Secretome analysis of human BMSCs and identification of SMOC1 as an important ECM protein in osteoblast differentiation.
Extracellular matrix proteins have been implicated in the regulation of osteoblast differentiation of bone marrow derived mesenchymal stem cells (BMSCs) through paracrine or autocrine mechanisms. In the current study, we analyzed the secretory protein profiles of BMSCs grown in osteogenic medium (OSM) and identified SPARC-related modular calcium-binding protein 1 (SMOC1), a member of the SPARC family, as a regulator of osteoblast differentiation of BMSCs. BMSCs with high and low osteogenic potential were grouped and stimulated with OSM, after which conditioned medium was collected and analyzed by LC-MS/MS. We identified 410 proteins, 64 of which were selectively secreted by high osteogenic potential BMSCs. Of these 64 secreted proteins, we selected extracellular matrix proteins for validation in BMSCs undergoing osteoblast differentiation and found that SMOC1 is highly expressed and secreted in BMSCs stimulated with OSM. To examine the role of SMOC1 in osteoblast differentiation, we analyzed the effect of SMOC1 knockdown and overexpression using shRNAs and wild-type cDNA, respectively. Knockdown of SMOC1 significantly inhibited mineralization and the expression of osteoblast differentiation markers, while overexpression of SMOC1 substantially increased the expression of osteoblast differentiation-related genes. Thus, validation of secretome profiling data identified SMOC1 as a putative regulator of osteoblast differentiation of BMSCs.
Choi
Young-Ae
YA
Department of Oral Pathology, School of Dentistry, BK21, IHBR, Kyungpook National University, Daegu, Korea.
Lim
Jiwon
J
Kim
Kyung Min
KM
Acharya
Bodhraj
B
Cho
Je-Yoel
JY
Bae
Yong-Chul
YC
Shin
Hong-In
HI
Kim
Shin-Yoon
SY
Park
Eui Kyun
EK
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015153:Blotting, Western; D001854:Bone Marrow Cells / Q000378:metabolism*; D002454:Cell Differentiation / Q000235:genetics*; D049109:Cell Proliferation; D002478:Cells, Cultured; D016326:Extracellular Matrix Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D005260:Female; D055785:Gene Knockdown Techniques; D006801:Humans; D008297:Male; D008875:Middle Aged; D010006:Osteoblasts / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D010012:Osteogenesis / Q000235:genetics; D015676:Osteonectin / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D020543:Proteome / Q000737:chemistry / Q000378:metabolism*; D040901:Proteomics / Q000379:methods; D015203:Reproducibility of Results; D013234:Stem Cells / Q000378:metabolism*
D016326:Extracellular Matrix Proteins; D015676:Osteonectin; D020543:Proteome; C468135:SMOC1 protein, human