TY - JOUR
T1 - Induction of molecular chaperones by hyperosmotic stress in mouse inner medullary collecting duct cells
AU - Rauchman, Michael I.
AU - Pullman, James
AU - Gullans, Steven R.
PY - 1997/7
Y1 - 1997/7
N2 - The extreme hyperosmotic conditions that exist in the renal inner medulla enable the urinary concentrating mechanism to function. In this study, we evaluated whether stress-related molecular chaperones are induced in response to hyperosmotic stress in mouse inner medullary collecting duct (mIMCD3) cells. Exposure of cells to medium supplemented with 100 mM NaCl for 4 or 24 h resulted in an increase in heat shock protein-72 (HSP-72) (inducible form) by Western blot. Immunocytochemistry confirmed the increase of HSP-72 and showed that hyperosmotic stress resulted in a localization of HSP-72 predominantly to the nucleoplasm that surrounds the nucleoli and to the cytoplasm, a subcellular distribution pattern different from that seen with heat shock. Using a denatured protein (casein)-affinity column with ATP elution, we identified a number of putative molecular chaperones (46, 60, 78, and 200 kDa) that are upregulated in response to 4 h of hyperosmotic NaCl treatment. Microsequencing identified one of these proteins to be the mitochondrial chaperone mtHSP-70, a member of HSP-70 family, and another to be similar to β-actin. We also found high levels of HSP-72 in cells chronically adapted to hypertonicity, indicating that chaperones are still required to maintain certain cellular functions even after nonperturbing organic osmolytes are known to accumulate. These results suggest an important role for molecular chaperones in the adaptation of renal medullary epithelial cells to the hyperosmotic conditions that exist in the inner medulla in vivo.
AB - The extreme hyperosmotic conditions that exist in the renal inner medulla enable the urinary concentrating mechanism to function. In this study, we evaluated whether stress-related molecular chaperones are induced in response to hyperosmotic stress in mouse inner medullary collecting duct (mIMCD3) cells. Exposure of cells to medium supplemented with 100 mM NaCl for 4 or 24 h resulted in an increase in heat shock protein-72 (HSP-72) (inducible form) by Western blot. Immunocytochemistry confirmed the increase of HSP-72 and showed that hyperosmotic stress resulted in a localization of HSP-72 predominantly to the nucleoplasm that surrounds the nucleoli and to the cytoplasm, a subcellular distribution pattern different from that seen with heat shock. Using a denatured protein (casein)-affinity column with ATP elution, we identified a number of putative molecular chaperones (46, 60, 78, and 200 kDa) that are upregulated in response to 4 h of hyperosmotic NaCl treatment. Microsequencing identified one of these proteins to be the mitochondrial chaperone mtHSP-70, a member of HSP-70 family, and another to be similar to β-actin. We also found high levels of HSP-72 in cells chronically adapted to hypertonicity, indicating that chaperones are still required to maintain certain cellular functions even after nonperturbing organic osmolytes are known to accumulate. These results suggest an important role for molecular chaperones in the adaptation of renal medullary epithelial cells to the hyperosmotic conditions that exist in the inner medulla in vivo.
KW - Heat shock protein-70
KW - Heat shock proteins
KW - Mitochondrial chaperone heat shock protein-70
KW - Osmotic stress
KW - Renal medulla
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U2 - 10.1152/ajprenal.1997.273.1.f9
DO - 10.1152/ajprenal.1997.273.1.f9
M3 - Article
C2 - 9249587
AN - SCOPUS:0030845194
SN - 1931-857X
VL - 273
SP - F9-F17
JO - American Journal of Physiology - Renal Physiology
JF - American Journal of Physiology - Renal Physiology
IS - 1 42-1
ER -