Nuclear accumulation of multiple protein kinases during prolactin-induced proliferation of Nb2 rat lymphoma cells.
Intracellular kinases play important roles in signal transduction and are involved in the surface receptor-mediated regulation of cellular functions, including mitogenesis. In the present study, we examined the possible involvement of various protein kinases in the passage of a mitogenic signal from the cell surface to the nucleus of Nb2 cells, a rat nodal lymphoma cell line in which prolactin is a mitogen. Following a prolactin challenge, various kinase activities were monitored at short intervals in different cellular fractions over a 60 min period. Protein kinase C (PKC) activity in the cytosolic fraction rapidly declined to 50% of its original activity within the first 30 min, while PKC activity in the nuclear fractions increased sharply, reaching its highest level by 30 min following a prolactin challenge. There were also increases in both casein kinase and protein tyrosine kinase (PTK) activities in the nuclear fractions during the first 30 min following a prolactin challenge that paralleled PKC activity. The activities of all three kinases declined thereafter, reaching levels close to their respective basal values by 60 min following initiation of prolactin treatment. These observations suggest the possibility that multiple protein kinases may be involved in mitogenic signal transduction for prolactin in Nb2 cells.
Ganguli
S
S
Indiana University School of Medicine, Terre Haute Center for Medical Education 47809, USA.
Hu
L
L
Menke
P
P
Collier
R J
RJ
Gertler
A
A
D015720:5'-Nucleotidase / Q000378:metabolism; D000818:Animals; D047388:Casein Kinases; D002455:Cell Division / Q000187:drug effects; D002458:Cell Fractionation; D002467:Cell Nucleus / Q000187:drug effects / Q000201:enzymology* / Q000648:ultrastructure; D004273:DNA, Neoplasm / Q000187:drug effects; D008223:Lymphoma; D008854:Microscopy, Electron; D011388:Prolactin / Q000494:pharmacology*; D011493:Protein Kinase C / Q000378:metabolism; D011494:Protein Kinases / Q000235:genetics* / Q000378:metabolism*; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D051381:Rats; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D013953:Thymus Neoplasms; D014178:Translocation, Genetic; D014407:Tumor Cells, Cultured / Q000166:cytology / Q000187:drug effects / Q000201:enzymology
D004273:DNA, Neoplasm; D011388:Prolactin; D011494:Protein Kinases; D011505:Protein-Tyrosine Kinases; D047388:Casein Kinases; D011493:Protein Kinase C; D015720:5'-Nucleotidase