title: Type XII collagen regulates osteoblast polarity and communication during bone formation.
abstract: Differentiated osteoblasts are polarized in regions of bone deposition, demonstrate extensive cell interaction and communication, and are responsible for bone formation and quality. Type XII collagen is a fibril-associated collagen with interrupted triple helices and has been implicated in the osteoblast response to mechanical forces. Type XII collagen is expressed by osteoblasts and localizes to areas of bone formation. A transgenic mouse null for type XII collagen exhibits skeletal abnormalities including shorter, more slender long bones with decreased mechanical strength as well as altered vertebrae structure compared with wild-type mice. Col12a(-/-) osteoblasts have decreased bone matrix deposition with delayed maturation indicated by decreased bone matrix protein expression. Compared with controls, Col12a(-/-) osteoblasts are disorganized and less polarized with disrupted cell-cell interactions, decreased connexin43 expression, and impaired gap junction function. The data demonstrate important regulatory roles for type XII collagen in osteoblast differentiation and bone matrix formation.
authors.affiliation: Department of Pathology and Cell Biology, College of Medicine, University of South Florida, Tampa, FL 33612, USA.
authors.forename: Yayoi
authors.initials: Y
authors.lastname: Izu
authors.forename: Mei
authors.initials: M
authors.lastname: Sun
authors.forename: Daniela
authors.initials: D
authors.lastname: Zwolanek
authors.forename: Guido
authors.initials: G
authors.lastname: Veit
authors.forename: Valerie
authors.initials: V
authors.lastname: Williams
authors.forename: Byeong
authors.initials: B
authors.lastname: Cha
authors.forename: Karl J
authors.initials: KJ
authors.lastname: Jepsen
authors.forename: Manuel
authors.initials: M
authors.lastname: Koch
authors.forename: David E
authors.initials: DE
authors.lastname: Birk
mesh_terms: D000818:Animals; D001857:Bone Matrix / Q000378:metabolism / Q000648:ultrastructure; D001842:Bone and Bones / Q000033:anatomy & histology / Q000378:metabolism; D002450:Cell Communication / Q000502:physiology*; D002454:Cell Differentiation / Q000502:physiology; D016764:Cell Polarity; D024082:Collagen Type XII / Q000235:genetics / Q000378:metabolism*; D018031:Connexin 43 / Q000378:metabolism; D006801:Humans; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D010006:Osteoblasts / Q000166:cytology* / Q000502:physiology*; D010012:Osteogenesis / Q000502:physiology*; D013314:Stress, Mechanical
chemical_list: D024082:Collagen Type XII; D018031:Connexin 43