Identification of the functional activity of the [A-4] amelogenin gene splice product in newborn mouse ameloblasts

Iacob, Stanca; Veis, Arthur

doi:10.1016/j.bone.2008.01.023

Cited by 20 publications

(27 citation statements)

References 28 publications

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“…This PCR analysis showed that the larger amelogenin splice variant containing all exons with the exception of exon 4, was specifically upregulated in TgLRAP pre-secretory ameloblasts. These PCR results showing an upregulation of full length (M180) amelogenin in response to increased LRAP are consistent with reports by Iacob and Veis, who found that when exogenous LRAP protein was added to the LS8 ameloblast lineage cell line M180 mRNA was upreguated 13.6 fold upregulation after 24hrs (Iacob and Veis, 2008). Xu and co-workers reported that amelogenin full length protein, but not LRAP can stabilize amelogenin mRNA.…”

Section: Discussionsupporting

confidence: 91%

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Leucine rich amelogenin peptide alters ameloblast differentiation in vivo

et al. 2013

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Highly mineralized tooth enamel develops from an extracellular matrix chiefly comprised of amelogenins formed by splicing of 7 (human) or 9 (rodent) exons secreted from specialized epithelia cells known as ameloblasts. Here we examined the role of the 59 amino acid alternatively spliced amelogenin known as Leucine Rich Amelogenin Peptide (LRAP) on enamel formation, using transgenic murine models in which LRAP overexpression is driven by an amelogenin promotor (TgLRAP). Beginning in the secretory stage of mouse amelogenesis, we found a reduced thickness of enamel matrix and a loss of Tomes’ processes, followed by upregulated amelogenin mRNA expression, inhibited amelogenin secretion and loss of cell polarity. In the prescretory stage (P0) amelogenin m180 mRNA expression was increased 58 fold along with a 203 fold increase in MMP-20 expression and 3.5 and 3.2 fold increased in respectively enamelin and ameloblastin. When LRAP was overexpressed on an amelogenin knockout mouse model, the ameloblasts were not affected. Further, expression of the global chromatin organizer and transcription factor SATB1 was reduced in secretory stage TgLRAP ameloblasts. These findings identify a cellular role for LRAP in enamel formation that is not directly related to directing enamel crystal formation as is reported to be the primary function of full length amelogenins. The effect of LRAP overexpression in upregulating amelogenins, MMP-20 and SATB1, suggests a role in protein regulation critical to ameloblast secretion and matrix processing, to form a mineralized enamel matrix.

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Section: Discussionsupporting

confidence: 91%

“…Addition of exogenous LRAP to mouse enamel organ derived LS8 cells showed co-localization with LRAP (referred to as A-4) and lysosomal-associated membrane protein 1 (LAMP1), as well as an activation of the nitric oxide signaling pathway (Iacob and Veis, 2008; Le et al, 2007)…”

Section: Introductionmentioning

confidence: 99%

Leucine rich amelogenin peptide alters ameloblast differentiation in vivo

et al. 2013

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“…A number of alternatively spliced amelogenin isoforms are found in the enamel matrix, but the importance, function and abundance of each isoform is incompletely understood [4, 7]. In the past decade, a mixture of enamel matrix proteins called Emdogain was identified and used with success in clinical dentistry to promote repair of hard and soft periodontal tissue [8, 9].…”

Section: Introductionmentioning

confidence: 99%

Leucine-rich amelogenin peptide induces osteogenesis by activation of the Wnt pathway

Warotayanont

Frenkel

Snead

et al. 2009

Biochemical and Biophysical Research Communications

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We previously showed that one of the amelogenin splicing isoforms, Leucine-rich Amelogenin Peptide (LRAP), induced osteogenic differentiation of mouse embryonic stem cells; however, the signaling pathway(s) activated by LRAP remained unknown. Here, we demonstrated that the canonical Wnt/β-catenin signaling is activated upon LRAP treatment, as evidenced by elevated β-catenin level and increased Wnt reporter gene activity. Furthermore, a specific Wnt inhibitor sFRP-1 completely blocks the LRAP-mediated Wnt signaling. However, exogenous recombinant Wnt3a alone was less effective at osteogenic induction of mouse ES cells in comparison to LRAP. Using a quantitative real-time PCR array, we discovered that LRAP treatment up-regulated the expression of Wnt agonists and down-regulated the expression of Wnt antagonists. We conclude that LRAP activates the canonical Wnt signaling pathway to induce osteogenic differentiation of mouse ES cells through the concerted regulation of Wnt agonists and antagonists.

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“…These results indicate that csLRAP might have similar effects on chondrogenic cell proliferation involving LAMP-1 protein but may have a different effect on mineralized tissue-forming cells like osteoblasts or cementoblasts. It has been suggested that LAMP-1 involves the enamel epithelial cell differentiation 20) and amelogenin gene expression in ameloblast cell line promoted by LRAP 38) . And recent studies have indicated that LAMP-1 expression could be involved in osteoblast MC3T3 differentiation and the regulation of calcification 39) .…”

Section: Discussionmentioning

confidence: 99%

Effects of a Chemically Synthesized Leucine-Rich Amelogenin Peptide (csLRAP) on Chondrogenic and Osteogenic Cells

Matsuda

Hatakeyama

Nakashima

et al. 2017

J. Hard Tissue Biology.

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Amelogenin is one of the enamel matrices secreted by ameloblasts and is known to have at least 15 alternative mRNA splicing isoforms. The leucine rich amelogenin peptide (LRAP) is one of most abundant amelogenin isoforms and numerous studies have shown that amelogenin peptides including LRAP, are expressed in cartilage and bone. Lysosome-associated membrane protein-1 (LAMP-1) has been identified as amelogenin binding partner, however, the mechanism of action for LRAP in chondrogenesis or osteogenesis is still unclear. This study aimed to assay the effect of chemically synthesized LRAP (csLRAP) on chondrogenic or osteogenic differentiation with the involvement of LAMP-1. The csLRAP used in this study was generated by F-moc solid phase chemistry based on the mouse LRAP amino acid sequence and was added to the culture medium of the chondrogenic cells, ATDC5 and the osteoblast cells, MC3T3-E1. Both chondrogenic and osteoblast cells, in which an immunopositive reaction to LAMP-1 antibody was observed by immunocytochemistry, showed significant suppression in cell number in the presence of csLRAP at 10 g/ml compared to that in control, but this effect was rescued in the presence of LAMP-1 antibody. On the other hand, the intensity of alcian blue staining in chondrogenic cells and alizarin red staining in osteoblast cells was significantly increased in the presence of csLRAP at a dose of 10 g/ml after 4 weeks culture, and this effect was suppressed in the presence LAMP-1 antibody. Moreover, the chondrogenic or osteogenic differentiation marker genes including Sox9, Type II Collagen, Type X Collagen, Runx2, Alkaline Phosphatase, and Type I Collagen, were upregulated in the presence of csLRAP after one week of culture and were suppressed in the presence of LAMP-1 antibody. These results suggest that csLRAP could promote osteogenic and chondrogenic differentiation in vitro, and that LAMP-1 may be involved in the differentiation and proliferation of these cells.

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Identification of the functional activity of the [A-4] amelogenin gene splice product in newborn mouse ameloblasts

Cited by 20 publications

References 28 publications

Leucine rich amelogenin peptide alters ameloblast differentiation in vivo

Leucine rich amelogenin peptide alters ameloblast differentiation in vivo

Leucine-rich amelogenin peptide induces osteogenesis by activation of the Wnt pathway

Effects of a Chemically Synthesized Leucine-Rich Amelogenin Peptide (csLRAP) on Chondrogenic and Osteogenic Cells

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