The Function Of ABC Transporter Rv1273c-Rv1272c And The Role Of MicroRNAs In Diagnosis Of Tuberculosis

PART 1 THE FUNCTION OF RV1273 C AND RV1272 C IN MYCOBACTERIUM TUBERCULOSISMycobacterium tuberculosis, an intracellular bacterium, mainly lives in the phagosome of the macrophage. It competitively uptakes nutrients within the host to maintain its survival. Thus, the ATP-binding cassette transporters involved in the process mentioned above are essential for its pathogenicity. It has been reported that there are thirty-eight ATP-binding cassette transporters encoded by the genome of M. tuberculosis. This sort of proteins facilitates the transport of various substrates ranging from ions, sugars, amino acids, oligopeptides, etc. Among them, Rv1273 c and Rv1272 c have been predicted to be an ABC transporter in the plasma membrane of M. tuberculosis. Rv1273 c was detected seven times higher in abundance in the membrane of M. tuberculosis H37 Rv than H37 Ra. Rv1272 c was proved to be one of the genes essential for the intracellular survival during infection in mice. All above indicate that Rv1273 c and Rv1272 c are closely related to the virulence of M. tuberculosis. However, the function of them remains unknown. In the present work, we overexpressed Rv1273 c and Rv1272 c in Mycobacterium smegmatis mc2155 and detected the accumulation rates of EB in cells, thus proved that it was an importer. We also knocked out their homologous genes, MSMEG₅008 and MSMEG₅009, and evaluated the growth of the mutant strain in different cultural conditions in vitro. The results indicated their essential roles in growth in poor nutritional environment and their potential roles in Zn2+ and Cu2+ transportation. Our findings enrich the knowledge of ATP-binding cassette transporters and their relation to virulence in M. tuberculosis, thus providing scientific basis for the treatment of tuberculosis and the development of new vaccine.PART 2 THE ROLE OF MICRORNAS IN DIAGNOSIS OF TUBERCULOSISNowadays tuberculosis remains a major health threaten worldwide, which makes the understand of its pathogenesis and diagnosis in early-stage essential for reducing the incidence, prevalence and mortality of tuberculosis. However, current diagnostic techniques have failed to meet the requirement of early, rapid, accurate detection of tuberculosis. Micro RNAs are small non-coding RNAs playing essential regulative roles in a various of physiological and pathophysiological processes. Since the introduction of microarray technology detecting micro RNAs, it has been widely applied to explore mechanisms behind different physiological and pathophysiological processes and to distinguish patients from healthy population. More importantly, recent studies have further broaden our knowledge of regarding micro RNAs as biomarkers of tuberculosis. Although microarray technology has a widespread application in studies on functional genomics, microarray-based findings are considered to be not reproducible due to the limited sample size as well as improper data analysis. This makes the meta-analysis which is capable to combine information from multiple studies a reasonable approach to increase the reliability of the results. For meta-analysis having such an advantage, we pooled a number of micro RNA expression datasets from studies on tuberculosis with either other infectious diseases or malignancies and subjected them to meta-analysis. As a result, most of the meta-signatures have been proved their regulative roles in immune response and metabolic alteration, indicating their biological significance in tuberculosis pathogenesis. Results of hierarchical clustering showed clear distinction between tuberculosis patients and healthy population, patients of other infectious diseases as well as malignancies, suggesting their potential capability for tuberculosis diagnosis. Taken together, the present work provide the theoretical basis for application of micro RNAs to diagnosis of tuberculosis.