Stabilization of cortical actin induces internalization of transient receptor potential 3 (Trp3)-associated caveolar Ca2+ signaling complex and loss of Ca2+ influx without disruption of Trp3-inositol trisphosphate receptor association.
Ca(2+) influx via plasma membrane Trp3 channels is proposed to be regulated by a reversible interaction with inositol trisphosphate receptor (IP(3)R) in the endoplasmic reticulum. Condensation of the cortical actin layer has been suggested to physically disrupt this interaction and inhibit Trp3-mediated Ca(2+) influx. This study examines the effect of cytoskeletal reorganization on the localization and function of Trp3 and key Ca(2+) signaling proteins. Calyculin-A treatment resulted in formation of condensed actin layer at the plasma membrane; internalization of Trp3, Galpha(q/11), phospholipase Cbeta, and caveolin-1; and attenuation of 1-oleoyl-2-acetyl-sn-glycerol- and ATP-stimulated Sr(2+) influx. Importantly, Trp3 and IP(3)R-3 remained co-localized inside the cell and were co-immunoprecipitated. Jasplakinolide also induced internalization of Trp3 and caveolin-1. Pretreatment of cells with cytochalasin D or staurosporine did not affect Trp3 but prevented calyculin-A-induced effects. Based on these data, we suggest that Trp3 is assembled in a caveolar Ca(2+) signaling complex with IP(3)R, SERCA, Galpha(q/11), phospholipase Cbeta, caveolin-1, and ezrin. Furthermore, our data demonstrate that conditions which stabilize cortical actin induce loss of Trp3 activity due to internalization of the Trp3-signaling complex, not disruption of IP(3)R-Trp3 interaction. This suggests that localization of the Trp3-associated signaling complex, rather than Trp3-IP(3)R coupling, depends on the status of the actin cytoskeleton.
Lockwich
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T
Secretory Physiology Section, Gene Therapy and Therapeutics Branch, NIDCR, National Institutes of Health Bethesda, Maryland 20892, USA.
Singh
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BB
Liu
X
X
Ambudkar
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IS
D000199:Actins / Q000502:physiology*; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000032:analysis / Q000378:metabolism*; D020013:Calcium Signaling; D000252:Calcium-Transporting ATPases / Q000032:analysis; D021941:Caveolae / Q000737:chemistry*; D051242:Caveolin 1; D022461:Caveolins / Q000032:analysis; D002478:Cells, Cultured; D003599:Cytoskeleton / Q000502:physiology; D006801:Humans; D053496:Inositol 1,4,5-Trisphosphate Receptors; D008387:Marine Toxins; D010080:Oxazoles / Q000494:pharmacology; D011193:Potassium Iodide / Q000494:pharmacology; D018160:Receptors, Cytoplasmic and Nuclear / Q000032:analysis / Q000378:metabolism*; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; D050052:TRPC Cation Channels; D010738:Type C Phospholipases / Q000502:physiology
D000199:Actins; C495540:CAV1 protein, human; D015220:Calcium Channels; D051242:Caveolin 1; D022461:Caveolins; C506926:ITPR1 protein, human; D053496:Inositol 1,4,5-Trisphosphate Receptors; D008387:Marine Toxins; D010080:Oxazoles; D018160:Receptors, Cytoplasmic and Nuclear; D050052:TRPC Cation Channels; C104603:TRPC3 cation channel; D011193:Potassium Iodide; C059041:calyculin A; D010738:Type C Phospholipases; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; D000252:Calcium-Transporting ATPases; D002118:Calcium