| First Author | Shima H | Year | 1998 |
| Journal | EMBO J | Volume | 17 |
| Issue | 22 | Pages | 6649-59 |
| PubMed ID | 9822608 | Mgi Jnum | J:52107 |
| Mgi Id | MGI:1328458 | Doi | 10.1093/emboj/17.22.6649 |
| Citation | Shima H, et al. (1998) Disruption of the p70(s6k)/p85(s6k) gene reveals a small mouse phenotype and a new functional S6 kinase. EMBO J 17(22):6649-59 |
| abstractText | Recent studies have shown that the p70(s6k)/p85(s6k) signaling pathway plays a critical role in cell growth by modulating the translation of a family of mRNAs termed 5'TOPs, which encode components of the protein synthetic apparatus. Here we demonstrate that homozygous disruption of the p70(s6k)/p85(s6k) gene does not affect viability or fertility of mice, but that it has a significant effect on animal growth, especially during embryogenesis. Surprisingly, S6 phosphorylation in liver or in fibroblasts from p70(s6k)/p85(s6k)-deficient mice proceeds normally in response to mitogen stimulation. Furthermore, serum-induced S6 phosphorylation and translational up-regulation of 5'TOP mRNAs were equally sensitive to the inhibitory effects of rapamycin in mouse embryo fibroblasts derived from p70(s6k)/p85(s6k)-deficient and wild-type mice. A search of public databases identified a novel p70(s6k)/p85(s6k) homolog which contains the same regulatory motifs and phosphorylation sites known to control kinase activity. This newly identified gene product, termed S6K2, is ubiquitously expressed and displays both mitogen-dependent and rapamycin-sensitive S6 kinase activity. More striking, in p70(s6k)/p85(s6k)-deficient mice, the S6K2 gene is up-regulated in all tissues examined, especially in thymus, a main target of rapamycin action. The finding of a new S6 kinase gene, which can partly compensate for p70(s6k)/p85(s6k) function, underscores the importance of S6K function in cell growth. |
