Growth hormone sensitivity in mice is associated with changes in signal terminators during growth

MARTINEZ CS; SOTELO AI; TURYN D; PIAZZA VG; MIQUET JG

Córdoba, Argentina

Congreso; The First South American Spring Symposium in Signal Transduction and Molecular Medicine (SISTAM); 2010

Signal Transduction and Molecular Medicine

Growth hormone (GH) is an anabolic hormone that promotes longitudinal growth. Downregulation of GH signaling is achieved by induction of suppressors of cytokine signaling (SOCS), activation of tyrosine-phosphatases and internalization/degradation of GH-GHR complex. Somatic growth exhibits two instances of rapid growth in rodents: perinatally, independent of GH, and peripuberally, dependent on GH, at the third week of age. In order to assess negative modulators of GH signaling during growth, Swiss mice of three representative ages were chosen: lactating mice (1wk), mice showing major GH response (2.5wk), and young adults (9wk). Protein levels were assayed by immunoblotting of liver extracts. Suppressors CIS and SOCS3 content was significantly higher in pups compared to young adults, the opposite was observed for SOCS2 (n=12, P<0.05). Phosphatases SHP1 and SHP2 abundance presented no age difference, while PTP1B displayed a profile similar to that of CIS and SOCS3. Although GH secretion is sexually dimorphic, no gender difference was observed for the proteins studied. We propose CIS, SOCS3 and PTP1B may modulate transition to GH-dependent growth by mitigating GH action before the onset of puberty, while SOCS2 may regulate GH action mainly in the young adult.