Na(+)-K(+)-ATPase gene expression during in vitro development of rat fetal forebrain.
The existence of at least three isoforms of Na(+)-K(+)-ATPase in adult brain tissues [alpha 1, kidney type; alpha 2 [or alpha(+)]; alpha 3] suggests that these genes might be regulated in a cell-specific and time-dependent manner during development. We have studied this question in serum-free aggregating cell cultures of mechanically dissociated rat fetal telencephalon. At the protein level, the relative rate of synthesis of the pool of alpha 1-, alpha 2-, and alpha 3-subunits increased approximately twofold over 15 days of culture, leading to a marked increase in the immunochemical pool of alpha-subunits as measured by a panspecific polyclonal antibody. Concomitantly, Na(+)-K(+)-ATPase enzyme-specific activity increased three- (lower forebrain) to sixfold (upper forebrain). The transcripts of all three alpha-isoforms and beta-subunit were detected in vitro in similar proportion to the level observed in vivo. alpha 3-mRNA (3.7 kb) was more abundant than alpha 1 (3.7 kb) or alpha 2 (5.3 and 3.4 kb). Cytosine arabinoside (0.4 microM) and cholera toxin (0.1 microM) were used to selectively eliminate glial cells or neurons, respectively. It was found that alpha 2-mRNA is predominantly transcribed in glial cell cultures, whereas alpha 3- and beta 1-mRNA (2.7, 2.3, and 1.8 kb) are predominant in neuronal cultures.
Corthésy-Theulaz
I
I
Institut de Pharmacologie, Université de Lausanne, Switzerland.
Mérillat
A M
AM
Honegger
P
P
Rossier
B C
BC
D000818:Animals; D015152:Blotting, Northern; D001921:Brain / Q000201:enzymology*; D002449:Cell Aggregation; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000201:enzymology; D002772:Cholera Toxin / Q000494:pharmacology; D003561:Cytarabine / Q000494:pharmacology; D005314:Embryonic and Fetal Development / Q000235:genetics; D005786:Gene Expression Regulation; D007668:Kidney / Q000201:enzymology; D046911:Macromolecular Substances; D009457:Neuroglia / Q000187:drug effects; D009474:Neurons / Q000187:drug effects; D012313:RNA / Q000235:genetics / Q000302:isolation & purification; D051381:Rats; D000254:Sodium-Potassium-Exchanging ATPase / Q000235:genetics* / Q000378:metabolism; D013687:Telencephalon / Q000166:cytology / Q000196:embryology* / Q000201:enzymology
D046911:Macromolecular Substances; D003561:Cytarabine; D012313:RNA; D002772:Cholera Toxin; D000254:Sodium-Potassium-Exchanging ATPase