Vitalizing passive STIM1 domains for Orai channel activation
Sprache der Bezeichnung:
Store-operated Ca2+ entry (SOCE) is essential for many processes ranging from the cellular to the physiological level. Ca2+ entry, initiated by the endoplasmic reticulum (ER) Ca2+ sensor STIM1, regulates various functions including Ca2+ homeostasis, cell growth, proliferation, gene expression and differentiation. Several loss of function mutations of STIM1 result in immune dysfunctions and myopathy. In this project, using electrophysiology, FRET measurements, the new FIRE approach (FRET In a Restricted Environment), and confocal fluorescence imaging we aim to elucidate the molecular processes of STIM1 activation especially focusing on the STIM1 transmembrane domain (TM) and CC1?2. The latter has recently raised some interest, as a mutation therein (R304W) has been associated with the Stormorken syndrome. The impact of the STIM1 TM and CC1?2 domains on the activation state of STIM1 and its coupling to Orai have been only marginally analyzed up to date. Examination of STIM1 TM and CC1?2 mutants with different methods using full length STIM1, conformational sensor constructs and small fragments of STIM1 attached to the ER membrane or cytosolically expressed will help to explore the activating / modulatory role of these two STIM1 domains and the detailed mechanistic steps of STIM1 / Orai activation in the healthy and pathologic system.