Integration of miRNA-lncRNA-mRNA profiles in liver tissue from EpCAM knockout mice

The epithelial cell adhesion molecule (EpCAM) is highly expressed in the liver during development and diseases. However, its role in the development and pathology of liver remains to be explored. The liver tissues of EpCAM-/- and wildtype (WT) mice at P0 stage were used for RNA sequencing. The differently expressed miRNAs, lncRNAs and mRNAs were selected and confirmed by qPCR. The expression of metabolism-related gene SET domain bifurcated 2 (Setdb2) was significantly increased in the liver of EpCAM-/- mice; the triglyceride (TG) and total cholesterol (TC) levels in the liver were also markedly decreased in EpCAM-/- mice. The microRNA (miRNA)-long noncoding RNA (lncRNA)-mRNA regulatory networks indicated that EpCAM may play important roles in glucose and lipid metabolism of the liver during development and in disease. The comprehensive miRNA, lncRNA and mRNA expression profiles in the developing liver of EpCAM-/- mice established here might help to elucidate functions and mechanisms of EpCAM during development and in diseases of the liver.

Structural Analysis of SMYD3 Lysine Methyltransferase for the Development of Competitive and Specific Enzyme Inhibitors

Lysine methylation is among the key posttranslational modifications to histones that contribute to epigenetic regulation. SMYD3 is a lysine methyltransferase that is essential for the proliferation of a range of tumorigenic cells. The findings that SMYD3 is significantly upregulated in most colorectal carcinomas, hepatocellular carcinomas, and breast cell carcinomas support a model in which its aberrant expression modifies established patterns of gene expression, ultimately driving unrestrained proliferation. Herein, we dissect the unique structural features of SMYD3 relative to other SET enzymes, with an emphasis on the implications for selective design of therapeutics for the clinical management of cancer. Further, we illustrate the ability of inhibitors targeting the SET domain of SMYD3 to reduce the viability of colorectal and lung carcinoma cells.

The histone methyltransferase NSD3 contributes to cohesin loading during mitotic exit

During the cell cycle, dynamic post-translational modifications modulate the association of the cohesin complex with chromatin. Phosphorylation / dephosphorylation and acetylation / deacetylation of histones and of cohesin components ensure correct establishment of cohesion during S phase and its proper dissolution during mitosis. In contrast, little is known about the contribution of methylation to the regulation of sister chromatid cohesion. We performed a RNA interference-mediated inactivation screen against 14 histone methyltransferases of the SET domain family that highlighted NSD3 as a factor essential for sister chromatid cohesion in mitosis. We established that NSD3 ensures proper level of the cohesin loader MAU2 and of cohesin itself onto chromatin at mitotic exit. Consistent with its implication in the loading of kollerin and cohesin complexes onto chromatin, we showed that NSD3 associates with chromatin in early anaphase prior to that of MAU2 and RAD21 and dissociates from chromatin upon cell's entry into prophase. Finally, we demonstrated that of the two NSD3 variant that exist in somatic cells, the long form that carries the methyltransferase activity is the one that acts in cohesion regulation. Taken together, these results describe a novel factor associated with histone methylation in cohesin loading.

The Methyltransferase Smyd1 Mediates LPS-Triggered Up-Regulation of IL-6 in Endothelial Cells

The lysine methyltransferase Smyd1 with its characteristic catalytic SET-domain is highly enriched in the embryonic heart and skeletal muscles, participating in cardiomyogenesis, sarcomere assembly and chromatin remodeling. Recently, significant Smyd1 levels were discovered in endothelial cells (ECs) that responded to inflammatory cytokines. Based on these biochemical properties, we hypothesized that Smyd1 is involved in inflammation-triggered signaling in ECs and therefore, investigated its role within the LPS-induced signaling cascade. Human endothelial cells (HUVECs and EA.hy926 cells) responded to LPS stimulation with higher intrinsic Smyd1 expression. By transfection with expression vectors containing gene inserts encoding either intact Smyd1, a catalytically inactive Smyd1-mutant or Smyd1-specific siRNAs, we show that Smyd1 contributes to LPS-triggered expression and secretion of IL-6 in EA.hy926 cells. Further molecular analysis revealed this process to be based on two signaling pathways: Smyd1 increased the activity of NF-κB and promoted the trimethylation of lysine-4 of histone-3 (H3K4me3) within the IL-6 promoter, as shown by ChIP-RT-qPCR combined with IL-6-promoter-driven luciferase reporter gene assays. In summary, our experimental analysis revealed that LPS-binding to ECs leads to the up-regulation of Smyd1 expression to transduce the signal for IL-6 up-regulation via activation of the established NF-κB pathway as well as via epigenetic trimethylation of H3K4.

Non-histone methylation of SET7/9 and its biological functions

Background: (su(var)-3-9,enhancer-of-zeste,trithorax) domain-containing protein 7/9 (SET7/9) is a member of the protein lysine methyltransferases (PLMTs or PKMTs) family. It contains a SET domain. Recent studies demonstrate that SET7/9 methylates both lysine 4 of histone 3 (H3-K4) and lysine(s) of non-histone proteins, including transcription factors, tumor suppressors, and membrane-associated receptors. Objective: This article mainly reviews the non-histone methylation effects of SET7/9 and its functions in tumorigenesis and development. Methods: PubMed was screened for this information. Results: SET7/9 plays a key regulatory role in various biological processes such as cell proliferation, transcription regulation, cell cycle, protein stability, cardiac morphogenesis, and development. In addition, SET7/9 is involved in the pathogenesis of hair loss, breast cancer progression, human carotid plaque atherosclerosis, chronic kidney disease, diabetes, obesity, ovarian cancer, prostate cancer, hepatocellular carcinoma, and pulmonary fibrosis. Conclusion: SET7/9 is an important methyltransferase, which can catalyze the methylation of a variety of proteins. Its substrates are closely related to the occurrence and development of tumors.

Spatiotemporal dynamics of SETD5-containing NCoR–HDAC3 complex determines enhancer activation for adipogenesis

Enhancer activation is essential for cell-type specific gene expression during cellular differentiation, however, how enhancers transition from a hypoacetylated “primed” state to a hyperacetylated-active state is incompletely understood. Here, we show SET domain-containing 5 (SETD5) forms a complex with NCoR-HDAC3 co-repressor that prevents histone acetylation of enhancers for two master adipogenic regulatory genes Cebpa and Pparg early during adipogenesis. The loss of SETD5 from the complex is followed by enhancer hyperacetylation. SETD5 protein levels were transiently increased and rapidly degraded prior to enhancer activation providing a mechanism for the loss of SETD5 during the transition. We show that induction of the CDC20 co-activator of the ubiquitin ligase leads to APC/C mediated degradation of SETD5 during the transition and this operates as a molecular switch that facilitates adipogenesis.

Evolution of Human-specific Alleles Protecting Cognitive Function of Grandmothers

Late-onset Alzheimers Disease (LOAD) pathology is rare in our closest living evolutionary relatives (chimpanzees), which also express much lower microglial levels of CD33(Siglec-3), a myelomonocytic receptor inhibiting innate immune reactivity by extracellular V-set domain recognition of sialic acid(Sia)-containing self-associated molecular patterns (SAMPs). We earlier showed that V-set domain-deficient CD33-variant allele, protective against LOAD, is derived and specific to hominin-lineage. We now report that CD33 also harbors multiple hominin-specific V-set domain mutations and explore selection forces that may have favored such genomic changes. N-glycolylneuraminic acid (Neu5Gc), the preferred Sia-ligand of ancestral CD33 is absent in humans, due to hominin-specific, fixed loss-of-function mutation in CMAH, which generates CMP-Neu5Gc from its precursor, CMP-N-acetylneuraminic acid (Neu5Ac). Extensive mutational analysis and MD-simulations indicate that fixed change in amino acid 21 of hominin V-set domain and conformational changes related to His45 corrected for Neu5Gc-loss by switching to Neu5Ac-recognition. Considering immune-evasive molecular mimicry of SAMPs by pathogens, we found that human-specific pathogens Neisseria gonorrhoeae and Group B Streptococcus (affecting fertility and fetuses/neonates respectively) selectively bind huCD33 and this binding is significantly impacted by amino acid 21 modification. Alongside LOAD-protective CD33 alleles, humans harbor additional, derived, population-universal, cognition-protective variants absent in great ape genomes. Interestingly, 11 of 13 SNPs in these human genes (including CD33), that protect the cognitive health of elderly populations, are not shared by genomes of archaic hominins: Neanderthals and Denisovans. Finally, we present a plausible evolutionary scenario to compile, correlate and comprehend existing knowledge about huCD33 evolution and suggest that grandmothering emerged in humans.