| First Author | Welle S | Year | 2006 |
| Journal | Am J Physiol Endocrinol Metab | Volume | 290 |
| Issue | 3 | Pages | E409-15 |
| PubMed ID | 16219664 | Mgi Jnum | J:106054 |
| Mgi Id | MGI:3617278 | Doi | 10.1152/ajpendo.00433.2005 |
| Citation | Welle S, et al. (2006) Myofibrillar protein synthesis in myostatin-deficient mice. Am J Physiol Endocrinol Metab 290(3):E409-15 |
| abstractText | Either increased protein synthesis or prolonged protein half-life is necessary to support the excessive muscle growth and maintenance of enlarged muscles in myostatin-deficient mice. This issue was addressed by determining in vivo rates of myofibrillar protein synthesis in mice with constitutive myostatin deficiency (Mstn(DeltaE3/DeltaE3)) or normal myostatin expression (Mstn(+/+)) by measuring tracer incorporation after a systemic flooding dose of l-[ring-(2)H(5)]phenylalanine. At 5-6 wk of age, Mstn(DeltaE3/DeltaE3) mice had increased muscle mass (40%), fractional rates of myofibrillar synthesis (14%), and protein synthesis per whole muscle (60%) relative to Mstn(+/+) mice. With maturation, fractional rates of synthesis declined >50% in parallel with decreased DNA and RNA [total, 28S rRNA, and poly(A) RNA] concentrations in muscle. At 6 mo of age, Mstn(DeltaE3/DeltaE3) mice had even greater increases in muscle mass (90%) and myofibrillar synthesis per muscle (85%) relative to Mstn(+/+) mice, but the fractional rate of synthesis was normal. Estimated myofibrillar protein half-life was not affected by myostatin deficiency. Muscle DNA concentrations were reduced in both young and mature Mstn(DeltaE3/DeltaE3) mice, whereas RNA concentrations were normal, so the ratio of RNA to DNA was approximately 30% greater than normal in Mstn(DeltaE3/DeltaE3) mice. Thus the increased protein synthesis and RNA content per muscle in myostatin-deficient mice cannot be explained entirely by an increased number of myonuclei. |
