Role of the microtubule cytoskeleton in the function of the store-operated Ca2+ channel activator STIM1.
We examined the role of the microtubule cytoskeleton in the localization and store-operated Ca(2+) entry (SOCE) function of the endoplasmic reticulum (ER) Ca(2+) sensor stromal interaction molecule 1 (STIM1) in HEK 293 cells. STIM1 tagged with an enhanced yellow fluorescent protein (EYFP-STIM1) exhibited a fibrillar localization that colocalized with endogenous alpha-tubulin. Depolymerization of microtubules with nocodazole caused a change from a fibrillar EYFP-STIM1 localization to one that was similar to that of the ER. Treatment of HEK 293 cells with nocodazole had a detrimental impact on SOCE and the associated Ca(2+) release-activated Ca(2+) current (I(CRAC)). This inhibition was significantly reversed in cells overexpressing EYFP-STIM1, implying that the primary inhibitory effect of nocodazole is related to STIM1 function. Surprisingly, nocodazole treatment alone induced significant SOCE and I(CRAC) in cells expressing EYFP-STIM1, and this was accompanied by an increase in EYFP-STIM1 fluorescence near the plasma membrane. We conclude that microtubules play a facilitative role in the SOCE signaling pathway by optimizing the localization of STIM1.
Smyth
Jeremy T
JT
Laboratory of Signal Transduction, National Institute of Environmental Health Sciences, NIH, Department of Health and Human Services, PO Box 12233, Research Triangle Park, NC 27709, USA.
DeHaven
Wayne I
WI
Bird
Gary S
GS
Putney
James W
JW
D002118:Calcium / Q000378:metabolism; D015220:Calcium Channels / Q000378:metabolism*; D020013:Calcium Signaling / Q000502:physiology*; D002460:Cell Line; D003599:Cytoskeleton / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000378:metabolism; D006801:Humans; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D008870:Microtubules / Q000378:metabolism*; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism*; D015739:Nocodazole / Q000378:metabolism; D018408:Patch-Clamp Techniques; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D000071737:Stromal Interaction Molecule 1; D014404:Tubulin / Q000378:metabolism; D050257:Tubulin Modulators / Q000378:metabolism
D015220:Calcium Channels; D008565:Membrane Proteins; D009363:Neoplasm Proteins; D011993:Recombinant Fusion Proteins; C103530:STIM1 protein, human; D000071737:Stromal Interaction Molecule 1; D014404:Tubulin; D050257:Tubulin Modulators; D015739:Nocodazole; D002118:Calcium