The microRNA signature in response to insulin reveals its implication in the transcriptional action of insulin in human skeletal muscle and the role of a sterol regulatory element-binding protein-1c/myocyte enhancer factor 2C pathway.
OBJECTIVE
Factors governing microRNA expressions in response to changes of cellular environment are still largely unknown. Our aim was to determine whether insulin, the major hormone controlling whole-body energy homeostasis, is involved in the regulation of microRNA expressions in human skeletal muscle.


METHODS
We carried out comparative microRNA (miRNA) expression profiles in human skeletal muscle biopsies before and after a 3-h euglycemic-hyperinsulinemic clamp, with TaqMan low-density arrays. Then, using DNA microarrays, we determined the response to insulin of the miRNA putative target genes in order to determine their role in the transcriptional action of insulin. We further characterized the mechanism of action of insulin on two representative miRNAs, miR-1 and miR-133a, in human muscle cells.


RESULTS
Insulin downregulated the expressions of 39 distinct miRNAs in human skeletal muscle. Their potential target mRNAs coded for proteins that were mainly involved in insulin signaling and ubiquitination-mediated proteolysis. Bioinformatic analysis suggested that combinations of different downregulated miRNAs worked in concert to regulate gene expressions in response to insulin. We further demonstrated that sterol regulatory element-binding protein (SREBP)-1c and myocyte enhancer factor 2C were involved in the effect of insulin on miR-1 and miR-133a expression. Interestingly, we found an impaired regulation of miRNAs by insulin in the skeletal muscle of type 2 diabetic patients, likely as consequences of altered SREBP-1c activation.


CONCLUSIONS
This work demonstrates a new role of insulin in the regulation of miRNAs in human skeletal muscle and suggests a possible implication of these new modulators in insulin resistance.
Granjon
Aurélie
A
Institut de la Recherche Agronomique (INRA) 1235, INSERM 870, INSA-Lyon, Régulations Métaboliques Nutrition et Diabète, Université Lyon, Oullins, France.
Gustin
Marie-Paule
MP
Rieusset
Jennifer
J
Lefai
Etienne
E
Meugnier
Emmanuelle
E
Güller
Isabelle
I
Cerutti
Catherine
C
Paultre
Christian
C
Disse
Emmanuel
E
Rabasa-Lhoret
Rémi
R
Laville
Martine
M
Vidal
Hubert
H
Rome
Sophie
S
D001706:Biopsy; D002460:Cell Line; D018076:DNA, Complementary / Q000235:genetics; D003924:Diabetes Mellitus, Type 2 / Q000235:genetics / Q000503:physiopathology; D015536:Down-Regulation; D005786:Gene Expression Regulation; D015309:Glucose Clamp Technique; D006801:Humans; D006943:Hyperglycemia / Q000503:physiopathology; D006946:Hyperinsulinism / Q000503:physiopathology; D007328:Insulin / Q000235:genetics*; D064326:MEF2 Transcription Factors; D035683:MicroRNAs / Q000235:genetics*; D018482:Muscle, Skeletal / Q000502:physiology*; D018006:Myogenic Regulatory Factors / Q000502:physiology*; D020411:Oligonucleotide Array Sequence Analysis; D016133:Polymerase Chain Reaction; D012016:Reference Values; D051780:Sterol Regulatory Element Binding Protein 1 / Q000235:genetics / Q000502:physiology*; D014158:Transcription, Genetic
D018076:DNA, Complementary; D007328:Insulin; D064326:MEF2 Transcription Factors; D035683:MicroRNAs; D018006:Myogenic Regulatory Factors; D051780:Sterol Regulatory Element Binding Protein 1