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Mest but Not MiR-335 Affects Skeletal Muscle Growth and Regeneration.

Hiramuki Y, Sato T, Furuta Y, Surani MA, Sehara-Fujisawa A - PLoS ONE (2015)

Bottom Line: When skeletal muscle fibers are injured, they regenerate and grow until their sizes are adjusted to surrounding muscle fibers and other relevant organs.In addition to reduced body weight in Mest+/-; DMD- mice, decreased muscle growth was observed in Mest+/- mice during cardiotoxin-induced regeneration, suggesting roles of Mest in muscle regeneration.Thus, Mest likely mediates muscle regeneration through regulation of imprinted gene networks in skeletal muscle.

View Article: PubMed Central - PubMed

Affiliation: Department of Growth Regulation, Institute for Frontier Medical Sciences, Kyoto University, Kyoto, Japan.

ABSTRACT
When skeletal muscle fibers are injured, they regenerate and grow until their sizes are adjusted to surrounding muscle fibers and other relevant organs. In this study, we examined whether Mest, one of paternally expressed imprinted genes that regulates body size during development, and miR-335 located in the second intron of the Mest gene play roles in muscle regeneration. We generated miR-335-deficient mice, and found that miR-335 is a paternally expressed imprinted microRNA. Although both Mest and miR-335 are highly expressed during muscle development and regeneration, only Mest+/- (maternal/paternal) mice show retardation of body growth. In addition to reduced body weight in Mest+/-; DMD- mice, decreased muscle growth was observed in Mest+/- mice during cardiotoxin-induced regeneration, suggesting roles of Mest in muscle regeneration. Moreover, expressions of H19 and Igf2r, maternally expressed imprinted genes were affected in tibialis anterior muscle of Mest+/-; DMD- mice compared to DMD- mice. Thus, Mest likely mediates muscle regeneration through regulation of imprinted gene networks in skeletal muscle.

No MeSH data available.


Related in: MedlinePlus

Mest is required for skeletal muscle growth during regeneration.(A) H&E staining of TA muscles under normal condition (top panel) and 14 days after CTX-induced injury (middle and bottom panels). Bottom panel shows the extended images of a part of middle panel. (B) Average cross section areas of TA muscles in WT (n = 3), Mest+/- (n = 4) and miR-335+/Neo mice (n = 6) under normal condition and WT (n = 7), Mest+/- (n = 4) and miR-335+/Neo mice (n = 6) 14 days after CTX injury. (C) H&E staining of TA muscles of DMD-, Mest+/-; DMD- and miR-335+/Neo; DMD- mice at 11–13 weeks old. (D) Average cross section areas of TA muscles in DMD- (n = 8), Mest+/-; DMD- (n = 4) and miR-335+/Neo; DMD- mice (n = 4) at 11–13 weeks old. Error bars indicate the s.e.m. #P = 0.0549 compared with WT mice. Scale bar: 100 μm.
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pone.0130436.g004: Mest is required for skeletal muscle growth during regeneration.(A) H&E staining of TA muscles under normal condition (top panel) and 14 days after CTX-induced injury (middle and bottom panels). Bottom panel shows the extended images of a part of middle panel. (B) Average cross section areas of TA muscles in WT (n = 3), Mest+/- (n = 4) and miR-335+/Neo mice (n = 6) under normal condition and WT (n = 7), Mest+/- (n = 4) and miR-335+/Neo mice (n = 6) 14 days after CTX injury. (C) H&E staining of TA muscles of DMD-, Mest+/-; DMD- and miR-335+/Neo; DMD- mice at 11–13 weeks old. (D) Average cross section areas of TA muscles in DMD- (n = 8), Mest+/-; DMD- (n = 4) and miR-335+/Neo; DMD- mice (n = 4) at 11–13 weeks old. Error bars indicate the s.e.m. #P = 0.0549 compared with WT mice. Scale bar: 100 μm.

Mentions: Although the expression of Mest is up-regulated in regenerating skeletal muscle induced by injection of CTX and in skeletal muscle of adult DMD– mice (Fig 1B and 1C), roles of Mest in muscle regeneration and pathology of DMD remain unknown. In order to clarify roles of Mest in muscle regeneration, we examined whether muscle regeneration induced by CTX was affected in Mest+/- mice. Ratios of myofibers with central nuclei in Mest+/- mice were comparable to those in WT mice, indicating that muscle regeneration occurs in the absence of Mest (Fig 4A). However, regenerating muscle fibers were significantly thinner in Mest+/- than those in WT mice when analyzed 14 days after CTX-injection while average cross section areas of intact TA muscle fibers of both WT and Mest+/- mice were similar to each other (Fig 4A and 4B). These results indicate that Mest is required for efficient muscle growth during muscle regeneration. Next, we investigated whether Mest affects pathology of DMD- mice. There is no significant difference in Cross Section Areas (CSA) between DMD- and Mest+/-; DMD- mice (Fig 4C and 4D). We analyzed body weight of DMD- and Mest+/-; DMD- mice. Fig 3C shows that body weights of Mest+/-; DMD- mice were consistently smaller than those of DMD- mice from 1 week to 11–13 weeks. If Mest promotes muscle regeneration in addition to body growth during postnatal development, the difference in body weights between DMD- and Mest+/-; DMD- mice should be accelerated after muscle degeneration and regeneration start in them. In contrast, such an accelerated difference in body weights would not be observed between WT and Mest+/- mice, which no regeneration occurs. As shown in S1 Fig, the ratio of Mest+/-; DMD-/ DMD- indeed became slightly lower than that of Mest+/-/WT after 4 weeks of age when muscle degeneration and regeneration start in those mice. The result implies contribution of Mest in body growth during muscle regeneration as well as contribution in body growth during postnatal development. Furthermore, we analyzed the relation between body and TA weight in 6 and 11–13 weeks DMD- and Mest+/-; DMD- mice. TA weights of Mest+/-; DMD- mice were significantly smaller at 6 weeks and slightly smaller at 11–13 weeks compared to those of DMD- mice although statistical significance could not be obtained with the latter probably due to small numbers of mice we analyzed (Fig 3F and 3H). TA/body weight was more or less constant among these mice (Fig 3G and 3I). In contrast, there was no significant difference in muscle growth during regeneration induced by CTX between WT and miR-335+/Neo mice and in growth of Dystrophin-deficient muscle between DMD- and miR-335+/Neo; DMD- mice (Fig 4A–4D). Therefore, these result suggest that Mest but not miR-335 is involved in skeletal muscle growth during regeneration.


Mest but Not MiR-335 Affects Skeletal Muscle Growth and Regeneration.

Hiramuki Y, Sato T, Furuta Y, Surani MA, Sehara-Fujisawa A - PLoS ONE (2015)

Mest is required for skeletal muscle growth during regeneration.(A) H&E staining of TA muscles under normal condition (top panel) and 14 days after CTX-induced injury (middle and bottom panels). Bottom panel shows the extended images of a part of middle panel. (B) Average cross section areas of TA muscles in WT (n = 3), Mest+/- (n = 4) and miR-335+/Neo mice (n = 6) under normal condition and WT (n = 7), Mest+/- (n = 4) and miR-335+/Neo mice (n = 6) 14 days after CTX injury. (C) H&E staining of TA muscles of DMD-, Mest+/-; DMD- and miR-335+/Neo; DMD- mice at 11–13 weeks old. (D) Average cross section areas of TA muscles in DMD- (n = 8), Mest+/-; DMD- (n = 4) and miR-335+/Neo; DMD- mice (n = 4) at 11–13 weeks old. Error bars indicate the s.e.m. #P = 0.0549 compared with WT mice. Scale bar: 100 μm.
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pone.0130436.g004: Mest is required for skeletal muscle growth during regeneration.(A) H&E staining of TA muscles under normal condition (top panel) and 14 days after CTX-induced injury (middle and bottom panels). Bottom panel shows the extended images of a part of middle panel. (B) Average cross section areas of TA muscles in WT (n = 3), Mest+/- (n = 4) and miR-335+/Neo mice (n = 6) under normal condition and WT (n = 7), Mest+/- (n = 4) and miR-335+/Neo mice (n = 6) 14 days after CTX injury. (C) H&E staining of TA muscles of DMD-, Mest+/-; DMD- and miR-335+/Neo; DMD- mice at 11–13 weeks old. (D) Average cross section areas of TA muscles in DMD- (n = 8), Mest+/-; DMD- (n = 4) and miR-335+/Neo; DMD- mice (n = 4) at 11–13 weeks old. Error bars indicate the s.e.m. #P = 0.0549 compared with WT mice. Scale bar: 100 μm.
Mentions: Although the expression of Mest is up-regulated in regenerating skeletal muscle induced by injection of CTX and in skeletal muscle of adult DMD– mice (Fig 1B and 1C), roles of Mest in muscle regeneration and pathology of DMD remain unknown. In order to clarify roles of Mest in muscle regeneration, we examined whether muscle regeneration induced by CTX was affected in Mest+/- mice. Ratios of myofibers with central nuclei in Mest+/- mice were comparable to those in WT mice, indicating that muscle regeneration occurs in the absence of Mest (Fig 4A). However, regenerating muscle fibers were significantly thinner in Mest+/- than those in WT mice when analyzed 14 days after CTX-injection while average cross section areas of intact TA muscle fibers of both WT and Mest+/- mice were similar to each other (Fig 4A and 4B). These results indicate that Mest is required for efficient muscle growth during muscle regeneration. Next, we investigated whether Mest affects pathology of DMD- mice. There is no significant difference in Cross Section Areas (CSA) between DMD- and Mest+/-; DMD- mice (Fig 4C and 4D). We analyzed body weight of DMD- and Mest+/-; DMD- mice. Fig 3C shows that body weights of Mest+/-; DMD- mice were consistently smaller than those of DMD- mice from 1 week to 11–13 weeks. If Mest promotes muscle regeneration in addition to body growth during postnatal development, the difference in body weights between DMD- and Mest+/-; DMD- mice should be accelerated after muscle degeneration and regeneration start in them. In contrast, such an accelerated difference in body weights would not be observed between WT and Mest+/- mice, which no regeneration occurs. As shown in S1 Fig, the ratio of Mest+/-; DMD-/ DMD- indeed became slightly lower than that of Mest+/-/WT after 4 weeks of age when muscle degeneration and regeneration start in those mice. The result implies contribution of Mest in body growth during muscle regeneration as well as contribution in body growth during postnatal development. Furthermore, we analyzed the relation between body and TA weight in 6 and 11–13 weeks DMD- and Mest+/-; DMD- mice. TA weights of Mest+/-; DMD- mice were significantly smaller at 6 weeks and slightly smaller at 11–13 weeks compared to those of DMD- mice although statistical significance could not be obtained with the latter probably due to small numbers of mice we analyzed (Fig 3F and 3H). TA/body weight was more or less constant among these mice (Fig 3G and 3I). In contrast, there was no significant difference in muscle growth during regeneration induced by CTX between WT and miR-335+/Neo mice and in growth of Dystrophin-deficient muscle between DMD- and miR-335+/Neo; DMD- mice (Fig 4A–4D). Therefore, these result suggest that Mest but not miR-335 is involved in skeletal muscle growth during regeneration.

Bottom Line: When skeletal muscle fibers are injured, they regenerate and grow until their sizes are adjusted to surrounding muscle fibers and other relevant organs.In addition to reduced body weight in Mest+/-; DMD- mice, decreased muscle growth was observed in Mest+/- mice during cardiotoxin-induced regeneration, suggesting roles of Mest in muscle regeneration.Thus, Mest likely mediates muscle regeneration through regulation of imprinted gene networks in skeletal muscle.

View Article: PubMed Central - PubMed

Affiliation: Department of Growth Regulation, Institute for Frontier Medical Sciences, Kyoto University, Kyoto, Japan.

ABSTRACT
When skeletal muscle fibers are injured, they regenerate and grow until their sizes are adjusted to surrounding muscle fibers and other relevant organs. In this study, we examined whether Mest, one of paternally expressed imprinted genes that regulates body size during development, and miR-335 located in the second intron of the Mest gene play roles in muscle regeneration. We generated miR-335-deficient mice, and found that miR-335 is a paternally expressed imprinted microRNA. Although both Mest and miR-335 are highly expressed during muscle development and regeneration, only Mest+/- (maternal/paternal) mice show retardation of body growth. In addition to reduced body weight in Mest+/-; DMD- mice, decreased muscle growth was observed in Mest+/- mice during cardiotoxin-induced regeneration, suggesting roles of Mest in muscle regeneration. Moreover, expressions of H19 and Igf2r, maternally expressed imprinted genes were affected in tibialis anterior muscle of Mest+/-; DMD- mice compared to DMD- mice. Thus, Mest likely mediates muscle regeneration through regulation of imprinted gene networks in skeletal muscle.

No MeSH data available.


Related in: MedlinePlus