mRNA encoding a new lipolytic enzyme expressed in rabbit lacrimal glands.

PURPOSE In previous work, lacrimal glands of female mice were shown to express an mRNA encoding pancreatic lipase-related protein 1 (PLRP1), a member of the triacylglycerol lipase family. To investigate the hypothesis that lacrimal glands express mRNAs encoding other lipolytic enzymes, the present study was conducted to look for triacylglycerol lipase-related mRNAs in the lacrimal glands of rabbits. METHODS Degenerate polymerase chain reaction (PCR) primers were designed based on two conserved amino acid motifs, RITGLD, and DI/(F)Y/(F)PNGG, in the triacylglycerol lipase family. Lacrimal gland cDNAs were amplified, and the expected 200-bp products were subcloned and sequenced. One product encoded a new lipase-related sequence, which was termed lacrimal lipase (LL). The complete cDNA sequence of rabbit LL was determined, and labeled LL cDNA was used to probe RNA blots of several rabbit tissues and a genomic DNA blot. RESULTS BLAST database searches indicated that the predicted amino acid sequence of LL is related to phosphatidylserine phospholipase A(1) (PS-PLA1) and to members of the triacylglycerol lipase family. Labeled LL cDNA hybridized to a 2.1-kb message in RNA blots of rabbit lacrimal gland, harderian gland, heart, liver, and pancreas. These blots demonstrated no gender-based differential expression in rabbit lacrimal or harderian glands. Hybridization of labeled LL cDNA to a genomic DNA blot suggested that LL was a single-copy gene. CONCLUSIONS Male and female rabbit lacrimal glands expressed an mRNA encoding LL, a new predicted member of the triacylglycerol lipase family.