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Calcineurin-mediated slow-type fiber expression and growth in reloading condition.
Med Sci Sports Exerc. 2006 Jun; 38(6):1065-72.MS

Abstract

PURPOSE

Calcineurin (CaN) signaling pathway has been implicated in the transcriptional regulation of slow muscle fiber genes and in muscle hypertrophy. Our aim was to investigate the functional role of CaN as a regulator of muscle growth and/or muscle fiber type under conditions of recovery from inactivity.

METHODS

Female ICR mice (8 wk of age, 28-32 g) were used. To examine the effects of hindlimb suspension (HS) and reloading on skeletal muscle fiber size and muscle fiber type, animals were designated to 8 wk of HS and subsequent reloading for 4 wk. During reloading, animals were treated with pharmacological inhibitors for CaN (FK506) by intraperitoneal administration (3-5 mg.kg.d). After each experimental period, antigravitational soleus muscle was analyzed.

RESULTS

HS treatment resulted in obvious muscle atrophy and slow-to-fast fiber-type transformation in the soleus muscle. Subsequent reloading for 4 wk following HS induced muscle regrowth and fiber-type reversion toward a slow profile. FK506 administration prevented this kind of reloading-induced transformation of muscle fiber type. Furthermore, it was confirmed that FK506 administration attenuated maintenance of fiber cross-sectional area and reloading-induced fiber regrowth, specifically in slow-type muscle fibers.

CONCLUSION

Reloading-induced fiber-type reversion toward a slow profile is prevented by the pharmacological inhibition of CaN. Additionally, inhibition of CaN prevented maintenance and regrowth of slow-type muscle fibers. These results implicate that the CaN signaling pathway is required in the slow-type muscle fiber program under maintenance and suspension-reloading conditions.

Authors+Show Affiliations

Graduate School of Comprehensive Human Sciences, University of Tsukuba, Ibaraki, JAPAN.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

16775546

Citation

Miyazaki, Mitsunori, et al. "Calcineurin-mediated Slow-type Fiber Expression and Growth in Reloading Condition." Medicine and Science in Sports and Exercise, vol. 38, no. 6, 2006, pp. 1065-72.
Miyazaki M, Hitomi Y, Kizaki T, et al. Calcineurin-mediated slow-type fiber expression and growth in reloading condition. Med Sci Sports Exerc. 2006;38(6):1065-72.
Miyazaki, M., Hitomi, Y., Kizaki, T., Ohno, H., Katsumura, T., Haga, S., & Takemasa, T. (2006). Calcineurin-mediated slow-type fiber expression and growth in reloading condition. Medicine and Science in Sports and Exercise, 38(6), 1065-72.
Miyazaki M, et al. Calcineurin-mediated Slow-type Fiber Expression and Growth in Reloading Condition. Med Sci Sports Exerc. 2006;38(6):1065-72. PubMed PMID: 16775546.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Calcineurin-mediated slow-type fiber expression and growth in reloading condition. AU - Miyazaki,Mitsunori, AU - Hitomi,Yoshiaki, AU - Kizaki,Takako, AU - Ohno,Hideki, AU - Katsumura,Toshihito, AU - Haga,Shukoh, AU - Takemasa,Tohru, PY - 2006/6/16/pubmed PY - 2006/10/28/medline PY - 2006/6/16/entrez SP - 1065 EP - 72 JF - Medicine and science in sports and exercise JO - Med Sci Sports Exerc VL - 38 IS - 6 N2 - PURPOSE: Calcineurin (CaN) signaling pathway has been implicated in the transcriptional regulation of slow muscle fiber genes and in muscle hypertrophy. Our aim was to investigate the functional role of CaN as a regulator of muscle growth and/or muscle fiber type under conditions of recovery from inactivity. METHODS: Female ICR mice (8 wk of age, 28-32 g) were used. To examine the effects of hindlimb suspension (HS) and reloading on skeletal muscle fiber size and muscle fiber type, animals were designated to 8 wk of HS and subsequent reloading for 4 wk. During reloading, animals were treated with pharmacological inhibitors for CaN (FK506) by intraperitoneal administration (3-5 mg.kg.d). After each experimental period, antigravitational soleus muscle was analyzed. RESULTS: HS treatment resulted in obvious muscle atrophy and slow-to-fast fiber-type transformation in the soleus muscle. Subsequent reloading for 4 wk following HS induced muscle regrowth and fiber-type reversion toward a slow profile. FK506 administration prevented this kind of reloading-induced transformation of muscle fiber type. Furthermore, it was confirmed that FK506 administration attenuated maintenance of fiber cross-sectional area and reloading-induced fiber regrowth, specifically in slow-type muscle fibers. CONCLUSION: Reloading-induced fiber-type reversion toward a slow profile is prevented by the pharmacological inhibition of CaN. Additionally, inhibition of CaN prevented maintenance and regrowth of slow-type muscle fibers. These results implicate that the CaN signaling pathway is required in the slow-type muscle fiber program under maintenance and suspension-reloading conditions. SN - 0195-9131 UR - https://www.unboundmedicine.com/medline/citation/16775546/Calcineurin_mediated_slow_type_fiber_expression_and_growth_in_reloading_condition_ L2 - https://doi.org/10.1249/01.mss.0000222833.43520.6e DB - PRIME DP - Unbound Medicine ER -