Expression and physiological role of CCN4/Wnt-induced secreted protein 1 mRNA splicing variants in chondrocytes.
CCN4/Wnt-induced secreted protein 1 (WISP1) is one of the CCN (CTGF/Cyr61/Nov) family proteins. CCN members have typical structures composed of four conserved cysteine-rich modules and their variants lacking certain modules, generated by alternative splicing or gene mutations, have been described in various pathological conditions. Several previous reports described a CCN4/WISP1 variant (WISP1v) lacking the second module in a few malignancies, but no information concerning the production of WISP1 variants in normal tissue is currently available. The expression of CCN4/WISP1 mRNA and its variants were analyzed in a human chondrosarcoma-derived chondrocytic cell line, HCS-2/8, and primary rabbit growth cartilage (RGC) chondrocytes. First, we found WISP1v and a novel variant of WISP1 (WISP1vx) to be expressed in HCS-2/8, as well as full-length WISP1 mRNA. This new variant was lacking the coding regions for the second and third modules and a small part of the first module. To monitor the expression of CCN4/WISP1 mRNA along chondrocyte differentiation, RGC cells were cultured and sampled until they were mineralized. As a result, we identified a WISP1v ortholog in normal RGC cells. Interestingly, the WISP1v mRNA level increased dramatically along with terminal differentiation. Furthermore, overexpression of WISP1v provoked expression of an alkaline phosphatase gene that is a marker of terminal differentiation in HCS-2/8 cells. These findings indicate that WISP1v thus plays a critical role in chondrocyte differentiation toward endochondral ossification, whereas HCS-2/8-specific WISP1vx may be associated with the transformed phenotypes of chondrosarcomas.
Yanagita
Takeshi
T
Department of Biochemistry & Molecular Dentistry, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Japan.
Kubota
Satoshi
S
Kawaki
Harumi
H
Kawata
Kazumi
K
Kondo
Seiji
S
Takano-Yamamoto
Teruko
T
Tanaka
Shinji
S
Takigawa
Masaharu
M
D053674:Aggrecans / Q000235:genetics; D000469:Alkaline Phosphatase / Q000235:genetics; D017398:Alternative Splicing; D000818:Animals; D055511:CCN Intercellular Signaling Proteins; D002356:Cartilage / Q000378:metabolism; D002454:Cell Differentiation / Q000235:genetics; D002460:Cell Line; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D019902:Chondrocytes / Q000378:metabolism*; D024043:Collagen Type II / Q000235:genetics; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D004622:Embryo, Mammalian / Q000378:metabolism; D020869:Gene Expression Profiling; D006367:HeLa Cells; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics* / Q000502:physiology; D051379:Mice; D008969:Molecular Sequence Data; D020033:Protein Isoforms / Q000235:genetics / Q000502:physiology; D011518:Proto-Oncogene Proteins / Q000235:genetics* / Q000502:physiology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011817:Rabbits; D017423:Sequence Analysis, RNA; D014162:Transfection
D053674:Aggrecans; D055511:CCN Intercellular Signaling Proteins; C116396:CCN4 protein, human; D024043:Collagen Type II; D018076:DNA, Complementary; D047908:Intracellular Signaling Peptides and Proteins; D020033:Protein Isoforms; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; D000469:Alkaline Phosphatase