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Hyperosmolarity stimulates heat shock protein 40 and 70 interaction with UT‐A1 urea transporter
Author(s) -
Chen Guangping,
Feng Xiuyang,
Frohlich Otto,
Yang Yuan,
Klein Janet D,
Sands Jeff M
Publication year - 2010
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.24.1_supplement.1024.27
Subject(s) - hsp70 , osmotic concentration , heat shock protein , urea , chemistry , transporter , osmotic shock , transfection , extracellular , intracellular , hsp90 , biochemistry , microbiology and biotechnology , biology , gene
Hyperosmolarity increases urea transporter UT‐A1 activity in the kidney inner medulla. Osmotic stress induces heat shock protein (HSP) expression. When using a 126‐aa fragment of the intracellular N‐terminus of UT‐A1 as bait in a yeast two‐hybrid assay, we identified heat shock protein 40 (HSP40) as a UT‐A1 interacting protein. HSP40 functions to regulate complex formation between HSP70 and client proteins. HSP70 has been shown to regulate water channel (AQP2), K+ channel, and CFTR activity. Increasing osmolarity (300 to 800 mOsm) by addition of NaCl in 0.5% FCS DMEM for 30 min increased both UT‐A1 and HSP40 expression in native IMCD suspension. We examined the direct interaction of UT‐A1 and heat shock proteins in HEK293 cells co‐transfected with UT‐A1, FLAG‐HSP40 and/or FLAG‐HSP70. Hyperosmolarity (500 mOsm for 30 min) enhanced HSP70 binding to UT‐A1. Functionally, co‐injection of UT‐A1 with HSP40 or HSP70 in oocytes increased UT‐A1 activity but it did not reach statistical significance. However, co‐injection of UT‐A1 with both HSP40 and HSP70 significantly increased UT‐A1 urea transport activity. In our study, we found that HSP40 is associated with UT‐A1 and regulates UT‐A1 urea transport activity in collaboration with HSP70.