Leucine rich amelogenin peptide prevents ovariectomy-induced bone loss in mice.

Amelogenins, major extra cellular matrix proteins of developing tooth enamel, are predominantly expressed by ameloblasts and play significant roles in the formation of enamel. Recently, amelogenin has been detected in various epithelial and mesenchymal tissues, implicating that it might have distinc...

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Main Authors: Naoto Haruyama, Takayoshi Yamaza, Shigeki Suzuki, Bradford Hall, Andrew Cho, Carolyn W Gibson, Ashok B Kulkarni
Format: Article
Language:English
Published: Public Library of Science (PLoS) 2021-01-01
Series:PLoS ONE
Online Access:https://doi.org/10.1371/journal.pone.0259966
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author Naoto Haruyama
Takayoshi Yamaza
Shigeki Suzuki
Bradford Hall
Andrew Cho
Carolyn W Gibson
Ashok B Kulkarni
author_facet Naoto Haruyama
Takayoshi Yamaza
Shigeki Suzuki
Bradford Hall
Andrew Cho
Carolyn W Gibson
Ashok B Kulkarni
author_sort Naoto Haruyama
collection DOAJ
description Amelogenins, major extra cellular matrix proteins of developing tooth enamel, are predominantly expressed by ameloblasts and play significant roles in the formation of enamel. Recently, amelogenin has been detected in various epithelial and mesenchymal tissues, implicating that it might have distinct functions in various tissues. We have previously reported that leucine rich amelogenin peptide (LRAP), one of the alternate splice forms of amelogenin, regulates receptor activator of NF-kappa B ligand (RANKL) expression in cementoblast/periodontal ligament cells, suggesting that the amelogenins, especially LRAP, might function as a signaling molecule in bone metabolism. The objective of this study was to identify and define LRAP functions in bone turnover. We engineered transgenic (TgLRAP) mice using a murine 2.3kb α1(I)-collagen promoter to drive expression of a transgene consisting of LRAP, an internal ribosome entry site (IRES) and enhanced green fluorescent protein (EGFP) to study functions of LRAP in bone formation and resorption. Calvarial cell cultures from the TgLRAP mice showed increased alkaline phosphatase (ALP) activity and increased formation of mineralized nodules compared to the cells derived from wild-type (WT) mice. The TgLRAP calvarial cells also showed an inhibitory effect on osteoclastogenesis in vitro. Gene expression comparison by quantitative polymerase chain reaction (Q-PCR) in calvarial cells indicated that bone formation makers such as Runx2, Alp, and osteocalcin were increased in TgLRAP compared to the WT cells. Meanwhile, Rankl expression was decreased in the TgLRAP cells in vitro. The ovariectomized (OVX) TgLRAP mice resisted bone loss induced by ovariectomy resulting in higher bone mineral density in comparison to OVX WT mice. The quantitative analysis of calcein intakes indicated that the ovariectomy resulted in increased bone formation in both WT and TgLRAP mice; OVX TgLRAP appeared to show the most remarkably increased bone formation. The parameters for bone resorption in tissue sections showed increased number of osteoclasts in OVX WT, but not in OVX TgLRAP over that of sham operated WT or TgLRAP mice, supporting the observed bone phenotypes in OVX mice. This is the first report identifying that LRAP, one of the amelogenin splice variants, affects bone turnover in vivo.
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spelling doaj.art-1ff28034690d423d956e4f50ae60b6922022-12-21T19:24:45ZengPublic Library of Science (PLoS)PLoS ONE1932-62032021-01-011611e025996610.1371/journal.pone.0259966Leucine rich amelogenin peptide prevents ovariectomy-induced bone loss in mice.Naoto HaruyamaTakayoshi YamazaShigeki SuzukiBradford HallAndrew ChoCarolyn W GibsonAshok B KulkarniAmelogenins, major extra cellular matrix proteins of developing tooth enamel, are predominantly expressed by ameloblasts and play significant roles in the formation of enamel. Recently, amelogenin has been detected in various epithelial and mesenchymal tissues, implicating that it might have distinct functions in various tissues. We have previously reported that leucine rich amelogenin peptide (LRAP), one of the alternate splice forms of amelogenin, regulates receptor activator of NF-kappa B ligand (RANKL) expression in cementoblast/periodontal ligament cells, suggesting that the amelogenins, especially LRAP, might function as a signaling molecule in bone metabolism. The objective of this study was to identify and define LRAP functions in bone turnover. We engineered transgenic (TgLRAP) mice using a murine 2.3kb α1(I)-collagen promoter to drive expression of a transgene consisting of LRAP, an internal ribosome entry site (IRES) and enhanced green fluorescent protein (EGFP) to study functions of LRAP in bone formation and resorption. Calvarial cell cultures from the TgLRAP mice showed increased alkaline phosphatase (ALP) activity and increased formation of mineralized nodules compared to the cells derived from wild-type (WT) mice. The TgLRAP calvarial cells also showed an inhibitory effect on osteoclastogenesis in vitro. Gene expression comparison by quantitative polymerase chain reaction (Q-PCR) in calvarial cells indicated that bone formation makers such as Runx2, Alp, and osteocalcin were increased in TgLRAP compared to the WT cells. Meanwhile, Rankl expression was decreased in the TgLRAP cells in vitro. The ovariectomized (OVX) TgLRAP mice resisted bone loss induced by ovariectomy resulting in higher bone mineral density in comparison to OVX WT mice. The quantitative analysis of calcein intakes indicated that the ovariectomy resulted in increased bone formation in both WT and TgLRAP mice; OVX TgLRAP appeared to show the most remarkably increased bone formation. The parameters for bone resorption in tissue sections showed increased number of osteoclasts in OVX WT, but not in OVX TgLRAP over that of sham operated WT or TgLRAP mice, supporting the observed bone phenotypes in OVX mice. This is the first report identifying that LRAP, one of the amelogenin splice variants, affects bone turnover in vivo.https://doi.org/10.1371/journal.pone.0259966
spellingShingle Naoto Haruyama
Takayoshi Yamaza
Shigeki Suzuki
Bradford Hall
Andrew Cho
Carolyn W Gibson
Ashok B Kulkarni
Leucine rich amelogenin peptide prevents ovariectomy-induced bone loss in mice.
PLoS ONE
title Leucine rich amelogenin peptide prevents ovariectomy-induced bone loss in mice.
title_full Leucine rich amelogenin peptide prevents ovariectomy-induced bone loss in mice.
title_fullStr Leucine rich amelogenin peptide prevents ovariectomy-induced bone loss in mice.
title_full_unstemmed Leucine rich amelogenin peptide prevents ovariectomy-induced bone loss in mice.
title_short Leucine rich amelogenin peptide prevents ovariectomy-induced bone loss in mice.
title_sort leucine rich amelogenin peptide prevents ovariectomy induced bone loss in mice
url https://doi.org/10.1371/journal.pone.0259966
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