Integrin receptor activation initiates the formation of integrin adhesion complexes (IACs) at the cell membrane that transduce adhesion-dependent signals to control a multitude of cellular functions. Proteomic analyses of isolated IACs have revealed an unanticipated molecular complexity; however, a global view of the consensus composition and dynamics of IACs is currently lacking. Here, we have integrated several IAC proteomes and generated a 2,412-protein integrin adhesome. Analysis of this dataset reveals the functional diversity of proteins in IACs and establishes a consensus adhesome of 60 proteins. The consensus adhesome likely represents a core cell adhesion machinery, centred around four axes comprising ILK-PINCH-kindlin, FAK-paxillin, talin-vinculin and α-actinin-zyxin-VASP, and includes underappreciated IAC components such as Rsu-1 and caldesmon. Proteomic quantification of IAC assembly and disassembly detailed the compositional dynamics of the core cell adhesion machinery. The definition of this consensus view of integrin adhesome components provides a resource for the research community.

Extracellular matrixes (ECMs) coat and subdivide animal tissues, but it is unclear how ECM formation is restricted to tissue surfaces and specific cell interfaces. During zebrafish somite morphogenesis, segmental assembly of an ECM composed of Fibronectin (FN) depends on the FN receptor Integrin α5β1. Using in vivo imaging and genetic mosaics, our studies suggest that incipient Itgα5 clustering along the nascent border precedes matrix formation and is independent of FN binding. Integrin clustering can be initiated by Eph/Ephrin signaling, with Ephrin reverse signaling being sufficient for clustering. Prior to activation, Itgα5 expressed on adjacent cells reciprocally and non-cell-autonomously inhibits spontaneous Integrin clustering and assembly of an ECM. Surface derepression of this inhibition provides a self-organizing mechanism for the formation and maintenance of ECM along the tissue surface. Within the tissue, interplay between Eph/Ephrin signaling, ligand-independent Integrin clustering and reciprocal Integrin inhibition restricts de novo ECM production to somite boundaries.

Dendritic spines are a characteristic feature of a number of neurons in the vertebrate nervous system and have been implicated in processes that include learning and memory. In spite of this, there has been no comprehensive analysis of the presence of spines in a classical genetic system, such as Drosophila, so far. Here, we demonstrate that a subset of processes along the dendrites of visual system interneurons in the adult fly central nervous system, called LPTCs, closely resemble vertebrate spines, based on a number of criteria. First, the morphology, size, and density of these processes are very similar to those of vertebrate spines. Second, they are enriched in actin and devoid of tubulin. Third, they are sites of synaptic connections based on confocal and electron microscopy. Importantly, they represent a preferential site of localization of an acetylcholine receptor subunit, suggesting that they are sites of excitatory synaptic input. Finally, their number is modulated by the level of the small GTPase dRac1. Our results provide a basis to dissect the genetics of dendritic spine formation and maintenance and the functional role of spines. '

Integrin activation, which is regulated by allosteric changes in receptor conformation, enables cellular responses to the chemical, mechanical and topological features of the extracellular microenvironment. A global view of how activation state converts the molecular composition of the region proximal to integrins into functional readouts is, however, lacking. Here, using conformation-specific monoclonal antibodies, we report the isolation of integrin activation state-dependent complexes and their characterization by mass spectrometry. Quantitative comparisons, integrating network, clustering, pathway and image analyses, define multiple functional protein modules enriched in a conformation-specific manner. Notably, active integrin complexes are specifically enriched for proteins associated with microtubule-based functions. Visualization of microtubules on micropatterned surfaces and live cell imaging demonstrate that active integrins establish an environment that stabilizes microtubules at the cell periphery. These data provide a resource for the interrogation of the global molecular connections that link integrin activation to adhesion signalling.

SummaryIntegrin α5β1 is a key receptor for the extracellular matrix protein fibronectin. Antagonists of human α5β1 have therapeutic potential as anti-angiogenic agents in cancer and diseases of the eye. However, the structure of the integrin is unsolved and the atomic basis of fibronectin and antagonist binding by α5β1 is poorly understood. Here we demonstrate that zebrafish α5β1 integrins do not interact with human fibronectin or the human α5β1 antagonists JSM6427 and cyclic peptide CRRETAWAC. Zebrafish α5β1 integrins do bind zebrafish fibronectin-1, and mutagenesis of residues on the upper surface and side of the zebrafish α5 subunit β-propeller domain shows that these residues are important for the recognition of RGD and synergy sites in fibronectin. Using a gain-of-function analysis involving swapping regions of the zebrafish α5 subunit with the corresponding regions of human α5 we show that blades 1-4 of the β-propeller are required for human fibronectin recognition, suggesting that fibronectin binding involves a broad interface on the side and upper face of the β-propeller domain. We find that the loop connecting blades 2 and 3 of the β-propeller (D3-A3 loop) contains residues critical for antagonist recognition, with a minor role played by residues in neighbouring loops. A new homology model of human α5β1 supports an important function for D3-A3 loop residues Trp-157 and Ala-158 in the binding of antagonists. These results will aid the development of reagents that block α5β1 functions in vivo.

Crosstalk between adhesion and growth factor receptors plays a critical role in tissue morphogenesis and repair, and aberrations contribute substantially to neoplastic disease. However, the mechanisms by which adhesion and growth factor receptor signalling are integrated, spatially and temporally, are unclear.We used adhesion complex enrichment coupled with quantitative proteomic analysis to identify rapid changes to adhesion complex composition and signalling following growth factor stimulation. Bioinformatic network and ontological analyses revealed a substantial decrease in the abundance of adhesion regulatory proteins and co-ordinators of endocytosis within 5 minutes of EGF stimulation. Together these data suggested a mechanism of EGF-induced receptor endocytosis and adhesion complex turnover.Combinatorial interrogation of the networks allowed a global and dynamic view of adhesion and growth factor receptor crosstalk to be assembled. By interrogating network topology we identified Eps8 as a putative node integrating α5β1 integrin and EGFR functions. Importantly, EGF stimulation promoted internalisation of both α5β1 and EGFR. However, perturbation of Eps8 increased constitutive internalisation of α5β1 and EGFR; suggesting that Eps8 constrains α5β1 and EGFR endocytosis in the absence of EGF stimulation. Consistent with this, Eps8 regulated Rab5 activity and was required for maintenance of adhesion complex organisation and for EGF-dependent adhesion complex disassembly. Thus, by co-ordinating α5β1 and EGFR trafficking mechanisms, Eps8 is able to control adhesion receptor and growth factor receptor bioavailability and cellular contractility.We propose that during tissue morphogenesis and repair, Eps8 functions to spatially and temporally constrain endocytosis, and engagement, of α5β1 and EGFR in order to precisely co-ordinate adhesion disassembly, cytoskeletal dynamics and cell migration.

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Rotunda była obiektem o charakterze militarnym w systemie obronnym Twierdzy Zamość w XIX wieku. Podczas II wojny światowej pełniła rolę jenieckiego obozu przejściowego niemieckiej Policji Bezpieczeństwa. W latach 1940-1944 zginęło tam wielu przedstawicieli lokalnych elit i członków konspiracji. Liczba szacunkowa ofiar wynosi około ośmiu tysięcy. Najprawdopodobniej przez obóz przeszło 50 tys. więźniów. Po wojnie było to pierwsze miejsce upamiętnione w regionie. Inicjatywa upamiętnienia była rezultatem działań społecznych. Pomimo różnych problemów, udało się zabezpieczyć obiekt wraz z przyległym terenem. W latach 50. XX w. ekshumowano na Rotundę wiele ciał ofiar II wojny światowej. Obecnie stanowi ona bardzo ważny symbol martyrologii na Zamojszczyźnie. Pochowano tam m.in. żołnierzy polskich, którzy polegli we wrześniu 1939 roku, partyzantów, ludność żydowską i romską oraz żołnierzy sowieckich.