Restoration of responsiveness to phorbol ester by reconstitution of a functional Na/K/Cl cotransporter in cotransporter-deficient BALB/c 3T3 cells

✍ Scribed by Yongjun Guo; Thomas G. O'Brien

• Publisher: John Wiley and Sons
• Year: 1996
• Tongue: English
• Weight: 698 KB
• Volume: 17
• Category: Article
• ISSN: 0899-1987
• DOI: 10.1002/(sici)1098-2744(199609)17:1<35::aid-mc5>3.0.co;2-j

✦ Synopsis

Previous studies in this laboratory have implicated the membrane transport protein Na/WCI cotransporter (NKCC1) as an important component of the signaling pathways activated by phorbol esters in BALB/c 3T3 cells.

The NKCC1 protein functions as a Na/WCI cotransporter in BALBlc 3T3 cells and many other cell types. Loss of NKCC1 function has been associated with loss of mitogenic responsiveness to phorbol ester. Here we report that expression of a cloned NKCCl cDNA fused to a tetracycline-regulated promoter in BALB/c 3T3 cells deficient in Na/WCI cotransport activity (clone El 2a cells) restored cotransport function. Compared with parental cotransport-deficient cells, transfected clones expressing the exogenous NKCCl gene responded like typical BALBk 3T3 cells to 12-0-tetradecanoylphorbol-13-acetate: loop diuretic-sensitive ffiRb' flux was inhibited, cell volume was decreased, and cell growth was stimulated. These results support our previous conclusion that the loss of responsiveness of El2a cells t o phorbol ester is caused by mutation of the endogenous NKCCl gene.