Growth and differentiation factor-11 is developmentally regulated in skeletal muscle and inhibits myoblast differentiation

Abstract

Growth and differentiation factor-11 (GDF-11) is a secreted protein that is closely related to myostatin, a known inhibitor of skeletal muscle development. The role of GDF-11 in regulating skeletal muscle growth remains unclear and the pattern of expression during post-natal growth has not been reported. Therefore, we sought to determine the expression of GDF-11 during post-natal growth and its effect on myoblast proliferation and differentiation. We collected gastrocnemius muscles from male and female mice at 2, 3, 4, 6, 12, 20 and 32 weeks of age (n = 6 per sex and age). In addition, gastrocnemius muscles were collected from male wild-type and myostatin knockout mice at 4, 6, 12 and 20 weeks of age (n = 6 per age and genotype). RNA was extracted and reverse transcribed. Northern analysis identified an expected 4.4 kb mRNA transcript for GDF-11 in gastrocnemius muscles of mice. The concentration of GDF-11 mRNA, as determined by quantitative PCR, was increased in gastrocnemius muscles from 2 to 6 weeks-a period of rapid postnatal muscle growth-and remained higher in male than female mice from 4 to 20 weeks of age (P < 0.05). Interestingly, the mRNA concentration of GDF-11 and its cognate receptors (ActRIIA, ActIIB and Alk5) were increased in gastrocnemius muscles of myostatin knockout compared with wild-type mice (P < 0.05), which may suggest a compensatory mechanism for the lack of myostatin. In support, recombinant GDF-11 inhibited differentiation of C 2 C 12 murine myoblasts and those isolated from myostatin knockout and wild-type mice (P < 0.05). Inhibited differentiation of C 2 C 12 myoblasts was associated with decreased mRNA expression of early and late molecular markers of differentiation (MyoD, myogenin, IGF-II, desmin and MyHC, P < 0.05). Our results suggest that GDF-11 regulates growth of skeletal muscles by inhibiting myoblast differentiation in an autocrine/paracrine manner and, perhaps, also plays a role in regulating sexually dimorphic growth.

Biochemistry and Biology of GDF11 and Myostatin

“…Yet, other data suggest that GDF11's role in myogenesis may be more complex. Gdf11 mRNA levels in mouse skeletal muscle appear to peak during the most rapid phase of postnatal muscle growth and are higher in males than in females, despite males having greater muscle mass 124 . Gdf11 expression is also increased in the muscles of MSTN-null mice, which nonetheless exhibit accelerated muscle growth and increased muscle mass 124 .…”

“…Gdf11 mRNA levels in mouse skeletal muscle appear to peak during the most rapid phase of postnatal muscle growth and are higher in males than in females, despite males having greater muscle mass 124 . Gdf11 expression is also increased in the muscles of MSTN-null mice, which nonetheless exhibit accelerated muscle growth and increased muscle mass 124 . These data raise the possibility that GDF11's actions in muscle may not fully overlap with those of MSTN such that GDF11 cannot compensate fully for the loss of MSTN in muscle.…”

“…In these systems, GDF11, like MSTN, can block myogenic differentiation 87, 122-124 . Yet, other data suggest that GDF11's role in myogenesis may be more complex.…”

Cancer-associated muscle weakness: What's bone got to do with it?

“…Myostatin antagonist has been investigated as a way to improve muscle wasting due to cachexia, as myostatin is a potent inhibitor of skeletal muscle differentiation and growth. 50 GDF-11 shares 90% sequence homology with myostatin and in skeletal muscle inhibits myoblast differentiation, 51 suggesting Cancer and muscle weakness DL Waning et al that GDF-11 may act in a very similar manner as myostatin. It is likely that these proteins promote the muscle wasting characteristic of cachexia, whereas other mediators contribute to muscle dysfunction by altering calcium handling (RyR1 and SERCA) or myofibrillar proteins in muscle cells (Figure 3).…”

Molecular Mechanisms of Bone Metastasis and Associated Muscle Weakness

“…Activin A has also been shown to function with Myostatin to reduce muscle size (56). GDF-11 shares 90% sequence homology with Myostatin and in skeletal muscle inhibits myoblast differentiation (57) suggesting that GDF-11 may act in a very similar manner as Myostatin.…”