Regulatory interaction of HNF1-alpha to microRNA-194 gene during intestinal epithelial cell differentiation.
ABSTRACT Maintenance of intestinal epithelium is based on well-balanced molecular mechanisms that confer the stable and continuous supply of specialized epithelial cell lineages from multipotent progenitors. Lineage commitment decisions in intestinal epithelium system involve multiple regulatory systems that interplay each other to establish the cellular identities. Here, we demonstrate that the microRNA system could be involved in intestinal epithelial cell differentiation and that microRNA-194 (miR194) is highly induced during this process and controlled by a transcription factor, HNF-alpha, that is well known to regulate gene expression in intestinal epithelial cells. Thus, the 5' conserved genomic region of miR-1942 gene, the inducible class of miR-194 parental gene, contains a binding motif for HNF1-alpha. This consensus region is required for the transcription of miR-1942 and active in intestinal epithelial cell line, Caco-2, in-vivo. Our observations indicate that microRNA genes could be targets of lineage specific transcription factors and that microRNAs are regulated in intestinal epithelial cells in a tissue specific manner. Given that role of microRNA in fine tuning of gene expression patterns, our results suggest that HNF1-alpha regulates the gene expression program by not only direct activation of genes but also modulation through induction of microRNAs such as miR-194, in intestinal epithelial cells. This represents a novel molecular machinery that might specify the fates of intestinal epithelial cell lineages during their differentiation.
- SourceAvailable from: Yan-Hong Han[Show abstract] [Hide abstract]
ABSTRACT: Epithelial barrier dysfunction during HIV infection has largely been attributed to the rapid and severe depletion of CD4 T cells in the gastrointestinal (GI) tract. Although it is known that changes in mucosal gene expression contribute to intestinal enteropathy, the role of small non-coding RNAs, specifically microRNA (miRNA), has not been investigated. Using the simian immunodeficiency virus (SIV) infected non-human primate model of HIV pathogenesis, we investigated the effect of viral infection on the miRNA expression in the intestinal mucosa. SIV infection led to a striking decrease in the expression of mucosal miRNAs compared to uninfected controls. This decrease coincided with an increase in 5'-3'-exoribonuclease 2 protein and alterations in DICER1 and Argonaute 2 expression. Targets of depleted miRNA belonged to molecular pathways involved in epithelial proliferation, differentiation, and immune response. Decreased expression of several miRNA involved in maintaining epithelial homeostasis in the gut was localized to the proliferative crypt region of the intestinal epithelium. Our findings suggest that SIV induced decreased expression of miRNAs involved in epithelial homeostasis, disrupted expression of miRNA biogenesis machinery, and increased expression XRN2 are involved in the development of epithelial barrier dysfunction and gastroenteropathy. MicroRNA (miRNA) regulate the development and function of intestinal epithelial cells and many viruses disrupt normal host miRNA expression. In this study, we demonstrate that SIV and HIV disrupt expression of miRNA in the small intestine during infection. The depletion of several key miRNA is localized to proliferative crypt region of the gut epithelium. These miRNA are known to control expression of genes involved in inflammation, cell death and epithelial maturation. Our data indicate that this disruption might be caused by altered expression of miRNA biogenesis machinery during infection. These findings suggest that the disruption of miRNA in the small intestine likely plays a role in intestinal enteropathy during HIV infection.Journal of Virology 03/2014; · 4.65 Impact Factor
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ABSTRACT: Studies have shown that miR-194 functions as a tumor suppressor and is associated with tumor growth and metastasis. We studied the effects of miR-194 in osteosarcoma and the possible mechanism by which miR-194 affected the survival, apoptosis and metastasis of osteosarcoma. Both human osteosarcoma cell lines SOSP-9607 and U2-OS were transfected with recombinant lentiviruses to regulate miR-194 expression. Overexpression of miR-194 partially inhibited the proliferation, migration, and invasion of osteosarcoma cells in vitro, as well as tumor growth and pulmonary metastasis of osteosarcoma cells in vivo. Potential miR-194 target genes were predicted using bioinformatics. Luciferase reporter assay, real-time quantitative PCR and western blotting confirmed that CDH2 (N-cadherin) and IGF1R were targets of miR-194. Using real-time quantitative PCR, we evaluated the expression of miR-194 and two miR-194 target genes, CDH2 and IGF1R in osteosarcoma samples from 107 patients and 99 formalin- or paraformalin-fixed paraffin-embedded tissues. The expressions of the target genes were also examined in osteosarcoma samples using immunohistochemistry. Overexpression of miR-194 inhibited tumor growth and metastasis of osteosarcoma probably by downregulating CDH2 and IGF1R. miR-194 may prove to be a promising therapeutic agent for osteosarcoma.International journal of oncology. 07/2014;
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ABSTRACT: Recent studies have increasingly linked microRNAs to colorectal cancer (CRC). MiR-194 has been reported deregulated in different tumor types, whereas the function of miR-194 in CRC largely remains unexplored. Here we investigated the biological effects, mechanisms and clinical significance of miR-194. Functional assay revealed that overexpression of miR-194 inhibited CRC cell viability and invasion in vitro and suppressed CRC xenograft tumor growth in vivo. Conversely, block of miR-194 in APC(Min/+) mice promoted tumor growth. Furthermore, miR-194 reduced the expression of AKT2 both in vitro and in vivo. Clinically, the expression of miR-194 gradually decreased from 20 normal colorectal mucosa (N-N) cases through 40 colorectal adenomas (CRA) cases and then to 40 CRC cases, and was negatively correlated with AKT2 and pAKT2 expression. Furthermore, expression of miR-194 in stool samples was gradually decreased from 20 healthy cases, 20 CRA cases, then to 28 CRC cases. Low expression of miR-194 in CRC tissues was associated with large tumor size (P=0.006), lymph node metastasis (P=0.012) and shorter survival (HR =2.349, 95% CI = 1.242 to 4.442; P=0.009). In conclusion, our data indicated that miR-194 acted as a tumor suppressor in the colorectal carcinogenesis via targeting PDK1/AKT2/XIAP pathway, and could be a significant diagnostic and prognostic biomarker for CRC.Theranostics 01/2014; 4(12):1193-208. · 7.83 Impact Factor