Project description:Tooth development is a complex process orchestrated by intricate gene regulatory networks, involving both odontogenic epithelium and ectomesenchyme. Six1, a pivotal transcription factor (TF), is involved in the development of the lower incisor. However, its precise role during incisor development and the molecular mechanisms underpinning its regulatory functions remain poorly understood. This study employs Six1 deletion mouse models to elucidate the critical regulatory role of Six1 in governing dental mesenchyme development. By performing single-cell RNA sequencing (scRNA-seq), we constructed a comprehensive transcriptome atlas of tooth germ development from the bud to bell stage. Our analyses suggest that the dental follicle (DF) and the dental papilla (DP) are differentiated from dental ectomesenchyme (DEM), and identify the key transcription factors (TFs) underlying these distinct states. Notably, we show that Dlx1, Dlx2, and Dlx5 (Dlx1/2/5) may function as the key TFs that promote the formation of DP. We further show that the deletion of Six1 perturbs dental mesenchyme development by impeding the transitions from DEM to DP states. Importantly, SIX1 directly binds to the promoters of Dlx1/2/5 to promote their co-expression, which subsequently leads to widespread epigenetic and transcriptional remodeling. In summary, our findings unveil Six1's indispensable role in incisor development, offering key insights into transcription factor-driven regulatory networks that govern dental mesenchyme cell fate transitions during tooth development.
Project description:Tooth development is a complex process orchestrated by intricate gene regulatory networks, involving both odontogenic epithelium and ectomesenchyme. Six1, a pivotal transcription factor (TF), is involved in the development of the lower incisor. However, its precise role during incisor development and the molecular mechanisms underpinning its regulatory functions remain poorly understood. This study employs Six1 deletion mouse models to elucidate the critical regulatory role of Six1 in governing dental mesenchyme development. By performing single-cell RNA sequencing (scRNA-seq), we constructed a comprehensive transcriptome atlas of tooth germ development from the bud to bell stage. Our analyses suggest that the dental follicle (DF) and the dental papilla (DP) are differentiated from dental ectomesenchyme (DEM), and identify the key transcription factors (TFs) underlying these distinct states. Notably, we show that Dlx1, Dlx2, and Dlx5 (Dlx1/2/5) may function as the key TFs that promote the formation of DP. We further show that the deletion of Six1 perturbs dental mesenchyme development by impeding the transitions from DEM to DP states. Importantly, SIX1 directly binds to the promoters of Dlx1/2/5 to promote their co-expression, which subsequently leads to widespread epigenetic and transcriptional remodeling. In summary, our findings unveil Six1's indispensable role in incisor development, offering key insights into transcription factor-driven regulatory networks that govern dental mesenchyme cell fate transitions during tooth development.
Project description:The hypothalamic arcuate nucleus contains multiple types of neurons controlling critical physiological processes. However, the gene regulatory network directing their development remains rudimentary. Here we report that two transcription factors Otp and Dlx1 segregate the identity of orexigenic/anti-thermogenic NPY/AgRP- and growth-promoting GHRH-neurons in the developing arcuate nucleus. Otp-null and Dlx1-null mice lose NPY/AgRP and GHRH expression, respectively. Dlx1-null mice also show enhanced expression of Otp/NPY/AgRP, which is normalized in Dlx1;Otp-double mutant mice. Correspondingly, Dlx1-null mice exhibit decreased growth, lower body temperature and increased feeding. Furthermore, our genome-wide studies identify Otp as a negative target gene of Dlx1. Therefore, Otp is critical for NPY/AgRP-neuronal development, while Dlx1 promotes GHRH-neuronal development and antagonizes NPY/AgRP-neuronal development. These results identify a mechanism for segregating the identity of two functionally related neurons, and the Dlx1-Otp axis likely contributes to coordinating energy balance and growth by maintaining a proper ratio of NPY/AgRP- to GHRH-neurons.
Project description:One of the key questions in developmental biology is how from universally shared molecular mechanisms and pathways, is it possible to generate organs displaying similar or complementary functions, with a wide range of different shapes or tissue organization? The dentition represents a valuable system to address the issues of differential molecular signatures generating specific tooth types. We performed a comparative transcriptomic analysis of developing murine lower incisors, mandibular molars and maxillary molars at the developmental cap stage (E14.5) prior to recognizable tooth shape and cusp pattern. We compared gene expression profiles in developing murine lower incisor and molars, as well as between the lower and upper (mandibular and maxillary) first molars
Project description:In the developing subpallium, the fate decision between neurons and glia is driven by expression of Dlx1/2 or Olig1/2 respectively, two sets of transcription factors (TFs) with a mutually repressive relationship. The mechanism by which Dlx1/2 repress progenitor and oligodendrocyte fate, while promoting transcription of genes needed for differentiation, is not fully understood. We identified a motif within DLX1 that binds RBBP4, a NuRD complex subunit. ChIP-seq studies of genomic occupancy of DLX1 and six different members of the NuRD complex show that DLX1 and NuRD colocalize to putative regulatory elements (pREs) enriched near other transcription factor genes. Loss of Dlx1/2 leads to dysregulation of genome accessibility at pREs near genes repressed by Dlx1/2, including Olig2. Consequently, heterozygosity of Dlx1/2 and Rbbp4 leads to an increase in the production of OLIG2+ cells. These findings highlight the importance of the interplay between TFs and chromatin remodelers in regulating cell fate decisions.
Project description:The Dlx homeodomain transcription factors are implicated in regulating the function of inhibitory neurons; therefore understanding their functions will provide insights into disorders such as epilepsy, mental retardation, autism and cerebral palsy. Comparing gene expression in the embryonic basal ganglia and cortex in wild type and dlx1/2 mutant mice will provide information regarding the types of genes that are downstream of Dlx1/2 function. Perform gene array analyses in duplicate or triplicate; compare expression profile of total RNA from wild type and dlx1/2 telencephalons. I am sending separate samples of the Basal Ganglia (BG) and cortex. I want to perform gene expression comparison between: 1) wild type and dlx1/2 basal ganglia (BG) 2) wild typee and dlx1/2 cortex (ctx). Age of all mice has been indicated as 14 days to satisfy system requirements, however all mice are embryonic day 14.5.
Project description:Higher expression levels of DLX1 has been associated with primary and metastatic prostate tumor. DLX1 along with HOXC6 is well-established diagnostic biomarker for the early detection of prostate cancer (PCa). However, the mechanism involved in DLX1 up-regulation and functional significance in metastatic castration-resistant prostate cancer (mCRPC) progression remains unexplored. Here, we identified that DLX1 serves as an oncogene thereby regulating several oncogenic properties associated with PCa progression.