scholarly journals Role of the Insulin-Like Growth Factor I Decline in the Induction of Atrogin-1/MAFbx during Fasting and Diabetes

Endocrinology ◽  
2004 ◽  
Vol 145 (11) ◽  
pp. 4806-4812 ◽  
Author(s):  
Mischael Dehoux ◽  
Ronald Van Beneden ◽  
Nevi Pasko ◽  
Pascale Lause ◽  
Josiane Verniers ◽  
...  
Keyword(s):  
Growth Factor ◽  
Effective Dose ◽  
Fold Increase ◽  
Muscle Cells ◽  
Inhibitory Effect ◽  
Physiological Concentration ◽  
Igf I ◽  
Transcriptional Effect ◽  
The Relationship

Abstract In catabolic conditions, atrogin-1/MAFbx, a muscle-specific ubiquitin-ligase required for muscle atrophy, is increased, and concentrations of IGF-I, a growth factor known to have antiproteolytic action, are reduced. To define the relationship between the decline in IGF-I and the induction of atrogin-1/MAFbx, we studied the effect of IGF-I replacement on atrogin-1/MAFbx mRNA in rats fasted for 51 h and in rats made diabetic with streptozotocin (STZ). Fasting produced a 5.8-fold increase in atrogin-1/MAFbx (P < 0.001). This was attenuated to a 2.5-fold increase by injections of IGF-I (P < 0.05 vs. fasting). Animals with STZ-induced diabetes experienced a 15.1-fold increase in atrogin-1/MAFbx (P < 0.001). Normalization of their circulating IGF-I concentrations by IGF-I infusion blunted the induction of atrogin-1/MAFbx to 6.3-fold (P < 0.05 vs. STZ diabetes without IGF-I). To further delineate the regulation of atrogin-1/MAFbx by IGF-I, we studied a model of cultured muscle cells. We observed that IGF-I produced a time- and dose-dependent reduction of atrogin-1/MAFbx mRNA, with a 50% effective dose of 5 nm IGF-I, a physiological concentration. The degradation rate of atrogin-1/MAFbx mRNA was not affected by IGF-I, suggesting that the reduction of atrogin-1/MAFbx mRNA by IGF-I is a transcriptional effect. Exposure of muscle cells in culture to dexamethasone increased atrogin-1/MAFbx mRNA with a 50% effective dose of 10 nm, a pharmacological concentration. In the presence of dexamethasone, IGF-I at physiological concentrations retained its full inhibitory effect on atrogin-1/MAFbx mRNA. We conclude that IGF-I inhibits atrogin-1/MAFbx expression and speculate that this effect might contribute to the antiproteolytic action of IGF-I in muscle.

scholarly journals FoxO1 is not a key transcription factor in the regulation of myostatin (mstn-1a and mstn-1b) gene expression in trout myotubes

2011 ◽  
Vol 301 (1) ◽  
pp. R97-R104 ◽  
Author(s):  
Iban Seiliez ◽  
Nathalie Sabin ◽  
Jean-Charles Gabillard
Keyword(s):  
Gene Expression ◽  
Transcription Factor ◽  
Growth Factor ◽  
Nuclear Translocation ◽  
Protein Activity ◽  
Gh Treatment ◽  
Its Gene ◽  
Igf I ◽  
The Relationship

In mammals, much evidence has demonstrated the important role of myostatin (MSTN) in regulating muscle mass and identified the transcription factor forkhead box O (FoxO) 1 as a key regulator of its gene expression during atrophy. However, in trout, food deprivation leads to muscle atrophy without an increase of the expression of mstn genes in the muscle. We therefore studied the relationship between FoxO1 activity and the expression of both mstn genes ( mstn1a and mstn1b) in primary culture of trout myotubes. To this aim, two complementary studies were undertaken. In the former, FoxO1 protein activity was modified with insulin-like growth factor-I (IGF-I) treatment, and the consequences on the expression of both mstn genes were monitored. In the second experiment, the expression of both studied genes was modified with growth hormone (GH) treatment, and the activation of FoxO1 protein was investigated. We found that IGF-I induced the phosphorylation of FoxO1 and FoxO4. Moreover, under IGF-I stimulation, FoxO1 was no longer localized in the nucleus, indicating that this growth factor inhibited FoxO1 activity. However, IGF-I treatment had no effect on mstn1a and mstn1b expression, suggesting that FoxO1 would not regulate the expression of mstn genes in trout myotubes. Furthermore, the treatment of myotubes with GH decreased the expression of both mstn genes but has no effect on the phosphorylation of FoxO1, FoxO3, and FoxO4 nor on the nuclear translocation of FoxO1. Altogether, our results showed that mstn1a and mstn1b expressions were not associated with FoxO activity, indicating that FoxO1 is likely not a key regulator of mstn genes in trout myotubes.

Regulation of insulin-like growth factor-I gene expression by growth factors in cultured vascular smooth muscle cells

1990 ◽  
Vol 125 (3) ◽  
pp. 381-386 ◽  
Author(s):  
K. E. Bornfeldt ◽  
H. J. Arnqvist ◽  
G. Norstedt
Keyword(s):  
Gene Expression ◽  
Smooth Muscle ◽  
Growth Factor ◽  
Smooth Muscle Cells ◽  
Muscle Cells ◽  
Basic Fgf ◽  
Aortic Smooth Muscle ◽  
Factor I ◽  
Igf I ◽  
I Gene

ABSTRACT The aim of this investigation was to study the regulation of insulin-like growth factor-I (IGF-I) gene expression in cultured rat aortic smooth muscle cells. Near-confluent cells were deprived of serum for 24 h and then exposed to IGF-I, insulin, serum, basic fibroblast growth factor (basic FGF), platelet-derived growth factor (PDGF-BB; consisting of B-chain homodimer) or GH for 24 h. Levels of IGF-I mRNA were measured by solution hybridization. The level of IGF-I mRNA was markedly decreased by 10% (v/v) newborn calf serum (78 ± 4 (s.e.m.) % decrease), 1 nmol basic FGF/1 (53 ± 8%), and 1 nmol PDGF-BB/1 (40 ± 3%) when measured after 24 h. The effect of PDGF-BB was significant after 6 h and became more marked after 24 h. GH (1 nmol/l or 0.1 μmol/l or insulin (1 nmol/l had no effect after 24 h, whereas IGF-I (1 nmol/l and insulin (10 μmol/l increased IGF-I mRNA 64 ± 20% and 46±14% respectively. The increase caused by IGF-I was demonstrated after 3 h, and was most marked after 24 h. Using Northern blot analysis of cultured aortic smooth muscle cells, IGF-I transcripts of 7-4, 1.7 and 1.1–0.8 kilobases were observed. Exposure of the cells to 10% serum, 1 nmol basic FGF/1 or 1 nmol PDGF-BB/1 for 48 h increased the cell number by 104 ±7%, 64 ± 3% and 61±22% respectively, while IGF-I, insulin and GH had little effect. In conclusion, IGF-I, and high concentrations of insulin, increased IGF-I mRNA in vascular smooth muscle cells, whereas factors which were stronger mitogens decreased IGF-I gene expression. Journal of Endocrinology (1990) 125, 381–386

The role of insulin-like growth factor-I (IGF-I) and estradiol in rabbit corpus luteum progesterone production

Endocrine ◽  
1997 ◽  
Vol 6 (1) ◽  
pp. 73-77 ◽  
Author(s):  
Serena H. Chen ◽  
Vanna Zanagnolo ◽  
Sangchai Preutthipan ◽  
Kenneth P. Roberts ◽  
Sandra B. Goodman ◽  
...  
Keyword(s):  
Growth Factor ◽  
Corpus Luteum ◽  
Insulin Like Growth Factor ◽  
Factor I ◽  
Progesterone Production ◽  
Igf I ◽  
Growth Factor I

The (Na+/K+)-ATPase Activity in the Developing Rat Retina: The Role of Insulin-Like Growth Factor-I (IGF-I)

2014 ◽  
Vol 35 (2) ◽  
pp. 243-254 ◽  
Author(s):  
Sheila Maturana-Teixeira ◽  
Luis Eduardo Gomes Braga ◽  
Raul Carpi Santos ◽  
Karin da Costa Calaza ◽  
Elizabeth Giestal-de-Araujo ◽  
...  
Keyword(s):  
Growth Factor ◽  
Atpase Activity ◽  
Insulin Like Growth Factor ◽  
Rat Retina ◽  
Factor I ◽  
Igf I ◽  
Growth Factor I ◽  
Developing Rat

The calcium signal for BALB/MK keratinocyte terminal differentiation counteracts epidermal growth factor (EGF) very early in the EGF-induced proliferative pathway

1988 ◽  
Vol 8 (2) ◽  
pp. 557-563
Author(s):  
P P Di Fiore ◽  
J Falco ◽  
I Borrello ◽  
B Weissman ◽  
S A Aaronson
Keyword(s):  
Growth Factor ◽  
Epidermal Growth Factor ◽  
Dna Synthesis ◽  
Fold Increase ◽  
Inhibitory Effect ◽  
Lymphoid Cells ◽  
Epidermal Keratinocytes ◽  
Calcium Signal ◽  
High Calcium ◽  
Epidermal Growth

BALB/MK mouse epidermal keratinocytes require epidermal growth factor (EGF) for proliferation and terminally differentiate in response to high calcium concentrations. We show that EGF is an extremely potent mitogen, causing BALB/MK cultures to enter the cell cycle in a synchronous manner associated with a greater than 100-fold increase in DNA synthesis. Analysis of the expression of proto-oncogenes which have been reported to be activated during the cascade of events following growth factor stimulation of fibroblasts or lymphoid cells revealed a very rapid but transient 100-fold increase in c-fos RNA but little or no effect on the other proto-oncogenes analyzed. Exposure of EGF-synchronized BALB/MK cells to high levels of calcium was associated with a striking decrease in the early burst of c-fos RNA as well as the subsequent peak of cell DNA synthesis. Since the inhibitory effect of high calcium on c-fos RNA expression was measurable within 30 min, our studies imply that the EGF proliferative and calcium differentiation signals must interact very early in the pathway of EGF-induced proliferation. Our results also establish that c-fos RNA modulation is an important early marker of cell proliferation in epithelial as well as mesenchymal cells.

PDGF-BB-induced DNA synthesis is delayed by angiotensin II in vascular smooth muscle cells

1998 ◽  
Vol 274 (5) ◽  
pp. H1742-H1748 ◽  
Author(s):  
Gunilla Dahlfors ◽  
Yun Chen ◽  
Maria Wasteson ◽  
Hans J. Arnqvist
Keyword(s):  
Smooth Muscle ◽  
Growth Factor ◽  
Smooth Muscle Cells ◽  
Dna Synthesis ◽  
Receptor Antagonist ◽  
Muscle Cells ◽  
Inhibitory Effect ◽  
Ang Ii ◽  
Β Receptor ◽  
Tgf Β1

The interaction of ANG II with platelet-derived growth factor (PDGF)-BB-induced DNA synthesis was studied in cultured rat aortic smooth muscle cells. PDGF-BB-induced DNA synthesis was delayed (∼6–8 h) by ANG II as shown by a time-course experiment. Losartan, an AT1-receptor antagonist, blocked the transient inhibitory effect of ANG II, whereas the AT2-receptor antagonist PD-123319 had no effect. Autocrine- or paracrine-acting transforming growth factor-β1 (TGF-β1), believed to be a mediator of ANG II-induced inhibitory effects, was not responsible for the delay of PDGF-BB-induced DNA synthesis, because a potent TGF-β1 neutralizing antibody could not reverse this effect of ANG II, nor was the delay of the PDGF-BB effect caused by inhibition of PDGF-β-receptor phosphorylation as shown by Western blot analysis of immunoprecipitated PDGF-β receptor. In conclusion, our results show that ANG II can exert a transient inhibitory effect on PDGF-BB-induced proliferation via the AT1 receptor.

Vasoconstriction: a new activity for platelet-derived growth factor

Science ◽  
1986 ◽  
Vol 232 (4746) ◽  
pp. 87-90 ◽  
Author(s):  
BC Berk ◽  
RW Alexander ◽  
TA Brock ◽  
MA Gimbrone ◽  
RC Webb
Keyword(s):  
Smooth Muscle ◽  
Growth Factor ◽  
Smooth Muscle Cells ◽  
Muscle Cells ◽  
Rat Aorta ◽  
Platelet Derived Growth Factor ◽  
Free Calcium ◽  
Free Calcium Concentration ◽  
Cytosolic Free Calcium Concentration

Platelet-derived growth factor (PDGF) is a potent mitogen for vascular smooth muscle cells that has been implicated in the pathogenesis of atherosclerosis. The potential role of PDGF in the altered vasoreactivity of atherosclerotic vessels has been studied through an examination of its effects on contractility in the rat aorta. PDGF caused a concentration-dependent contraction of aortic strips and was significantly more potent on a molar basis than the classic vasoconstrictor peptide angiotensin II. Furthermore, PDGF increased the cytosolic free calcium concentration in cultured rat aortic smooth muscle cells. These observations suggest a new biological activity for PDGF that may contribute to the enhanced vasoreactivity of certain atherosclerotic vessels.

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