Modulation of matrix mineralization by Vwc2-like protein and its novel splicing isoforms.
In search of new cysteine knot protein (CKP) family members, we found a novel gene called von Willebrand factor C domain-containing protein 2-like (Vwc2l, also known as Brorin-like) and its transcript variants (Vwc2l-1, Vwc2l-2 and Vwc2l-3). Based on the deduced amino acid sequence, Vwc2l-1 has a signal peptide and 2 cysteine-rich (CR) domains, while Vwc2l-2 lacks a part of 2nd CR domain and Vwc2l-3 both CR domains. Although it has been reported that the expression of Brorin-like was predominantly observed in brain, we found that Vwc2l transcript variants were detected in more ubiquitous tissues. In osteoblasts, the induction of Vwc2l expression was observed at matrix mineralization stage. When Vwc2l was stably transfected into osteoblasts, the matrix mineralization was markedly accelerated in Vwc2l-expressing clones compared to that in the control, indicating the modulatory effect of Vwc2l protein on osteoblastic cell function. The mechanistic insight of Vwc2l-modulation was further investigated and we found that the expression of Osterix, one of the key osteogenic markers, was significantly increased by addition of all Vwc2l isoform proteins. Taken together, Vwc2l is a novel secreted protein that promotes matrix mineralization by modulating Osterix expression likely through TGF-β superfamily growth factor signaling pathway. Our data may provide mechanistic insights into the biological functions of this novel CKP member in bone and further suggest a novel approach to enhance osteoblast function, which enables to accerelate bone formation, regeneration and healing.
Department of Periodontology and Oral Biology, Boston University, Henry M. Goldman School of Dental Medicine, 700 Albany Street, Boston, MA 02118, USA.
Yoshio
Y
Ohyama
Michitsuna
M
Katafuchi
Ahmed
A
Almehmadi
Sundharamani
S
Venkitapathi
Haytham
H
Jaha
Jason
J
Ehrenman
Joseph
J
Morcos
Reem
R
Aljamaan
Yoshiyuki
Y
Mochida
D041721:3T3-L1 Cells; D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D001857:Bone Matrix / Q000378:metabolism / Q000502:physiology*; D002113:Calcification, Physiologic; D002454:Cell Differentiation; D057809:HEK293 Cells; D006801:Humans; D008297:Male; D051379:Mice; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D010006:Osteoblasts / Q000378:metabolism / Q000502:physiology; D010012:Osteogenesis; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D000076182:Sp7 Transcription Factor; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic; D016212:Transforming Growth Factor beta / Q000378:metabolism
D009419:Nerve Tissue Proteins; D020033:Protein Isoforms; D000076182:Sp7 Transcription Factor; C479466:Sp7 protein, mouse; D014157:Transcription Factors; D016212:Transforming Growth Factor beta; C546360:Vwc2l protein, mouse