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Expression of intersectin 1/2 is repressed by aldosterone through microRNAs in the CCD to alter ENaC‐mediated Na + transport (893.4)
Author(s) -
Butterworth Michael,
Liu Xiaoning,
Edinger Robert
Publication year - 2014
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.28.1_supplement.893.4
Subject(s) - epithelial sodium channel , aldosterone , endocytosis , microbiology and biotechnology , chemistry , internalization , medicine , endocrinology , cell , sodium , biology , biochemistry , organic chemistry
Aldosterone is a well characterized regulator of the epithelial sodium channel (ENaC), and increases transepithelial Na+ transport in the kidney CCD. Here we report on two related scaffold proteins, intersectin (Itsn) 1 and 2 that are aldosterone repressed via microRNA regulation. Itsns are involved in coordinating vesicle trafficking events and modulating several signaling pathways. In a cultured mCCD‐cl1 cell line, Itsn expression is reduced by aldosterone (50nM, from 6hrs), which in turn increases ENaC activity. Exogenous depletion of Itsn 1&2 by siRNA increases ENaC activity (175±18% over control), while overexpression of Itsns reduces ENaC activity (40±6% of control, n=8). Immunolocalization of Itsn demonstrates a vesicular staining pattern consistent with a role in mediating ENaC endocytosis. To confirm this, we performed transepithelial capacitance recordings to assess changes in membrane surface area and demonstrate an increase in membrane retrieval with Itsn overexpression. Similar to its reported role in ROMK internalization we demonstrate here that Itsn is an aldosterone‐repressed protein (via microRNAs), involved in the altering of ENaC surface expression by regulating channel endocytosis. The molecular mechanism that underlies this function is currently under investigation. Grant Funding Source : Supported by DK078917