In vivo impact of a 4 bp deletion mutation in the DLX3 gene on bone development

Choi, Sun Jin; Roodman, G. David; Feng, Jerry Q.; Song, Inmyung; Amin, Kishore; Hart, P. Suzanne; Wright, J. T.; Haruyama, Naoto; Hart, T. C.

doi:10.1016/j.ydbio.2008.10.014

Cited by 24 publications

(27 citation statements)

References 40 publications

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“…In the TDO model, transgenic mice lacked an enhanced dynamic bone formation rate and the increased bone volume and BMD trabecular phenotype was attributed to decreased osteoclast bone resorption activity due to increased IFN-g. 13 In contrast, our analyses in Dlx3 OCN-cKO mice support that increased trabecular bone mass does not arise from impaired osteoclastic activity but from direct enhancement of the boneforming osteoblast activity. This leads to accelerated bone formation, thereby inducing an imbalance in homeostasis in favor of bone apposition.…”

Section: Discussioncontrasting

confidence: 50%

“…12 A transgenic mouse model expressing the TDO DLX3 gene mutation driven by the osteoblast-specific 2.3 Col1A1 promoter was characterized by Choi et al 13 This model resulted in increased trabecular bone volume in young and adult mice; however, the diaphysis phenotype was not described. Despite bone marrow stromal cells (BMSCs) from mutants exhibiting enhanced osteoblastic differentiation and increased bone marker expression ex vivo, the dynamic bone formation rate was not increased in vivo and the trabecular phenotype was attributed to decreased osteoclast formation and bone resorption activity due to the increased serum levels of IFN-g. 13 Taken together, these data highlight an important role for DLX3 in bone; however, the studies above 12,13 provide contrasting results and emphasize that the function of DLX3 in the postnatal and adult skeleton has not yet been fully elucidated. To address the in vivo role of DLX3 in osteoblastogenesis, bone density, and remodeling in the appendicular skeleton, we generated conditional knockouts (cKOs) of Dlx3 in mesenchymal cells (Dlx3 Prx1-cKO ) and in osteogenic lineage cells (Dlx3 OCN-cKO ).…”

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confidence: 99%

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DLX3 regulates bone mass by targeting genes supporting osteoblast differentiation and mineral homeostasis in vivo

Isaac

Gordon

et al. 2014

Cell Death Differ

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Human mutations and in vitro studies indicate that DLX3 has a crucial function in bone development, however, the in vivo role of DLX3 in endochondral ossification has not been established. Here, we identify DLX3 as a central attenuator of adult bone mass in the appendicular skeleton. Dynamic bone formation, histologic and micro-computed tomography analyses demonstrate that in vivo DLX3 conditional loss of function in mesenchymal cells (Prx1-Cre) and osteoblasts (OCN-Cre) results in increased bone mass accrual observed as early as 2 weeks that remains elevated throughout the lifespan owing to increased osteoblast activity and increased expression of bone matrix genes. Dlx3OCN-conditional knockout mice have more trabeculae that extend deeper in the medullary cavity and thicker cortical bone with an increased mineral apposition rate, decreased bone mineral density and increased cortical porosity. Trabecular TRAP staining and site-specific Q-PCR demonstrated that osteoclastic resorption remained normal on trabecular bone, whereas cortical bone exhibited altered osteoclast patterning on the periosteal surface associated with high Opg/Rankl ratios. Using RNA sequencing and chromatin immunoprecipitation-Seq analyses, we demonstrate that DLX3 regulates transcription factors crucial for bone formation such as Dlx5, Dlx6, Runx2 and Sp7 as well as genes important to mineral deposition (Ibsp, Enpp1, Mepe) and bone turnover (Opg). Furthermore, with the removal of DLX3, we observe increased occupancy of DLX5, as well as increased and earlier occupancy of RUNX2 on the bone-specific osteocalcin promoter. Together, these findings provide novel insight into mechanisms by which DLX3 attenuates bone mass accrual to support bone homeostasis by osteogenic gene pathway regulation. Endochondral bone formation (EBF) and homeostasis require a regulated program of mesenchymal condensation, chondrocyte differentiation, vascular invasion, cartilage resorption, osteoprogenitor recruitment and differentiation and bone remodeling. These key processes are under the control of essential bone transcription factors (TFs), including RUNX2, SP7 and homeodomain protein families such as HOX, MSX and DLX.1-3 DLX proteins are important regulators of developmental and differentiation processes, including skeletal development. [4][5][6] A missense mutation in DLX5 leads to split hand and foot malformation 7 and DLX5 and DLX6 are positive transcriptional regulators of osteochondroblastic differentiation. 6 DLX3 is defined as an osteogenic regulator, as human mutations in DLX3 lead to tricho-dento-osseous (TDO) syndrome, an ectodermal dysplasia that causes increased bone mineral density (BMD) in intramembranous and endochondral bones. In vitro, osteocalcin (Ocn), Runx2 9,10 and osteoactivin [9][10][11] are directly regulated by DLX3, and overexpression of DLX3 in osteoprogenitors stimulates transcription of osteogenic markers. 9Recently, we investigated the effects of neural crest deletion of Dlx3 in craniofacial bones. 12 The gene signature of craniofacial...

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Section: Discussioncontrasting

confidence: 50%

mentioning

confidence: 99%

DLX3 regulates bone mass by targeting genes supporting osteoblast differentiation and mineral homeostasis in vivo

Isaac

Gordon

et al. 2014

Cell Death Differ

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“…Dlx3 is a member of the distalless homeobox family that interacts with transcription factors specific to mineralized tissue to regulate craniofacial and postnatal skeletal development (33)(34)(35)(36)(37)(38)(39)(40)(41)(42)(43). Our results indicate that there is a cellular requirement for miR-665 to fine-tune the expression of Dlx3 within physiologic limits for maturation of progenitors to odontoblasts.…”

Section: Discussionmentioning

confidence: 78%

“…Mutations in DLX3 in humans have been associated with tricho-dento-osseous syndrome (TDO; OMIM 190320) and amelogenesis imperfecta with taurodontism (AIHHT; OMIM 104510), both of which are conditions characterized by abnormalities in tooth formation (35)(36)(37)(38)(39). During development, Dlx3 expression occurs in cranial neural crest cells, endochondral osteoblasts, odontoblasts, ameloblasts, hypertrophic chondrocytes, and the developing limb (40,41), and Dlx3-knockout mice die from placental failure at embryonic day 9.5 (E9.5), prior to bone and tooth formation (28).…”

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confidence: 99%

MicroRNA 665 Regulates Dentinogenesis through MicroRNA-Mediated Silencing and Epigenetic Mechanisms

Heair

Kemper

Roy

et al. 2015

Molecular and Cellular Biology

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bStudies of proteins involved in microRNA (miRNA) processing, maturation, and silencing have indicated the importance of miRNAs in skeletogenesis, but the specific miRNAs involved in this process are incompletely defined. Here, we identified miRNA 665 (miR-665) as a potential repressor of odontoblast maturation. Studies with cultured cell lines and primary embryonic cells showed that miR-665 represses the expression of early and late odontoblast marker genes and stage-specific proteases involved in dentin maturation. Notably, miR-665 directly targeted Dlx3 mRNA and decreased Dlx3 expression. Furthermore, RNA-induced silencing complex (RISC) immunoprecipitation and biotin-labeled miR-665 pulldown studies identified Kat6a as another potential target of miR-665. KAT6A interacted physically and functionally with RUNX2, activating tissue-specific promoter activity and prompting odontoblast differentiation. Overexpression of miR-665 reduced the recruitment of KAT6A to Dspp and Dmp1 promoters and prevented KAT6A-induced chromatin remodeling, repressing gene transcription. Taken together, our results provide novel molecular evidence that miR-665 functions in an miRNA-epigenetic regulatory network to control dentinogenesis. D entinogenesis is the process by which dentin, the major mineralized tissue of teeth, is formed through progressive cytodifferentiation of progenitor cells to mature odontoblasts (1). Multiple layers of gene regulation, including those by microRNA (miRNA), orchestrate the physiologic process of dentinogenesis in a stage-specific manner (2). Progenitor cells, including dental papilla cells or dental follicle cells, derived from the ectomesenchyme of the cranial neural crest, differentiate into preodontoblasts and produce predentin. Predentin stimulates further differentiation of the cells it surrounds, giving rise to mature odontoblasts that produce dentin. Odontoblast secretion of dentin extracellular matrix proteins, including dentin sialophosphoprotein (DSPP) and dentin matrix protein 1 (DMP1), aids in the process of mineralization that forms primary dentin. However, the mechanisms of odontoblast-specific gene regulation by miRNA during dentinogenesis are not clearly understood.miRNAs are endogenous, noncoding RNAs implicated in posttranscriptional RNA silencing (3-9). The importance of miRNAs in skeletogenesis has been shown in mice by loss-offunction analysis of proteins involved in miRNA processing (Drosha and DGCR8), maturation (Dicer), and silencing (argonaute 2; AGO2), which revealed embryonic lethality and severe developmental defects upon loss of these proteins (10-15). Furthermore, cartilage-specific deletion of Dicer led to accelerated differentiation and subsequent cell death (11), whereas osteoblast-and osteoclast-specific deletion increased bone mass (13,16). Current studies on miRNA regulation of gene expression indicate a key role for this process in tooth development (17)(18)(19)(20) and in controlling cellular signaling (18,(21)(22)(23)(24)(25) and differentiation (2,26). However, ...

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“…[52,53] Dlx3 collaborates with transcription factors unique to mineralized tissue to regulate craniofacial and postnatal skeletal development. [54][55][56] Dlx3 stimulates dentinogenesis. The posttranscriptional regulation of Dlx3 by miR-665 controlled by BMP2 and RUNX2, implies an combined network of signaling and transcription factors that coordinate the stagespecific events of odontoblast differentiation.…”

Section: Dentinogenesismentioning

confidence: 99%

Untitled

Juneius

2016

AJP

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Aim: To review the literature on the oral health status of the population, evidence-based understanding of epigenetic mechanisms, and its significant role in diseases occurring in the oral cavity. Background: Epigenetics is the study of heritable changes in gene expression that does not involve changes to the underlying DNA sequence. In other words, it is a change in phenotype without a change in genotype, which in turn affects the way cells read genes. Epigenetic change is a regular and natural occurrence but can also be influenced by several factors including age, the environment/lifestyle, and disease state. The field of epigenetics is quickly growing, and it is believed that both the environment and lifestyle can interact with the genome to influence epigenetic change. These changes may be reflected at various stages throughout a person's life and even in later generations. Conclusion: Epigenetic codes help us understand the biological phenotype that arises from the interaction of the human genome with the environment in health and in disease. Epigenetics is a major turn away from molecular biology. Current epigenetics not only offers new insights into gene regulation and heredity, but also it challenges the way we think about evolution, genetics, and development. Most interestingly, it suggests testable mechanisms whereby environmental factors (ranging from stress to infection) can influence genetic expression.

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In vivo impact of a 4 bp deletion mutation in the DLX3 gene on bone development

Cited by 24 publications

References 40 publications

DLX3 regulates bone mass by targeting genes supporting osteoblast differentiation and mineral homeostasis in vivo

DLX3 regulates bone mass by targeting genes supporting osteoblast differentiation and mineral homeostasis in vivo

MicroRNA 665 Regulates Dentinogenesis through MicroRNA-Mediated Silencing and Epigenetic Mechanisms

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