title: microRNA-16 Is Downregulated During Insulin Resistance and Controls Skeletal Muscle Protein Accretion.
abstract: Insulin resistant diabetes, currently at epidemic levels in developed countries, begins in the skeletal muscle and is linked to altered protein turnover. microRNAs downregulate targeted mRNA translation decreasing the amount of translated protein, thereby regulating many cellular processes. Regulation of miRNAs and their function in skeletal muscle insulin resistance is largely unexplored. The purpose of this study was to identify the effects of insulin resistance on contents of skeletal muscle miRNAs with potential functions in protein turnover. We examined miRs -1, -16, -23, -27, -133a, -133b, and -206 in muscles of Zucker rats. miR-1 was 5- to 10-fold greater in obesity, whereas miRs-16 and -133b were repressed ∼50% in obese compared to lean rats, with no other alterations in miRNA contents. miR-16 correlated to protein synthesis in lean, but not obese rats. miR-16 reduction by lipid overload was verified in-vivo by diet-induced obesity and in-vitro using a diacylglycerol analog. A role for miR-16 in protein turnover of skeletal myocytes was established using transient overexpression and anti-miR inhibition. miR-16 overexpression resulted in lower protein synthesis (puromycin incorporation, ∼25-50%), mTOR (∼25%), and p70S6K1 (∼40%) in starved and insulin stimulated myoblasts. Conversely, anti-miR-16 increased basal protein synthesis (puromycin incorporation, ∼75%), mTOR (∼100%), and p70S6K1 (∼100%). Autophagy was enhanced by miR-16 overexpression (∼50% less BCL-2, ∼100% greater LC3II/I, ∼50% less p62) and impaired with miR-16 inhibition (∼45% greater BCL-2, ∼25% less total LC3, ∼50% greater p62). This study demonstrates reduced miR-16 during insulin resistance and establishes miR-16 control of protein accretion in skeletal muscle. J. Cell. Biochem. 117: 1775-1787, 2016. © 2015 Wiley Periodicals, Inc.
authors.affiliation: Integrative Muscle Metabolism Laboratory, Human Performance Laboratory, Department of Health, Human Performance and Recreation, University of Arkansas, Fayetteville, Arkansas, 72701.
authors.forename: David E
authors.initials: DE
authors.lastname: Lee
authors.affiliation: Integrative Muscle Metabolism Laboratory, Human Performance Laboratory, Department of Health, Human Performance and Recreation, University of Arkansas, Fayetteville, Arkansas, 72701.
authors.forename: Jacob L
authors.initials: JL
authors.lastname: Brown
authors.affiliation: Integrative Muscle Metabolism Laboratory, Human Performance Laboratory, Department of Health, Human Performance and Recreation, University of Arkansas, Fayetteville, Arkansas, 72701.
authors.forename: Megan E
authors.initials: ME
authors.lastname: Rosa
authors.affiliation: Exercise Muscle Biology Laboratory, Human Performance Laboratory, Department of Health, Human Performance and Recreation, University of Arkansas, Fayetteville, Arkansas, 72701.
authors.forename: Lemuel A
authors.initials: LA
authors.lastname: Brown
authors.affiliation: Exercise Muscle Biology Laboratory, Human Performance Laboratory, Department of Health, Human Performance and Recreation, University of Arkansas, Fayetteville, Arkansas, 72701.
authors.forename: Richard A
authors.initials: RA
authors.lastname: Perry
authors.affiliation: Muscle Biology Laboratory, Department of Health and Kinesiology, Texas A&M University, College Station, Texas, 77843.
authors.forename: Michael P
authors.initials: MP
authors.lastname: Wiggs
authors.affiliation: Muscle Biology Laboratory, Department of Health and Kinesiology, Texas A&M University, College Station, Texas, 77843.
authors.forename: Mats I
authors.initials: MI
authors.lastname: Nilsson
authors.affiliation: Applied Exercise Science Laboratory, Department of Health and Kinesiology, Texas A&M University, College Station, Texas, 77843.
authors.forename: Stephen F
authors.initials: SF
authors.lastname: Crouse
authors.affiliation: Muscle Biology Laboratory, Department of Health and Kinesiology, Texas A&M University, College Station, Texas, 77843.
authors.forename: James D
authors.initials: JD
authors.lastname: Fluckey
authors.affiliation: Exercise Muscle Biology Laboratory, Human Performance Laboratory, Department of Health, Human Performance and Recreation, University of Arkansas, Fayetteville, Arkansas, 72701.
authors.forename: Tyrone A
authors.initials: TA
authors.lastname: Washington
authors.affiliation: Integrative Muscle Metabolism Laboratory, Human Performance Laboratory, Department of Health, Human Performance and Recreation, University of Arkansas, Fayetteville, Arkansas, 72701.|Muscle Biology Laboratory, Department of Health and Kinesiology, Texas A&M University, College Station, Texas, 77843.|Applied Exercise Science Laboratory, Department of Health and Kinesiology, Texas A&M University, College Station, Texas, 77843.
authors.forename: Nicholas P
authors.initials: NP
authors.lastname: Greene
mesh_terms: D000818:Animals; D001343:Autophagy; D007333:Insulin Resistance; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D009124:Muscle Proteins / Q000235:genetics / Q000378:metabolism*; D032448:Myoblasts, Skeletal / Q000378:metabolism*; D009765:Obesity / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D011924:Rats, Zucker
chemical_list: C547573:MIRN16 microRNA, rat; D035683:MicroRNAs; D009124:Muscle Proteins
keywords: AUTOPHAGY; PROTEIN SYNTHESIS; SUnSET; TYPE II DIABETES MELLITUS