AJP - Renal Physiology, Vol 257, Issue 6 1039-F1049, Copyright © 1989 by American Physiological Society
Isolation of mutant renal (LLC-PK1) epithelia defective in basolateral, Na(+)-independent glucose transport
J. M. Mullin, K. V. Snock, M. T. McGinn and L. M. Kofeldt
Lankenau Medical Research Center, Philadelphia, Pennsylvania 19151.
To obtain mutant renal epithelia defective in the uptake of 2-deoxyglucose
(Na(+)-independent glucose transport), LLC-PK1 renal epithelial cells were
subjected to a combination of DNA alkylation, tritium-suicide with
2-[3H]deoxyglucose, and replica plating. One of the mutant sublines
obtained, LLC-PK1M-7A, possesses only 40% of the 2-deoxyglucose uptake rate
of the parent line, LLC-PK1M, and this defect is stable over at least 30
population doublings. Initial rate of 3-O-methylglucose transport into
these mutant cells is only 20% of the parental rate, and efflux of
3-O-methylglucose from the mutant cells is correspondingly low. Glucose
metabolism in the mutant cells does not appear to be altered, nor is free
glucose accumulated in the cells against a concentration gradient. The
uptake rate of L-leucine is the same in both mutant and parent, whereas the
(Na(+)-dependent) uptake of alpha-methyl-D-glucoside and
methylaminoisobutyric acid is greater in the mutant than the parent. The
population doubling times of LLC-PK1M and LLC-PK1M-7A cultures are similar.
LLC-PK1M-7A cell morphology is similar to LLC-PK1M when cultures are
subconfluent, but on reaching confluence, LLC-PK1M-7A appear larger than
LLC-PK1M cells. Their measured cell volume is then 150% of the volume of
the parent cells. Future studies of the LLC-PK1M-7A mutant, and acquisition
of additional mutant sublines, should elucidate the roles of
transepithelial glucose transport in proximal tubular cell physiology.
