Cloning of a human gene closely related to the genes coding for the c-myc single-strand binding proteins

Genetic determinants of coping, resilience and self-esteem in schizophrenia suggest a primary role for social factors and hippocampal neurogenesis

Schizophrenia is a severe psychiatric disorder, associated with a reduction in life expectancy of 15-20 years. Available treatments are at least partially effective in most affected individuals, and personal resources such as resilience (successful adaptation despite adversity) and coping abilities (strategies used to deal with stressful or threatening situations), are important determinants of disease outcomes and long-term sustained recovery. Published findings support the existence of a genetic background underlying resilience and coping, with variable heritability estimates. However, genome-wide analyses concerning the genetic determinants of these personal resources, especially in the context of schizophrenia, are lacking. Here, we performed a genome-wide association study coupled with accessory analyses to investigate potential genetic determinants of resilience, coping and self-esteem in 490 schizophrenia patients. Results revealed a complex genetic background partly overlapping with that of neuroticism, worry and schizophrenia itself and support the importance of social aspects in shapingthese psychological constructs. Hippocampal neurogenesis and lipid metabolism appear to be potentially relevant biological underpinnings, and specific miRNAs such as miR-124 and miR-137 may warrant further studies as potential biomarkers. In conclusion, this study represents an important first step in the identification of genetic and biological correlates shaping resilience, coping resources and self-esteem in schizophrenia.

Impact of RBMS 3 Progression on Expression of EMT Markers

Epithelial-to-mesenchymal transition (EMT) is a complex cellular process that allows cells to change their phenotype from epithelial to mesenchymal-like. Type 3 EMT occurs during cancer progression. The aim of this study was to investigate the role of RNA-binding motif single-stranded interacting protein 3 (RBMS 3) in the process of EMT. To investigate the impact of RBMS 3 on EMT, we performed immunohistochemical (IHC) reactions on archived paraffin blocks of invasive ductal breast carcinoma (n = 449), allowing us to analyze the correlation in expression between RBMS 3 and common markers of EMT. The IHC results confirmed the association of RBMS 3 with EMT markers. Furthermore, we performed an in vitro study using cellular models of triple negative and HER-2-enriched breast cancer with the overexpression and silencing of RBMS 3. RT-qPCR and Western blot methods were used to detect changes at both the mRNA and protein levels. An invasion assay and confocal microscopy were used to study the migratory potential of cells depending on the RBMS 3 expression. The studies conducted suggest that RBMS 3 may potentially act as an EMT-promoting agent in the most aggressive subtype of breast cancer, triple negative breast cancer (TNBC), but as an EMT suppressor in the HER-2-enriched subtype. The results of this study indicate the complex role of RBMS 3 in regulating the EMT process and present it as a future potential target for personalized therapies and a diagnostic marker in breast cancer.

Tumor suppressor function of RBMS3 overexpression in EOC associated with immune cell infiltration

Objectives

Epithelial ovarian cancer (EOC) is considered to be a prevalent female malignancy with both high incidence and mortality. It is reported that RNA-binding protein 3 (RBMS3) executives a tumor suppressor function in different cancers. This investigation was designed to examine the expression of RBMS3 in epithelial ovarian cancer, the effects on EOC cells, and its connection to immune cells that infiltrate tumors in the EOC microenvironment.

Methods

The expression levels of RBMS3 in EOC tissues as well as their correlations with immune cell infiltration and clinical outcome were examined using bioinformatics approaches. Western blotting as well as immunohistochemistry were carried out to determine the protein levels in EOC tissues. In addition, qRT-PCR was employed to look at the expression of the mRNA. The role of RBMS3 in EOC cells was investigated, and an RBMS3 lentiviral vector was developed. The effects of RBMS3 on subcutaneous tumor development, the proliferation protein Ki-67, the tumor angiogenesis indicator CD31, and its function in controlling the tumor immune microenvironment were evaluated by in vivo tests.

Results

There was a considerable decrease in RBMS3 expression in EOC tissues, which was linked to a poor prognosis for patients and the infiltration of multiple immune cell. Given immunohistochemical studies, tissues with increased RBMS3 expression had decreased markers of myeloid-derived suppressor cells, regulatory T cells, and M2 macrophages, whereas M1 macrophage markers were elevated. RBMS3 appears to suppress the capabilities of proliferating, invading, and migrating in EOC cells according to in vitro tests, whereas tumors overexpressing RBMS3 developed more slowly in syngeneic mouse models. The overexpression of RBMS3 led to a decline in the levels of Ki-67 protein and CD31. Additionally, it showed a negatively correlation with markers of regulatory T cell, myeloid-derived suppressor cell, and M2 macrophage but a positive correlation with markers of M1 macrophage.

Conclusions

The findings revealed that elevated RBMS3 expression plays a tumor suppressor role in EOC and was connected to patient survival in EOC. The studies conducted in vitro and in vivo demonstrated a link between RBMS3 expression and the infiltration of certain immune cells, indicating a function for RBMS3 in the immunosuppressive tumor microenvironment and its promising efficiency as a novel target for immunotherapy against EOC.

RBMS3-induced circHECTD1 encoded a novel protein to suppress the vasculogenic mimicry formation in glioblastoma multiforme

Glioblastoma multiforme (GBM) is a highly vascularized malignant cancer of the central nervous system, and the presence of vasculogenic mimicry (VM) severely limits the effectiveness of anti-vascular therapy. In this study, we identified downregulated circHECTD1, which acted as a key VM-suppressed factor in GBM. circHECTD1 elevation significantly inhibited cell proliferation, migration, invasion and tube-like structure formation in GBM. RIP assay was used to demonstrate that the flanking intron sequence of circHECTD1 can be specifically bound by RBMS3, thereby inducing circHECTD1 formation to regulate VM formation in GBM. circHECTD1 was confirmed to possess a strong protein-encoding capacity and the encoded functional peptide 463aa was identified by LC-MS/MS. Both circHECTD1 and 463aa significantly inhibited GBM VM formation in vivo and in vitro. Analysis of the 463aa protein sequence revealed that it contained a ubiquitination-related domain and promoted NR2F1 degradation by regulating the ubiquitination of the NR2F1 at K396. ChIP assay verified that NR2F1 could directly bind to the promoter region of MMP2, MMP9 and VE-cadherin, transcriptionally promoting the expression of VM-related proteins, which in turn enhanced VM formation in GBM. In summary, we clarified a novel pathway for RBMS3-induced circHECTD1 encoding functional peptide 463aa to mediate the ubiquitination of NR2F1, which inhibited VM formation in GBM. This study aimed to reveal new mechanisms of GBM progression in order to provide novel approaches and strategies for the anti-vascular therapy of GBM. The schematic illustration showed the inhibitory effect of circHECTD1-463aa in the VM formation in GBM.

Signaling Mechanisms of Stem Cell Therapy for Intervertebral Disc Degeneration

Low back pain is the leading cause of disability worldwide. Intervertebral disc degeneration (IDD) is the primary clinical risk factor for low back pain and the pathological cause of disc herniation, spinal stenosis, and spinal deformity. A possible approach to improve the clinical practice of IDD-related diseases is to incorporate biomarkers in diagnosis, therapeutic intervention, and prognosis prediction. IDD pathology is still unclear. Regarding molecular mechanisms, cellular signaling pathways constitute a complex network of signaling pathways that coordinate cell survival, proliferation, differentiation, and metabolism. Recently, stem cells have shown great potential in clinical applications for IDD. In this review, the roles of multiple signaling pathways and related stem cell treatment in IDD are summarized and described. This review seeks to investigate the mechanisms and potential therapeutic effects of stem cells in IDD and identify new therapeutic treatments for IDD-related disorders.

Expression of RBMS3 in Breast Cancer Progression

The aim of the study was to evaluate the localization and intensity of RNA-binding motif single-stranded-interacting protein 3 (RBMS3) expression in clinical material using immunohistochemical (IHC) reactions in cases of ductal breast cancer (in vivo), and to determine the level of RBMS3 expression at both the protein and mRNA levels in breast cancer cell lines (in vitro). Moreover, the data obtained in the in vivo and in vitro studies were correlated with the clinicopathological profiles of the patients. Material for the IHC studies comprised 490 invasive ductal carcinoma (IDC) cases and 26 mastopathy tissues. Western blot and RT-qPCR were performed on four breast cancer cell lines (MCF-7, BT-474, SK-BR-3 and MDA-MB-231) and the HME1-hTERT (Me16C) normal immortalized breast epithelial cell line (control). The Kaplan-Meier plotter tool was employed to analyze the predictive value of overall survival of RBMS3 expression at the mRNA level. Cytoplasmatic RBMS3 IHC expression was observed in breast cancer cells and stromal cells. The statistical analysis revealed a significantly decreased RBMS3 expression in the cancer specimens when compared with the mastopathy tissues (p < 0.001). An increased expression of RBMS3 was corelated with HER2(+) cancer specimens (p < 0.05) and ER(-) cancer specimens (p < 0.05). In addition, a statistically significant higher expression of RBMS3 was observed in cancer stromal cells in comparison to the control and cancer cells (p < 0.0001). The statistical analysis demonstrated a significantly higher expression of RBMS3 mRNA in the SK-BR-3 cell line compared with all other cell lines (p < 0.05). A positive correlation was revealed between the expression of RBMS3, at both the mRNA and protein levels, and longer overall survival. The differences in the expression of RBMS3 in cancer cells (both in vivo and in vitro) and the stroma of breast cancer with regard to the molecular status of the tumor may indicate that RBMS3 could be a potential novel target for the development of personalized methods of treatment. RBMS3 can be an indicator of longer overall survival for potential use in breast cancer diagnostic process.

Disruption of RBMS3 suppresses PD-L1 and enhances antitumor immune activities and therapeutic effects of auranofin against triple-negative breast cancer

Programmed cell death protein-1 (PD-1)/programmed cell death ligand-1 (PD-L1) interaction exerts a vital role in tumor-associated immune evasion. While strategies disrupting PD-1/PD-L1 axis have shown clinical benefits in various cancers, the limited response rate prompts us to investigate the complex mechanisms underlying the molecular regulation of PD-L1. Here, we identify the RNA binding protein RBMS3 as a crucial PD-L1 regulator in triple-negative breast cancer (TNBC). Correlation analysis shows that Rbms3 significantly correlates with immunosuppressive CD274, Rbms1, NT5E and ENTPD1. RBMS3 protein binds to CD274 mRNA specifically in TNBC cells to increase PD-L1 levels. Mechanistically, RBMS3 stabilizes CD274 mRNA by interacting with its 3'UTR, which represents as an intrinsic cancer cell mechanism for driving PL-D1 upregulation in TNBC. RBMS3 depletion not only destabilizes the mRNA stability and protein expression of PD-L1, but also suppresses the migratory abilities of TNBC MDA-MB-231 cells. Importantly, combination of RBMS3 ablation with auranofin (AUF), an FDA-approved thioredoxin reductase inhibitor, facilitates anti-tumor T-cell immunity in vivo and improves AUF-mediated anti-cancer effect. Taken together, our findings reveal RBMS3 as a key post-transcriptional regulator of PD-L1 and how they contribute to immune escape in TNBC, which could lead to novel combinatorial therapeutic strategies to enhance the efficacy of cancer immunotherapy.

Comprehensive single-cell transcriptional profiling defines shared and unique epithelial injury responses during kidney fibrosis

The underlying cellular events driving kidney fibrogenesis and metabolic dysfunction are incompletely understood. Here, we employed single-cell combinatorial indexing RNA sequencing to analyze 24 mouse kidneys from two fibrosis models. We profiled 309,666 cells in one experiment, representing 50 cell types/states encompassing epithelial, endothelial, immune, and stromal populations. Single-cell analysis identified diverse injury states of the proximal tubule, including two distinct early-phase populations with dysregulated lipid and amino acid metabolism, respectively. Lipid metabolism was defective in the chronic phase but was transiently activated in the very early stages of ischemia-induced injury, where we discovered increased lipid deposition and increased fatty acid β-oxidation. Perilipin 2 was identified as a surface marker of intracellular lipid droplets, and its knockdown in vitro disrupted cell energy state maintenance during lipid accumulation. Surveying epithelial cells across nephron segments identified shared and unique injury responses. Stromal cells exhibited high heterogeneity and contributed to fibrogenesis by epithelial-stromal crosstalk.

Transposon Mutagenesis Reveals RBMS3 Silencing as a Promoter of Malignant Progression of BRAFV600E-Driven Lung Tumorigenesis

Mutationally activated BRAF is detected in approximately 7% of human lung adenocarcinomas, with BRAFT1799A serving as a predictive biomarker for treatment of patients with FDA-approved inhibitors of BRAFV600E oncoprotein signaling. In genetically engineered mouse (GEM) models, expression of BRAFV600E in the lung epithelium initiates growth of benign lung tumors that, without additional genetic alterations, rarely progress to malignant lung adenocarcinoma. To identify genes that cooperate with BRAFV600E for malignant progression, we used Sleeping Beauty-mediated transposon mutagenesis, which dramatically accelerated the emergence of lethal lung cancers. Among the genes identified was Rbms3, which encodes an RNA-binding protein previously implicated as a putative tumor suppressor. Silencing of RBMS3 via CRISPR/Cas9 gene editing promoted growth of BRAFV600E lung organoids and promoted development of malignant lung cancers with a distinct micropapillary architecture in BRAFV600E and EGFRL858R GEM models. BRAFV600E/RBMS3Null lung tumors displayed elevated expression of Ctnnb1, Ccnd1, Axin2, Lgr5, and c-Myc mRNAs, suggesting that RBMS3 silencing elevates signaling through the WNT/β-catenin signaling axis. Although RBMS3 silencing rendered BRAFV600E-driven lung tumors resistant to the effects of dabrafenib plus trametinib, the tumors were sensitive to inhibition of porcupine, an acyltransferase of WNT ligands necessary for their secretion. Analysis of The Cancer Genome Atlas patient samples revealed that chromosome 3p24, which encompasses RBMS3, is frequently lost in non-small cell lung cancer and correlates with poor prognosis. Collectively, these data reveal the role of RBMS3 as a lung cancer suppressor and suggest that RBMS3 silencing may contribute to malignant NSCLC progression.

SIGNIFICANCE

Loss of RBMS3 cooperates with BRAFV600E to induce lung tumorigenesis, providing a deeper understanding of the molecular mechanisms underlying mutant BRAF-driven lung cancer and potential strategies to more effectively target this disease.

Role of RBMS3 Novel Potential Regulator of the EMT Phenomenon in Physiological and Pathological Processes

RNA-binding protein 3 (RBMS3) plays a significant role in embryonic development and the pathogenesis of many diseases, especially cancer initiation and progression. The multiple roles of RBMS3 are conditioned by its numerous alternative expression products. It has been proven that the main form of RBMS3 influences the regulation of microRNA expression or stabilization. The absence of RBMS3 activates the Wnt/β-catenin pathway. The expression of c-Myc, another target of the Wnt/β-catenin pathway, is correlated with the RBMS3 expression. Numerous studies have focused solely on the interaction of RBMS3 with the epithelial-mesenchymal transition (EMT) protein machinery. EMT plays a vital role in cancer progression, in which RBMS3 is a new potential regulator. It is also significant that RBMS3 may act as a prognostic factor of overall survival (OS) in different types of cancer. This review presents the current state of knowledge about the role of RBMS3 in physiological and pathological processes, with particular emphasis on carcinogenesis. The molecular mechanisms underlying the role of RBMS3 are not fully understood; hence, a broader explanation and understanding is still needed.

RNA binding protein RBMS3 is a common EMT effector that modulates triple-negative breast cancer progression via stabilizing PRRX1 mRNA

The epithelial-to-mesenchymal transition (EMT) has been recognized as a driving force for tumor progression in breast cancer. Recently, our group identified the RNA Binding Motif Single Stranded Interacting Protein 3 (RBMS3) to be significantly associated with an EMT transcriptional program in breast cancer. Additional expression profiling demonstrated that RBMS3 was consistently upregulated by multiple EMT transcription factors and correlated with mesenchymal gene expression in breast cancer cell lines. Functionally, RBMS3 was sufficient to induce EMT in two immortalized mammary epithelial cell lines. In triple-negative breast cancer (TNBC) models, RBMS3 was necessary for maintaining the mesenchymal phenotype and invasion and migration in vitro. Loss of RBMS3 significantly impaired both tumor progression and spontaneous metastasis in vivo. Using a genome-wide approach to interrogate mRNA stability, we found that ectopic expression of RBMS3 upregulates many genes that are resistant to degradation following transcriptional blockade by actinomycin D (ACTD). Specifically, RBMS3 was shown to interact with the mRNA of EMT transcription factor PRRX1 and promote PRRX1 mRNA stability. PRRX1 is required for RBMS3-mediated EMT and is partially sufficient to rescue the effect of RBMS3 knockdown in TNBC cell lines. Together, this study identifies RBMS3 as a novel and common effector of EMT, which could be a promising therapeutic target for TNBC treatment.

Tumor Suppressor Effect of RBMS3 in Breast Cancer

Background:

RBMS3 (RNA-binding motif, single-stranded-intervacting protein 3) acts as a tumor-suppressive gene in a number of human cancers, however, its role in breast cancer is not fully understood. This study aimed to investigate the expression and clinicopathological significance of RBMS3 in breast cancer.

Methods:

A total of 998 breast cancer tissue samples in The Cancer Genome Atlas (TCGA) database with survival outcomes were divided into high RBMS3 expression and low expression groups using the median as the cutoff. Clinicopathological characteristics and prognosis were compared between the 2 groups.

Results:

TCGA showed that RBMS3 mRNA was downregulated in breast cancer tissues, and RBMS3 downregulation was correlated with poor prognosis. Immunohistochemistry staining of 127 paraffin-embedded breast cancer tissues showed that RBMS3 protein was localized in the cytoplasm and nucleus; however, nuclear staining was present in 90.0% of normal breast tissues but only 28.3% of breast cancer tissues. Decreased RBMS3 protein expression was significantly correlated with estrogen receptor (ER)-negative status and death at final follow-up. Patients with lower RBMS3 protein expression had substantially shorter survival than those with higher RBMS3 expression. Univariate and multivariate analysis indicated that the combination of RBMS3 expression and ER status (a variable designated as “cofactor”) was an independent prognostic factor in patients with breast cancer (hazard ratio [HR] = 0.420, 95% confidence interval [CI]: 0.223-0.791, P = 0.007).

Conclusion:

RBMS3 downregulation was correlated with poor prognosis in breast cancer patients, and the combination of RBMS3 expression and ER status was an independent prognostic factor.

LncRNA MEG3 regulates breast cancer proliferation and apoptosis through miR-141-3p/RBMS3 axis

Maternally expressed 3 (MEG3) and RNA binding motif single stranded interacting protein 3 (RBMS3) are abnormally expressed in breast cancer susceptibility genes (BRCA), but the mechanism of the two in breast cancer (BC) is unclear. By performing in vivo and in vitro experiments, we found that MEG3 and RBMS3 were low-expressed, negatively correlated with high-expressed miR-141-3p, were positively correlated with each other in BC. MEG3 targeted miR-141-3p, and miR-141-3p targeted RBMS3. MEG3, which was mainly distributed in BC cytoplasm, could down-regulate miR-141-3p and up-regulate RBMS3, and reverse effect of miR-141-3p on related gene expressions and on promoting cancer development. Overexpressed MEG3 inhibited growth of xenografts, promoted cell apoptosis via regulating apoptosis related factors, and up-regulated RBMS3 expression but down-regulated miR-141-3p. The findings of this study showed that MEG3 inhibited proliferation and promoted apoptosis of BC cells through the miR-141-3p/RBMS3 axis, and MEG3 inhibited growth of xenografts through miR-141-3p.

Increased expression of RBMS3 predicts a favorable prognosis in human gallbladder carcinoma

Multiple regions in the short arm of chromosome 3 are frequently deleted in a variety of solid tumors including gallbladder carcinoma (GBC). RNA binding motif, single‑stranded interacting protein 3 (RBMS3), a tumor suppressor gene (TSG), is located in this region. However, the role of RBMS3 in GBC remains unclear. Reverse transcription‑quantitative polymerase chain reaction (RT‑qPCR) and western blotting were performed to evaluate the mRNA and protein expression levels of RBMS3 in 41 fresh frozen GBC tissues and paired normal tissues. An immunohistochemical assay was performed on a tissue microarray (TMA, consisting of 125 cases GBC and 47 normal controls). Microvessel density (MVD) counts were determined using CD34 immunohistochemical staining. Moreover, univariate and multivariate analyses were performed to determine the correlations between RBMS3 expression, MVD and patient prognosis. Cellular functions including proliferation, clonogenicity and apoptosis, were assessed to further identify in vitro roles of RBMS3. It was revealed that both mRNA and protein expression levels of RBMS3 were significantly lower in GBC tissues than in normal controls. Multivariate Cox regression analyses demonstrated cytoplasmic RBMS3 expression as an independent prognostic factor correlated with GBC angiogenesis, histopathological differentiation and TNM stage. Kaplan‑Meier curves revealed that patients with lower cytoplasmic RBMS3 levels had a significantly worse OS than patients with higher cytoplasmic RBMS3 expression. Additionally, ectopic expression of RBMS3 markedly suppressed GBC cell proliferation and clonogenicity and promoted apoptosis in vitro. These findings indicated the potential of cytoplasmic RBMS3 as a tumor prognostic biomarker and a promising therapeutic target for GBC.

Identification of the differential expression of genes and upstream microRNAs in small cell lung cancer compared with normal lung based on bioinformatics analysis

Small cell lung cancer (SCLC) is one of the most lethal cancer, mainly attributing to its high tendency to metastasis. Mounting evidence has demonstrated that genes and microRNAs (miRNAs) are related to human cancer onset and progression including invasion and metastasis.An eligible gene dataset and an eligible miRNA dataset were downloaded from the Gene Expression Omnibus (GEO) database based our screening criteria. Differentially expressed genes (DE-genes) or DE-miRNAs for each dataset obtained by the R software package. The potential target genes of the top 10 DE-miRNAs were predicted by multiple databases. For annotation, visualization and integrated discovery, Metascape 3.0 was introduced to perform enrichment analysis for the DE-genes and the predicted target genes of the selected top 10 DE-miRNAs, including Pathway and Process Enrichment Analysis or protein-protein interaction enrichment analysis. The intersection of predicted target genes and DE-genes was taken as the final DE-genes. Then apply the predicted miRNAs-targets relationship of top 10 DE-miRNAs to the final DE-genes to gain more convinced DE-miRNAs, DE-genes and their one to one relationship.GSE19945 (miRNA microarray) and GSE40275 (gene microarray) datasets were selected and downloaded. 56 DE-miRNAs and 861 DE-genes were discovered. 297 miRNAs-targets relationships (284 unique genes) were predicted as the target of top 10 upregulating DE-miRNAs. 245 miRNAs-targets relationships (238 unique genes) were identified as the target of top 10 downregulating DE-miRNAs. The key results of enrichment analysis include protein kinase B signaling, transmembrane receptor protein tyrosine kinase signaling pathway, negative regulation of cell differentiation, response to growth factor, cellular response to lipid, muscle structure development, response to growth factor, signaling by Receptor Tyrosine Kinases, epithelial cell migration, cellular response to organic cyclic compound, Cell Cycle (Mitotic), DNA conformation change, cell division, DNA replication, cell cycle phase transition, blood vessel development, inflammatory response, Staphylococcus aureus infection, leukocyte migration, and myeloid leukocyte activation. Differential expression of genes-upstream miRNAs (RBMS3-hsa-miR-7-5p, NEDD9-hsa-miR-18a-5p, CRIM1-hsa-miR-18a-5p, TGFBR2-hsa-miR-9-5p, MYO1C-hsa-miR-9-5p, KLF4-hsa-miR-7-5p, EMP2-hsa-miR-1290, TMEM2-hsa-miR-18a-5p, CTGF-hsa-miR-18a-5p, TNFAIP3-hsa-miR-18a-5p, THBS1-hsa-miR-182-5p, KPNA2-hsa-miR-144-3p, GPR137C-hsa-miR-1-3p, GRIK3-hsa-miR-144-3p, and MTHFD2-hsa-miR-30a-3p) were identified in SCLC.RBMS3, NEDD9, CRIM1, KPNA2, GPR137C, GRIK3, hsa-miR-7-5p, hsa-miR-18a-5p, hsa-miR-144-3p, hsa-miR-1-3p along with the pathways included protein kinase B signaling, muscle structure development, Cell Cycle (Mitotic) and blood vessel development may gain a high chance to play a key role in the prognosis of SCLC, but more studies should be conducted to reveal it more clearly.

Genetic Interactions Affect Lung Function in Patients with Systemic Sclerosis

Scleroderma, or systemic sclerosis (SSc), is an autoimmune disease characterized by progressive fibrosis of the skin and internal organs. The most common cause of death in people with SSc is lung disease, but the pathogenesis of lung disease in SSc is insufficiently understood to devise specific treatment strategies. Developing targeted treatments requires not only the identification of molecular processes involved in SSc-associated lung disease, but also understanding of how these processes interact to drive pathology. One potentially powerful approach is to identify alleles that interact genetically to influence lung outcomes in patients with SSc. Analysis of interactions, rather than individual allele effects, has the potential to delineate molecular interactions that are important in SSc-related lung pathology. However, detecting genetic interactions, or epistasis, in human cohorts is challenging. Large numbers of variants with low minor allele frequencies, paired with heterogeneous disease presentation, reduce power to detect epistasis. Here we present an analysis that increases power to detect epistasis in human genome-wide association studies (GWAS). We tested for genetic interactions influencing lung function and autoantibody status in a cohort of 416 SSc patients. Using Matrix Epistasis to filter SNPs followed by the Combined Analysis of Pleiotropy and Epistasis (CAPE), we identified a network of interacting alleles influencing lung function in patients with SSc. In particular, we identified a three-gene network comprising WNT5A, RBMS3, and MSI2, which in combination influenced multiple pulmonary pathology measures. The associations of these genes with lung outcomes in SSc are novel and high-confidence. Furthermore, gene coexpression analysis suggested that the interactions we identified are tissue-specific, thus differentiating SSc-related pathogenic processes in lung from those in skin.

Ecological genomics of adaptation to unpredictability in experimental rotifer populations

Elucidating the genetic basis of phenotypic variation in response to different environments is key to understanding how populations evolve. Facultatively sexual rotifers can develop adaptive responses to fluctuating environments. In a previous evolution experiment, diapause-related traits changed rapidly in response to two selective regimes (predictable vs unpredictable) in laboratory populations of the rotifer Brachionus plicatilis. Here, we investigate the genomic basis of adaptation to environmental unpredictability in these experimental populations. We identified and genotyped genome-wide polymorphisms in 169 clones from both selective regimes after seven cycles of selection using genotyping by sequencing (GBS). Additionally, we used GBS data from the 270 field clones from which the laboratory populations were established. This GBS dataset was used to identify candidate SNPs under selection. A total of 76 SNPs showed divergent selection, three of which are candidates for being under selection in the particular unpredictable fluctuation pattern studied. Most of the remaining SNPs showed strong signals of adaptation to laboratory conditions. Furthermore, a genotype-phenotype association approach revealed five SNPs associated with two key life-history traits in the adaptation to unpredictability. Our results contribute to elucidating the genomic basis for adaptation to unpredictable environments and lay the groundwork for future evolution studies in rotifers.

The RNA binding protein RBMS3 inhibits the metastasis of breast cancer by regulating Twist1 expression

Background

Metastasis remains the biggest obstacle for breast cancer treatment. Therefore, identification of specific biomarker of metastasis is very necessary. The RNA binding protein 3 (RBMS3) acts as a tumor suppressor in various cancers. Whereas, its role and underlying molecular mechanism in breast cancer is far from elucidated.

Methods

Quantitative real-time PCR and western blots were carried out to determine the expression of RBMS3 in breast cancer cells and tissues. Transwell and in vivo metastasis assay were conducted to investigate the effects of RBMS3 on migration, invasion and metastasis of breast cancer cells. Transcriptome sequencing was applied to screen out the differential gene expression affected by RBMS3. RNA immunoprecipitation assay combined with luciferase reporter assay were performed to explore the direct correlation between RBMS3 and Twist1 mRNA.

Results

RBMS3 was downregulated in breast cancer and ectopic expression of RBMS3 contributed to inhibition of cell migration, invasion in vitro and lung metastasis in vivo. Furthermore, RBMS3 negatively regulated Twsit1 expression via directly binding to 3′-UTR of Twist1 mRNA, and thereby decreased Twist1-induced expression of matrix metalloproteinase 2 (MMP2). Additionally, Twist1-induced cell migration, invasion and lung metastasis could be reversed by the upregulation of RBMS3.

Conclusions

In summary, our study revealed a novel mechanism of the RBMS3/Twsit1/MMP2 axis in the regulation of invasion and metastasis of breast cancer, which may become a potential molecular marker for breast cancer treatment.

Differential transcriptional changes in human alveolar epithelial A549 cells exposed to airborne PM2.5 collected from Shanghai, China

Fine particulate matters (PM_2.5) are the core pollutants of haze episode, which pose a serious threat to the human health of developing countries. However, the mechanisms involved in PM_2.5-induced hazard influence are not to fully elucidated. In the present study, human lung epithelial cells (A549) were exposed to various concentrations of PM_2.5 samples collected from Shanghai, China. Illumina RNA-Seq method with transcriptome, Gene Ontology (GO), and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis were further employed to identify the detrimental effects of PM_2.5 on A549 cells in vitro. A total of 712 differentially expressed genes were obtained from global transcriptome profiling of A549 cells after PM_2.5 exposure. In addition, GO function enrichment analysis revealed that major differentially expressed genes (DEGs) involved in the biological process of the immune system and the response to the stress. KEGG pathway analysis further proposes that infectious disease, cancers, cardiovascular disease, and immune disease pathway were the key human disease events that occur in A549 cells under PM_2.5 stress. The data obtained here shed light on the related biological process and gene signaling pathways affected by PM_2.5 exposure. This study aids our understanding of the complicated mechanisms related to PM_2.5-induced health effects and is informative for the prevention and treatment of PM_2.5-induced systemic diseases.

Down regulation of RNA binding motif, single-stranded interacting protein 3, along with up regulation of nuclear HIF1A correlates with poor prognosis in patients with gastric cancer

Frequent loss of multiple regions in short arm of chromosome 3 is found in various tumors including gastric cancer (GC). RNA binding motif, single-stranded interacting protein 3 (RBMS3) is a tumor suppressor gene located in this region and mediates cancer angiogenesis. However, the role of RBMS3 in GC remains unclear.

To evaluate whether RBMS3, together with HIF1A, another key regulator of angiogenesis, predicts GC prognosis, the levels of RBMS3 and HIF1A were first examined by quantitative PCR (qPCR) and western blot from 27 fresh frozen GC and paired normal gastric tissues and then tested by immunohistochemistry (IHC) from 191 GC and 46 normal controls. Moreover, uni- and multivariate analysis were employed to assess the correlations between their levels and microvessel density (MVD) and clinical prognosis. To further identify RBMS3 function in vitro, cell proliferation assay, clonogenic assay, flow cytometry analysis and endothelial cell tube formation assay were employed.

We found that RBMS3 level was decreased, whereas HIF1A was elevated in GC. Furthermore, we demonstrated that RBMS3 was an independent prognostic factor and the levels of RBMS3 and HIF1A were associated with GC angiogenesis and histopathological differentiation: patients with lower RBMS3 level and higher nuclear HIF1A expression had poorer prognosis. Besides, gain- and loss-of-function study revealed RBMS3 regulation on G1/S progression, cell proliferation and the tube formation of human umbilical vein endothelial cells (HUVECs) in vitro. These findings implicated that RBMS3 and nuclear HIF1A could act as prognostic biomarkers and therapeutic targets for GC.

RBMS3 Inhibits the Proliferation and Metastasis of Breast Cancer Cells

RBMS3, a gene encoding a glycine-rich RNA-binding protein, belongs to the family of c-Myc gene single-strand binding proteins (MSSP). Recently, several reports have provided evidence that RBMS3 was deregulated in a diverse range of solid tumors and played a critical role in tumor progression. However, it remains unclear whether RBMS3 inhibits the progression of human breast cancer. Thus, the aim of this study was to investigate the role of RBMS3 in breast cancer and explore the underlying mechanism in breast cancer progression. Our results showed, for the first time, that the expression of RBMS3 at both the mRNA and protein levels was significantly downregulated in human breast cancer tissues and cell lines. In addition, RBMS3 overexpression dramatically suppressed the proliferation, migration, and invasion of breast cancer cells in vitro and attenuated tumor growth in vivo. Furthermore, we observed that RBMS3 greatly inhibited the protein expression of β-catenin, cyclin D1, and c-Myc in breast cancer cells. In summary, we have shown that RBMS3 inhibited the proliferation and tumorigenesis of breast cancer cells, at least in part, through inactivation of the Wnt/β-catenin signaling pathway. Thus, RBMS3 may be a potential treatment target for breast cancer.

Identification of transcription factors that may reprogram lung adenocarcinoma

BACKGROUND

Lung adenocarcinoma is one of most threatening disease to human health. Although many efforts have been devoted to its genetic study, few researches have been focused on the transcription factors which regulate tumor initiation and progression by affecting multiple downstream gene transcription. It is proved that proper transcription factors may mediate the direct reprogramming of cancer cells, and reverse the tumorigenesis on the epigenetic and transcription levels.

METHODS

In this paper, a computational method is proposed to identify the core transcription factors that can regulate as many as possible lung adenocarcinoma associated genes with as little as possible redundancy. A greedy strategy is applied to find the smallest collection of transcription factors that can cover the differentially expressed genes by its downstream targets. The optimal subset which is mostly enriched in the differentially expressed genes is then selected.

RESULTS

Seven core transcription factors (MCM4, VWF, ECT2, RBMS3, LIMCH1, MYBL2 and FBXL7) are detected, and have been reported to contribute to tumorigenesis of lung adenocarcinoma. The identification of the transcription factors provides a new insight into its oncogenic role in tumor initiation and progression, and benefits the discovery of functional core set that may reverse malignant transformation and reprogram cancer cells.

Genetic mapping with multiple levels of phenotypic information reveals determinants of lymphocyte glucocorticoid sensitivity

Clinical response to glucocorticoids, steroid hormones widely used as pharmaceuticals, varies extensively in that many individuals (∼30%) show a weak response to treatment. Although little is known about the molecular basis of this variation, regulatory polymorphisms are likely to play a key role given that glucocorticoids act largely through activation of a transcription factor, the glucocorticoid receptor. In an effort to characterize the molecular basis of variation in glucocorticoid sensitivity, we measured in vitro lymphocyte glucocorticoid sensitivity and transcriptome-wide response to glucocorticoids in peripheral-blood mononuclear cells from African American healthy donors. We found that variation in lymphocyte glucocorticoid sensitivity was correlated with transcriptional response at 27 genes (false-discovery rate < 0.1). Furthermore, a genome-wide association scan revealed a quantitative trait locus (QTL) for lymphocyte glucocorticoid sensitivity (rs11129354, p = 4 × 10(-8)); it was also associated with transcriptional response at multiple genes, including many (14/27) where transcriptional response was correlated with lymphocyte glucocorticoid sensitivity. Using allelic-imbalance assays, we show that this QTL is a glucocorticoid-dependent cis-regulatory polymorphism for RBMS3, which encodes an RNA-binding protein known as a tumor suppressor. We found that siRNA-mediated knockdown of RBMS3 expression increased cellular proliferation in PBMCs, consistent with the role of the gene as a negative regulator of proliferation. We propose that differences in lymphocyte glucocorticoid sensitivity reflect variation in transcriptional response, which is influenced by a glucocorticoid-dependent regulatory polymorphism that acts in cis relative to RBMS3 and in trans to affect the transcriptional response of multiple distant genes.

Gene-gene interaction between RBMS3 and ZNF516 influences bone mineral density

Osteoporosis is characterized by low bone mineral density (BMD), a highly heritable trait that is determined, in part, by the actions and interactions of multiple genes. Although an increasing number of genes have been identified to have independent effects on BMD, few studies have been performed to identify genes that interact with one another to affect BMD. In this study, we performed gene-gene interaction analyses in selected candidate genes in individuals with extremely high versus low hip BMD (20% tails of the distributions), in two independent U.S. Caucasian samples. The first sample contained 916 unrelated subjects with extreme hip BMD Z-scores selected from a population composed of 2286 subjects. The second sample consisted of 400 unrelated subjects with extreme hip BMD Z-scores selected from a population composed of 1000 subjects. Combining results from these two samples, we found one interacting gene pair (RBMS3 versus ZNF516) which, even after Bonferroni correction for multiple testing, showed consistently significant effects on hip BMD. RMBS3 harbored two single-nucleotide polymorphisms (SNPs), rs6549904 and rs7640046, both of which had significant interactions with an SNP, rs4891159, located on ZNF516 (p = 7.04 × 10(-11) and 1.03 × 10(-10) ). We further validated these results in two additional samples of Caucasian and African descent. The gene pair, RBMS3 versus ZNF516, was successfully replicated in the Caucasian sample (p = 8.07 × 10(-3) and 2.91 × 10(-3) ). For the African sample, a significant interaction was also detected (p = 0.031 and 0.043), but the direction of the effect was opposite to that observed in the three Caucasian samples. By providing evidence for genetic interactions underlying BMD, this study further delineates the genetic architecture of osteoporosis.

Rbms3 functions in craniofacial development by posttranscriptionally modulating TGF-β signaling

Rbms3 regulates TGF-βr signaling, a critical pathway for chondrogenesis, by binding and stabilizing Smad2 transcripts.

Cranial neural crest cells form much of the facial skeleton, and abnormalities in their development lead to severe birth defects. In a novel zebrafish protein trap screen, we identified an RNA-binding protein, Rbms3, that is transiently expressed in the cytoplasm of condensing neural crest cells within the pharyngeal arches. Morphants for rbms3 displayed reduced proliferation of prechondrogenic crest and significantly altered expression for chondrogenic/osteogenic lineage markers. This phenotype strongly resembles cartilage/crest defects observed in Tgf-βr2:Wnt1-Cre mutants, which suggests a possible link with TGF-β signaling. Consistent with this are the findings that: (a) Rbms3 stabilized a reporter transcript with smad2 3′ untranslated region, (b) RNA immunoprecipitation with full-length Rbms3 showed enrichment for smad2/3, and (c) pSmad2 levels were reduced in rbms3 morphants. Overall, these results suggest that Rbms3 posttranscriptionally regulates one of the major pathways that promotes chondrogenesis, the transforming growth factor β receptor (TGF-βr) pathway.

RBMS3 at 3p24 inhibits nasopharyngeal carcinoma development via inhibiting cell proliferation, angiogenesis, and inducing apoptosis

Deletion of the short arm of chromosome 3 is one of the most frequent genetic alterations in many solid tumors including nasopharyngeal carcinoma (NPC), suggesting the existence of one or more tumor suppressor genes (TSGs) within the frequently deleted region. A putative TSG RBMS3 (RNA binding motif, single stranded interacting protein 3), located at 3p24-p23, has been identified in our previous study. Here, we reported that downregulation of RBMS3 was detected in 3/3 NPC cell lines and 13/15 (86.7%) primary NPC tissues. Functional studies using both overexpression and suppression systems demonstrated that RBMS3 has a strong tumor suppressive role in NPC. The tumor suppressive mechanism of RBMS3 was associated with its role in cell cycle arrest at the G1/S checkpoint by upregulating p53 and p21, downregulating cyclin E and CDK2, and the subsequent inhibition of Rb-ser780. Further analysis demonstrated that RBMS3 had a pro-apoptotic role in a mitochondrial-dependent manner via activation of caspase-9 and PARP. Finally, RBMS3 inhibited microvessel formation, which may be mediated by down-regulation of MMP2 and β-catenin and inactivation of its downstream targets, including cyclin-D1, c-Myc, MMP7, and MMP9. Taken together, our findings define a function for RBMS3 as an important tumor suppressor gene in NPC.

Tumor suppressor genes on frequently deleted chromosome 3p in nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is among the most common malignancies in southern China. Deletion of genomic DNA, which occurs during the complex pathogenesis process for NPC, represents a pivotal mechanism in the inactivation of tumor suppressor genes (TSGs). In many circumstances, loss of TSGs can be detected as diagnostic and prognostic markers in cancer. The short arm of chromosome 3 (3p) is a frequently deleted chromosomal region in NPC, with 3p21.1-21.2 and 3p25.2-26.1 being the most frequently deleted minimal regions. In recent years, our research group and others have focused on the identification and characterization of novel target TSGs at 3p, such as RASSF1A, BLU, RBMS3, and CHL1, in the development and progression of NPC. In this review, we summarize recent findings of TSGs at 3p and discuss some of these genes in detail. A better understanding of TSGs at 3p will significantly improve our understanding of NPC pathogenesis, diagnosis, and treatment.

Downregulation of RBMS3 is associated with poor prognosis in esophageal squamous cell carcinoma

Deletions on chromosome 3p occur often in many solid tumors, including esophageal squamous cell carcinoma (ESCC), suggesting the existence at this location of one or more tumor suppressor genes (TSG). In this study, we characterized RBMS3 gene encoding an RNA-binding protein as a candidate TSG located at 3p24. Downregulation of RBMS3 mRNA and protein levels was documented in approximately 50% of the primary ESCCs examined. Clinical association studies determined that RBMS3 downregulation was associated with poor clinical outcomes. RBMS3 expression effectively suppressed the tumorigenicity of ESCC cells in vitro and in vivo, including by inhibition of cell growth rate, foci formation, soft agar colony formation, and tumor formation in nude mice. Molecular analyses revealed that RBMS3 downregulated c-Myc and CDK4, leading to subsequent inhibition of Rb phosphorylation. Together, our findings suggest a tumor suppression function for the human RBMS3 gene in ESCC, acting through c-Myc downregulation, with genetic loss of this gene in ESCC contributing to poor outcomes in this deadly disease.

Single-nucleotide polymorphism-mass array reveals commonly deleted regions at 3p22 and 3p14.2 associate with poor clinical outcome in esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC) is one of the most common solid tumors in the world with poor prognosis. Deletion of chromosome 3p is one of the most frequent chromosomal alterations in ESCC, suggesting the existence of one or more tumor suppressor genes (TSGs) at this region. In the present study, a recently developed high-throughput and high-resolution technology, single-nucleotide polymorphism (SNP)-mass array, was applied to investigate loss of heterozygosity on 3p in 100 primary ESCC cases with 386 SNP markers. Four commonly deleted regions (CDRs) at 3p26.3, 3p22, 3p21.3 and 3p14.2 were identified. Absent and down-regulated expression of several candidate TSGs, including CHL1, PCAF, RBMS3, PLCD1 and CACNA2D3, were detected in primary ESCC tumors and ESCC cell lines. Moreover, deletions of CDRs 2 and 4 were correlated with advanced tumor stage and deletion of CDR2 was associated with tumor metastasis in ESCC. Our findings provided evidence that minimal deleted regions at 3p26.3, 3p22, 3p21.3 and 3p14.2 containing potential TSGs may contribute to the pathogenesis of esophageal cancer.

Identification of a neuron-specific human gene, KIAA1110, that is a guanine nucleotide exchange factor for ARF1

To identify neuron-specific genes, we performed gene expression profiling, cDNA microarray and in silico ESTs (expressed sequence tags) analyses. We identified a human neuron-specific gene, KIAA1110 (homologue of rat synArfGEF (Po)), that is a member of the guanine nucleotide exchange factor (GEF) for the ADP-ribosylation factor (ARF). RT-PCR analysis showed that the KIAA1110 gene was expressed specifically in the brain among adult human tissues, whereas no apparent expression was observed in immature neural tissues/cells, such as fetal brain, glioma tissues/cells, and neural stem/precursor cells (NSPCs). The KIAA1110 protein was shown to be expressed in mature neurons but not in undifferentiated NSPCs. Immunohistochemical analysis also showed that KIAA1110 was expressed in neurons of the human adult cerebral cortex. Furthermore, the pull-down assay revealed that KIAA1110 has a GEF activity toward ARF1 that regulates transport along the secretion pathway. These results suggest that KIAA1110 is expressed specifically in mature neurons and may play an important role in the secretion pathway as a GEF for ARF1.

RNA-binding protein RBMS3 is expressed in activated hepatic stellate cells and liver fibrosis and increases expression of transcription factor Prx1

Hepatic stellate cells (HSCs) are mesenchymal cells of the liver, activation of which is responsible for excessive synthesis of extracellular matrix, including type I collagen, and development of liver fibrosis. The activation of HSCs is driven by transcription factors and pair-related homeobox transcription factor Prx1 was identified as one of the transcription factors involved in this process, because transcription of collagen alpha1(I) gene is stimulated by Prx1 in HSCs and in the liver. Here, we show that expression of the RNA-binding protein RBMS3 is upregulated in the activation of HSCs and fibrotic livers. Immunoprecipitation followed by differential display identified Prx1 mRNA as one of the mRNAs interacting with RBMS3. The RBMS3 sequence-specific binding site was mapped to 60 nt located 1946 nt 3' of the stop codon of Prx1 mRNA. Ectopic expression of RBMS3 in quiescent HSCs, which express trace amounts of type I collagen, increased expression of Prx1 mRNA and collagen alpha1(I) mRNA. Expression of reporter Prx1 mRNA containing the RBMS3 binding site was higher than the mRNA lacking this site. Over-expression of RBMS3 further increased the steady-state level of the reporter mRNA-containing RBMS3 binding site, but had no effect on the mRNA lacking this site. Binding of RBMS3 to the Prx1 3' UTR increased the half-life of this mRNA, resulting in increased protein synthesis. These results suggest that RBMS3, by binding Prx1 mRNA in a sequence-specific manner, controls Prx1 expression and indirectly collagen synthesis. This is the first description of the function of RBMS3, as a key regulator of profibrotic potential of HSCs, representing a novel mechanism by which activated HSCs contribute to liver fibrosis.

Multi-level gene expression profiles affected by thymidylate synthase and 5-fluorouracil in colon cancer

Background

Thymidylate synthase (TS) is a critical target for cancer chemotherapy and is one of the most extensively studied biomarkers for fluoropyrimidine-based chemotherapy. In addition to its critical role in enzyme catalysis, TS functions as an RNA binding protein to regulate the expression of its own mRNA translation and other cellular mRNAs, such as p53, at the translational level. In this study, a comprehensive gene expression analysis at the levels of both transcriptional and post-transcriptional regulation was conducted to identify response markers using human genome array with TS-depleted human colon cancer HCT-C18 (TS-) cells and HCT-C18 (TS+) cells stably transfected with the human TS cDNA expression plasmid.

Results

A total of 38 genes were found to be significantly affected by TS based on the expression profiles of steady state mRNA transcripts. However, based on the expression profiles of polysome associated mRNA transcripts, over 149 genes were affected by TS overexpression. This indicates that additional post-transcriptionally controlled genes can be captured with profiling polysome associated mRNA population. This unique approach provides a comprehensive overview of genes affected by TS. Additional novel post-transcriptionally regulated genes affected by 5-fluorouracil (5-FU) treatment were also discovered via similar approach.

Conclusion

To our knowledge, this is the first time that a comprehensive gene expression profile regulated by TS and 5-FU was analyzed at the multiple steps of gene regulation. This study will provide candidate markers that can be potentially used for predicting therapeutic outcomes for fluoropyrimidine-based cancer chemotherapy.

Positive regulation of Fas gene expression by MSSP and abrogation of Fas-mediated apoptosis induction in MSSP-deficient mice

MSSP has been identified as a transcription factor that regulates the c-myc gene. MSSP was later found to positively or negatively regulate a variety of genes, including alpha-smooth actin, MHC class I, MHC class 2 and the thyrotropin receptor. The knockout mice for the Mssp gene developed by us revealed that these mice became partially embryonic lethal due to a low concentration of progesterone at E2.5. In this study, we further analyzed Mssp-knockout mice and found that the expression of the Fas gene was repressed, resulting in abrogation of Fas-mediated induction of apoptosis both in Mssp-knockout mice and primary thymocytes. MSSP was then found to stimulate promoter activity of the Fas gene by binding to a region spanning -1035 to -635 in chromatin immunoprecipitation assays. Binding of MSSP in the MSSP-binding sequence, TCTAAT, located in this region was confirmed by mobility shift assays, and deletion of this sequence from the Fas promoter was found to result in loss of MSSP-dependent stimulating activity. The results suggest that MSSP is an important mediator for Fas-induced apoptosis in vivo and in vitro.

Identification of novel Drosophila neural precursor genes using a differential embryonic head cDNA screen

During Drosophila neuroblast lineage development, temporally ordered transitions in neuroblast gene expression have been shown to accompany the changing repertoire of functionally diverse cells generated by neuroblasts. To broaden our understanding of the biological significance of these ordered transitions in neuroblast gene expression and the events that regulate them, additional genes have been sought that participate in the timing and execution of these temporally controlled events. To identify dynamically expressed neural precursor genes, we have performed a differential cDNA hybridization screen on a stage specific embryonic head cDNA library, followed by whole-mount embryo in situ hybridizations. Described here are the embryonic expression profiles of 57 developmentally regulated neural precursor genes. Information about 2389 additional genes identified in this screen, including 1614 uncharacterized genes, is available on-line at 'BrainGenes: a search for Drosophila neural precursor genes' (http://sdb.bio.purdue.edu/fly/brain/ahome.htm).

Disruption of MSSP, c-myc single-strand binding protein, leads to embryonic lethality in some homozygous mice

BACKGROUND

MSSP, c-myc single-strand binding protein, works as a factor for DNA replication, transcription, apoptosis induction, and myc/ras cooperative transformation. The cDNAs encoding four of the family proteins, MSSP-1, MSSP-2, Scr2 and Scr3, were cloned. These proteins possess two copies of putative RNA binding domains, RNP-A and RNP-B, and these RNA binding domains have been suggested to be indispensable to the functions of MSSP.

RESULTS

To elucidate its role in vivo, we generated Mssp knockout mice by homologous recombination in embryonic stem cells. Although intercrossing of Mssp+/- mice gave rise to mice homozygous to the mutant Mssp allele (Mssp-/-) and the Mssp-/- mice, once born, did not display an overt phenotype, the ratio of littermates born among Mssp+/+, Mssp+/- and Mssp-/- mice was 1 : 1.6 : 0.5, which is not a typical Mendelian ratio. When E2.5 embryos from the pregnant mice were cultured in vitro for 5 days, the inner cell mass and trophoblast giant cells in wild-type (Mssp+/+) E2.5 embryos developed normally. However, Mssp-/- E2.5 embryos displayed significant defects in growth and development. Since Mssp was expressed in uterine gland-transported glycogen, we evaluated the hormonal state of wild-type and Mssp-/- mice. The progesterone concentration of Mssp-/- mice was decrease to 6.5% of that of wild-type mice at E2.5.

CONCLUSIONS

These results suggest that the deletion of the mssp gene results in both the growth defect in the embryo and the hormonal defect in adult female mouse. The embryonic defect and a decreased concentration of progesterone in female mice reflect a development defect of the pre-implantation embryo in Mssp-/- mice, thereby leading to embryonic lethality.