Meeting Abstract
Mammalian leucyl-cystinyl aminopeptidase (LNPEP) – also as placental leucine aminopeptidase (P-LAP), insulin-regulated aminopeptidase (IRAP), vasopressinase, and oxytocinase – is a membrane-bound zinc dependent metalloexopeptidase enzyme that inactivates cyclic polypeptides including nonapeptide hormones of the vasopressin/oxytocin family. LNPEP activity plays a key role in the clearance of oxytocin during pregnancy in humans, and changes in renal LNPEP expression have been implicated as a mechanism of negative feedback for vasopressin’s effects on renal water resorption. The evolutionary diversity and function of LNPEP in other vertebrate classes, however, remains unknown, even though nonapeptides of the vasopressin/oxytocin family have been studied extensively in the regulation of hydromineral balance and social behaviors in many non-mammalian taxa. Here, we isolated and sequenced a full length cDNA of 3,376 bps for a LNPEP-like enzyme from the ovarian tissue of the Amargosa pupfish Cyprinodon nevadensis amargosae. This pupfish inhabits in a remote desert river in the Death Valley region of California, USA, and has been studied for the effects of the teleost nonapeptide arginine vasotocin (AVT) on behavior and osmoregulation. The isolated cDNA encodes 1,033 amino acids and shares 62% residue identity with a putative LNPEP enzyme from zebrafish (Danio rerio) and 50% with LNPEP isoform 1 of humans. The tissue distribution of lnpep mRNAs in C. n. amargosae is being determined. As an initial step toward evaluating whether variation in brain LNPEP expression may link to social behavior, we also are exploring patterns of hypothalamic lnpep mRNA expression relative to the aggressive behavior and social rank of male and female pupfish.
