Trps1 Regulates Development of Craniofacial Skeleton and Is Required for the Initiation of Palatal Shelves Fusion

Eed controls craniofacial osteoblast differentiation and mesenchymal proliferation from the neural crest

The histone methyltransferase Polycomb repressive complex 2 (PRC2) is required for specification of the neural crest, and mis-regulation of neural crest development can cause severe congenital malformations. PRC2 is necessary for neural crest induction, but the embryonic, cellular, and molecular consequences of PRC2 activity after neural crest induction are incompletely understood. Here we show that Eed, a core subunit of PRC2, is required for craniofacial osteoblast differentiation and mesenchymal proliferation after induction of the neural crest. Integrating mouse genetics with single-cell RNA sequencing, our results reveal that conditional knockout of Eed after neural crest cell induction causes severe craniofacial hypoplasia, impaired craniofacial osteogenesis, and attenuated craniofacial mesenchymal cell proliferation that is first evident in post-migratory neural crest cell populations. We show that Eed drives mesenchymal differentiation and proliferation in vivo and in primary craniofacial cell cultures by regulating diverse transcription factor programs that are required for specification of post-migratory neural crest cells. These data enhance understanding of epigenetic mechanisms that underlie craniofacial development, and shed light on the embryonic, cellular, and molecular drivers of rare congenital syndromes in humans.

TRPS1 maintains luminal progenitors in the mammary gland by repressing SRF/MRTF activity

The transcription factor TRPS1 is a context-dependent oncogene in breast cancer. In the mammary gland, TRPS1 activity is restricted to the luminal population and is critical during puberty and pregnancy. Its function in the resting state remains however unclear. To evaluate whether it could be a target for cancer therapy, we investigated TRPS1 function in the healthy adult mammary gland using a conditional ubiquitous depletion mouse model where long-term depletion does not affect fitness. Using transcriptomic approaches, flow cytometry and functional assays, we show that TRPS1 activity is essential to maintain a functional luminal progenitor compartment. This requires the repression of both YAP/TAZ and SRF/MRTF activities. TRPS1 represses SRF/MRTF activity indirectly by modulating RhoA activity. Our work uncovers a hitherto undisclosed function of TRPS1 in luminal progenitors intrinsically linked to mechanotransduction in the mammary gland. It may also provide new insights into the oncogenic functions of TRPS1 as luminal progenitors are likely the cells of origin of many breast cancers.

The Clinical and Molecular Spectrum of Trichorhinophalangeal Syndrome Types I and II in a Turkish Cohort Involving 22 Patients

OBJECTIVE

Trichorhinophalangeal syndrome is a rare autosomal dominant disorder characterized by distinctive craniofacial and skeletal abnormalities. This study aimed to delineate the trichorhinophalangeal syndrome phenotype and to compare the clinical and molecular findings between trichorhinophalangeal syndrome types I and II.

MATERIALS AND METHODS

A total of 22 trichorhinophalangeal syndrome patients aged 0.9-45 years from 17 families were enrolled. Nineteen patients were diagnosed with trichorhin ophalangeal syndrome I and 3 with trichorhinophalangeal syndrome II. Genetic analyses were made by TRPS1 sequencing and/or chromosomal microarray analyses.

RESULTS

A novel frameshift variant (c.531_532del), a known missense variant, and whole-gene deletions were the pathogenic TRPS1 variants detected in trichorhinophalangeal syndrome I. Three trichorhinophalangeal syndrome II patients had large deletions with variable breakpoints involving the TRPS1-EXT1 interval. All patients had the typical craniofacial findings of trichorhinophalangeal syndrome such as a pear-shaped nose, long philtrum, and thin upper lip, as well as cone-shaped epiphyses. Sparse hair and eyebrows (20/22), short metacarpals and metatarsals (20/22), and small hands (19/22) were common. While craniofacial and limb abnormalities were similar in trichorhinophalangeal syndrome I and II, 3 of 19 trichorhinophal angeal syndrome I patients had mild, and 2 of 3 trichorhinophalangeal syndrome II patients had severe intellectual disability. Three trichorhinophalangeal syndrome II patients including the patient with the EXT1 deletion beginning from exon 2 had exostoses. In trichorhinophal angeal syndrome II, although microdeletion sizes and facial or skeletal features were not correlated, patients with larger deletions had severe intellectual disability.

CONCLUSION

This study has expanded the existing knowledge on the phenotype-genotype spectrum in trichorhinophalangeal syndrome. We suggest including the EXT1 gene partially in the minimal critical region for trichorhinophalangeal syndrome II.

Functional mechanisms of TRPS1 in disease progression and its potential role in personalized medicine

The gene of transcriptional repressor GATA binding 1 (TRPS1), as an atypical GATA transcription factor, has received considerable attention in a plethora of physiological and pathological processes, and may become a promising biomarker for targeted therapies in diseases and tumors. However, there still lacks a comprehensive exploration of its functions and promising clinical applications. Herein, relevant researches published in English from 2000 to 2022 were retrieved from PubMed, Google Scholar and MEDLINE, concerning the roles of TRPS1 in organ differentiation and tumorigenesis. This systematic review predominantly focused on summarizing the structural characteristics and biological mechanisms of TRPS1, its involvement in tricho-rhino-phalangeal syndrome (TRPS), its participation in the development of multiple tissues, the recent advances of its vital features in metabolic disorders as well as malignant tumors, in order to prospect its potential applications in disease detection and cancer targeted therapy. From the clinical perspective, the deeply and thoroughly understanding of the complicated context-dependent and cell-lineage-specific mechanisms of TRPS1 would not only gain novel insights into the complex etiology of diseases, but also provide the fundamental basis for the development of therapeutic drugs targeting both TRPS1 and its critical cofactors, which would facilitate individualized treatment.

Deficiency of Mineralization-Regulating Transcription Factor Trps1 Compromises Quality of Dental Tissues and Increases Susceptibility to Dental Caries

Dental caries is the most common chronic disease in children and adults worldwide. The complex etiology of dental caries includes environmental factors as well as host genetics, which together contribute to inter-individual variation in susceptibility. The goal of this study was to provide insights into the molecular pathology underlying increased predisposition to dental caries in trichorhinophalangeal syndrome (TRPS). This rare inherited skeletal dysplasia is caused by mutations in the TRPS1 gene coding for the TRPS1 transcription factor. Considering Trps1 expression in odontoblasts, where Trps1 supports expression of multiple mineralization-related genes, we focused on determining the consequences of odontoblast-specific Trps1 deficiency on the quality of dental tissues. We generated a conditional Trps1Col1a1 knockout mouse, in which Trps1 is deleted in differentiated odontoblasts using 2.3kbCol1a1-CreERT2 driver. Mandibular first molars of 4wk old male and female mice were analyzed by micro-computed tomography (μCT) and histology. Mechanical properties of dentin and enamel were analyzed by Vickers microhardness test. The susceptibility to acid demineralization was compared between WT and Trps1Col1a1cKO molars using an ex vivo artificial caries procedure. μCT analyses demonstrated that odontoblast-specific deletion of Trps1 results in decreased dentin volume in male and female mice, while no significant differences were detected in dentin mineral density. However, histology revealed a wider predentin layer and the presence of globular dentin, which are indicative of disturbed mineralization. The secondary effect on enamel was also detected, with both dentin and enamel of Trps1Col1a1cKO mice being more susceptible to demineralization than WT tissues. The quality of dental tissues was particularly impaired in molar pits, which are sites highly susceptible to dental caries in human teeth. Interestingly, Trps1Col1a1cKO males demonstrated a stronger phenotype than females, which calls for attention to genetically-driven sex differences in predisposition to dental caries. In conclusion, the analyses of Trps1Col1a1cKO mice suggest that compromised quality of dental tissues contributes to the high prevalence of dental caries in TRPS patients. Furthermore, our results suggest that TRPS patients will benefit particularly from improved dental caries prevention strategies tailored for individuals genetically predisposed due to developmental defects in tooth mineralization.