Hyperosmolarity-induced gene stimulation is mediated by the negative calcium responsive element.
The negative calcium responsive elements of the parathyroid hormone gene bind to a specific set of nuclear proteins in an extracellular calcium (Ca2+e)-dependent manner. We have found that one of the negative calcium responsive elements, named oligo B, is found in the 5'-flanking region of such vasoactive genes as the vasopressin and atrial natriuretic polypeptide genes. Furthermore, the oligo B-like sequence in the former gene is conserved throughout evolution. Because expression of some of these vasoactive genes is altered by external stimuli which change cell volume, we examined whether oligo B is involved in gene regulation by hyperosmolarity. Here, we demonstrate that the binding between oligo B and its binding nuclear proteins including a redox factor 1 was reduced by hyperosmolarity generated by sodium chloride but not by urea. Such attenuated binding was reversed by dephosphorylating nuclear proteins by a potato acid phosphatase, suggesting that NaCl treatment elicited phosphorylation of these nuclear proteins to weaken their binding activity to oligo B. Furthermore, these nuclear events led to hyperosmolarity-mediated transcriptional stimulation of the genes bearing this DNA element in the cultured cells.
Okazaki
T
T
Endocrine Genetics and Hypertension Unit, 4th Department of Internal Medicine, University of Tokyo School of Medicine, Bunkyo-ku, Tokyo 112, Japan. okbgeni-tky@umin.u-tokyo.ac
Ishikawa
T
T
Nishimori
S
S
Igarashi
T
T
Hata
K
K
Fujita
T
T
D002118:Calcium / Q000378:metabolism*; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D015500:Chloramphenicol O-Acetyltransferase / Q000235:genetics; D005786:Gene Expression Regulation / Q000502:physiology*; D005822:Genetic Vectors; D006367:HeLa Cells; D006801:Humans; D009994:Osmolar Concentration; D010766:Phosphorylation; D014158:Transcription, Genetic
D015500:Chloramphenicol O-Acetyltransferase; D002118:Calcium