Regulation of skeletal muscle growth by the IGF1-Akt/PKB pathway: insights from genetic models

Skeletal Muscle

Table 4 In vivo transfection experiments leading to perturbation of the IGF1-Akt pathway in adult skeletal muscle¹

Transgene	Perturbation	Effect	References
Igf1 (via virus)	Overexpression of Igf1	Muscle fiber hypertrophy (and muscle regeneration)	[50, 106]
Igf1	Overexpression of Igf1	Prevention of glucocorticoid-induced muscle atrophy	[48, 138]
RasV12C40 (Ras double mutant)	Activation of the PI3K-Akt pathway	Muscle fiber hypertrophy, which is blocked by rapamycin	[58, 69]
c.a. PI3K²	Activation of PI3K	Muscle fiber hypertrophy	[69, 78]
c.a. Akt	Activation of Akt	Muscle fiber hypertrophy, which is blocked by rapamycin	[69, 78]
c.a. Akt (via virus)	Activation of Akt	Muscle fiber hypertrophy	[139]
c.a.FoxO3	Activation of FoxO3	Muscle fiber atrophy and activation of atrogin-1 reporter	[91]
Small interfering RNA to FoxO1 and FoxO3	Knockdown of FoxO1 and FoxO3 by RNA interference	Prevention of atrogin-1 reporter upregulation induced by starvation	[91]
Rheb³	Activation of Rheb and mTORC1	Muscle fiber hypertrophy	[140]
Small interfering RNA to N-WASP	Knockdown of N-WASP⁴ by RNA interference	Muscle fiber atrophy	[86]

¹Experiments based on intramuscular injection of plasmid DNA or viral vector or small interfering RNA expression vector. Injection of plasmid DNA or siRNA expression vector was followed by electroporation.
²Constitutively active PI3K.
³Ras homolog enriched in brain
⁴Neuronal Wiscott-Aldrich syndrome protein (N-WASP).

ISSN: 2044-5040