The microRNA miR-17-3p inhibits mouse cardiac fibroblast senescence by targeting Par4.

The microRNA miR-17-92 cluster plays a fundamental role in heart development. The aim of this study was to investigate the effect of a member of this cluster, miR-17, on cardiac senescence. We examined the roles of miR-17 in senescence and demonstrated that miR-17-3p attenuates cardiac aging in the myocardium by targeting Par4 (also known as PAWR). This upregulates the downstream proteins CEBPB, FAK, N-cadherin, vimentin, Oct4 and Sca-1 (also known as stem cell antigen-1), and downregulates E-cadherin. Par4 has been reported as a tumor suppressor gene that induces apoptosis in cancer cells, but not in normal cells. Repression of Par4 by miR-17-3p enhances the transcription of CEBPB and FAK, which promotes mouse cardiac fibroblast (MCF) epithelial-to-mesenchymal transition (EMT) and self-renewal, resulting in cellular senescence and apoptosis resistance. We conclude that Par4 can bind to the CEBPB promoter and inhibit its transcription. Decreased Par4 expression increases the amount of CEBPB, which binds to the FAK promoter and enhances FAK transcription. Par4, CEBPB and FAK form a senescence signaling pathway, playing roles in modulating cell survival, growth, apoptosis, EMT and self-renewal. Through this novel senescence signaling axis, miR-17-3p represses Par4 expression, acting pleiotropically as a negative modulator of cardiac aging and cardiac fibroblast cellular senescence.

Noncoding RNAs in Tumor Angiogenesis.

Solid tumors require angiogenesis to grow beyond 2 mm in size. In most cases, tumor cells undergo angiogenic switch and secrete substances that are required for generation of new capillary sprouting from existing blood vessels. Tumor angiogenesis is driven by a complex interplay between pro-angiogenic (VEGF/VEGFR, PDGF/PDGFR) and anti-angiogenic factors (TSP-1/TSP-2) within the tumor microenvironment. In addition, control of tissue remodeling and degradation by matrix metalloproteinases (MMPs) and tissue inhibitor of metalloproteinases (TIMPs) contribute to tumor angiogenesis. Furthermore, tumor suppressors or oncogenes that control cellular motility and maintain or promote hypoxia (HIFs and MYC) are also actively playing roles in tumor angiogenesis. Noncoding RNAs (ncRNAs), including microRNAs, are a novel class of regulatory molecules that control the gene expression in a posttranscriptional manner. MicroRNAs regulate important physiological processes, such as proliferation, apoptosis, and differentiation, as well as pathological conditions including oncogenesis. Accumulating evidence suggests that microRNAs directly modulate the process of angiogenesis by targeting important angiogenic factors and signaling molecules. Understanding the molecular mechanism behind the regulation of angiogenesis by microRNAs is important due to their therapeutic potential which may lead to improving outcome for cancer patients. Besides, ncRNAs with a regulatory role in angiogenesis, such as long noncoding RNAs (lncRNAs), have been identified in the genome. However, the mechanisms of the vast majority of lncRNAs are currently unknown. For the few lncRNAs characterized at the functional level, accumulating evidence shows that they play important roles in malignant diseases. The function and mechanism in angiogenesis will be described in this chapter.

Anti-microRNA-378a enhances wound healing process by upregulating integrin beta-3 and vimentin.

Delayed or impaired wound healing is a major public health issue worldwide, especially in patients with diabetes mellitus and vascular atherosclerosis. MicroRNAs have been identified as key regulators of wound healing. Here, we show that miR-Pirate378a transgenic mice (and thus have inhibited miR-378a-5p function) display enhanced wound healing. Expression of vimentin and ß3 integrin, two important modulators of wound healing, is markedly elevated in the transgenic mice. MiR-Pirate378a-transfected cells display greater mobility during migration assays, which was hypothesized to be due to the upregulation of vimentin and ß3 integrin. Both molecules were confirmed to be targets of miR-378a, and thus their expression could be rescued by miR-Pirate378a. Overexpression of vimentin also contributed to fibroblast differentiation, and upregulation of ß3 integrin was responsible for increased angiogenesis. Mice treatment with miR-Pirate378a-conjugated nanoparticles displayed enhanced wound healing. Thus, we have demonstrated that knockdown of miR-378a increased the expression of its target proteins, vimentin, and ß3 integrin, which accelerated fibroblast migration and differentiation in vitro and enhanced wound healing in vivo.

A circular RNA promotes tumorigenesis by inducing c-myc nuclear translocation.

Circular RNAs (circRNAs) are a subclass of noncoding RNAs widely expressed in mammalian cells. We report here the tumorigenic capacity of a circRNA derived from angiomotin-like1 (circ-Amotl1). Circ-Amotl1 is highly expressed in patient tumor samples and cancer cell lines. Single-cell inoculations using circ-Amotl1-transfected tumor cells showed a 30-fold increase in proliferative capacity relative to control. Agarose colony-formation assays similarly revealed a 142-fold increase. Tumor-take rate in nude mouse xenografts using 6-day (219 cells) and 3-day (9 cells) colonies were 100%, suggesting tumor-forming potential of every cell. Subcutaneous single-cell injections led to the formation of palpable tumors in 41% of mice, with tumor sizes >1 cm3 in 1 month. We further found that this potent tumorigenicity was triggered through interactions between circ-Amotl1 and c-myc. A putative binding site was identified in silico and tested experimentally. Ectopic expression of circ-Amotl1 increased retention of nuclear c-myc, appearing to promote c-myc stability and upregulate c-myc targets. Expression of circ-Amotl1 also increased the affinity of c-myc binding to a number of promoters. Our study therefore reveals a novel function of circRNAs in tumorigenesis, and this subclass of noncoding RNAs may represent a potential target in cancer therapy.

Homozygosity mapping in an anophthalmic pedigree provides evidence of additional genetic heterogeneity.

PURPOSE: Anophthalmia is a heterogeneous developmental disorder characterized by absent eyes whose diverse etiology encompasses chromosomal and monogenic aberrations, as well as environmental causes. Since the molecular basis has been defined in only a small proportion of cases and extending this offers potential to enhance understanding of key steps in ocular development, a consanguineous anophthalmic pedigree was investigated using homozygosity mapping. METHODS: DNA samples from six individuals, two anophthalmic, were genotyped with an array featuring approximately 620,000 single nucleotide polymorphisms (SNPs) in order to identify homozygous or copy number variant (CNV) regions. Candidate genes located in regions of identity by descent (IBD) defined by homozygosity mapping were subsequently screened by direct sequencing. RESULTS: Genotyping identified five homozygous intervals (4q26-28.1, 13q12.11, 14q22.1-22.2, 15q26.2-26.3 and 19q13.12) larger than 1 Mb that do not correspond with the known loci and which contain a total of 205 annotated genes. No CNVs were identified that segregated with the disease phenotype, and sequencing of five candidate genes (PRDM5, FGF2, SOS2, POU2F2 and CIC) did not identify any mutations. CONCLUSIONS: Although constrained by the pedigree's size, the homozygosity mapping approach employed in this study extends the locus heterogeneity of anophthalmia. The results indicate that a novel molecular cause remains to be determined in this pedigree with the causative gene likely located within one of the five IBD regions.