MEDIUM TONICITY REGULATES EXPRESSION OF THE NA--DEPENDENT BETAINE TRANSPORTER IN MADIN-DARBY CANINE KIDNEY-CELLS BY INCREASING TRANSCRIPTION OF THE TRANSPORTER GENE( DEPENDENT AND CL)
S. Uchida et al., MEDIUM TONICITY REGULATES EXPRESSION OF THE NA--DEPENDENT BETAINE TRANSPORTER IN MADIN-DARBY CANINE KIDNEY-CELLS BY INCREASING TRANSCRIPTION OF THE TRANSPORTER GENE( DEPENDENT AND CL), The Journal of clinical investigation, 91(4), 1993, pp. 1604-1607
Betaine is one of the major compatible osmolytes accumulated by kidney
derived Madin-Darby canine kidney cells cultured in hypertonic medium
. Betaine is accumulated by Na+- and Cl--dependent uptake from the med
ium. To gain insight into the mechanism by which hypertonicity evokes
an increase in the V(max) of the betaine transporter in Madin-Darby ca
nine kidney cells, we measured the relative abundance of mRNA for the
transporter in cells shifted to a hypertonic medium and found parallel
increases in mRNA abundance and cotransporter activity. The increase
in mRNA levels preceded the increase in transporter activity slightly.
Transcription of the gene for the transporter rose rapidly and to the
same relative extent as mRNA abundance in cells shifted to hypertonic
medium, indicating that transcription of the gene for the cotransport
er plays a major role in regulating the accumulation of betaine in res
ponse to hypertonicity.