Phosphoproteome determination of LPA treated osteocytes
EMSL Project ID
25292
Abstract
Osteocytes arise from bone-forming osteoblasts that become surrounded by mineralized matrix and comprise greater than 90% of all bone cells. Osteocytes form a junctionally-connected sensory network that is postulated to transduce physical strain into signals that maintain bone mass and mechanical integrity. Osteocytes are characterized by long membrane extensions (dendrites) with which these cells communicate with neighboring osteocytes and osteoblasts. A loss of osteocyte connectivity is associated with human pathological conditions such as osteoporosis and osteoarthritis. The proteins responsible for the formation and function of osteocyte dendrites are unknown, and the current lack of information regarding the relationship between osteocyte morphology and function represents a critical gap in the understanding of bone physiology. In this application we propose to identify the proteomes of mouse osteocyte dendrites and cell bodies as a means to test the postulate that subsets of proteins reside preferentially in these cell regions. We devised a method for the physical separation of osteocyte dendrites from cell bodies using cells grown on microporous membranes. These samples will be subjected to mass spectrometry-based proteomic analysis. The lipid growth factor lysophosphatidic acid (LPA) has many potent effects on osteoblasts, the precursor cell to osteocytes, and our recent data show that LPA induced the formation of dendrite-like membrane extensions. Therefore, we also propose to determine the phosphoproteome of LPA-treated osteocyte cell fractions to test the hypothesis that LPA-induced dendrite formation requires the phosphorylation of specific proteins. These studies will provide valuable new insight into the function of osteocytes and contribute to the formulation of mechanistic models of osteocyte dendrite formation. The elucidation of the proteome and the LPA-linked phosphoproteome of osteocyte dendrites and cell bodies may provide unique targets for the treatment of bone wasting diseases and disuse atrophies associated with limb immobilization, extended bed rest, or long-term exposure to microgravity.
Project Details
Project type
Large-Scale EMSL Research
Start Date
2007-10-01
End Date
2008-10-05
Status
Closed
Released Data Link
Team
Principal Investigator
Related Publications
Poster presentation at the annual meeting of the American Society for Bone and Mineral Research