title: Role of the NH2 -terminal fragment of dentin sialophosphoprotein in dentinogenesis.
abstract: Dentin sialophosphoprotein (DSPP) is a large precursor protein that is proteolytically processed into a NH2 -terminal fragment [composed of dentin sialoprotein (DSP) and a proteoglycan form (DSP-PG)] and a COOH-terminal fragment [dentin phosphoprotein (DPP)]. In vitro studies indicate that DPP is a strong initiator and regulator of hydroxyapatite crystal formation and growth, but the role(s) of the NH2 -terminal fragment of DSPP (i.e., DSP and DSP-PG) in dentinogenesis remain unclear. This study focuses on the function of the NH2 -terminal fragment of DSPP in dentinogenesis. Here, transgenic (Tg) mouse lines expressing the NH2 -terminal fragment of DSPP driven by a 3.6-kb type I collagen promoter (Col 1a1) were generated and cross-bred with Dspp null mice to obtain mice that express the transgene but lack the endogenous Dspp (Dspp KO/DSP Tg). We found that dentin from the Dspp KO/DSP Tg mice was much thinner, more poorly mineralized, and remarkably disorganized compared with dentin from the Dspp KO mice. The fact that Dspp KO/DSP Tg mice exhibited more severe dentin defects than did the Dspp null mice indicates that the NH2 -terminal fragment of DSPP may inhibit dentin mineralization or may serve as an antagonist against the accelerating action of DPP and serve to prevent predentin from being mineralized too rapidly during dentinogenesis.
authors.affiliation: Texas A&M Health Science Center Baylor College of Dentistry, Dallas, TX 75246, USA.
authors.forename: Monica P
authors.initials: MP
authors.lastname: Gibson
authors.forename: Qilin
authors.initials: Q
authors.lastname: Liu
authors.forename: Qinglin
authors.initials: Q
authors.lastname: Zhu
authors.forename: Yongbo
authors.initials: Y
authors.lastname: Lu
authors.forename: Priyam
authors.initials: P
authors.lastname: Jani
authors.forename: Xiaofang
authors.initials: X
authors.lastname: Wang
authors.forename: Ying
authors.initials: Y
authors.lastname: Liu
authors.forename: Michael L
authors.initials: ML
authors.lastname: Paine
authors.forename: Malcolm L
authors.initials: ML
authors.lastname: Snead
authors.forename: Jian Q
authors.initials: JQ
authors.lastname: Feng
authors.forename: Chunlin
authors.initials: C
authors.lastname: Qin
mesh_terms: D000818:Animals; D003804:Dentin / Q000737:chemistry / Q000378:metabolism*; D003810:Dentinogenesis / Q000235:genetics / Q000502:physiology*; D016326:Extracellular Matrix Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D007150:Immunohistochemistry; D051379:Mice; D018345:Mice, Knockout; D008855:Microscopy, Electron, Scanning; D010750:Phosphoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger; D060888:Real-Time Polymerase Chain Reaction; D012795:Sialoglycoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014074:Tooth Calcification / Q000235:genetics / Q000502:physiology*; D055114:X-Ray Microtomography; D000099311:Dentin Sialophosphoprotein
chemical_list: D016326:Extracellular Matrix Proteins; D010750:Phosphoproteins; D012333:RNA, Messenger; D012795:Sialoglycoproteins; D000099311:Dentin Sialophosphoprotein