Question

“Disease-specific serum miRNA profiles may serve as biomarkers and might reveal potential new avenues for therapy. An HBV-specific serum miRNA profile associated with HBV surface antigen (HBsAg) particles has recently been reported, and AGO2 and miRNAs have been shown to be stably associated with HBsAg in serum. We identified HBV-associated serum miRNAs using the Toray 3D array system in 10 healthy controls and 10 patients with chronic hepatitis B virus (HBV) infection. 19 selected miRNAs were then measured by quantitative RT-PCR in 248 chronic HBV patients and 22 healthy controls. MiRNA expression in serum versus liver tissue was also compared using biopsy samples. To examine the role of AGO2 during the HBV life cycle, we analyzed intracellular co-localization of AGO2 and HBV core (HBcAg) and surface (HBsAg) antigens using immunocytochemistry and proximity ligation assays in stably transfected HepG2 cells. The effect of AGO2 ablation on viral replication was assessed using siRNA. Several miRNAs, including miR-122, miR-22, and miR-99a, were up-regulated at least 1.5 fold (P<2E-08) in serum of HBV-infected patients. AGO2 and HBcAg were found to physically interact and co-localize in the ER and other subcellular compartments. HBs was also found to co-localize with AGO2 and was detected in multiple subcellular compartments. Conversely, HBx localized non-specifically in the nucleus and cytoplasm, and no interaction between AGO2 and HBx was detected. SiRNA ablation of AGO2 suppressed production of HBV DNA and HBs antigen in the supernatant.”

https://www.ncbi.nlm.nih.gov/pubmed/23091627

1. What are miRNAs and how could they be used as biomarkers for disease?   

Answer 1

miRNA are also called MicroRNA and is a class of small noncoding RNA which have many important regulaory role in post transcriptional protein level regulation. They also hhave regulatory functions like cell differentiation, cellular processes etc. Hence expression of these miRNA due to regulatory function; important in early detection of disease. The expression level changes when there is a disease. According to change in expression level disease are detected early. Some miRNW are most common assiciated with Cancer and also able to detect type of cancer. Prostate cancer is also may detected and disease other than Alzeimer disease may also diagnosed by expression of miRNA in Cerebrospinal fluid. The mist important characteristics of miRNA is that these are present in biofluids like blood, lymph etc.