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Role of ABCA1 on membrane cholesterol content, insulin-dependent Akt phosphorylation and glucose uptake in adult skeletal muscle fibers from mice
Ist Teil von
Biochimica et biophysica acta. Molecular and cell biology of lipids, 2018-12, Vol.1863 (12), p.1469-1477
Ort / Verlag
Netherlands: Elsevier B.V
Erscheinungsjahr
2018
Link zum Volltext
Quelle
ScienceDirect Journals (5 years ago - present)
Beschreibungen/Notizen
The ATP-binding cassette transporter A1 (ABCA1) promotes cellular cholesterol efflux, leading to cholesterol binding to the extracellular lipid-free apolipoprotein A-I. ABCA1 regulates lipid content, glucose tolerance and insulin sensitivity in adipose tissue. In skeletal muscle, most GLUT4-mediated glucose transport occurs in the transverse tubule, a system composed by specialized cholesterol-enriched invaginations of the plasma membrane. We have reported that insulin resistant mice have higher cholesterol levels in transverse tubule from adult skeletal muscle. These high levels correlate with decreased GLUT4 trafficking and glucose uptake; however, the role of ABCA1 on skeletal muscle insulin-dependent glucose metabolism remains largely unexplored. Here, we evaluated the functional role of the ABCA1 on insulin-dependent signaling pathways, glucose uptake and cellular cholesterol content in adult skeletal muscle. Male mice were fed for 8 weeks with normal chow diet (NCD) or high fat diet (HFD). Compared to NCD-fed mice, ABCA1 mRNA levels and protein content were lower in muscle homogenates from HFD-fed mice. In Flexor digitorum brevis muscle from NCD-fed mice, shABCA1-RFP in vivo electroporation resulted in 65% reduction of ABCA1 protein content, 1.6-fold increased fiber cholesterol levels, 74% reduction in insulin-dependent Akt (Ser473) phosphorylation, total suppression of insulin-dependent GLUT4 translocation and decreased 2-NBDG uptake compared to fibers electroporated with the scrambled plasmid. Pre-incubation with methyl-β cyclodextrin reestablished both GLUT4 translocation and 2-NBDG transport. Based on the present results, we suggest that decreased ABCA1 contributes to the anomalous cholesterol accumulation and decreased glucose transport displayed by skeletal muscle membranes in the insulin resistant condition.
•A novel role of ABCA1 in skeletal muscle is proposed.•ABCA1 down-regulation increases cholesterol content and decreases the insulin-dependent Akt phosphorylation in fibers.•Both, insulin-dependent GLUT4 translocation and glucose uptake is decreases in ABCA1 down-regulated muscle fibers.•ABCA1 may be a novel therapeutic target for IR and an attractive target for new therapies for DMII.