title: Regulation of serum-responsive transmembrane kinase EhTMKB1-9 by an unsaturated lipid, oleic acid in protistan parasite Entamoeba histolytica.
abstract: Transmembrane kinases of Entamoeba histolytica are known to play a wide range of roles from virulence, phagocytosis, and proliferation to stress response. Transmembrane kinase EhTMKB1-9 is thought to be involved in early proliferative response and it was originally identified as a serum inducible gene. Ability to stimulate EhTMKB1 expression of serum starved cells resides in unsaturated fatty acids associated with albumin fraction of serum and the mechanism of stimulation follows activation of EhTMKB1-9 promoter. Gel shift assay showed the presence of proteins that bind to the specific site of EhTMKB1-9 upstream region and the concentration of these protein(s) go down on serum starvation, but level of binding protein(s) go up on serum or fatty acid replenishment. This increase in concentration of binding molecule(s) is due to new synthesis rather than activation of existing molecule(s) as a protein synthesis inhibitor blocked enhanced level of gel shifted material on replenishment. The stimulating activity resides in the fatty acyl chain, but not in the head group. Moreover, the fatty acid initiates signaling through class I PI3 kinases that result in activation of EhTMKB1-9 expression. These results suggest a novel mechanism of gene regulation in E. histolytica, and unsaturated fatty acids as potential new signaling molecules.
authors.affiliation: School of Life Sciences, Jawaharlal Nehru University, New Delhi, India.
authors.forename: Arpita
authors.initials: A
authors.lastname: Saha
authors.affiliation: School of Environmental Sciences, Jawaharlal Nehru University, New Delhi, India.
authors.forename: Sudha
authors.initials: S
authors.lastname: Bhattacharya
authors.affiliation: School of Life Sciences, Jawaharlal Nehru University, New Delhi, India. Electronic address: alok.bhattacharya@gmail.com.
authors.forename: Alok
authors.initials: A
authors.lastname: Bhattacharya
mesh_terms: D004748:Entamoeba histolytica / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D004749:Entamoebiasis / Q000097:blood / Q000469:parasitology*; D005227:Fatty Acids / Q000378:metabolism; D015971:Gene Expression Regulation, Enzymologic; D019301:Oleic Acid / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases / Q000235:genetics / Q000378:metabolism; D011401:Promoter Regions, Genetic; D011485:Protein Binding; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D015800:Protozoan Proteins / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction
chemical_list: D005227:Fatty Acids; D015800:Protozoan Proteins; D019301:Oleic Acid; D011494:Protein Kinases; D019869:Phosphatidylinositol 3-Kinases
keywords: Entamoeba histolytica; Gene expression; Signaling; Transmembrane kinases; Unsaturated fatty acids