Isolation and characterization of the human homeobox gene HOX D1

A Neural Crest-specific Overexpression Mouse Model Reveals the Transcriptional Regulatory Effects of Dlx2 During Maxillary Process Development

Craniofacial morphogenesis is a complex process that requires precise regulation of cell proliferation, migration, and differentiation. Perturbations of this process cause a series of craniofacial deformities. Dlx2 is a critical transcription factor that regulates the development of the first branchial arch. However, the transcriptional regulatory functions of Dlx2 during craniofacial development have been poorly understood due to the lack of animal models in which the Dlx2 level can be precisely modulated. In this study, we constructed a Rosa26 site-directed Dlx2 gene knock-in mouse model Rosa26 ^{CAG-LSL-Dlx2-3xFlag} for conditionally overexpressing Dlx2. By breeding with wnt1 ^cre mice, we obtained wnt1 ^cre ; Rosa26 ^Dlx2/- mice, in which Dlx2 is overexpressed in neural crest lineage at approximately three times the endogenous level. The wnt1 ^cre ; Rosa26 ^Dlx2/- mice exhibited consistent phenotypes that include cleft palate across generations and individual animals. Using this model, we demonstrated that Dlx2 caused cleft palate by affecting maxillary growth and uplift in the early-stage development of maxillary prominences. By performing bulk RNA-sequencing, we demonstrated that Dlx2 overexpression induced significant changes in many genes associated with critical developmental pathways. In summary, our novel mouse model provides a reliable and consistent system for investigating Dlx2 functions during development and for elucidating the gene regulatory networks underlying craniofacial development.

Hox-D genes expression in pediatric low-grade gliomas: real-time-PCR study

HOX genes encode transcription factors, which play a key role in morphogenesis and cell differentiation during embryogenesis. Several observations indicate that a deregulated expression of these genes may result in tumor development and progression. Actually, several HOX genes are aberrantly expressed in many tumors and cell lines derived from them. Little is known about the expression of HOX genes in brain tumors. In the present work, we study the relative expression of HOX-D genes (D1, D3, D4, D8, D9, D10, D11, D12, D13) with real-time polymerase chain reaction in a group of 14 pediatric low-grade gliomas. We compare the HOX-D expression level of the 14 tumors with the average expression level of six non-neoplastic human brain tissues. HOX-D1 and HOX-D12 resulted over-expressed in neoplastic samples with respect to non-neoplastic brain parenchyma. Conversely, HOX-D3 was expressed at a lower level in gliomas with respect to non-neoplastic brain. HOX-D4, HOX-D11, and HOX-D13 were never expressed. HOX-D8, HOX-D9, and HOX-D10 were exceptionally expressed in non-neoplastic samples and irregularly expressed in tumors. The observation that all but three HOX-D genes studied are expressed with different pattern in neoplastic and non-neoplastic brain tissue may support the hypothesis that HOX-D genes play a role in the pathogenesis of pediatric low-grade gliomas.

Molecular Regulation of Müllerian Development by Hox Genes

HOX genes are a family of regulatory molecules that encode conserved transcription factors controlling aspects of morphogenesis and cell differentiation during normal embryonic development. All metazoans possess a common genetic system for embryonic patterning, and this system is also used in the reproductive tract. Hox genes are also expressed in the adult uterus. Hox genes are essential both for the development of mullerian tract in the embryonic period and adult function. Sex steroids regulate Hox gene expression during embryonic and endometrial development in the menstrual cycle. EMX2 and beta(3)-integrin acting downstream of Hoxa10 gene are likely involved in both these developmental processes. This article reviews the role and molecular regulation of Hox genes in reproductive tract development.