The patatin-like lipase family in Gallus gallus.
BACKGROUND
In oviparous species, genes encoding proteins with functions in lipid remodeling, such as specialized lipases, may have evolved to facilitate the assembly and utilization of yolk lipids by the embryo. The mammalian gene family of patatin-like phospholipases (PNPLAs) has received significant attention, but studies in other vertebrates are lacking; thus, we have begun investigations of PNPLA genes in the chicken (Gallus gallus).


RESULTS
We scanned the draft chicken genome using human PNPLA sequences, and performed PCR to amplify and sequence orthologous cDNAs. Full-length cDNA sequences of galline PNPLA2/ATGL, PNPLA4, -7, -8, -9, and the activator protein CGI-58, as well as partial cDNA sequences of avian PNPLA1, -3, and -6 were obtained. The high degree of sequence identities (~50 to 80%) between the avian and human orthologs suggests conservation of important enzymatic functions. Quantitation by qPCR of the transcript levels of PNPLAs and CGI-58 in 21 tissues indicates that expression patterns and levels diverge greatly between species. A particularly interesting tissue in which certain PNPLAs may contribute to physiological specialization is the extraembryonic yolk sac.


CONCLUSIONS
Knowledge about the exact in-vivo functions of PNPLAs in any system is still sparse. Thus, studies about the temporal expression patterns and functions of the enzymes identified here, and of other already known extracellular lipases and co-factors, in the yolk sac and embryonic tissues during embryogenesis are called for. Based on the information obtained, further studies are anticipated to provide important insights of the roles of PNPLAs in the yolk sac and embryo development.
Saarela
Jani
J
The Max F. Perutz Laboratories, Department of Medical Biochemistry, Medical University of Vienna, Dr. Bohr Gasse 9/2, A-1030 Vienna, Austria. jani.saarela@ktl.fi
Jung
Gerlinde
G
Hermann
Marcela
M
Nimpf
Johannes
J
Schneider
Wolfgang J
WJ
D000595:Amino Acid Sequence; D000818:Animals; D002645:Chickens / Q000235:genetics*; D019295:Computational Biology; D020869:Gene Expression Profiling; D016678:Genome; D006801:Humans; D050356:Lipid Metabolism; D051379:Mice; D008969:Molecular Sequence Data; D009865:Oocytes / Q000378:metabolism; D010740:Phospholipases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D010802:Phylogeny; D016415:Sequence Alignment
D010740:Phospholipases