Oncotarget. 2017 Jan 24;8(4):5943-5953. doi: 10.18632/oncotarget.13966.

Myostatin-deficiency in mice increases global gene expression at the Dlk1-Dio3 locus in the skeletal muscle.

PMID: 27992376

 

Study Highlight

A deficiency or a mutation of myostatin gene in mammals leads to 200-300 % increase in skeletal muscle weight (Figure 1), therefore, myostatin is a promising therapeutic target for skeletal muscle wasting caused by diseases and aging. However, downstream target molecules of myostatin have not been fully identified yet [1].

 

In this study, we identified the Dlk1-Dio3 locus as a novel target of myostatin in skeletal muscle [2]. The Dlk1-Dio3 locus, located at the chromosome 12qF1 (Chr12qF1) in mouse, contains the paternally and maternally expressed coding and non-coding genes (Dlk1, Rtl1/Peg11, and Dio3 are paternally expressed, and Gtl2/Meg3, antiRtl1/Rtl1as, Rian/Meg8, Mirg, and more than 100 miRNAs are maternally expressed) (Figure 2A), and is also known as the callipyge locus that is related to the postnatal skeletal muscle hypertrophy in sheep [3].

 

In the myostatin-deficient skeletal muscle, we found increased expression of coding and non-coding Chr12qF1 genes including miRNAs (Figure 2B). Among the increased Chr12qF1 miRNAs, miR-411 and miR-540-3p were shown to increase the myotube diameters of skeletal muscle cell line. Mechanistically, we found hypomethylation of Gtl2-DMR (differentially methylated region) that regulates the Chr12qF1 genes expression [4,5] in the myostatin-deficient skeletal muscle.

 

It is also interesting to note that a drastic increase in IG-DMR ncRNA expression (more that 10 times) that is required for the expression of Chr12qF1 transcripts in mouse ESCs [6] was observed in the myostatin-deficient skeletal muscle. The molecular function of non-coding RNAs (ncRNAs) in the regulation of skeletal muscle mass remains to be characterized [7].

 

In summary, our findings highlight the Dlk1-Dio3 (the callipyge) locus as a new target of myostatin in the skeletal muscle.

 

 

Figure 1. The pictures of upper- and lower-limbs of wild-type and MSTN KO mice. Myostatin knockout mice show a significant increase in the skeletal muscle mass.

 

 

Figure 2. The table indicating the changes of expression of the Dlk1-Dio3 locus in MSTN-deficient skeletal muscle. A. The schematic diagram of the Dlk1-Dio3 locus. This imprinted locus contains the paternally (shown as boxes with oblique lines) and maternally expressed genes (shown as white boxes). Dlk1, Rtl1, and Dio3 are paternally expressed, whereas Gtl2, Rtl1as, Rian, Mirg, and miRNAs (shown as black arrowheads) are maternally expressed. The two differentially methylated regions (IG-DMR and Gtl2-DMR) are shown as black boxes. B. MSTN-deficiency increases the paternally and maternally expressed genes with the altered methylation status and the expression of epigenetic modulators. The single, double, and triple arrows indicate the low, middle, and high change of target molecules, respectively.

 

Acknowledgements:

This work was supported by JSPS KAKENHI (25860151, 16K08599, and 17K08646), Intramural Research Grants (26-8, 29-4) for Neurological and Psychiatric Disorders of NCNP, and a Grant-in-Aid from the NAKATOMI Foundation.

 

Contact:

Kunihiro Tsuchida, M.D., Ph.D.

Professor, Division for Therapies Against Intractable Diseases

Institute for Comprehensive Medical Science, Fujita Health University

Toyoake, Aichi 470-1192, Japan

Tel: +81-562-93-9384; Fax: +81-562-93-5791

E-mail: tsuchida@fujita-hu.ac.jp;

 

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