title: Impact of insulin deprivation and treatment on sphingolipid distribution in different muscle subcellular compartments of streptozotocin-diabetic C57Bl/6 mice.
abstract: Insulin deprivation in type 1 diabetes (T1D) individuals increases lipolysis and plasma free fatty acids (FFA) concentration, which can stimulate synthesis of intramyocellular bioactive lipids such as ceramides (Cer) and long-chain fatty acid-CoAs (LCFa-CoAs). Ceramide was shown to decrease muscle insulin sensitivity, and at mitochondrial levels it stimulates reactive oxygen species production. Here, we show that insulin deprivation in streptozotocin diabetic C57BL/6 mice increases quadriceps muscle Cer content, which was correlated with a concomitant decrease in the body fat and increased plasma FFA, glycosylated hemoglobin level (%Hb A1c), and muscular LCFa-CoA content. The alternations were accompanied by an increase in protein expression in LCFa-CoA and Cer synthesis (FATP1/ACSVL5, CerS1, CerS5), a decrease in the expression of genes implicated in muscle insulin sensitivity (GLUT4, GYS1), and inhibition of insulin signaling cascade by Aktα and GYS3β phosphorylation under acute insulin stimulation. Both the content and composition of sarcoplasmic fraction sphingolipids were most affected by insulin deprivation, whereas mitochondrial fraction sphingolipids remained stable. The observed effects of insulin deprivation were reversed, except for content and composition of LCFa-CoA, CerS protein expression, GYS1 gene expression, and phosphorylation status of Akt and GYS3β when exogenous insulin was provided by subcutaneous insulin implants. Principal component analysis and Pearson's correlation analysis revealed close relationships between the features of the diabetic phenotype, the content of LCFa-CoAs and Cers containing C18-fatty acids in sarcoplasm, but not in mitochondria. Insulin replacement did not completely rescue the phenotype, especially regarding the content of LCFa-CoA, or proteins implicated in Cer synthesis and muscle insulin sensitivity. These persistent changes might contribute to muscle insulin resistance observed in T1D individuals.
authors.affiliation: Division of Endocrinology and Metabolism, Mayo Clinic College of Medicine, Rochester, Minnesota.
authors.forename: Piotr
authors.initials: P
authors.lastname: Zabielski
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Blachnio-Zabielska
authors.forename: Ian R
authors.initials: IR
authors.lastname: Lanza
authors.forename: Srinivas
authors.initials: S
authors.lastname: Gopala
authors.forename: S
authors.initials: S
authors.lastname: Manjunatha
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Jakaitis
authors.forename: Xuan-Mai
authors.initials: XM
authors.lastname: Persson
authors.forename: Jaime
authors.initials: J
authors.lastname: Gransee
authors.forename: Katherine A
authors.initials: KA
authors.lastname: Klaus
authors.forename: Jill M
authors.initials: JM
authors.lastname: Schimke
authors.forename: Michael D
authors.initials: MD
authors.lastname: Jensen
authors.forename: K Sreekumaran
authors.initials: KS
authors.lastname: Nair
mesh_terms: D000818:Animals; D002518:Ceramides / Q000378:metabolism; D003921:Diabetes Mellitus, Experimental / Q000378:metabolism*; D051275:Glucose Transporter Type 4 / Q000378:metabolism; D007328:Insulin / Q000378:metabolism* / Q000494:pharmacology*; D008297:Male; D051379:Mice; D018482:Muscle, Skeletal / Q000187:drug effects / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects / Q000502:physiology; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D013107:Sphingolipids / Q000378:metabolism*; D013347:Subcellular Fractions / Q000378:metabolism
chemical_list: D002518:Ceramides; D051275:Glucose Transporter Type 4; D007328:Insulin; D017382:Reactive Oxygen Species; D013107:Sphingolipids; D051057:Proto-Oncogene Proteins c-akt
keywords: ceramide; long-chain fatty acid-coenzyme A; mitochondria; skeletal muscle; type 1 diabetes