase deposition method. We observed that HMDS provides the most reliable printing surface for cell micropatterning, notably because it forms a hydrophobic organosilane monolayer that favors the retainment of surface antifouling agents on the coverslips. We showed that, under specific mechanical cues, emerin-null human skin fibroblasts display a significantly more deformed nucleus than skin fibroblasts expressing wild type emerin, indicating that emerin plays a crucial role in nuclear adaptability to mechanical stresses. We further showed that proper nuclear responses to forces involve a significant relocation of emerin from the inner nuclear envelope towards the outer nuclear envelope and the endoplasmic reticulum membrane network. Cell micropatterning by fibronectin microcontact printing directly on HMDS-treated glass represents a simple approach to apply steady-state biophysical cues to cells and study their specific mechanobiology responses in vitro.

Thesis (PhD) - Swinburne University of Technology, Industrial Research Institute Swinburne - 2006.
A thesis submitted in fulfilment of the requirements for the degree of Doctor of Philosophy, Industrial Research Institute Swinburne, Swinburne University of Technology - 2006. Typescript. Includes bibliographical references (p. 184-197).

Bio-microdevices are miniaturised devices based on biologically derived components (e.g., DNA, proteins, and cells) combined or integrated with microfabricated substrates. These devices are of interest for numerous applications, ranging from drug discovery, to environmental monitoring, to tissue engineering. Before a bio-microdevice can be fully developed, specific fabrication issues need to be addressed. One of the most important is the spatial immobilization of selected biomolecules in specific micro-areas of the device. Among the biomolecules of interest, the controlled immobilization of proteins to surfaces is particularly challenging due to the complexity of these macromolecules and their tendency to lose bioactivity during the immobilization step. The present Thesis reports on three novel micropatterning techniques for the spatial immobilization of proteins with bioactivity retention and improved read-out of the resulting micropatterns. The technologies developed are based on three different micropatterning approaches, namely 1) direct-writing UV laser microablation (proLAB), 2) a novel microcontact printing method (�CPTA) and 3) a replica molding method combined with bead selfassembly (BeadMicroArray). The first two technologies, proLAB and �CPTA, are an implementation of existing techniques (laser ablation and �CP, respectively), whereas the third, i.e., the BeadMicroArray, is a totally new technique and type of patterning platform. 'ProLAB' is a technology that uses a micro-dissection tool equipped with a UV laser (the LaserScissors�) for ablating a substrate made of a layer of ablatable material, gold, deposited over a thin polymer layer. The latter layer is transparent to the laser but favours protein adsorption. In the present work microchannels were chosen as the structure of interest with the aim of arranging them in 'bar-codes', so to create an 'information-addressable' microarray. This platform was fabricated and its application to specific antigen binding demonstrated. The second technique that was developed is a microstamping method which exploits the instability of a high-aspect ratio rubber stamp fabricated via soft-lithography. The technique is denominated microcontact printing trapping air (�CPTA) since the collapsing of a rubber stamp made of an array of micro-pillars over a plane glass surface resulted in the formation of a large air gap around the entire array. The method can be successfully employed for printing micro-arrays of proteins, maintaining biological activity. The technique was compared with robotic spotting and found that microarrays obtained with the �CPTA method were more homogeneous and had a higher signal-tonoise ratio. The third technique developed, the BeadMicroArray, introduces a totally new platform for the spatial addressable immobilization of proteins. It combines replica molding with microbead self-assembling, resulting in a platform where diagnostic beads are entrapped at the tip of micropillars arranged in a microarray format. The fabrication of the BeadMicroArray involves depositing functional microbeads in an array of V-shaped wells using spin coating. The deposition is totally random, and conditions were optimised to fill about half the array during spin coating. After replica molding, the resulting polymer mold contains pyramid-shaped posts with beads entrapped at the very tip of the post. Thanks to the fabrication mode involved, every BeadMicroArray fabricated contains a unique geometric code, therefore assigning a specific code to each microarray. In the present work it was demonstrated that the functionality of the beads after replica molding remains intact, and that proteins can be selectively immobilized on the beads, for instance via biorecognition. The platform showed a remarkable level of selectively which, together with an efficient blocking towards protein non-specific adsorption, lead to a read-out characterized by a very good signal-to-noise. Also, after recognition, a code was clearly visible, therefore showing the encoding capacity of this unique microarray.

L'impression protéique a initialement été utilisée pour reproduire et comprendre l’influence de la matrice extracellulaire sur les cellules et certains de leurs composants. Au cours de la dernière décennie, l'impression subcellulaire s’est développée, permettant d’étudier les interactions protéiques et leur rôle dans les voies de signalisation ainsi que dans la formation de synapses, immunologiques ou neuronales.La connexion synaptique est médiée par les protéines d’adhésion synaptique présentes de chaque côté de la synapse. En raison de la complexité de l’environnement synaptique mais également du manque de modèle in vitro permettant d’étudier la connexion synaptique dans un environnement biomimétique et contrôlé, les rôles exacts de ces protéines dans la synaptogénèse restent encore incertains. L’impression protéique subcellulaire est une solution potentielle pour combler ce manque. Pour cela, nous avons développé deux modèles biomimétiques basés sur l’impression protéique : un premier, utilisant des cellules hétérologues, permettant d’obtenir des informations sur la cinétique d’interaction des couples protéiques et ainsi de lier cela à leur fonction potentielle. Et un deuxième, utilisant des neurones primaires hippocampique, permettant de former des synapses artificielles pour étudier la nano-organisation de la synapse au cours du développement.Le système d’impression protéique PRIMO, commercialisé par Alvéole, qui co-finance cette thèse, est peu utilisé par les neuroscientifiques. En plus des objectifs biologiques, l'objectif industriel de cette thèse est de développer des méthodologies et des preuves de concept afin de démontrer les avantages et la faisabilité de la technologie PRIMO en neuroscience.En couplant notre premier modèle avec des techniques d’imagerie sur cellules vivantes (sptPALM et FRAP), nous avons pu différencier des cinétiques d’interaction entre différents couples de protéines d’adhésion synaptique mais également pour des interactions avec des protéines d’échafaudage. Une interaction labile pour SynCAM1, qui est connue pour son rôle dans la morphologie synaptique. Une forte et stable interaction pour Neuroligine1- Neurexine1β, due à la dimérisation de Neuroligine1, qui est indispensable pour la fonctionnalité de la synapse.Avec le second modèle, nous avons démontré, en présence de LRRTM2, la formation spécifique de synapses artificielles. Ces hémi-synapses présentent des caractéristiques morphologiques et fonctionnelles proches de synapses natives, avec la présence de vésicules et d’une activité calcique spontanée. Cependant, nous n’avons pas réussi à former de postsynapses artificielles avec Neurexine1β. Basés sur nos observations et une analyse bibliographique, nous avons formulé l’hypothèse que la postsynapse pourrait être le compartiment initiateur de la synaptogenèse.En conclusion, cette étude démontre : (1) que l’impression subcellulaire est un excellent modèle pour étudier la connectivité synaptique et l’adhésion de manière générale, aussi bien d’un point de vue fonctionnel qu’organisationnel. (2) Que les modèles d’hémi-synapses utilisant l’impression protéique sont plus spécifiques que les anciens modèles. (3) Que le système PRIMO ouvre de nombreuses perspectives en neurosciences via ses capacités d’impressions quantitatives
Micropatterning was initially employed to replicate and understand the influence of the extracellular matrix on cells and some of their components. Over the past decade, subcellular printing has emerged, enabling the study of protein interactions and their role in signaling pathways as well as in the formation of synaptic, immunological, or neuronal pathways.The synaptic connection is mediated by synaptic adhesion proteins present on each side of the synapse. Due to the complexity of the synaptic environment and the lack of in vitro models to study synaptic connection in a biomimetic and controlled environment, the exact roles of these proteins in synaptogenesis remain uncertain. Subcellular protein printing presents a potential solution to address this gap. For this purpose, we have developed two biomimetic models based on protein printing: a first one using heterologous cells, providing insights into the interaction kinetics of protein pairs and linking them to their potential function. And a second one using primary neurons, allowing the formation of artificial synapses to study synaptic nano-organization during development.The protein printing system PRIMO, commercialized by Alvéole, which is co-funding this thesis, is underutilized by neuroscientists. Besides these biological objectives, the industrial aim of this thesis is to develop methodologies and proofs of concept to demonstrate the advantages and feasibility of the PRIMO technology in neuroscience.By coupling our first model, based on heterologous cells, with live-cell imaging techniques (sptPALM and FRAP), we differentiated interaction kinetics among various synaptic adhesion protein pairs and also for interactions with scaffold proteins. A labile interaction was observed for SynCAM1, known for its role in synaptic morphology. A strong and stable interaction was evident for Neuroligin1/Neurexine1β due to Neuroligin1's dimerization, which is essential for synaptic functionality.With the second model using primary hippocampal neurons, we demonstrated, in the presence of LRRTM2, the specific formation of artificial synapses. These hemi-synapses exhibited morphological and functional characteristics close to native synapses, including the presence of vesicles and spontaneous calcium activity. However, we were unable to form artificial postsynapses with Neurexine1β. Based on our observations and bibliographic analysis, we hypothesize that the postsynapse could be the initiating compartment for synaptogenesis.In conclusion, this study demonstrates: (1) that subcellular printing is an excellent model to study synaptic connectivity and adhesion from both a functional and organizational perspective. (2) That models of hemi-synapses using micropatterning are more specific than previous models. (3) That the PRIMO system opens numerous perspectives in neuroscience through its quantitative printing capabilities

Self assembled monolayers (SAMs) are widely used for surface modification. Alkylsilane monolayers are one of the most widely deposited and studied SAMs. My work focuses on the preparation, patterning, and application of alkysilane monolayers. 3-aminopropyltriethoxysilane (APTES) is one of the most popular silanes used to make active surfaces for surface modification. To possibly improve the surface physical properties and increase options for processing this material, I prepared and studied a series of amino silane surfaces on silicon/silicon dioxide from APTES and two other related silanes by chemical vapor deposition (CVD). I also explored CVD of 3-mercaptopropyltrimethoxysilane on silicon and quartz. Several deposition conditions were investigated. Results show that properties of silane monolayers are quite consistent under different conditions. For monolayer patterning, I developed a new and extremely rapid technique, which we termed laser activation modification of semiconductor surfaces or LAMSS. This method consists of wetting a semiconductor surface with a reactive compound and then firing a highly focused nanosecond pulse of laser light through the transparent liquid onto the surface. The high peak power of the pulse at the surface activates the surface so that it reacts with the liquid with which it is in contact. I also developed a new application for monolayer patterning. I built a technologically viable platform for producing protein arrays on silicon that appears to meet all requirements for industrial application including automation, low cost, and high throughput. This method used microlens array (MA) patterning with a laser to pattern the surface, which was followed by protein deposition. Stencil lithography is a good patterning technique compatible with monolayer modification. Here, I added a new patterning method and accordingly present a simple, straightforward procedure for patterning silicon based on plasma oxidation through a stencil mask. We termed this method subsurface oxidation for micropatterning silicon (SOMS).

Abstract The growth of cellular constructs in tissue scaffolds depends on the delivery of nutrients and growth factors as well as the substrate on which they are grown. Micropatterning techniques have also made it possible to grow cells on a wide variety of substrates with greatly different topography which significantly alter cellular contact and communication. Fluid flow is critical not only in this delivery of nutrients and growth factors, but also in the interaction of the cell’s cytoskeleton with its attachment matrix. Similarly, fluid flow is known to play an important role in cell to cell communication via its regulatory effect on various gap junction proteins of the connexon family. The mechano/transduction and cell to cell signaling mechanisms will be examined for both cells with a smooth topography, such as vascular endothelium cells which are involved in angiogenesis and cells with cell processes and microvilli whose tethering attachments and protrusions interact with fluid flow in a different manner.