AF10 (MLLT10) prevents somatic cell reprogramming through regulation of DOT1L-mediated H3K79 methylation.

BACKGROUND: The histone H3 lysine 79 (H3K79) methyltransferase DOT1L is a key chromatin-based barrier to somatic cell reprogramming. However, the mechanisms by which DOT1L safeguards cell identity and somatic-specific transcriptional programs remain unknown. RESULTS: We employed a proteomic approach using proximity-based labeling to identify DOT1L-interacting proteins and investigated their effects on reprogramming. Among DOT1L interactors, suppression of AF10 (MLLT10) via RNA interference or CRISPR/Cas9, significantly increases reprogramming efficiency. In somatic cells and induced pluripotent stem cells (iPSCs) higher order H3K79 methylation is dependent on AF10 expression. In AF10 knock-out cells, re-expression wild-type AF10, but not a DOT1L binding-impaired mutant, rescues overall H3K79 methylation and reduces reprogramming efficiency. Transcriptomic analyses during reprogramming show that AF10 suppression results in downregulation of fibroblast-specific genes and accelerates the activation of pluripotency-associated genes. CONCLUSIONS: Our findings establish AF10 as a novel barrier to reprogramming by regulating H3K79 methylation and thereby sheds light on the mechanism by which cell identity is maintained in somatic cells.

Gene variants of TCF7L2 are histopathologically important in colorectal cancers but do not have direct association with MYC expression.

Rapidly accumulating preclinical and clinical studies have helped us to unveil underlying mechanisms of colorectal cancer development and progression. Deregulated signaling pathways play instrumental role in carcinogenesis, drug resistance and metastasis. Wnt signaling cascade has attracted considerable attention in colorectal cancer as many ground-breaking researches have highlighted central role of Wnt pathway in pathogenesis of colorectal cancer. T-Cell Transcription Factors (TCFs) have been shown to work synchronously with ß-catenin to fuel colorectal cancer development and progression. Chromatin immuno-precipitation coupled with high-throughput sequencing (ChIP-Seq) data sets has deepened our knowledge about critical role of risk-associated SNPs. Increasingly it is being reported that many risk-associated SNPs are located within binding sites for transcription factors and consequently risk status of these SNPs may modify binding pattern of transcriptional factors and thus rewire the transcriptional regulation. DNA was extracted from peripheral blood samples of 117 colorectal cancer patients and 127 healthy subjects. TCF7L2 variants (rs6983267, rs7903146) were examined by the PCR-RFLP method. Tumor and the surrounding tissues were dissected from 37 CRC patients and RNA isolation was performed. The gene expression of c-myc was determined by RT-PCR. T allele carriage of rs6983267 variant was found to be associated with CRC (p=0.042). TT genotype of rs7903146 was associated with late tumor stage (T3+T4) (p=0.037) and presence of mucinous component (p=0.031). TTCT haplotype was found to be statistically higher in CRC compared to the control group (p=0.007). There was no statistically significant difference in c-myc gene expression. TCF7L2 gene variants may play an important role in histopathologic aspects associated with CRC and it is independent of c-myc gene expression.

Proteomics in Cell Division.

Cell division requires a coordinated action of the cell cycle machinery, cytoskeletal elements, chromosomes, and membranes. Cell division studies have greatly benefitted from the mass spectrometry (MS)-based proteomic approaches for probing the biochemistry of highly dynamic complexes and their coordination with each other as a cell progresses into division. In this review, the authors first summarize a wide-range of proteomic studies that focus on the identification of sub-cellular components/protein complexes of the cell division machinery including kinetochores, mitotic spindle, midzone, and centrosomes. The authors also highlight MS-based large-scale analyses of the cellular components that are largely understudied during cell division such as the cell surface and lipids. Then, the authors focus on posttranslational modification analyses, especially phosphorylation and the resulting crosstalk with other modifications as a cell undergoes cell division. Combining proteomic approaches that probe the biochemistry of cell division components with functional genomic assays will lead to breakthroughs toward a systems-level understanding of cell division.

Expression of miR-373 and its predicted target genes E-cadherin and CD44 in patients with laryngeal squamous cell carcinoma.

Laryngeal squamous cell carcinoma (LSCC) is a genomically complex disease that is difficult to target, and efforts have been made to identify new treatment strategies and   molecular markers that might stratify patients and individualize options for treatment. miR-373 has diametrically opposed roles in different stages and types of cancers. miR-373 has been suggested to quantitatively control E-cadherin and CD44 expression. We studied the expression of miR-373, E-cadherin and CD44 in laryngeal squamous cell carcinoma and evaluated the association between the disease and clinical characteristics of patients. Tumor tissues were collected from 24 laryngeal cancer patients. Adjacent normal tissue samples were also obtained as controls. After RNA isolation, we assessed the miR-373, E-cadherin and CD44 levels. As endogenous controls, we used the small RNA U6 and GAPDH TaqMan® to normalize the levels of expression of miR-373, E-cadherin and CD44. The fold change in the expression of the genes in larynx tumor and control tissues was calculated using the 2-ΔΔCT method. miR-373 was significantly upregulated in seventeen tumor samples compared to controls. However, the expression levels of both E-cadherin and CD44 mRNA were found to be significantly downregulated in tumor versus control regions (p=0.026 and p=0.005, respectively). We did not find any significant difference in the expression levels of miR-373, E-cadherin or CD44 and cancer risk factors. miR-373, E-cadherin and CD44 may be involved in the etiopathogenesis of laryngeal cancer. It can be suggested that E-cadherin and CD44 are functional targets of miR-373, but we need further studies to investigate this hypothesis.