Identification and validation of the pathways and functions regulated by the orphan nuclear receptor, ROR alpha1, in skeletal muscle

Nucleic Acids Res. 2010 Jul;38(13):4296-312. doi: 10.1093/nar/gkq180. Epub 2010 Mar 24.

Abstract

The retinoic acid receptor-related orphan receptor (ROR) alpha has been demonstrated to regulate lipid metabolism. We were interested in the ROR alpha 1 dependent physiological functions in skeletal muscle. This major mass organ accounts for approximately 40% of the total body mass and significant levels of lipid catabolism, glucose disposal and energy expenditure. We utilized the strategy of targeted muscle-specific expression of a truncated (dominant negative) ROR alpha 1 Delta DE in transgenic mice to investigate ROR alpha 1 signaling in this tissue. Expression profiling and pathway analysis indicated that ROR alpha influenced genes involved in: (i) lipid and carbohydrate metabolism, cardiovascular and metabolic disease; (ii) LXR nuclear receptor signaling and (iii) Akt and AMPK signaling. This analysis was validated by quantitative PCR analysis using TaqMan low-density arrays, coupled to statistical analysis (with Empirical Bayes and Benjamini-Hochberg). Moreover, westerns and metabolic profiling were utilized to validate the genes, proteins and pathways (lipogenic, Akt, AMPK and fatty acid oxidation) involved in the regulation of metabolism by ROR alpha 1. The identified genes and pathways were in concordance with the demonstration of hyperglycemia, glucose intolerance, attenuated insulin-stimulated phosphorylation of Akt and impaired glucose uptake in the transgenic heterozygous Tg-ROR alpha 1 Delta DE animals. In conclusion, we propose that ROR alpha 1 is involved in regulating the Akt2-AMPK signaling pathways in the context of lipid homeostasis in skeletal muscle.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • AMP-Activated Protein Kinases / metabolism
  • Acetyl-CoA Carboxylase / metabolism
  • Animals
  • Blood Glucose
  • Cell Line
  • Fatty Acids / biosynthesis
  • Gene Expression Profiling
  • Glucose Intolerance / metabolism
  • Humans
  • Insulin / pharmacology
  • Liver X Receptors
  • Mice
  • Mice, Transgenic
  • Muscle, Skeletal / enzymology
  • Muscle, Skeletal / metabolism*
  • Nuclear Receptor Subfamily 1, Group F, Member 1 / genetics
  • Nuclear Receptor Subfamily 1, Group F, Member 1 / metabolism*
  • Nuclear Receptor Subfamily 1, Group F, Member 1 / physiology
  • Orphan Nuclear Receptors / metabolism
  • Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha
  • Proto-Oncogene Proteins c-akt / genetics
  • Proto-Oncogene Proteins c-akt / metabolism
  • Sequence Deletion
  • Signal Transduction
  • Sterol Regulatory Element Binding Protein 1 / metabolism
  • Trans-Activators / metabolism
  • Transcription Factors

Substances

  • Blood Glucose
  • Fatty Acids
  • Insulin
  • Liver X Receptors
  • Nuclear Receptor Subfamily 1, Group F, Member 1
  • Orphan Nuclear Receptors
  • Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha
  • Ppargc1a protein, mouse
  • RORA protein, human
  • Sterol Regulatory Element Binding Protein 1
  • Trans-Activators
  • Transcription Factors
  • Proto-Oncogene Proteins c-akt
  • AMP-Activated Protein Kinases
  • Acetyl-CoA Carboxylase