A proteomic analysis of adult rat bone reveals the presence of cartilage/chondrocyte markers.
The non-mineral component of bone matrix consists of 90% collagenous, 10% non-collagenous proteins. These proteins regulate mineralization, growth, cell signaling and differentiation, and provide bone with its tensile strength. Expression of bone matrix proteins have historically been studied individually or in small numbers owing to limitations in analytical technologies. Current mass-spectrometric and separations technologies allow a global view of protein expression patterns in complex samples. To our knowledge, no proteome profile of bone matrix has yet been reported. Therefore, we have used mass spectrometry as a tool to generate a profile of proteins present in the extracellular matrix of adult rat bone. Overall, 108 and 25 proteins were identified with high confidence in the metaphysis and diaphysis, respectively, using a bottom up proteomic technique. Twenty-one of these proteins were present in both the metaphysis and diaphysis including the bone specific proteins, osteocalcin, type I collagen, osteopontin, osteoregulin, and bone sialoprotein. Interestingly, type II collagen, a protein thought to be exclusively expressed in cartilage, was identified in both the metaphysis and diaphysis. This observation was validated by Western blot. Additionally, the presence of aggrecan, another protein expressed in cartilage was identified in the bone matrix extracts by Western blot. The proteome profile generated using this technology represents an initial survey of the acid soluble proteins of bone matrix which provides a reference for the analysis of deviations from the normal composition due to perturbations or disease states.
Schreiweis
Melissa A
MA
Integrative Biology, Eli Lilly and Company, Indianapolis, IN 46285, USA
Butler
Jon P
JP
Kulkarni
Nalini H
NH
Knierman
Michael D
MD
Higgs
Richard E
RE
Halladay
David L
DL
Onyia
Jude E
JE
Hale
John E
JE
D053674:Aggrecans / Q000378:metabolism; D000818:Animals; D015415:Biomarkers / Q000737:chemistry* / Q000378:metabolism; D001857:Bone Matrix / Q000737:chemistry; D001842:Bone and Bones / Q000033:anatomy & histology / Q000737:chemistry* / Q000378:metabolism; D002356:Cartilage / Q000737:chemistry* / Q000378:metabolism; D019902:Chondrocytes / Q000737:chemistry* / Q000378:metabolism; D024043:Collagen Type II / Q000378:metabolism; D005260:Female; D008969:Molecular Sequence Data; D020543:Proteome / Q000032:analysis*; D051381:Rats; D017207:Rats, Sprague-Dawley
D053674:Aggrecans; D015415:Biomarkers; D024043:Collagen Type II; D020543:Proteome