Calcitriol Increases Ceramide, Diacylglycerol, and Expression of Genes Involved in Lipid Packaging in Skeletal Muscle

Author

Grace Elizabeth Jefferson, University of KentuckyFollow

Date Available

12-24-2016

Year of Publication

2016

Document Type

Master's Thesis

Degree Name

Master of Science (MS)

College

Education

Department/School/Program

Kinesiology and Health Promotion

Advisor

Dr. Lance Bollinger

Co-Director of Graduate Studies

Dr. Mark Abel

Abstract

Background: Vitamin D is crucial for skeletal muscle function. 25-hidroxyvitamin D (25(OH)D) has been correlated with skeletal muscle mass and intramyocellular lipid (IMCL) content. The purpose of this study was to understand how calcitriol, the active vitamin D metabolite, directly affects myocellular size and lipid partitioning.

Methods: C₂C₁₂ myotubes were treated with calcitriol (100nM) or vehicle control for 24 or 96 h. Myotube diameter and protein synthesis rate were measured to determine effects of calcitriol on myocellular size. Intramyocellular triacylglycerol (IMTG), diacylglycerol (DAG), and ceramide content were measured by LC/MS. Expression of genes involved in lipid packaging and lipolysis were measured by RT-PCR. Insulin-stimulated phosphorylated Akt (Thr 308) was determined by western blot.

Results: Calcitriol did not affect myocellular size or protein synthesis rate. Calcitriol increased total DAG and ceramides in a sub-species specific manner. Calcitriol increased IMTG area, but did not affect total IMTG content. Calcitriol reduced mRNA content of diglyceride acyltransferase and increased mRNA content of lipid packaging genes. Calcitriol did not negatively affect insulin-stimulated pAkt.

Conclusions: These results suggest calcitriol directly alters lipid content and packaging in skeletal muscle cells. Altering the expression of lipid packaging genes and increasing IMCL subspecies content may be mechanisms by which vitamin D improves skeletal muscle function in vivo.

Digital Object Identifier (DOI)

http://dx.doi.org/10.13023/ETD.2016.255

Recommended Citation

Jefferson, Grace Elizabeth, "Calcitriol Increases Ceramide, Diacylglycerol, and Expression of Genes Involved in Lipid Packaging in Skeletal Muscle" (2016). Theses and Dissertations--Kinesiology and Health Promotion. 31.
https://uknowledge.uky.edu/khp_etds/31