ShRNA-mediated gene silencing of lipoprotein lipase improves insulin sensitivity in L6 skeletal muscle cells.
In previous studies, we demonstrated that down-regulation of lipoprotein lipase in L6 muscle cells increased insulin-stimulated glucose uptake. In the current study, we used RNA interference technology to silence the LPL gene in L6 cells and generate a LPL-knock-down (LPL-KD) cell line. ShRNA transfected cells showed a 88% reduction in the level of LPL expression. The metabolic response to insulin was compared in wild-type (WT) and LPL-KD cells. Insulin-stimulated glycogen synthesis and glucose oxidation were respectively, 2.4-fold and 2.6-fold greater in LPL-KD cells compared to WT cells. Oxidation of oleic acid was reduced by 50% in LPL-KD cells compared to WT cells even in the absence of insulin. The contribution of LPL in regulating fuel metabolism was confirmed by adding back purified LPL to the culture media of LPL-KD cells. The presence of 10 μg/mL LPL resulted in LPL-KD cells reverting back to lower glycogen synthesis and glucose oxidation and increased fatty acid oxidation. Thus, LPL depletion appeared to mimic the action of insulin. These finding suggests an inverse correlation between muscle LPL levels and insulin-stimulated fuel homeostasis.
Department of Chemistry and Biochemistry, California State University Northridge, Northridge, CA 91330-8262, USA.
Majib
M
Jan
Department of Chemistry and Biochemistry, California State University Northridge, Northridge, CA 91330-8262, USA. Electronic address: jheem.medh@csun.edu.
Jheem D
JD
Medh
D000199:Actins / Q000235:genetics / Q000378:metabolism; D000818:Animals; D002460:Cell Line; D015870:Gene Expression / Q000187:drug effects; D005947:Glucose / Q000378:metabolism; D006003:Glycogen / Q000096:biosynthesis; D007004:Hypoglycemic Agents / Q000494:pharmacology; D007328:Insulin / Q000494:pharmacology; D007333:Insulin Resistance; D008071:Lipoprotein Lipase / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D018485:Muscle Fibers, Skeletal / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D019301:Oleic Acid / Q000378:metabolism; D010084:Oxidation-Reduction / Q000187:drug effects; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000235:genetics; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction
D000199:Actins; D007004:Hypoglycemic Agents; D007328:Insulin; D034741:RNA, Small Interfering; D019301:Oleic Acid; D006003:Glycogen; D008071:Lipoprotein Lipase; D005947:Glucose
Fatty acid oxidation; Glucose oxidation; Glycogen synthesis; Insulin sensitivity; L6 skeletal muscle cells; Lipoprotein lipase; shRNA