title: Caveolin-1 regulation of store-operated Ca(2+) influx in human airway smooth muscle.
abstract: Caveolae, plasma membrane invaginations with constitutive caveolin proteins, harbour proteins involved in intracellular calcium ([Ca(2+)](i)) regulation. In human airway smooth muscle (ASM), store-operated Ca(2+) entry (SOCE) is a key component of [Ca(2+)](i) regulation, and contributes to increased [Ca(2+)](i) in inflammation. SOCE involves proteins Orai1 and stromal interaction molecule (STIM)1. We investigated the link between caveolae, SOCE and inflammation in ASM. [Ca(2+)](i) was measured in human ASM cells using fura-2. Small interference RNA (siRNA) or overexpression vectors were used to alter expression of caveolin-1 (Cav-1), Orai1 or STIM1. Tumour necrosis factor (TNF)-α was used as a representative pro-inflammatory cytokine. TNF-α increased SOCE following sarcoplasmic reticulum Ca(2+) depletion, and increased whole-cell and caveolar Orai1 (but only intracellular STIM1). Cav-1 siRNA decreased caveolar and whole-cell Orai1 (but not STIM1) expression, and blunted SOCE, even in the presence of TNF-α. STIM1 overexpression substantially enhanced SOCE: an effect only partially reversed by Cav-1 siRNA. In contrast, Orai1 siRNA substantially blunted SOCE even in the presence of TNF-α. Cav-1 overexpression significantly increased Orai1 expression and SOCE, especially in the presence of TNF-α. These results demonstrate that caveolar expression and regulation of proteins such as Orai1 are important for [Ca(2+)](i) regulation in human ASM cells and its modulation during inflammation.
authors.affiliation: Dept of Anesthesiology, Mayo Clinic College of Medicine, Rochester, MN 55905, USA.
authors.forename: Venkatachalem
authors.initials: V
authors.lastname: Sathish
authors.forename: Amard J
authors.initials: AJ
authors.lastname: Abcejo
authors.forename: Michael A
authors.initials: MA
authors.lastname: Thompson
authors.forename: Gary C
authors.initials: GC
authors.lastname: Sieck
authors.forename: Y S
authors.initials: YS
authors.lastname: Prakash
authors.forename: Christina M
authors.initials: CM
authors.lastname: Pabelick
mesh_terms: D001249:Asthma / Q000378:metabolism; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000378:metabolism; D051242:Caveolin 1 / Q000096:biosynthesis*; D002460:Cell Line; D005786:Gene Expression Regulation; D006801:Humans; D007249:Inflammation; D008565:Membrane Proteins / Q000378:metabolism; D018613:Microscopy, Confocal / Q000379:methods; D008954:Models, Biological; D009130:Muscle, Smooth / Q000378:metabolism*; D009363:Neoplasm Proteins / Q000378:metabolism; D000071740:ORAI1 Protein; D034741:RNA, Small Interfering / Q000378:metabolism; D012137:Respiratory System / Q000378:metabolism*; D000071737:Stromal Interaction Molecule 1; D013347:Subcellular Fractions / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D015220:Calcium Channels; D051242:Caveolin 1; D008565:Membrane Proteins; D009363:Neoplasm Proteins; D000071740:ORAI1 Protein; C510746:ORAI1 protein, human; D034741:RNA, Small Interfering; C103530:STIM1 protein, human; D000071737:Stromal Interaction Molecule 1; D014409:Tumor Necrosis Factor-alpha; D002118:Calcium