Fibromodulin and Biglycan Modulate Periodontium through TGFβ/BMP Signaling

Abstract

A full understanding of the key regulators controlling periodontal development and homeostasis is necessary for the design of improved periodontal regenerative therapies. Small leucinerich proteoglycans (SLRPs) are extracellular matrix molecules suggested to regulate collagen organization and cell signaling. Mice with double-deficiency of 2 SLRPs, fibromodulin and biglycan (dKO), acquire skeletal abnormalities, but their roles in regulating the periodontium remain undefined and were the focus of our studies. Transmission electron microscopy studies showed abnormal collagen fibrils in the periodontal ligament (PDL) and altered remodeling of alveolar bone in dKO mice. Immunohistochemistry (IHC) revealed increased staining of SLRPs (asporin, lumican, and decorin) and dentin matrix protein-1 (DMP1, a mechanosensory/osteocyte marker), while osteoblast markers, bone sialoprotein and osteopontin, remained unchanged. Disruption of homeostasis was further evidenced by increased expression of receptor-activator of nuclear factor-κB ligand (RANKL) and elevated numbers of osteoclasts, especially noted around the alveolar bone of molars (buccal side) and incisors. Polymerase chain reaction (PCR) array revealed hyperactive transforming growth factors beta/bone morphogenetic protein (TGFβ/BMP) signaling in dKO PDL tissues, which was further confirmed by elevated expression of phosphorylated Smad5 (p-Smad5) by IHC in dKO PDL. These studies highlight the importance of SLRPs in maintaining periodontal homeostasis through regulation of TGFβ/BMP signaling, matrix turnover, and collagen organization.

Osteopontin regulates dentin and alveolar bone development and mineralization

“…Among the decreased factors in Ank −/− mice was fibromodulin (FMOD), a small leucine-rich proteoglycan (SLRP) known to modulate collagen fibril formation in the PDL and implicated in periodontal homeostasis [33–35]. Immunohistochemistry for FMOD revealed strong staining patterns in both Ank −/− and WT periodontia at 60 dpn (Supplementary Fig.…”

Global proteome profiling of dental cementum under experimentally-induced apposition

“…Key markers associated with DC formation included secreted phosphoproteins, bone sialoprotein (BSP), osteopontin (OPN), and dentin matrix protein 1 (DMP1), and mineralization-regulating enzyme tissue-nonspecific alkaline phosphatase (TNAP) (Figure 3C–F) [9, 17, 20, 23]. Several proteoglycans were identified, including decorin (DCN), biglycan (BGN), fibromodulin (FMOD), asporin (ASPN), lumican (LUM), and osteomodulin/osteoadherin (OSAD), and these potential mineralization regulators have been identified in DC (Figure 3G–J) and the periodontium [10, 18, 24–26]. We also identified periostin (POSTN) (Figure 3K), vimentin (VIM), tenascin (TNN), and vitronectin (VTN), which have been identified in DC and/or associated embedded PDL tissues [5, 10, 27–29].…”

“…Expression of ASPN, a class II small leucine rich proteoglycan (SLRP), has been reported in dentin, alveolar bone, DC, and PDL [10, 18, 38, 39]. ASPN is reported to bind collagen and regulate bio-mineralization, as well as affecting fibroblast growth factor (FGF) signaling and inflammatory response [40–43].…”

“…IHC was performed on paraffin sections using an avidin-biotinylated peroxidase enzyme complex (ABC) based kit (Vector Labs, Burlingame, CA, USA) with 3-amino-9-ethylcarbazole (AEC) chromogenic substrate (Vector Labs), as described previously [17]. Primary antibodies included: Goat polyclonal IgG anti-asporin (ASPN; Abcam Inc., Cambridge, MA, USA) [18]; Rabbit polyclonal IgG anti-biglycan (BGN; LF-159, provided by Dr. Larry Fisher, NIDCR/NIH, Bethesda, MD, USA) [10, 19]; Rabbit polyclonal IgG anti-bone sialoprotein (BSP; Provided by Dr. Renny Franceschi, University of Michigan, Ann Arbor, MI)[20]; Rabbit polyclonal IgG anti-collagen type I alpha 1 (COL1A1; LF-68, provided by Dr. Larry Fisher)[19]; Rabbit polyclonal IgG anti-collagen type XI alpha 1 (COL11A1; Abcam Inc.); Rabbit polyclonal IgG anti-collagen type XII (COL12; KR-33, provided by Dr. Manual Koch, University of Cologne, Germany)[21]; Rabbit polyclonal IgG anti-decorin (DCN; LF-114, provided by Dr. Larry Fisher)[10, 19]; Rabbit polyclonal IgG anti-fibromodulin (FMOD; LF-150, provided by Dr. Larry Fisher)[10]; Rabbit polyclonal IgG anti-osteopontin (OPN; LF-175, provided by Dr. Larry Fisher) [17]; Rabbit polyclonal IgG anti-periostin (POSTN; Abcam Inc.)[10]; and Rabbit polyclonal anti-osteonectin/secreted protein acidic and rich in cysteine (SPARC; BON-I, provided by Dr. Larry Fisher). Immunostaining of COL11A1 employed a trypsin digest antigen retrival step (Thermo Fisher Scientific, Waltham, MA, USA).…”

Potential Role of Long Non‐Coding RNA in Osteogenic Differentiation of Human Periodontal Ligament Stem Cells

“…It is generally accepted that the function and preservation of teeth depends on the periodontium, including: 1) periodontal ligament (PDL); 2) cementum; and 3) alveolar bone 1 , 2 . PDL can renew and repair itself, but this ability is limited.…”