ABSTRACT
BACKGROUND: In multiple sclerosis (MS), the immune system acts against myelin lesions of the central nervous system, destroying neuronal fibers resulting in signal transmission disturbances in the nervous system. MicroRNAs play important roles in the post-transcriptional regulation of gene expression and in the regulation of disease activity and its response to treatment. The goal of this study was to determine the role of miR-18a-5p by comparing its expression in MS patients and healthy subjects. METHODS: RNA was isolated from blood samples of 32 MS patients and 32 healthy individuals, and miR-18a-5p expression was determined by real-time polymerase chain reaction (real-time PCR). RESULTS: miR-18a-5p expression was significantly less in MS patients than in healthy subjects. CONCLUSION: The reduction of miR-18a-5p expression may be via pathway signaling. Altered signaling plays an important role in MS pathogenesis and the miR-18a-5p expression profile in blood cells can be described as a prognostic biomarker and identifier of high-risk individuals in MS.
ABSTRACT
BACKGROUND: Acetohydroxyacid Synthase (AHAS) is the first enzyme in the biosynthesis pathway of the branched chain amino acids. AHAS is the common target site of five herbicide chemical groups: sulfonylurea, imidazolinone, triazolopyrimidine, pyrimidinyl-thiobenzoates, and sulfonyl-aminocarbonyl-triazolinone. OBJECTIVE: The purification of protein enabled us to study the physical and biochemical properties of the enzyme. In addition in vitro activity of this enzyme was tested in the presence of four different sulfonylureaherbicides and the feedback regulation of enzyme was analyzed in the presence of branched amino acids. METHODS: The gene encoding catalytic subunit of rice AHAS (cOsAHAS) without part of the chloroplast transit sequence was cloned into the bacterial expression vector pET41a and heterologously expressed in Escherichia coli as carboxy-terminal extensions of glutathione-S-transferase (GST).The soluble protein was purified using affinity chromatography. The measurement of GSTOsAHAS activity was performed under optimized conditions at present of branched-chain amino acids and sulfonylurea herbicides independently. RESULTS: The optimum pH and temperature for GST-cOsAHAS activity was 8.0 and 37 °C, respectively. The specific activity and Km value of this enzyme toward pyruvate were 0.08 U/mg and 30 mM, respectively.GST-cOsAHAS was inhibited by herbicides tribenuron, sulfosulfuron, nicosulfuron and bensulfuron while the enzyme was insensitivieto end products. CONCLUSION: These results suggest that the recombinant form of GST-cOsAHAS is functionally active and carries the binding site for sulfynylurea herbicides. Furthermore, GST-cOsAHAS was insensitive to feedback inhibition by endproducts which indicates the existence of a regulator subunit in rice AHAS as previously has been described in other plant AHASs.
