NUSBLAT Alejandro David
congresos y reuniones científicas
Genome analysis of sphingolipid metabolism related genes in Tetrahymena thermophila andidentification of a Fatty Acid 2 Hydroxylase gene by somatic knockout.
Conferencia; Conference on Ciliate Molecular Biology 2015; 2015
Sphingolipids along with glycerophospholipidsand sterols are the primary structural lipids present in membranes of eukaryoticcells, and as other lipids alike, they play additional roles as secondmessengers in regulation of signal transduction pathways. They comprise adiverse group of over 100 bioactive different moieties involved in fundamentalcellular processes, such as proliferation, survival, cell death, adhesion,migration, angiogenesis, and embryogenesis.The lipid composition of the functionallydifferent membranes, including glycerophospholipids, sterols and sphingolipids,has been studied extensively in ciliates such as Tetrahymena and Paramecium.Nevertheless no related gene involved in sphingolipid metabolism has been identifiedso far.To address this issue we have undertaken agenome-wide survey of putative genes involved in sphingolipid metabolism in Tetrahymena thermophila from which anumber of candidates have been selected and we have also identified a sphingolipidfatty acid 2-hydroxylase in the ciliate by somatic knockout.This enzyme belongs to the fatty acidhydroxylase superfamily, and catalyzes the hydroxylation at position 2 of fattyacids that will then be attached to sphingoid bases, forming ceramides withN-acyl hydroxy fatty acid chain. A gene encoding for this same enzyme was firstidentified in the yeast Saccharomycescerevisiae and later in mammals (Homosapiens, Mus musculus and Rattus norvegicus) and plant (Arabidopsis thaliana). Although thephysiological role of cell and 2-HAG is largely unknown, in S. cerevisiae 2-OH sphingolipids areinvolved in endocytosis, while its alteration is associated to neurodegenerativediseases in humans.Gene deletion of the only fatty acid2-hydroxylase ortholog present in T.thermophila (TTHERM_00463850) eliminates the ability to synthesizesphingolipids with hydroxylations in the fatty acid chain. Gas chromatographycoupled mass spectrometry analysis of purified sphingolipids, showed that main 2-HFAs(16h:0, 17h:0, 18h:0 and 19h:0) present in the wild type strain were unable tobe detected in the knockout strain. The activity is not vital to the cell,though it may be linked to other phenotypes preliminarly assayed Further studies of sphingolipidmetabolism in ciliates could contribute to the understanding of the cellularand molecular mechanisms of metabolic pathways not only in the ciliates butalso in different human pathologies associated with sphingolipids disorders,such as Gaucher's disease, Niemann-Pick, among others.