Showing papers on "Lanosterol synthase published in 2015"

Lanosterol reverses protein aggregation in cataracts

Abstract: The human lens is comprised largely of crystallin proteins assembled into a highly ordered, interactive macro-structure essential for lens transparency and refractive index. Any disruption of intra- or inter-protein interactions will alter this delicate structure, exposing hydrophobic surfaces, with consequent protein aggregation and cataract formation. Cataracts are the most common cause of blindness worldwide, affecting tens of millions of people1, and currently the only treatment is surgical removal of cataractous lenses. The precise mechanisms by which lens proteins both prevent aggregation and maintain lens transparency are largely unknown. Lanosterol is an amphipathic molecule enriched in the lens. It is synthesized by lanosterol synthase (LSS) in a key cyclization reaction of a cholesterol synthesis pathway. Here we identify two distinct homozygous LSS missense mutations (W581R and G588S) in two families with extensive congenital cataracts. Both of these mutations affect highly conserved amino acid residues and impair key catalytic functions of LSS. Engineered expression of wild-type, but not mutant, LSS prevents intracellular protein aggregation of various cataract-causing mutant crystallins. Treatment by lanosterol, but not cholesterol, significantly decreased preformed protein aggregates both in vitro and in cell-transfection experiments. We further show that lanosterol treatment could reduce cataract severity and increase transparency in dissected rabbit cataractous lenses in vitro and cataract severity in vivo in dogs. Our study identifies lanosterol as a key molecule in the prevention of lens protein aggregation and points to a novel strategy for cataract prevention and treatment.

Downregulation of lanosterol synthase gene expression by antisense RNA technology in Saccharomyces cerevisiae

Abstract: The cyclization of 2,3-oxidosqualene is the key branch point of ergosterol and triterpenoid biosynthesis Downregulation of 2,3-oxidosqualene metabolic flux to ergosterol in Saccharomyces cerevisiae may redirect the metabolic flux toward the triterpenoid synthetic pathway In our study, primers were designed according to erg7 gene sequence of S cerevisiae Three fragments including 5' long fragment, 5' short fragment and erg7 coding region fragment were amplified by PCR 5' long fragment consists of the promoter and a part of erg7 coding region sequence 5' short fragment consists of a part of promoter and a part of erg7 coding region sequence These fragments were inserted reversely into pESC-URA to construct antisense expression plasmids The recombinant plasmids were transformed into S cerevisiae INVSc1 and recombinant strains were screened on the nutritional deficient medium SD-URA The erg7 expression level of recombinant strains, which harbored antisense expression plasmid of erg7 coding region, was similar to that of INVScl by semi-quantitative PCR detection But erg7 expression level of recombinant strains, which harbored 5' long antisense fragment and 5' short antisense fragment, was significantly lower than that of the control The results of TLC and HPLC showed that the ergosterol content of recombinant strains, which harbored 5' long antisense fragment, decreased obviously The ergosterol contents of the others were almost equal to that of INVSc1 Lanosterol synthase gene expression was downregulated by antisense RNA technology in S cerevisiae, which lays a foundation for reconstructing triterpenoid metabolic pathway in S cerevisiae by synthetic biology technology

Identification of a Putative Ganoderic Acid Pathway Enzyme in a Ganoderma Australe Transcriptome by Means of a Hidden Markov Model

Abstract: Ganoderma australe is a fungus widely used as a traditional medicine mainly in Eastern countries, but not studied in silico at the genomic level This species is probably related to other well characterized fungus with similar properties, which may facilitate gene finding through comparative molecular analysis using appropriated bioinformatics tools This paper aims to present a preliminary analysis of a G australe transcriptome through some computational biology techniques implementing Hidden Markov Models (HMM) in order to predict a key putative enzyme (lanosterol synthase, EC 54997) involved in the metabolic pathway of triterpenoids of therapeutic interest The findings suggest that the HMM approach results more efficient than traditional comparisons by homology based on methods of multiple sequences alignment Here we report the first evidence of a putative lanosterol synthase protein being expressed in cell cultures of G australe