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Cullin 4B (CUL4B) is a component of the Cullin4B-Ring E3 ligase complex (CRL4B) that functions in proteolysis and is implicated in tumorigenesis. Here, we report that CRL4B is associated with histone methyltransferase SUV39H1, heterochromatin protein 1 (HP1) and DNA methyltransferases 3A (DNMT3A). We showed that CRL4B, through catalyzing H2AK119 monoubiquitination, facilitates H3K9 tri-methylation and DNA methylation, two key epigenetic modifications involved in DNA methylation-based gene silencing. Depletion of CUL4B resulted in loss of not only H2AK119 monoubiquitination but also H3K9 trimethylation and DNA methylation, leading to derepression of a collection of genes, including the tumor suppressor IGFBP3. We demonstrated that CUL4B promotes cell proliferation and invasion, which are consistent with a tumorigenic phenotype, at least partially by repressing IGFBP3. We found that the expression of CUL4B is markedly upregulated in samples of human cervical carcinoma and is negatively correlated with the expression of IGFBP3. Our experiments unveiled a coordinated action between histone ubiquitination/methylation and DNA methylation in transcription repression, providing a mechanism for CUL4B in tumorigenesis.

Despite that HBsAg seroclearance can significantly reduce the risk for HCC, HCC can still develop in a proportion of CHB patient after HBsAg seroclearance. Closer attention should be paid to those patients with established cirrhosis or older age than 50 years at the time of HBsAg seroclearance.

Granular cells in ameloblastoma exhibit abnormal biological behaviors, particularly synthesis and secretion of protein. Synthesis of signaling molecules is upregulated, but secretion is arrested in some cases, while both are lost in other cases.

OBJECTIVEInsulin resistance plays a part in diabetic nephropathy (DN). The association between the peroxisome proliferator–activated receptor γ Pro to Ala alteration at codon 12 (Pro12Ala) polymorphism and the risk of insulin resistance has been confirmed. The association between the polymorphism and DN risk has also been widely studied recently, but no consensus was available up to now.RESEARCH DESIGN AND METHODSA systematic search of electronic databases (MEDLINE, Embase, and China National Knowledge Infrastructure) and reference lists of relevant articles was carried out, and then 18 case-control studies involving 3,361 DN cases and 5,825 control subjects were identified.RESULTSIn the overall analysis, the Ala12 variant was observed to be significantly associated with decreased DN risk (odds ratio 0.76 [95% CI 0.61–0.93]). Some evidence of heterogeneity among the included studies was detected, which could be explained by the difference of ethnicity and stage of DN. Subgroup analyses stratified by ethnicity and stage of DN were performed, and results indicated the Pro12Ala polymorphism was associated with the risk of DN in Caucasians but no similar association was observed in Asians. Additionally, we observed that Ala12 was associated with decreased risk of albuminuria. With only a few of subjects were available, we failed to detect statistically significant association between the polymorphism and end-stage renal disease (ESRD).CONCLUSIONSOur results indicated that the Ala12 variant is a significantly protective factor for DN. Future research should focus on the effect of Pro12Ala polymorphism on ESRD and gathering data of Africans.