Comparative structures and evolution of vertebrate lipase H (LIPH) genes and proteins: a relative of the phospholipase A1 gene families

Lipase H (LIPH) is a membrane-bound phospholipase generating 2-acyl lysophosphatidic acid (LPA) in the body. LPA is a lipid mediator required for maintaining homeostasis of diverse biological functions and in activating cell surface receptors such as P2Y5, which plays an essential role in hair growth. Bioinformatic methods were used to predict the amino acid sequences, secondary and tertiary structures, and gene locations for LIPH genes and encoded proteins using data from several vertebrate genome projects. Vertebrate LIPH genes contained ten coding exons transcribed on either the positive or negative DNA strands. Evidence is presented for duplicated LIPH genes for the chicken and zebra fish genomes. Vertebrate LIPH protein subunits shared 56–97 % sequence identities and exhibited sequence alignments and identities for key LIPH amino acid residues as well as extensive conservation of predicted secondary and tertiary structures with those previously reported for horse pancreatic lipase (LIPP), with ‘N-signal peptide’, ‘lipase,’ and ‘plat’ structural domains. Comparative studies of vertebrate LIPH sequences with other phospholipase A1-like lipases (LIPI and PS-PLA1), as well as vascular and pancreatic lipases, confirmed predictions for LIPH N-terminal signal peptides (residues 1–18); a conserved vertebrate LIPH N-glycosylation site (66NVT for human LIPH); active site ‘triad’ residues (Ser 154; Asp 178; His 248); disulfide bond residues (233–246; 270–281; 284–292; 427–446), and a ‘short’ 12 residue ‘active site lid’, which is comparable to other phospholipases examined. Phylogenetic analyses demonstrated the relationships and potential evolutionary origins of the vertebrate LIPH family of genes related to, but distinct from other phospholipase A1-like genes (LIPI and PS-PLA1), and from vascular lipase and pancreatic lipase gene families. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s13205-012-0087-z) contains supplementary material, which is available to authorized users

Vertebrate endothelial lipase: comparative studies of an ancient gene and protein in vertebrate evolution

Endothelial lipase (gene: LIPG; enzyme: EL) is one of three members of the triglyceride lipase family that contributes to lipoprotein degradation within the circulation system and plays a major role in HDL metabolism in the body. In this study, in silico methods were used to predict the amino acid sequences, secondary and tertiary structures, and gene locations for LIPG genes and encoded proteins using data from several vertebrate genome projects. LIPG is located on human chromosome 18 and is distinct from other human 'neutral lipase' genes, hepatic lipase (gene: LIPC; enzyme: HL) and lipoprotein lipase (gene: LPL; enzyme: LPL) examined. Vertebrate LIPG genes usually contained 10 coding exons located on the positive strand for most primates, as well as for horse, bovine, opossum, platypus and frog genomes. The rat LIPG gene however contained only 9 coding exons apparently due to the presence of a 'stop' codon' within exon 9. Vertebrate EL protein subunits shared 58-97% sequence identity as compared with 38-45% sequence identities with human HL and LPL. Four previously reported human EL N-glycosylation sites were predominantly conserved among the 10 potential N-glycosylation sites observed for the vertebrate EL sequences examined. Sequence alignments and identities for key EL amino acid residues were observed as well as conservation of predicted secondary and tertiary structures with those previously reported for horse pancreatic lipase (PL) (Bourne et al. 1994). Several potential sites for regulating LIPG gene expression were observed including CpG islands near the LIPG gene promoter and a predicted microRNA binding site near the 3'-untranslated region. Promoter regions containing functional polymorphisms that regulate HDL cholesterol in baboons were conserved among primates but not retained between primates and rodents. Phylogenetic analyses examined the relationships and potential evolutionary origins of the vertebrate LIPG gene subfamily with other neutral triglyceride lipase gene families, LIPC and LPL. It is apparent that the triglyceride lipase ancestral gene for the vertebrate LIPG gene predated the appearance of fish during vertebrate evolution[500 million years ago.Full Tex

Book Reviews

Reviews of the following books: Unearthed: Storied Artifacts and Remarkable Predecessors of the Saint Joseph’s College Campus by Steven L. Bridge; Creating Acadia National Park: The Biography of George Bucknam Dorr by Ronald H. Epp; The Human Shore: Seacoasts in Historyby John R. Gillis; Orion on the Dunes: A Biography of Henry Beston by Daniel G. Payne