Double edge: CDK2AP1 in cell-cycle regulation and epigenetic regulation

Transcriptomic comparison of corneal endothelial cells in young versus old corneas

Corneal endothelial cells, situated on the innermost layer of the cornea, are vital for maintaining its clarity and thickness by regulating fluid. In this study, we investigated the differences in the transcriptome between young and old corneal endothelial cells using next-generation sequencing (NGS). Cultured endothelial cells from both young and elderly donors were subjected to NGS to unravel the transcriptomic landscape. Subsequent analyses, facilitated by Metascape, allowed for the dissection of gene expression variances, unearthing pivotal biological pathways. A total of 568 genes showed differences, and were related to Endomembrane system organization, nuclear receptors meta pathway, efferocytosis, etc. Notably, a reduction in the expression of 260 genes was observed in the aged cells form old donors, and in the related analysis, eukaryotic translation initiation, integrator complex, and Hippo YAP signaling were significant. Conversely, 308 genes exhibited elevated expression levels in the elderly, correlating with processes including transition metal ion transport and glycoprotein biosynthesis. In conclusion, our investigation has revealed critical genes involved in the aging process of corneal endothelial cells and elucidated their underlying biological pathways. These insights are instrumental in selecting targets for therapeutic intervention, thereby facilitating the advancement of novel therapeutic approaches for the restoration and preservation of corneal endothelial cell function.

Effects of α-Particle Radiation on DNA Methylation in Human Hepatocytes

Objective: This paper explores the role of DNA methylation in α-irradiation damage at the cellular level. Methods: Human normal hepatocytes L-02 were irradiated using a 241 Am α source at doses of 0, 1.0, and 2.0 Gy. The methylation levels of the six differentially methylated genes were examined by pyrophosphate sequencing, and the mRNA expression levels of the six differentially methylated genes were examined by real-time fluorescence quantitative PCR. Results: The rate of γH2AX foci positive cells was significantly higher than that of the control group after irradiation of cells in different dose groups for 1 h and 2 h respectively (P < .05). The proportion of S-phase cells was significantly increased in the 1.0 Gy and 2.0 Gy dose groups compared with the control group (P < .05). The methylation levels of CDK2AP1, PDGFRL, PCDHB16 and FAS genes were significantly increased, while the mRNA expression levels were significantly decreased (P < .05). The expression levels of CDK2Apl, PCDHB16 and FAS were significantly negatively correlated with the methylation levels (P < .05). Conclusion: The α-particle radiation can affect gene expression at the epigenetic level, which led to the speculation that altered methylation levels of CDK2AP1, PCDHB16, and FAS genes may be involved in the α radiation damage process.

IL-33 stimulates the anticancer activities of eosinophils through extracellular vesicle-driven reprogramming of tumor cells

Immune cell-derived extracellular vesicles (EV) affect tumor progression and hold promise for therapeutic applications. Eosinophils are major effectors in Th2-related pathologies recently implied in cancer. Here, we evaluated the anti-tumor activities of eosinophil-derived EV following activation with the alarmin IL-33. We demonstrate that IL-33-activated mouse and human eosinophils produce higher quantities of EV with respect to eosinophils stimulated with IL-5. Following incorporation of EV from IL-33-activated eosinophils (Eo33-EV), but not EV from IL-5-treated eosinophils (Eo5-EV), mouse and human tumor cells increased the expression of cyclin-dependent kinase inhibitor (CDKI)-related genes resulting in cell cycle arrest in G0/G1, reduced proliferation and inhibited tumor spheroid formation. Moreover, tumor cells incorporating Eo33-EV acquired an epithelial-like phenotype characterized by E-Cadherin up-regulation, N-Cadherin downregulation, reduced cell elongation and migratory extent in vitro, and impaired capacity to metastasize to lungs when injected in syngeneic mice. RNA sequencing revealed distinct mRNA signatures in Eo33-EV and Eo5-EV with increased presence of tumor suppressor genes and enrichment in pathways related to epithelial phenotypes and negative regulation of cellular processes in Eo33-EV compared to Eo5-EV. Our studies underscore novel IL-33-stimulated anticancer activities of eosinophils through EV-mediated reprogramming of tumor cells opening perspectives on the use of eosinophil-derived EV in cancer therapy.

Genetic contribution of reproductive traits to risk of uterine leiomyomata: a large-scale, genome-wide, cross-trait analysis

BACKGROUND

Although phenotypic associations between female reproductive characteristics and uterine leiomyomata have long been observed in epidemiologic investigations, the shared genetic architecture underlying these complex phenotypes remains unclear.

OBJECTIVE

We aimed to investigate the shared genetic basis, pleiotropic effects, and potential causal relationships underlying reproductive traits (age at menarche, age at natural menopause, and age at first birth) and uterine leiomyomata.

STUDY DESIGN

With the use of large-scale, genome-wide association studies conducted among women of European ancestry for age at menarche (n=329,345), age at natural menopause (n=201,323), age at first birth (n=418,758), and uterine leiomyomata (ncases/ncontrols=35,474/267,505), we performed a comprehensive, genome-wide, cross-trait analysis to examine systematically the common genetic influences between reproductive traits and uterine leiomyomata.

RESULTS

Significant global genetic correlations were identified between uterine leiomyomata and age at menarche (rg, -0.17; P=3.65×10-10), age at natural menopause (rg, 0.23; P=3.26×10-07), and age at first birth (rg, -0.16; P=1.96×10-06). Thirteen genomic regions were further revealed as contributing significant local correlations (P<.05/2353) to age at natural menopause and uterine leiomyomata. A cross-trait meta-analysis identified 23 shared loci, 3 of which were novel. A transcriptome-wide association study found 15 shared genes that target tissues of the digestive, exo- or endocrine, nervous, and cardiovascular systems. Mendelian randomization suggested causal relationships between a genetically predicted older age at menarche (odds ratio, 0.88; 95% confidence interval, 0.85-0.92; P=1.50×10-10) or older age at first birth (odds ratio, 0.95; 95% confidence interval, 0.90-0.99; P=.02) and a reduced risk for uterine leiomyomata and between a genetically predicted older age at natural menopause and an increased risk for uterine leiomyomata (odds ratio, 1.08; 95% confidence interval, 1.06-1.09; P=2.30×10-27). No causal association in the reverse direction was found.

CONCLUSION

Our work highlights that there are substantial shared genetic influences and putative causal links that underlie reproductive traits and uterine leiomyomata. The findings suggest that early identification of female reproductive risk factors may facilitate the initiation of strategies to modify potential uterine leiomyomata risk.

The deleted in oral cancer (DOC1 aka CDK2AP1) tumor suppressor gene is downregulated in oral squamous cell carcinoma by multiple microRNAs

Cyclin-dependent kinase 2-associated protein 1 (CDK2AP1; also known as deleted in oral cancer or DOC1) is a tumor suppressor gene known to play functional roles in both cell cycle regulation and in the epigenetic control of embryonic stem cell differentiation, the latter as a core subunit of the nucleosome remodeling and histone deacetylation (NuRD) complex. In the vast majority of oral squamous cell carcinomas (OSCC), expression of the CDK2AP1 protein is reduced or lost. Notwithstanding the latter (and the DOC1 acronym), mutations or deletions in its coding sequence are extremely rare. Accordingly, CDK2AP1 protein-deficient oral cancer cell lines express as much CDK2AP1 mRNA as proficient cell lines. Here, by combining in silico and in vitro approaches, and by taking advantage of patient-derived data and tumor material in the analysis of loss of CDK2AP1 expression, we identified a set of microRNAs, namely miR-21-5p, miR-23b-3p, miR-26b-5p, miR-93-5p, and miR-155-5p, which inhibit its translation in both cell lines and patient-derived OSCCs. Of note, no synergistic effects were observed of the different miRs on the CDK2AP1-3-UTR common target. We also developed a novel approach to the combined ISH/IF tissue microarray analysis to study the expression patterns of miRs and their target genes in the context of tumor architecture. Last, we show that CDK2AP1 loss, as the result of miRNA expression, correlates with overall survival, thus highlighting the clinical relevance of these processes for carcinomas of the oral cavity.

The Association between Cyclin Dependent Kinase 2 Associated Protein 1 (CDK2AP1) and Molecular Subtypes of Lethal Prostate Cancer

Prostate cancer (PCa) is one of the most commonly diagnosed types of malignancy and is the second leading cause of cancer-related death in men in developed countries. Cyclin dependent kinase 2 associate protein 1(CDK2AP1) is an epigenetic and cell cycle regulator gene which has been downregulated in several malignancies, but its involvement in PCa has not yet been investigated in a clinical setting. We assessed the prognostic value of CDK2AP1 expression in a cohort of men diagnosed with PCa (n = 275) treated non-surgically by transurethral resection of the prostate (TURP) and studied the relationship between CDK2AP1 expression to various PCa molecular subtypes (ERG, PTEN, p53 and AR) and evaluated the association with clinical outcome. Further, we used bioinformatic tools to analyze the available TCGA PRAD transcriptomic data to explore the underlying mechanism. Our data confirmed increased expression of CDK2AP1 with higher Gleason Grade Group (GG) and metastatic PCa (p <0.0001). High CDK2AP1 expression was associated with worse overall survival (OS) (HR: 1.62, CI: 1.19−2.21, p = 0.002) and cause-specific survival (CSS) (HR: 2.012, CI 1.29−3.13, p = 0.002) using univariate analysis. When compared to each sub-molecular type. High CDK2AP1/PTEN-loss, abnormal AR or p53 expression showed even worse association to poorer OS and CCS and remained significant when adjusted for GG. Our data indicates that CDK2AP1 directly binds to p53 using the Co-Immunoprecipitation (Co-IP) technique, which was validated using molecular docking tools. This suggests that these two proteins have a significant association through several binding features and correlates with our observed clinical data. In conclusion, our results indicated that the CDK2AP1 overexpression is associate with worse OS and CSS when combined with certain PCa molecular subtypes; interaction between p53 stands out as the most prominent candidate which directly interacts with CDK2AP1.

CDK2AP1 influences immune infiltrates and serves as a prognostic indicator for hepatocellular carcinoma

Background: Hepatocellular carcinoma (HCC) is a tumor with high malignancy and poor 5-years survival rate. Excellent tumor markers are very important for early clinical diagnosis and prognosis evaluation. Previous studies have shown that CDK2AP1 (Cyclin-dependent kinase 2-associated protein 1) is involved in cell-cycle and epigenetic regulation. In the present study, we assess CDK2AP1 expression, prognostic value, immunomodulatory and possible influencing pathways in HCC.

Method: The Cancer Genome Atlas (TCGA) database was used to analyse gene expression, clinicopathology and prognosis. The protein level of CDK2AP1 in HCC tissues was detected in the Human Protein Atlas (HPA) database. The immune score in HCC to CDKAP1 expression were analyzed using ESTIMATE. Furthermore, we use Tumor IMmune Estimation Resource (TIMER) database to study CDK2AP1 expression and Immune Infiltration Levels in HCC. Co-expressed genes of CDK2AP1 were predicted and elaborated by LinkedOmics.

Results: In normal liver tissues, the expression of CDK2AP1 was significantly lower than tumor tissues, and was correlated with the level of clinical stage and histologic grade in HCC patients. Patients with high expression of CDK2AP1 have a poor prognosis than patients with low CDK2AP1 expression. CDK2AP1 expression level exhibits significantly positive correlations with the number of infiltrating B cells, CD4+ T cells, CD8+ T cells, Macrophages, Neutrophils, and DCs in HCC tissues. KEGG enrichment analysis showed that the related pathways affected by CDK2AP1 mainly include: Fc gamma R-mediated phagocytosis, Th1 and Th2 cell differentiation, Cell cycle, etc. Both in vitro and in vivo experiments confirmed that CDK2AP1 promotes the proliferation and metastasis in hepatocellular carcinoma. Our results highlight the role of CDK2AP1 as an important prognostic indicator and immunotherapy target for HCC patients.

Conclusion: We found CDK2AP1 as a new prognostic biomarker for HCC, which could help explain changes in the biological processes and immune environment lead to liver cancer development. Therefore, CDK2AP1 is a potential new target for HCC therapy.

A mouse-specific retrotransposon drives a conserved Cdk2ap1 isoform essential for development

Retrotransposons mediate gene regulation in important developmental and pathological processes. Here, we characterized the transient retrotransposon induction during preimplantation development of eight mammals. Induced retrotransposons exhibit similar preimplantation profiles across species, conferring gene regulatory activities, particularly through long terminal repeat (LTR) retrotransposon promoters. A mouse-specific MT2B2 retrotransposon promoter generates an N-terminally truncated Cdk2ap1ΔN that peaks in preimplantation embryos and promotes proliferation. In contrast, the canonical Cdk2ap1 peaks in mid-gestation and represses cell proliferation. This MT2B2 promoter, whose deletion abolishes Cdk2ap1ΔN production, reduces cell proliferation and impairs embryo implantation, is developmentally essential. Intriguingly, Cdk2ap1ΔN is evolutionarily conserved in sequence and function yet is driven by different promoters across mammals. The distinct preimplantation Cdk2ap1ΔN expression in each mammalian species correlates with the duration of its preimplantation development. Hence, species-specific transposon promoters can yield evolutionarily conserved, alternative protein isoforms, bestowing them with new functions and species-specific expression to govern essential biological divergence.

Differentially expressed genes in Alzheimer's disease highlighting the roles of microglia genes including OLR1 and astrocyte gene CDK2AP1

BACKGROUND

Alzheimer's disease (AD) is associated with abnormal tau and amyloid-β accumulation in the brain, leading to neurofibrillary tangles, neuropil threads and extracellular amyloid-β plaques. Treatment is limited to symptom management, a disease-modifying therapy is not available. To advance search of therapy approaches, there is a continued need to identify targets for disease intervention both by confirming existing hypotheses and generating new hypotheses.

METHODS

We conducted a mRNA-seq study to identify genes associated with AD in post-mortem brain samples from the superior temporal gyrus (STG, n ​= ​76), and inferior frontal gyrus (IFG, n ​= ​65) brain regions. Differentially expressed genes (DEGs) were identified correcting for gender and surrogate variables to capture hidden variation not accounted for by pre-planned covariates. The results from this study were compared with the transcriptome studies from the Accelerated Medicine Partnership - Alzheimer's Disease (AMP-AD) initiative. Over-representation and gene set enrichment analysis (GSEA) was used to identify disease-associated pathways. Protein-protein interaction (PPI) and weighted gene co-expression network analysis (WGCNA) analyses were carried out and co-expressed gene modules and their hub genes were identified and associated with additional phenotypic traits of interest.

RESULTS

Several hundred mRNAs were differentially expressed between AD cases and cognitively normal controls in the STG, while no and few transcripts met the same criteria (adjusted p less than 0.05 and fold change greater than 1.2) in the IFG. The findings were consistent at the gene set level with two out of three cohorts from AMP-AD. PPI analysis suggested that the DEGs were enriched in protein-protein interactions than expected by random chance. Over-representation and GSEA analysis suggested genes playing roles in neuroinflammation, amyloid-β, autophagy and trafficking being important for the AD disease process. At the gene level, 10 genes from the STG that were consistently differentially expressed in this study and in the MSBB study (one of the three cohorts within the AMP-AD initiative) were enriched in microglial genes (TREM2, C3AR1, ITGAX, OLR1, CD74, and HLA-DRA), but also included genes with a broader cell type expression pattern such as CDK2AP1. Among the DEGs with supporting evidence from an independent study, CDK2AP1 (most abundantly expressed in astrocyte) was the transcript with strongest association with antemortem cognitive measure (last Mini-Mental State Examination score) and neurofibril tangle burden but also associated with amyloid plaque burden, while OLR1 was the transcript with strongest association with amyloid plaque burden. GSEA and over-representation analyses revealed gene sets related to immune processes including neutrophil degranulation, interleukin 10 signaling, and interferon gamma signaling, complement and coagulation cascades, phosphatidylinositol signaling system, phagosome and neurotransmitter receptors and postsynaptic signal transmission were enriched from this study and replicated in an independent study.

CONCLUSION

This study identified differential gene sets, common with two out of three AMP-AD cohorts (ROSMAP and MSBB) and highlights microglia and astrocyte as the key cell-types with DGEs associated with AD clinical diagnosis, and/or antemortem cognitive measure as well as neuropathological indices. Future meta-analysis and causal inferential analysis will be helpful in pinpointing the most relevant pathways and genes to intervene.

Establishment and Characterization of a Sclerosing Spindle Cell Rhabdomyosarcoma Cell Line with a Complex Genomic Profile

Sclerosing spindle cell rhabdomyosarcoma (SSRMS) is a rare rhabdomyosarcomas (RMS) subtype. Especially cases bearing a myogenic differentiation 1 (MYOD1) mutation are characterized by a high recurrence and metastasis rate, often leading to a fatal outcome. SSRMS cell lines are valuable in vitro models for studying disease mechanisms and for the preclinical evaluation of new therapeutic approaches. In this study, a cell line established from a primary SSRMS tumor of a 24-year-old female after multimodal chemotherapeutic pretreatment has been characterized in detail, including immunohistochemistry, growth characteristics, cytogenetic analysis, mutation analysis, evaluation of stem cell marker expression, differentiation potential, and tumorigenicity in mice. The cell line which was designated SRH exhibited a complex genomic profile, including several translocations and deletions. Array-comparative genomic hybridization (CGH) revealed an overall predominating loss of gene loci. The mesenchymal tumor origin was underlined by the expression of mesenchymal markers and potential to undergo adipogenic and osteogenic differentiation. Despite myogenic marker expression, terminal myogenic differentiation was inhibited, which might be elicited by the MYOD1 hotspot mutation. In vivo tumorigenicity could be confirmed after subcutaneous injection into NOD/SCID/γ_c^null mice. Summarized, the SRH cell line is the first adult SSRMS cell line available for preclinical research on this rare RMS subtype.

Analyzing the Effects of Intrauterine Hypoxia on Gene Expression in Oocytes of Rat Offspring by Single Cell Transcriptome Sequencing

Intrauterine hypoxia is one of the most frequently occurring complications during pregnancy, and the effects of antenatal hypoxia in offspring are not restricted to the perinatal period. Previous studies have reported on this phenomenon, which is usually described as multigenerational or transgenerational inheritance. However, the exact mechanism of this type of inheritance is still not clear. Therefore, in the present study, we investigated the alteration in the gene expression of oocytes, derived from intrauterine hypoxia rats and their offspring, by transcriptome sequencing. Our results showed that 11 differentially expressed genes were inherited from the F1 to F2 generation. Interestingly, these differentially expressed genes were enriched in processes predominantly involved in lipid and insulin metabolism. Overall, our data indicated that alteration in the gene expression of oocytes may be associated with some metabolic diseases and could potentially be the basis of transgenerational or multigenerational inheritance, induced by an adverse perinatal environment.

DYNC1H1 gene methylation correlates with severity of spinal muscular atrophy

Methylation profiles of CpG islands within the SLC23A2, CDK2AP1, and DYNC1H1 genes and their association with spinal muscular atrophy (SMA) severity were studied. High clinical heterogeneity of SMA suggests the existence of different factors modifying SMA phenotype with gene methylation as a plausible one. The genes picked up in our earlier genome-wide methylation studies of SMA patients demonstrated obvious differences in their methylation patterns, thus suggesting the likely involvement of their protein products in SMA development. Significantly decreased methylation of CpG islands within exon 37 of the DYNC1H1 gene was observed in patients with a severe SMA manifestation (type I) compared to mildly affected SMA patients (types III-IV). This finding provides new information on peculiarities of methylation in clinically different types of SMA patients and gives a clue for identification of new SMA modifiers.

Knockdown of CDK2AP1 in human embryonic stem cells reduces the threshold of differentiation

Recent studies have suggested a role for the Cyclin Dependent Kinase-2 Associated Protein 1 (CDK2AP1) in stem cell differentiation and self-renewal. In studies with mouse embryonic stem cells (mESCs) derived from generated mice embryos with targeted deletion of the Cdk2ap1 gene, CDK2AP1 was shown to be required for epigenetic silencing of Oct4 during differentiation, with deletion resulting in persistent self-renewal and reduced differentiation potential. Differentiation capacity was restored in these cells following the introduction of a non-phosphorylatible form of the retinoblastoma protein (pRb) or exogenous Cdk2ap1. In this study, we investigated the role of CDK2AP1 in human embryonic stem cells (hESCs). Using a shRNA to reduce its expression in hESCs, we found that CDK2AP1 knockdown resulted in a significant reduction in the expression of the pluripotency genes, OCT4 and NANOG. We also found that CDK2AP1 knockdown increased the number of embryoid bodies (EBs) formed when differentiation was induced. In addition, the generated EBs had significantly higher expression of markers of all three germ layers, indicating that CDK2AP1 knockdown enhanced differentiation. CDK2AP1 knockdown also resulted in reduced proliferation and reduced the percentage of cells in the S phase and increased cells in the G2/M phase of the cell cycle. Further investigation revealed that a higher level of p53 protein was present in the CDK2AP1 knockdown hESCs. In hESCs in which p53 and CDK2AP1 were simultaneously downregulated, OCT4 and NANOG expression was not affected and percentage of cells in the S phase of the cell cycle was not reduced. Taken together, our results indicate that the knockdown of CDK2AP1 in hESCs results in increased p53 and enhances differentiation and favors it over a self-renewal fate.

DOC1-Dependent Recruitment of NURD Reveals Antagonism with SWI/SNF during Epithelial-Mesenchymal Transition in Oral Cancer Cells

The Nucleosome Remodeling and Deacetylase (NURD) complex is a key regulator of cell differentiation that has also been implicated in tumorigenesis. Loss of the NURD subunit Deleted in Oral Cancer 1 (DOC1) is associated with human oral squamous cell carcinomas (OSCCs). Here, we show that restoration of DOC1 expression in OSCC cells leads to a reversal of epithelial-mesenchymal transition (EMT). This is caused by the DOC1-dependent targeting of NURD to repress key transcriptional regulators of EMT. NURD recruitment drives extensive epigenetic reprogramming, including eviction of the SWI/SNF remodeler, formation of inaccessible chromatin, H3K27 deacetylation, and binding of PRC2 and KDM1A, followed by H3K27 methylation and H3K4 demethylation. Strikingly, depletion of SWI/SNF mimics the effects of DOC1 re-expression. Our results suggest that SWI/SNF and NURD function antagonistically to control chromatin state and transcription. We propose that disturbance of this dynamic equilibrium may lead to defects in gene expression that promote oncogenesis.

Dysregulated expression of microRNAs and mRNAs in pulmonary artery remodeling in ascites syndrome in broiler chickens

Ascites syndrome (AS), also known as pulmonary artery hypertension, remains a challenging disease that severely affects both humans and broiler chickens. Pulmonary artery remodeling presents a key step in the development of AS. In this study, we obtained pulmonary artery tissues from broilers with and without AS to perform miRNA sequencing analysis, miRNA-mRNA association analysis and pathological examinations. 29 significantly differentially expressed miRNAs were found both in known and novel miRNAs with 18 up-regulated and 11 down-regulated miRNAs. Their predicted potential targets were involved in a wide range of functional clusters as indicated via GO (Gene Ontology) and KEGG (Kyoto Encyclopedia of Genes and Genomes) analyses. The upregulation of miR-155, miR-23b-3p, miR-146b-5p and miR-146b-3p were found closely associated with the pathogenesis of pulmonary artery remodeling in AS progression. The association analysis for the miRNAs-mRNAs showed that these 29 significantly differentially expressed miRNAs regulate 162 differentially expressed target genes. Among them, 20 miRNAs correlated with 18 predicted target genes that appear to be involved in pulmonary artery remodeling, mainly in three broad physiological processes: the hypoxia sensing response (HIF1α, NHE1, STAT5 and STAT3), endothelial permeability dysfunction (CD44, TRAF2, CDK2AP1, LZTFL1, JAZF1, PEBP1, LRP1B, RPS14 and THBS2) and inflammation (MEOX2, STAT5, STAT3, IRF8, MAP3K8, IL-1BETA and TNFRSF1B). Pathological pulmonary artery remodeling in the AS broilers was consistently observed in the present study. Taken together, the current analysis further illuminates the molecular mechanism of pulmonary artery remodeling underlying AS progression.

Characterization of Two Distinct Nucleosome Remodeling and Deacetylase (NuRD) Complex Assemblies in Embryonic Stem Cells

Pluripotency and self-renewal, the defining properties of embryonic stem cells, are brought about by transcriptional programs involving an intricate network of transcription factors and chromatin remodeling complexes. The Nucleosome Remodeling and Deacetylase (NuRD) complex plays a crucial and dynamic role in the regulation of stemness and differentiation. Several NuRD-associated factors have been reported but how they are organized has not been investigated in detail. Here, we have combined affinity purification and blue native polyacrylamide gel electrophoresis followed by protein identification by mass spectrometry and protein correlation profiling to characterize the topology of the NuRD complex. Our data show that in mouse embryonic stem cells the NuRD complex is present as two distinct assemblies of differing topology with different binding partners. Cell cycle regulator Cdk2ap1 and transcription factor Sall4 associate only with the higher mass NuRD assembly. We further establish that only isoform Sall4a, and not Sall4b, associates with NuRD. By contrast, Suz12, a component of the PRC2 Polycomb repressor complex, associates with the lower mass entity. In addition, we identify and validate a novel NuRD-associated protein, Wdr5, a regulatory subunit of the MLL histone methyltransferase complex, which associates with both NuRD entities. Bioinformatic analyses of published target gene sets of these chromatin binding proteins are in agreement with these structural observations. In summary, this study provides an interesting insight into mechanistic aspects of NuRD function in stem cell biology. The relevance of our work has broader implications because of the ubiquitous nature of the NuRD complex. The strategy described here can be more broadly applicable to investigate the topology of the multiple complexes an individual protein can participate in.

Methylation levels of SLC23A2 and NCOR2 genes correlate with spinal muscular atrophy severity

Spinal muscular atrophy (SMA) is a monogenic neurodegenerative disorder subdivided into four different types. Whole genome methylation analysis revealed 40 CpG sites associated with genes that are significantly differentially methylated between SMA patients and healthy individuals of the same age. To investigate the contribution of methylation changes to SMA severity, we compared the methylation level of found CpG sites, designed as "targets", as well as the nearest CpG sites in regulatory regions of ARHGAP22, CDK2AP1, CHML, NCOR2, SLC23A2 and RPL9 in three groups of SMA patients. Of notable interest, compared to type I SMA male patients, the methylation level of a target CpG site and one nearby CpG site belonging to the 5'UTR of SLC23A2 were significantly hypomethylated 19-22% in type III-IV patients. In contrast to type I SMA male patients, type III-IV patients demonstrated a 16% decrease in the methylation levels of a target CpG site, belonging to the 5'UTR of NCOR2. To conclude, this study validates the data of our previous study and confirms significant methylation changes in the SLC23A2 and NCOR2 regulatory regions correlates with SMA severity.

Cyclin-dependent kinase 2-associated protein 1 suppresses growth and tumorigenesis of lung cancer

Cyclin-dependent kinase 2-associated protein 1 (CDK2AP1), a growth suppressor that negatively regulates CDK2 activity, has been implicated in various types of cancer; yet its role in lung cancer remains unclear. In the present study, a lentivirus-based system was used to specifically downregulate or upregulate CDK2AP1 expression. A549 lung cancer cells were treated with RNAi (RNA interference) or lentiviral vectors for overexpression. Ectopic overexpression of CDK2AP1 in A549 cells in vitro greatly impaired their proliferation and colony-forming ability and enhanced their chemosensitivity to cisplatin and paclitaxel and caused cell cycle arrest at G1/S transition accompanied by the reduction of expression of CDK4 and CDK7. Injection of the ectopically CDK2AP1-overexpressing A549 cells into nude mice resulted in growth arrest of solid lung cancer tumors in vivo. Knockdown of CDK2AP1 in A549 cells, however, gave rise to the opposite effects including promoting cell proliferation/growth, cell cycling in vitro and enhancing tumorigenesis in vivo. These results suggest that CDK2AP1 plays an important role in modulating the growth and tumorigenesis of lung cancer cells and also has significant effects on the chemosensitivity of pulmonary malignancies to chemotherapeutics. Hence, this study extends our knowledge on the relationship between CDK2AP1 and oncogenesis of lung cancer, indicating that CDK2AP1 may serve as a new molecular target for future lung cancer therapy.

Genome-wide analysis shows association of epigenetic changes in regulators of Rab and Rho GTPases with spinal muscular atrophy severity

Spinal muscular atrophy (SMA) is a monogenic disorder that is subdivided into four different types and caused by survival motor neuron gene 1 (SMN1) deletion. Discordant cases of SMA suggest that there exist additional severity modifying factors, apart from the SMN2 gene copy number. Here we performed the first genome-wide methylation profiling of SMA patients and healthy individuals to study the association of DNA methylation status with the severity of the SMA phenotype. We identified strong significant differences in methylation level between SMA patients and healthy controls in CpG sites close to the genes CHML, ARHGAP22, CYTSB, CDK2AP1 and SLC23A2. Interestingly, the CHML and ARHGAP22 genes are associated with the activity of Rab and Rho GTPases, which are important regulators of vesicle formation, actin dynamics, axonogenesis, processes that could be critical for SMA development. We suggest that epigenetic modifications may influence the severity of SMA and that these novel genetic positions could prove to be valuable biomarkers for the understanding of SMA pathogenesis.