Serum factors induce C-fos expression and rapid cell proliferation in adolescent but not in infant rat proximal tubule cells.
Kidney epithelial cells in short-term primary culture have been studied with regard to proliferative rate and expression on the c-fos protooncogene. The experiments were performed on subconfluent renal proximal tubule cells isolated from infant and adolescent rats. Proliferation was determined by 3H-thymidine autoradiography and nuclear content of c-fos protein by semiquantitative immunofluorescence. The basal proliferative rates in infant and adolescent renal proximal tubule cells were the same after 48 h of primary culture in Dulbecco's modified Eagle's medium with 10% FCS. Serum deprivation for 24 h caused a significant growth inhibition in both infant and adolescent cells. C-fos was expressed to the same extent in infant and adolescent serum-deprived cells. The rapid response to the addition of serum was markedly different in infant and adolescent cells. In adolescent cells, addition of serum led to a transient significant increase in the nuclear expression of c-fos protein, reaching a peak at 60 min. No increase in c-fos was seen in infant cells. In adolescent cells, the rate of proliferation increased 11-fold and 3H-thymidine labeling index reached 26.7 +/- 4.3%. In infant cells, the proliferative response to serum addition was significantly lower; the labeling index reached only 4.2 +/- 1.2%. It could be excluded that the attenuated response in infant cells was due to cell death or impaired metabolic function. The results imply that the principles of growth regulation change postnatally.
Larsson
S H
SH
Department of Pediatrics, St. Göran's Children's Hospital, Stockholm, Sweden.
Hultgårdh-Nilsson
A
A
Kölare
S
S
Luthman
J
J
Sejersen
T
T
Aperia
A
A
D000367:Age Factors; D000818:Animals; D002455:Cell Division; D002478:Cells, Cultured; D003470:Culture Media; D015870:Gene Expression; D007687:Kidney Tubules, Proximal / Q000166:cytology* / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism; D016760:Proto-Oncogene Proteins c-fos; D011519:Proto-Oncogenes; D051381:Rats; D011919:Rats, Inbred Strains
D003470:Culture Media; D011518:Proto-Oncogene Proteins; D016760:Proto-Oncogene Proteins c-fos