Increased expression of pp60c-src in gastric mucosa of aged rats.
The relationship between proliferative activity and the expression of pp60c-src in gastric mucosa (oxyntic gland area) of young (4-month) and aged (24-month) Fischer 344 rats was examined. Gastric mucosal proliferative activity, as assessed by 5-bromo-2'-deoxyuridine (BrdU) immunoreactive cells, was found to be 115% (p < .001) higher in aged than in young rats. This was associated with a 47% rise (p < .025) in overall tyrosine kinase (Tyr-k) activity and a 5-7-fold increase in autophosphorylation of four prominent protein bands with M(r) of 40, 55, 60, and 70 kDa in gastric mucosal membranes. A similar phenomenon was also observed for Tyr-k activity of pp60c-src in that the aged rats revealed a 69% (p < .025) higher enzyme activity and a 5-fold rise in the extent of autophosphorylation of this protein when compared with the corresponding values from young animals. Increased Tyr-k activity of pp60c-src in the gastric mucosa of aged rats could in part be due to higher levels of this protein because the relative concentration of pp60c-src, as assessed by Western blot analysis, showed a 2-5-fold increase over the young animals. In addition, the relative concentration of c-src mRNA in the gastric mucosa of aged rats was also found to be 5-6-fold higher than in young animals. We suggest that pp60c-src may play a role in regulating gastric mucosal proliferative processes in the gastric mucosa of aged rats.
Majumdar
A P
AP
Department of Veterans Affairs Medical Center, Allen Park, Michigan.
Tureaud
J
J
Relan
N K
NK
Kessel
A
A
Dutta
S
S
Hatfield
J S
JS
Fligiel
S E
SE
D000375:Aging / Q000235:genetics* / Q000378:metabolism; D000818:Animals; D001973:Bromodeoxyuridine; D002455:Cell Division; D005753:Gastric Mucosa / Q000166:cytology / Q000201:enzymology / Q000378:metabolism*; D015870:Gene Expression; D008565:Membrane Proteins / Q000378:metabolism; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D016392:Proto-Oncogene Proteins pp60(c-src) / Q000032:analysis / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D012313:RNA / Q000032:analysis / Q000235:genetics / Q000302:isolation & purification; D051381:Rats; D011916:Rats, Inbred F344
D008565:Membrane Proteins; D012313:RNA; D011505:Protein-Tyrosine Kinases; D016392:Proto-Oncogene Proteins pp60(c-src); D001973:Bromodeoxyuridine