| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
1 Institute of Physiology, University of Innsbruck, A-6010 Innsbruck, Austria; and 2 Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, Colorado 80523-1870
LLC-PK1-FBPase+ cells, which are
a gluconeogenic substrain of porcine renal LLC-PK1
cells, exhibit enhanced oxidative metabolism and increased levels of
phosphate-dependent glutaminase (PDG) activity. On adaptation to acidic
medium (pH 6.9, 9 mM HCO
3), LLC-PK1-FBPase+ cells also exhibit a greater
increase in ammonia production and respond with an increase in
assayable PDG activity. The changes in PDG mRNA levels were examined by
using confluent cells grown on plastic dishes or on permeable membrane
inserts. The latter condition increased the state of differentiation of
the LLC-PK1-FBPase+ cells. The levels of the
primary porcine PDG mRNAs were analyzed by using probes that are
specific for the 5.0-kb PDG mRNA (p2400) or that react equally with
both the 4.5- and 5.0-kb PDG mRNAs (p930 and r1500). In confluent dish-
and filter-grown LLC-PK1-FBPase+ cells, the
predominant 4.5-kb PDG mRNA is increased threefold after 18 h in acidic
media. However, in filter-grown epithelia, which sustain an imposed pH
and HCO3 gradient, this adaptive
increase is observed only when acidic medium is applied to both the
apical and the basolateral sides of the epithelia. Half-life
experiments established that induction of the 4.5-kb PDG mRNA was due
to its stabilization. An identical pattern of adaptive increases was
observed for the cytosolic PEPCK mRNA. In contrast, no adaptive changes
were observed in the levels of the 5.0-kb PDG mRNA in either cell
culture system. Furthermore, cultures were incubated in low-potassium
(0.7 mM) media for 24-72 h to decrease intracellular pH while
maintaining normal extracellular pH.
LLC-PK1-FBPase+ cells again responded with
increased rates of ammonia production and increased levels of the
4.5-kb PDG and PEPCK mRNAs, suggesting that an intracellular acidosis
is the initiator of this adaptive response. Because all of the observed
responses closely mimic those characterized in vivo, the
LLC-PK1-FBPase+ cells represent a valuable
tissue culture model to study the molecular mechanisms that regulate
renal gene expression in response to changes in acid-base balance.
metabolic acidosis; ammoniagenesis; gluconeogenesis; phosphoenolpyruvate carboxykinase; renal cell culture
This article has been cited by other articles:
|
|
 |
|
  M. Andratsch, E. Feifel, L. Taylor, M. O'Hayre, H. Schramek, N. P. Curthoys, and G. Gstraunthaler TGF-beta signaling and its effect on glutaminase expression in LLC-PK1-FBPase+ cells Am J Physiol Renal Physiol, September 1, 2007; 293(3): F846 - F853. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. Oliver III, E. Friday, F. Turturro, A. Lacy, and T. Welbourne Troglitazone's rapid and sustained activation of ERK1/2 induces cellular acidosis in LLC-PK1-F+ cells: physiological responses Am J Physiol Renal Physiol, June 1, 2005; 288(6): F1257 - F1266. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
T. Welbourne, E. Friday, R. Fowler, F. Turturro, and I. Nissim Troglitazone acts by PPAR{gamma} and PPAR{gamma}-independent pathways on LLC-PK1-F+ acid-base metabolism Am J Physiol Renal Physiol, January 1, 2004; 286(1): F100 - F110. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
E. Feifel, P. Obexer, M. Andratsch, S. Euler, L. Taylor, A. Tang, Y. Wei, H. Schramek, N. P. Curthoys, and G. Gstraunthaler p38 MAPK mediates acid-induced transcription of PEPCK in LLC-PK1-FBPase+ cells Am J Physiol Renal Physiol, October 1, 2002; 283(4): F678 - F688. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 L. D. Porter, H. Ibrahim, L. Taylor, and N. P. Curthoys Complexity and species variation of the kidney-type glutaminase gene Physiol Genomics, June 3, 2002; 9(3): 157 - 166. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
N. P. Curthoys and G. Gstraunthaler Mechanism of increased renal gene expression during metabolic acidosis Am J Physiol Renal Physiol, September 1, 2001; 281(3): F381 - F390. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 T. Welbourne, R. Routh, M. Yudkoff, and I. Nissim The Glutamine/Glutamate Couplet and Cellular Function Physiology, August 1, 2001; 16(4): 157 - 160. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 O. F. LATERZA and N. P. CURTHOYS Effect of Acidosis on the Properties of the Glutaminase mRNA pH-Response Element Binding Protein J. Am. Soc. Nephrol., September 1, 2000; 11(9): 1583 - 1588. [Abstract] [Full Text]
|
|
|
|
|
|
O. F. Laterza and N. P. Curthoys Specificity and functional analysis of the pH-responsive element within renal glutaminase mRNA Am J Physiol Renal Physiol, June 1, 2000; 278(6): F970 - F977. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Visit Other APS Journals Online |
