Functional & Integrative Genomics

, Volume 12, Issue 2, pp 357–365

Preservation of bone mass and structure in hibernating black bears (Ursus americanus) through elevated expression of anabolic genes

  • Vadim B. Fedorov
  • Anna V. Goropashnaya
  • Øivind Tøien
  • Nathan C. Stewart
  • Celia Chang
  • Haifang Wang
  • Jun Yan
  • Louise C. Showe
  • Michael K. Showe
  • Seth W. Donahue
  • Brian M. Barnes
Original Paper

DOI: 10.1007/s10142-012-0266-3

Cite this article as:
Fedorov, V.B., Goropashnaya, A.V., Tøien, Ø. et al. Funct Integr Genomics (2012) 12: 357. doi:10.1007/s10142-012-0266-3

Abstract

Physical inactivity reduces mechanical load on the skeleton, which leads to losses of bone mass and strength in non-hibernating mammalian species. Although bears are largely inactive during hibernation, they show no loss in bone mass and strength. To obtain insight into molecular mechanisms preventing disuse bone loss, we conducted a large-scale screen of transcriptional changes in trabecular bone comparing winter hibernating and summer non-hibernating black bears using a custom 12,800 probe cDNA microarray. A total of 241 genes were differentially expressed (P < 0.01 and fold change >1.4) in the ilium bone of bears between winter and summer. The Gene Ontology and Gene Set Enrichment Analysis showed an elevated proportion in hibernating bears of overexpressed genes in six functional sets of genes involved in anabolic processes of tissue morphogenesis and development including skeletal development, cartilage development, and bone biosynthesis. Apoptosis genes demonstrated a tendency for downregulation during hibernation. No coordinated directional changes were detected for genes involved in bone resorption, although some genes responsible for osteoclast formation and differentiation (Ostf1, Rab9a, and c-Fos) were significantly underexpressed in bone of hibernating bears. Elevated expression of multiple anabolic genes without induction of bone resorption genes, and the down regulation of apoptosis-related genes, likely contribute to the adaptive mechanism that preserves bone mass and structure through prolonged periods of immobility during hibernation.

Keywords

HibernationBone biosynthesisGene expressionApoptosis

Supplementary material

10142_2012_266_MOESM1_ESM.pdf (821 kb)
ESM 1(PDF 821 kb)

Copyright information

© Springer-Verlag 2012

Authors and Affiliations

  • Vadim B. Fedorov
    • 1
  • Anna V. Goropashnaya
    • 1
  • Øivind Tøien
    • 1
  • Nathan C. Stewart
    • 1
  • Celia Chang
    • 2
  • Haifang Wang
    • 3
  • Jun Yan
    • 3
  • Louise C. Showe
    • 2
  • Michael K. Showe
    • 2
  • Seth W. Donahue
    • 4
  • Brian M. Barnes
    • 1
  1. 1.Institute of Arctic BiologyUniversity of Alaska FairbanksFairbanksUSA
  2. 2.Systems and Computational Biology Centerthe Wistar InstitutePhiladelphiaUSA
  3. 3.CAS-MPG Partner Institute for Computational BiologyShanghai Institutes of Biological SciencesShanghaiChina
  4. 4.Department of Biomedical EngineeringMichigan Technological UniversityHoughtonUSA