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Mitochondria form an apical calcium signaling domain in renal cortical collecting duct cells
Author(s) -
GalarzaPaez Laura,
Eaton Douglas,
Lam Ho Yin,
Al Khalili Otor,
Duke Billie Jeanne,
Bao Hui Fang,
Ma Heping,
Thai Tiffany
Publication year - 2015
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.29.1_supplement.969.25
Subject(s) - ionomycin , apical membrane , microbiology and biotechnology , mitochondrion , apical cell , intracellular , calcium signaling , biology , calcium , calcium in biology , chemistry , biochemistry , cell , membrane , organic chemistry
In several epithelia, Mitochondria sequester intracellular Ca 2+ to create Ca 2+ signaling domains. We asked whether mitochondria could form barriers to Ca 2+ diffusion in renal cortical collecting duct (CCD) cells. We began by staining each of two cell lines (from Xenopus and mouse) with mitotracker red. Mitochondria in both cell lines were localized in bands with a prominent band near the apical surface and a weaker band at the basal pole. To determine the proximity of the apical band to the membrane, we fluorescently tagged PIP 2 to label the apical membrane and found that the apical mitochondrial band was localized just beneath the membrane. Many apical membrane proteins are regulated by endoplasmic reticular Ca 2+ release. If mitochondria do sequester calcium to create an apical membrane Ca 2+ signaling domain, the ER must be able to cross the mitochondrial barrier at certain points so that release of Ca 2+ from the ER can reach its desired targets. Cells co‐stained with mitotracker red and ERtracker blue showed that ER crossed the mitochondrial barrier in many places. Next we sought to determine whether mitochondrial bands can prevent movement of intracellular Ca 2+ from one pole to another. Live cells stained with the mitochondrial Ca 2+ dye Rhodamine 2‐AM showed Ca 2+ uptake in the apical but not basal band after treatment with the Ca 2+ ionophore ionomycin. Cells transfected with a membrane‐tethered intracellular Ca 2+ sensor showed increased Ca 2+ at the apical but not basal pole following apical ionomycin. These data suggest that mitochondrial bands in the CCD create an apical signaling domain for Ca 2+ regulation of membrane proteins. This work was supported by NIH R37‐DK037963 and T32‐ DK07656 and AHA 13POST16820072.