Identification of proline-rich protein 11 as a major regulator in mouse spermatogonia maintenance via an increase in BMI1 protein stability.

BACKGROUND: Spermatogenesis accompanied by self-renewal and differentiation of spermatogonia under complicated regulation is crucial for male fertility. Our previous study demonstrated that the loss of the B-lymphoma Mo-MLV insertion region 1 (BMI1) could cause male infertility and found a potential interaction between BMI1 and proline-rich protein 11 (PRR11); however, the specific co-regulatory effects of BMI1/PRR11 on spermatogonia maintenance remain unclear. METHODS AND RESULTS: The expression of PRR11 was downregulated in a mouse spermatogonia cell line (GC-1) via transfection with PRR11-siRNAs, and PRR11 knockdown was verified by real-time reverse transcriptase polymerase chain reaction (RT-qPCR). The proliferative activity of GC-1 cells was determined using the cell counting kit (CCK-8), colony formation, and 5-ethynyl-2-deoxyuridine (EdU) incorporation assay. A Transwell assay was performed to evaluate the effects of PRR11 on GC-1 cell migration. A terminal deoxynucleotidyl transferase dUTP nick end labeling assay was used to measure GC-1 cell apoptosis. Furthermore, co-immunoprecipitation, RT-qPCR, and western blot analyses were used for investigating the regulatory mechanisms involved in this regulation. It was found that downregulation of PRR11 could cause a marked inhibition of proliferation and migration and induced apoptosis in GC-1 cells. Moreover, silencing of PRR11 obviously led to a reduction in the BMI1 protein level. PRR11 was found to interact with BMII at the endogenous protein level. PRR11 knockdown produced a decrease in BMI1 protein stability via an increase in BMI1 ubiquitination after which derepression in the transcription of protein tyrosine phosphatase receptor type M (Ptprm) occurred. Importantly, knockdown of Ptprm in PRR11-deficient GC-1 cells led to a reversal of proliferation and migration of GC-1 cells. CONCLUSIONS: This study uncovered a novel mechanism by which PRR11 cooperated with BMI1 to facilitate GC-1 maintenance through targeting Ptprm. Our findings may provide a better understanding of the regulatory network in spermatogonia maintenance.

BMI1 promotes spermatogonia proliferation through epigenetic repression of Ptprm.

Spermatogonia are accountable for spermatogenesis and male fertility, but the underlying mechanisms involved in spermatogonia maintenance are not clear. B lymphoma Mo-MLV insertion region 1 (BMI1) is a key component of epigenetic silencers. BMI1 is essential for stem-cell maintenance. Here, we attempted to uncover the role of BMI1 in spermatogonia maintenance using a mouse spermatogonia cell line (GC-1) and Bmi1-knockout (KO) mouse model. We showed that BMI1 promoted the proliferation and inhibited apoptosis of GC-1 cells. Mechanistically, we present in vitro and in vivo evidence to show that BMI1 binds to the promoter region of the Protein tyrosine phosphatase receptor type M (PTPRM) gene, thereby driving chromatin remodeling and gene silencing. Knockdown of Ptprm expression significantly improved spermatogonia proliferation in BMI1-deficient GC-1 cells. Collectively, our data show, for the first time, an epigenetic mechanism involving in BMI1-mediated gene silencing in spermatogonia maintenance, and provide potential targets for the treatment of male infertility.

A quantitative trait GWAS on lens thickness identifies novel risk loci on PTPRM in the narrow angle individuals susceptible to PACG.

PURPOSE: PACG is one of the leading causes of blindness where lens thickness is a major risk factor for narrow-angle individuals. To our knowledge, no literature has been reported on candidate gene for lens thickness as a quantitative trait (QT). Here, we performed a genome-wide association analysis on lens thickness in the narrow-angle individuals. MATERIALS AND METHODS: We conducted a genome-wide association study (GWAS) in the narrow angle individuals to investigate comprehensive genetic insights on lens thickness. RESULTS: In QT-GWAS, we identified 145 genome-wide suggestive significant loci in the discovery cohort. Subsequently, we observed 13 SNPs that showed statistical significance around the region of PTRRM. Regional association analysis for top significant genotyped variants identified PTPRM as the most likely candidate for increased LT. Integrative bioinformatic analyses confirmed that the associated genomic region has potential regulatory roles for modulating transcription as enhancers. In the replication cohort, the sentinel genotype SNP was further associated significantly (P-value =0.000448) with high LT individuals. In both cohorts, the T allele of rs1941137 in the PTPRM gene indicates as a risk allele for the increased LT. CONCLUSION: In this study, we discovered evidence of a genomic association between chromosomal areas around the PTPRM and increased lens thickness, resulting in a narrow angle. The regulatory components corresponding to PTPRM variations might have a role in the thicker lens. We report that the genomic region near PTPRM, a gene of potential interest, is associated with increased lens thickness.

Gene Profiling of a 3D Psoriatic Skin Model Enriched in T Cells: Downregulation of PTPRM Promotes Keratinocyte Proliferation through Excessive ERK1/2 Signaling.

Psoriasis is a complex, immune-mediated skin disease involving a wide range of epithelial and immune cells. The underlying mechanisms that govern the epidermal defects and immunological dysfunction observed in this condition remain largely unknown. In recent years, the emergence of new, more sophisticated models has allowed the evolution of our knowledge of the pathogenesis of psoriasis. The development of psoriatic skin biomaterials that more closely mimic native psoriatic skin provides advanced preclinical models that will prove relevant in predicting clinical outcomes. In this study, we used a tissue-engineered, two-layered (dermis and epidermis) human skin substitute enriched in T cells as a biomaterial to study both the cellular and molecular mechanisms involved in psoriasis' pathogenesis. Gene profiling on microarrays revealed significant changes in the profile of genes expressed by the psoriatic skin substitutes compared with the healthy ones. Two genes, namely, PTPRM and NELL2, whose products influence the ERK1/2 signaling pathway have been identified as being deregulated in psoriatic substitutes. Deregulation of these genes supports excessive activation of the ERK1/2 pathway in psoriatic skin substitutes. Most importantly, electrophoresis mobility shift assays provided evidence that the DNA-binding properties of two downstream nuclear targets of ERK1/2, both the NF-κB and Sp1 transcription factors, are increased under psoriatic conditions. Moreover, the results obtained with the inhibition of RSK, a downstream effector of ERK1/2, supported the therapeutic potential of inhibiting this signaling pathway for psoriasis treatment. In conclusion, this two-layered human psoriatic skin substitute enriched in T cells may prove particularly useful in deciphering the mechanistic details of psoriatic pathogenesis and provide a relevant biomaterial for the study of potential therapeutic targets.

PTPRM, a candidate tumor suppressor gene in small intestinal neuroendocrine tumors.

Small intestinal neuroendocrine tumors (SI-NETs) are small, slow growing neoplasms with loss of one copy of chromosome 18 as a common event. Frequently mutated genes on chromosome 18 or elsewhere have not been found so far. The aim of this study was to investigate a possible tumor suppressor role of the transmembrane receptor type tyrosine phosphatase PTPµ (PTPRM at 18p11) in SI-NETs. Immunohistochemistry, quantitative RT-PCR, colony formation assay and quantitative CpG methylation analysis by pyrosequencing were performed. Undetectable/very low levels of PTPRM or aberrant pattern of immunostaining, with both negative and positive areas, were detected in the majority of tumors (33/40), and a significantly reduced mRNA expression in metastases compared to primary tumors was observed. Both the DNA methylation inhibitor 5-aza-2'-deoxycytidine and the S-adenosylhomocysteine hydrolase inhibitor 3-deazaneplanocin A (DZNep) induced PTPRM expression in CNDT2.5 and KRJ-I SI-NET cells. CpG methylation of upstream regulatory regions, the promoter region and the exon 1/intron 1 boundary was detected by pyrosequencing analysis of the two cell lines and not in the analyzed SI-NETs. Overexpression of PTPRM in the SI-NET cell lines reduced cell growth and cell proliferation and induced apoptosis. The tyrosine phosphatase activity of PTPRM was not involved in cell growth inhibition. The results support a role for PTPRM as a dysregulated candidate tumor suppressor gene in SI-NETs and further analyses of the involved mechanisms are warranted.

Comprehensive protein tyrosine phosphatase mRNA profiling identifies new regulators in the progression of glioma.

The infiltrative behavior of diffuse gliomas severely reduces therapeutic potential of surgical resection and radiotherapy, and urges for the identification of new drug-targets affecting glioma growth and migration. To address the potential role of protein tyrosine phosphatases (PTPs), we performed mRNA expression profiling for 91 of the 109 known human PTP genes on a series of clinical diffuse glioma samples of different grades and compared our findings with in silico knowledge from REMBRANDT and TCGA databases. Overall PTP family expression levels appeared independent of characteristic genetic aberrations associated with lower grade or high grade gliomas. Notably, seven PTP genes (DUSP26, MTMR4, PTEN, PTPRM, PTPRN2, PTPRT and PTPRZ1) were differentially expressed between grade II-III gliomas and (grade IV) glioblastomas. For DUSP26, PTEN, PTPRM and PTPRT, lower expression levels correlated with poor prognosis, and overexpression of DUSP26 or PTPRT in E98 glioblastoma cells reduced tumorigenicity. Our study represents the first in-depth analysis of PTP family expression in diffuse glioma subtypes and warrants further investigations into PTP-dependent signaling events as new entry points for improved therapy.