Regulation of IGF-I mRNA and signal transducers and activators of transcription-3 and -5 (Stat-3 and -5) by GH in C2C12 myoblasts

Robert A. Frost, Gerald J. Nystrom, Charles H. Lang

Research output: Contribution to journalArticle

70 Citations (Scopus)

Abstract

GH and IGF-I are critical hormones for the regulation of longitudinal growth and the maintenance of lean body mass in humans. The regulation of IGF-I expression by GH in hepatocytes is well documented; however less is known about the regulation of IGF-I in peripheral tissues such as muscle. We have examined the regulation of IGF-I mRNA by GH and IGF-I in C2C12 myoblasts. GH stimulated the accumulation of IGF-I mRNA dose- and time-dependently. An elevation of IGF-I mRNA was observed with GH doses as low as 0.75 ng/ml and after exposure to GH for as little as 1 h, and the increase required ongoing transcription and translation. GH applied in a pulsatile fashion for 10 min followed by an 8-h interpulse interval increased IGF-I mRNA to a greater extent than continuous exposure. GH stimulated tyrosine phosphorylation of the GH receptor, signal transducer and activator of transcription-3 (Stat3), and Stat5. Stat5 was resistant to additional phosphorylation if cells were given a GH pulse within 2 h of a previous GH exposure. The refractory period lasted for 4 h, and cells could be maximally stimulated again after 6 h. Stat3 phosphorylation was also enhanced in cells that were allowed to recover from a previous application of GH. The tyrosine kinase inhibitors, genistein, PP1, and AG-490, and the MAPK kinase inhibitor, PD98059, did not block Stat3 or Stat5 phosphorylation. In contrast, WHI-P154, a Janus kinase-3 inhibitor, dose-dependently prevented Stat3, but not Stat5, phosphorylation. GH-inducible nuclear transport of Stat3 was likewise inhibited by WHI-P154. Most importantly, GH-dependent IGF-I mRNA expression was inhibited by WHIP154. In contrast, IGF-I mRNA expression was inhibited by IGF-I peptide, and the effect of IGF-I was dominant over that of GH. IGF-I mRNA was regulated by both PI3K and MAPK signal transduction pathways, but IGF-I peptide signaled predominantly through a wortmannin-sensitive pathway to down-regulate its own mRNA. Our data suggest that Janus kinases (Jak2 or Jak3) and their downstream targets (Stat3 and Stat5) may play important roles in the expression of IGF-I mRNA and the myoblast response to GH. In addition, C2C12 cells appear to be a good model system to examine GH regulation of Janus kinase/Stat signaling and the regulation of IGF-I mRNA.

Original languageEnglish (US)
Pages (from-to)492-503
Number of pages12
JournalEndocrinology
Volume143
Issue number2
DOIs
StatePublished - Jan 1 2002

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STAT5 Transcription Factor
STAT3 Transcription Factor
Myoblasts
Insulin-Like Growth Factor I
Messenger RNA
Phosphorylation
Janus Kinases
Janus Kinase 3
Peptides
Cell Nucleus Active Transport

All Science Journal Classification (ASJC) codes

  • Endocrinology

Cite this

@article{1938e68387bf410fa5c4c0f22b5cad16,
title = "Regulation of IGF-I mRNA and signal transducers and activators of transcription-3 and -5 (Stat-3 and -5) by GH in C2C12 myoblasts",
abstract = "GH and IGF-I are critical hormones for the regulation of longitudinal growth and the maintenance of lean body mass in humans. The regulation of IGF-I expression by GH in hepatocytes is well documented; however less is known about the regulation of IGF-I in peripheral tissues such as muscle. We have examined the regulation of IGF-I mRNA by GH and IGF-I in C2C12 myoblasts. GH stimulated the accumulation of IGF-I mRNA dose- and time-dependently. An elevation of IGF-I mRNA was observed with GH doses as low as 0.75 ng/ml and after exposure to GH for as little as 1 h, and the increase required ongoing transcription and translation. GH applied in a pulsatile fashion for 10 min followed by an 8-h interpulse interval increased IGF-I mRNA to a greater extent than continuous exposure. GH stimulated tyrosine phosphorylation of the GH receptor, signal transducer and activator of transcription-3 (Stat3), and Stat5. Stat5 was resistant to additional phosphorylation if cells were given a GH pulse within 2 h of a previous GH exposure. The refractory period lasted for 4 h, and cells could be maximally stimulated again after 6 h. Stat3 phosphorylation was also enhanced in cells that were allowed to recover from a previous application of GH. The tyrosine kinase inhibitors, genistein, PP1, and AG-490, and the MAPK kinase inhibitor, PD98059, did not block Stat3 or Stat5 phosphorylation. In contrast, WHI-P154, a Janus kinase-3 inhibitor, dose-dependently prevented Stat3, but not Stat5, phosphorylation. GH-inducible nuclear transport of Stat3 was likewise inhibited by WHI-P154. Most importantly, GH-dependent IGF-I mRNA expression was inhibited by WHIP154. In contrast, IGF-I mRNA expression was inhibited by IGF-I peptide, and the effect of IGF-I was dominant over that of GH. IGF-I mRNA was regulated by both PI3K and MAPK signal transduction pathways, but IGF-I peptide signaled predominantly through a wortmannin-sensitive pathway to down-regulate its own mRNA. Our data suggest that Janus kinases (Jak2 or Jak3) and their downstream targets (Stat3 and Stat5) may play important roles in the expression of IGF-I mRNA and the myoblast response to GH. In addition, C2C12 cells appear to be a good model system to examine GH regulation of Janus kinase/Stat signaling and the regulation of IGF-I mRNA.",
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Regulation of IGF-I mRNA and signal transducers and activators of transcription-3 and -5 (Stat-3 and -5) by GH in C2C12 myoblasts. / Frost, Robert A.; Nystrom, Gerald J.; Lang, Charles H.

In: Endocrinology, Vol. 143, No. 2, 01.01.2002, p. 492-503.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Regulation of IGF-I mRNA and signal transducers and activators of transcription-3 and -5 (Stat-3 and -5) by GH in C2C12 myoblasts

AU - Frost, Robert A.

AU - Nystrom, Gerald J.

AU - Lang, Charles H.

PY - 2002/1/1

Y1 - 2002/1/1

N2 - GH and IGF-I are critical hormones for the regulation of longitudinal growth and the maintenance of lean body mass in humans. The regulation of IGF-I expression by GH in hepatocytes is well documented; however less is known about the regulation of IGF-I in peripheral tissues such as muscle. We have examined the regulation of IGF-I mRNA by GH and IGF-I in C2C12 myoblasts. GH stimulated the accumulation of IGF-I mRNA dose- and time-dependently. An elevation of IGF-I mRNA was observed with GH doses as low as 0.75 ng/ml and after exposure to GH for as little as 1 h, and the increase required ongoing transcription and translation. GH applied in a pulsatile fashion for 10 min followed by an 8-h interpulse interval increased IGF-I mRNA to a greater extent than continuous exposure. GH stimulated tyrosine phosphorylation of the GH receptor, signal transducer and activator of transcription-3 (Stat3), and Stat5. Stat5 was resistant to additional phosphorylation if cells were given a GH pulse within 2 h of a previous GH exposure. The refractory period lasted for 4 h, and cells could be maximally stimulated again after 6 h. Stat3 phosphorylation was also enhanced in cells that were allowed to recover from a previous application of GH. The tyrosine kinase inhibitors, genistein, PP1, and AG-490, and the MAPK kinase inhibitor, PD98059, did not block Stat3 or Stat5 phosphorylation. In contrast, WHI-P154, a Janus kinase-3 inhibitor, dose-dependently prevented Stat3, but not Stat5, phosphorylation. GH-inducible nuclear transport of Stat3 was likewise inhibited by WHI-P154. Most importantly, GH-dependent IGF-I mRNA expression was inhibited by WHIP154. In contrast, IGF-I mRNA expression was inhibited by IGF-I peptide, and the effect of IGF-I was dominant over that of GH. IGF-I mRNA was regulated by both PI3K and MAPK signal transduction pathways, but IGF-I peptide signaled predominantly through a wortmannin-sensitive pathway to down-regulate its own mRNA. Our data suggest that Janus kinases (Jak2 or Jak3) and their downstream targets (Stat3 and Stat5) may play important roles in the expression of IGF-I mRNA and the myoblast response to GH. In addition, C2C12 cells appear to be a good model system to examine GH regulation of Janus kinase/Stat signaling and the regulation of IGF-I mRNA.

AB - GH and IGF-I are critical hormones for the regulation of longitudinal growth and the maintenance of lean body mass in humans. The regulation of IGF-I expression by GH in hepatocytes is well documented; however less is known about the regulation of IGF-I in peripheral tissues such as muscle. We have examined the regulation of IGF-I mRNA by GH and IGF-I in C2C12 myoblasts. GH stimulated the accumulation of IGF-I mRNA dose- and time-dependently. An elevation of IGF-I mRNA was observed with GH doses as low as 0.75 ng/ml and after exposure to GH for as little as 1 h, and the increase required ongoing transcription and translation. GH applied in a pulsatile fashion for 10 min followed by an 8-h interpulse interval increased IGF-I mRNA to a greater extent than continuous exposure. GH stimulated tyrosine phosphorylation of the GH receptor, signal transducer and activator of transcription-3 (Stat3), and Stat5. Stat5 was resistant to additional phosphorylation if cells were given a GH pulse within 2 h of a previous GH exposure. The refractory period lasted for 4 h, and cells could be maximally stimulated again after 6 h. Stat3 phosphorylation was also enhanced in cells that were allowed to recover from a previous application of GH. The tyrosine kinase inhibitors, genistein, PP1, and AG-490, and the MAPK kinase inhibitor, PD98059, did not block Stat3 or Stat5 phosphorylation. In contrast, WHI-P154, a Janus kinase-3 inhibitor, dose-dependently prevented Stat3, but not Stat5, phosphorylation. GH-inducible nuclear transport of Stat3 was likewise inhibited by WHI-P154. Most importantly, GH-dependent IGF-I mRNA expression was inhibited by WHIP154. In contrast, IGF-I mRNA expression was inhibited by IGF-I peptide, and the effect of IGF-I was dominant over that of GH. IGF-I mRNA was regulated by both PI3K and MAPK signal transduction pathways, but IGF-I peptide signaled predominantly through a wortmannin-sensitive pathway to down-regulate its own mRNA. Our data suggest that Janus kinases (Jak2 or Jak3) and their downstream targets (Stat3 and Stat5) may play important roles in the expression of IGF-I mRNA and the myoblast response to GH. In addition, C2C12 cells appear to be a good model system to examine GH regulation of Janus kinase/Stat signaling and the regulation of IGF-I mRNA.

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