Zellkortex-Regulation durch CA(2+)-bindende Proteine der S100 Familie
Zusammenfassung der Projektergebnisse
S100 proteins are a family of EF hand-type proteins that bind to and regulate different effectors in their Ca2+-bound state. We had previously identified two of these effectors for the S100P protein that act in the cell cortex, the membrane-cytoskeleton linker ezrin and the cortical scaffold protein IQGAP1. In the funded project we have now characterized these interactions in more detail and we have studied the conformational activation of ezrin. We could show that tripartite ezrin/S100P/IQGAP1 complexes exist and could also identify a novel, direct interaction between ezrin and IQGAP1. Ezrin is involved in recruiting IQGAP to submembraneous regions and this represents a novel mode of IQGAP1 regulation, possibly involved in the cell’s response to growth factor stimulation. In resting cells ezrin resides in a closed inactive conformation that is stabilized by direct interactions between the N- and C-terminal ERM association domains (ERMAD). This association can be relieved by the binding of PIP2 or S100P to the N-ERMAD and/or phosphorylation of the conserved Thr-567 in the C-ERMAD. As these regulatory events play an important role in the activation of ezrin’s membrane-cytoskeleton cross-linking function we developed a novel assay involving model membranes and intramolecular Förster resonance energy transfer to study the conformational opening of the molecule. This revealed that PIP2 binding and Thr-567 phosphorylation most likely act synergistically in activating the ezrin molecule. Ezrin and the two other members of the ERM protein family, moesin and radixin, have been shown to participate in cell division, in particular during initial cell rounding and spindle orientation. To assess whether these proteins, based on their membrane-cytoskeleton linker function, also participate in cytokinesis, we analyzed their dynamic distribution during mitosis and inspected cells devoid of all three ERM proteins for possible defects in cytokinesis. This revealed that all ERM proteins specifically localize to the forming cleavage furrow and that their absence appears to result in a delay of cell division suggesting a role in cleavage furrow formation/ingression. In collaboration with other groups we also analyzed cortical functions of another S100 protein, S100A10, and characterized how cell adhesion proteins can control cortical events in cell division and migration. This led to the identification of a novel S100A10 effector protein, the CCR10 chemokine receptor, and revealed that the junctional adhesion molecule JAM-A is critically involved in cortical anchorage and thus proper positioning of the mitotic spindel in polarized epithelial cells.
Projektbezogene Publikationen (Auswahl)
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(2014). Formation and characterization of supported lipid bilayers containing phosphatidylinositol-4,5-bisphisphate and cholesterol as functional surfaces. Langmuir. 30:14877-14886
Drücker P, Grill D, Gerke V, Galla HJ
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(2015) Conformational changes in ezrin analyzed by Förster resonance energy transfer. PhD thesis, Münster
Shabardina, V.
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(2015). Annexin A4 is a novel direct regulator of adenylyl cyclase type 5. FASEB J. 29:3773-3787
Heinick A, Husser X, Himmler K, Kirchhefer U, Nunes F, Schulte JS, Seidl MD, Rolfes C, Dedman JR, Kaetzel MA, Gerke V, Schmitz W, Müller FU
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(2015). Ezrin interacts with the scaffold protein IQGAP1 and affects its cortical localization. Biochim Biophys Acta Mol Cell Res. 1853:2086-2094
Nammalwar RC, Heil A, Gerke V
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(2015). JAM- A regulates cortical dynein localization through Cdc42 to control planar spindle orientation during mitosis. Nat Commun. 6:8128
Tuncay H, Brinkmann BF, Steinbacher T, Schürmann A, Gerke V, Iden S, Ebnet K
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(2016) Protein interactions in the cortical cytoskeleton – Analysis of ezrin, radixin, moesin family complexes. PhD thesis, Münster
Nammalwar, R.
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(2016). CC chemokine receptor 10 cell surface presentation in melanocytes is regulated by the novel interaction partner S100A10. Sci Rep. 6:22649
Hessner F, Dlugos CP, Chehab T, Schaefer C, Homey B, Gerke V, Weide T, Pavenstädt H, Rescher U
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(2016). Mode of ezrin-membrane interaction as a function of PIP2 binding and pseudophosphorylation. Biophys J. 110:2710-2719
Shabardina V, Kramer C, Gerdes B, Braunger J, Cordes A, Schäfer J, Mey I, Grill D, Gerke V, Steinem C
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(2016). VE-cadherin interacts with cell polarity protein Pals1 to regulate vascular lumen formation. Mol Biol Cell. 27:2811-2821
Brinkmann BF, Steinbacher T, Hartmann C, Kummer D, Pajonczyk D, Mirzapourshafiyi F, Nakayama M, Weide T, Gerke V, Ebnet K
