Previous studies have revealed the critical roles of N6-methyladenosine (m6A) modification of mRNA in embryonic stem cells (ESCs), but the biological function of m6A in large intergenic noncoding RNA (lincRNA) is unknown. Here, we showed that the internal m6A modification of linc1281 mediates a competing endogenous RNA (ceRNA) model to regulate mouse ESC (mESC) differentiation. We demonstrated that loss of linc1281 compromises mESC differentiation and that m6A is highly enriched within linc1281 transcripts. Linc1281 with RRACU m6A sequence motifs, but not an m6A-deficient mutant, restored the phenotype in linc1281-depleted mESCs. Mechanistic analyses revealed that linc1281 ensures mESC identity by sequestering pluripotency-related let-7 family microRNAs (miRNAs), and this RNA-RNA interaction is m6A dependent. Collectively, these findings elucidated the functional roles of linc1281 and its m6A modification in mESCs and identified a novel RNA regulatory mechanism, providing a basis for further exploration of broad RNA epigenetic regulatory patterns.

In recent years, increasing evidence has suggested a strong association between diabetes mellitus (DM) and hepatocellular carcinoma (HCC). To provide a quantitative assessment of this association, we performed a systematic review and metaanalysis of cohort studies. We collected studies through a literature search of Medline from January 1, 1966 and EMBASE from January 1, 1974, through July 31, 2010. Summary relative risks (SRRs) with their corresponding 95% confidence intervals (CIs) were calculated using a random-effects model. A total of 25 cohort studies that met our inclusion and exclusion criteria were included in our analysis. Among these, 18 studies showed that DM was associated with an increased incidence of HCC (SRRs 5 2.01, 95% CI: 1.61-2.51), compared with individuals without DM. There was a statistically significant heterogeneity among these studies (Q 5 136.68, p < 0.001, I 2 5 87.6%). Analyses subgrouped by controlling confounders revealed that the increased incidence of HCC was independent of geographic location, alcohol consumption, history of cirrhosis, or infections with hepatitis B (HBV) or hepatitis C virus (HCV). In addition, DM was also positively associated with HCC mortality (SRR 5 1.56; 95% CI: 1.30-1.87), with no significant evidence of heterogeneity among studies (Q 5 1.16, p 5 0.56, I 2 50%). There were no significant publication bias (p 5 0.79 for Egger's regression asymmetry test). These findings strongly support a positive association between DM and increased risk of HCC in both males and females.Hepatocellular carcinoma (HCC) is one of the most prevalent tumor types, with increased incidence and mortality in recent years. Annually, approximately 500,000 new cases are diagnosed worldwide and a nearly equivalent number die of this disease. Chronic infection with hepatitis B (HBV) or hepatitis C virus (HCV) has been considered the most important etiologic risk factors for human HCC. 1 In addition, excessive alcohol consumption, cigarette smoking, and environmental exposure to aflatoxin are also risk factors for HCC development. 2 However, many individuals who have been exposed to these risk factors never develop HCC, while 15-50% of cases occur among those without exposure. 3 Coinciding with increased HCC incidence, the prevalence of DM has also grown markedly over the past two decades in most countries. 4,5 In recent years, DM has become highly suspect as a risk factor for several malignancies, including cancers of the breast, 6 endometrium, 7 pancreas, 8 and liver. 9 A systematic review and meta-analysis of 26 studies (13 case-control and 13 cohort) conducted in 2005 showed that individuals with DM had a 2.5-fold greater risk of HCC [pooled odds ratio in caseÀcontrol studies ¼ 2.5; 95% confidence interval (CI): 1.8-3.5; pooled relative risk (RR) in cohort studies ¼ 2.5; 95% CI: 1.9-3.2] compared to controls. This significant association between diabetes and HCC was independent of alcohol consumption or hepatitis viral infections. 9 Since then, other relevant studies on the associat...

It has been reported that SARS-CoV-2 may use ACE2 as a receptor to gain entry into human cells, in a way similar to that of SARS-CoV. Analyzing the distribution and expression level of ACE2 may therefore help reveal underlying mechanisms of viral susceptibility and post-infection modulation. In this study, we utilized previously uploaded information on ACE2 expression in various conditions including SARS-CoA to evaluate the role of ACE2 in SARS-CoV and extrapolate that to COVID-19. We found that the expression of ACE2 in healthy populations and patients with underlying diseases was not significantly different. However, based on the elevated expression of ACE2 in cigarette smokers, we speculate that long-term smoking may be a risk factor for COVID-19. Analysis of ACE2 in SARS-CoV infected cells suggests that ACE2 is not only a receptor but is also involved in post-infection regulation, including immune response, cytokine secretion, and viral genome replication. Moreover, we constructed Protein-protein interaction (PPI) networks and identified hub genes in viral activity and cytokine secretion. Our findings may help clinicians and researchers gain more insight into the pathogenesis of SARS-CoV-2 and design therapeutic strategies for COVID-19.