New 'Mighty Mouse' Formula Found

mystyc writes to tell us that scientists at Johns Hopkins have improved upon their original "mighty mice" discovery. Teamed with the biotech firm MetaMorphix and pharmaceutical company Wyeth, they have found a new agent that interacts with the muscle-limiting protein myostatin that was able to trigger a 60% increase in muscle size after just two weekly injections.

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Abstract / free full paper link

[Frangible]

ABSTRACT: Myostatin is a secreted protein that normally functions as a negative regulator of muscle growth. Agents capable of blocking the myostatin signaling pathway could have important applications for treating human muscle degenerative diseases as well as for enhancing livestock production. Here we describe a potent myostatin inhibitor, a soluble form of the activin type IIB receptor (ACVR2B), which can cause dramatic increases in muscle mass (up to 60% in 2 weeks) when injected into wild-type mice. Furthermore, we show that the effect of the soluble receptor is attenuated but not eliminated in Mstn(-/-) mice, suggesting that at least one other ligand in addition to myostatin normally functions to limit muscle growth. Finally, we provide genetic evidence that these ligands signal through both activin type II receptors, ACVR2 and ACVR2B, to regulate muscle growth in vivo.

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