Possible role of LRP1, a CCN2 receptor, in chondrocytes.
Low density lipoprotein receptor (LDLR)-related protein 1 (LRP1/CD91) is one of the receptors of CCN2 that conducts endochondral ossification and cartilage repair. LRP1 is a well-known endocytic receptor, but its distribution among chondrocytes remains to be elucidated. We herein demonstrate for the first time that the distribution of LRP1 in chondrocytes except for hypertrophic chondrocytes in vivo and in vitro. Interestingly, the LRP1 levels were higher in mature chondrocytic HCS-2/8 and osteoblastic SaOS-2 than in other cells, whereas the other LDLR family members involved in ossification were detected at lower levels in HCS-2/8. It was interesting to note that in HCS-2/8, LRP1 was observed not only on the cell surface and in the cytoplasm, but also in the nucleus. Exogenously added CCN2 was incorporated into HCS-2/8, which was partially co-localized with LRP1, and targeted to the recycling endosomes and nucleus as well as the lysosomes. These findings suggest specific roles of LRP1 in cartilage biology.
Kawata
Kazumi
K
Department of Biochemistry and Molecular Dentistry, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 2-5-1 Shikata-Cho, Okayama-shi, Okayama 700-8525, Japan.
Eguchi
Takanori
T
Kubota
Satoshi
S
Kawaki
Harumi
H
Oka
Morihiko
M
Minagi
Shogo
S
Takigawa
Masaharu
M
D000818:Animals; D001483:Base Sequence; D002356:Cartilage / Q000502:physiology*; D002460:Cell Line; D019902:Chondrocytes / Q000378:metabolism*; D004705:Endocytosis / Q000502:physiology; D011992:Endosomes / Q000378:metabolism; D026503:Low Density Lipoprotein Receptor-Related Protein-1; D051379:Mice; D008807:Mice, Inbred BALB C; D010006:Osteoblasts / Q000166:cytology / Q000378:metabolism / Q000473:pathology; D010012:Osteogenesis / Q000502:physiology*; D011817:Rabbits; D011973:Receptors, LDL / Q000378:metabolism / Q000502:physiology*; D013997:Time Factors; D025521:Tumor Suppressor Proteins / Q000502:physiology*
D026503:Low Density Lipoprotein Receptor-Related Protein-1; C486645:Lrp1 protein, mouse; D011973:Receptors, LDL; D025521:Tumor Suppressor Proteins