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.

Fibroblasts can be reprogrammed to induced pluripotent stem cells (iPSCs) by application of transcription factors octamer-binding protein 4 (Oct4), SRY-box containing gene 2 (Sox2), Kruppel-like factor 4 (Klf4), and c-Myelocytomatosis oncogene (c-Myc) (OSKM), but the underlying mechanisms remain unclear. Here, we report that exog-

Induced pluripotent stem (iPS) cells, especially those reprogrammed from patient somatic cells, have a great potential usage in regenerative medicine. The expression of p53 has been proven as a key barrier limiting iPS cell generation, but how p53 is regulated during cell reprogramming remains unclear. In this study, we found that the ectopic expression of miR-138 significantly improved the efficiency of iPS cell generation via Oct4, Sox2, and Klf4, with or without c-Myc (named as OSKM or OSK, respectively), without sacrificing the pluripotent characteristics of the generated iPS cells. Exploration of the mechanism showed that miR-138 directly targeted the 3 0 untranslated region (UTR) of p53, significantly decreasing the expression of p53 and its downstream genes. Furthermore, the ectopic expression of p53 having a mutant 3 0 -UTR, which cannot be bound by miR-138, seriously impaired the effect of miR-138 on p53 signaling and OSKM-initiated somatic cell reprogramming. Combined with the fact that miR-138 is endogenously expressed in fibroblasts, iPS cells, and embryonic stem cells, our study demonstrated that regulation of the p53 signaling pathway and promotion of iPS cell generation represent an unrevealed important function of

Sin3a is a core component of histone-deacetylation-activity-associated transcriptional repressor complex, playing important roles in early embryo development. Here, we reported that down-regulation of Sin3a led to the loss of embryonic stem cell (ESC) self-renewal and skewed differentiation into mesendoderm lineage. We found that Sin3a functioned as a transcriptional coactivator of the critical Nodal antagonist Lefty1 through interacting with Tet1 to de-methylate the Lefty1 promoter. Further studies showed that two amino acid residues (Phe147, Phe182) in the PAH1 domain of Sin3a are essential for Sin3a–Tet1 interaction and its activity in regulating pluripotency. Furthermore, genome-wide analyses of Sin3a, Tet1 and Pol II ChIP-seq and of 5mC MeDIP-seq revealed that Sin3a acted with Tet1 to facilitate the transcription of a set of their co-target genes. These results link Sin3a to epigenetic DNA modifications in transcriptional activation and have implications for understanding mechanisms underlying versatile functions of Sin3a in mouse ESCs.

Histone deacetylase 10 (HDAC10) is a member of the class II HDACs, and its role in cancer is emerging. In this study, we found that HDAC10 is highly expressed in lung cancer tissues. It resides mainly in the cytoplasm of lung cancer cells but resides in the nucleus of adjacent normal cells. Further examinations revealed that HDAC10 resides in the cytoplasm in multiple lung cancer cell lines, including the A549, H358 and H460 cell lines, but mainly resides in the nucleus of normal lung epithelial 16HBE cells. A leucine-rich motif, R505L506L507C508V509A510L511, was identified as its nuclear localization signal (NLS), and a mutant (Mut-505-511) featuring mutations to A at each of its original R and L positions was found to be nuclear-localization defective. Functional analysis revealed that HDAC10 promoted lung cancer cell growth and that its knockdown induced cell cycle arrest and apoptosis. Mechanistic studies showed that HDAC10 knockdown significantly decreased the phosphorylation of AKT at Ser473 and that AKT expression significantly rescued the cell cycle arrest and apoptosis elicited by HDAC10 knockdown. A co-immunoprecipitation assay suggested that HDAC10 interacts with AKT and that inhibition of HDAC10 activity decreases its interaction with and phosphorylation of AKT. Finally, we confirmed that HDAC10 promoted lung cancer proliferation in a mouse model. Our study demonstrated that HDAC10 localizes and functions in the cytoplasm of lung cancer cells, thereby underscoring its potential role in the diagnosis and treatment of lung cancer.

No abstract

Clarifying the regulatory mechanisms of embryonic stem cell (ESC) neural differentiation is helpful not only for understanding neural development but also for obtaining high-quality neural progenitor cells required by stem cell therapy of neurodegenerative diseases. Here, we found that long noncoding RNA 1604 (lncRNA-1604) was highly expressed in cytoplasm during neural differentiation, and knockdown of lncRNA-1604 significantly repressed neural differentiation of mouse ESCs both in vitro and in vivo. Bioinformatics prediction and mechanistic analysis revealed that lncRNA-1604 functioned as a novel competing endogenous RNA of miR-200c and regulated the core transcription factors ZEB1 and ZEB2 during neural differentiation. Furthermore, we also demonstrated the critical role of miR-200c and ZEB1/2 in mouse neural differentiation. Either introduction of miR-200c sponge or overexpression of ZEB1/2 significantly reversed the lncRNA-1604 knockdown-induced repression of mouse ESC neural differentiation. Collectively, these findings not only identified a previously unknown role of lncRNA-1604 and ZEB1/2 but also elucidated a new regulatory lncRNA-1604/miR-200c/ZEB axis in neural differentiation. Stem Cells 2018;36:325-336.

Angiogenesis is crucially involved in many physiological and pathological processes including tumor growth, but the molecular mechanisms regulating angiogenesis are incompletely understood. In this study, we investigated the functions and mechanism of histone deacetylase 10 (HDAC10), a member of the HDAC II family, in regulation of angiogenesis. HDAC10 overexpression in human umbilical vein endothelial cells (HUVECs) promoted tube formation, whereas depletion of HDAC10 from HUVECs inhibited tube formation in vitro and in vivo. Mechanistically, HDAC10 overexpression increased extracellular-regulated kinase 1/2 (ERK1/2) activation, whereas depletion of HDAC10 inhibited ERK1/2 activation. Finally, HDAC10 promoted ERK1/2 phosphorylation by deacetylating the promoter of protein tyrosine phosphatase, non-receptor type 22 (PTPN22) and inhibiting the expression of PTPN22, which is a negative regulator of ERK phosphorylation. Collectively, our results identify HDAC10 as a key regulator of angiogenesis and reveal that HDAC10 functions in this process by binding and deacetylating the PTPN22 promoter and subsequently inhibiting PTPN22 expression, which in turn increases ERK1/2 phosphorylation. Our studies suggest that HDAC10 is a potential target for therapeutic intervention to inhibit angiogenesis and tumor growth.