Identification and Expression of PPAR in Sinonovacula constricta and Their Potential Regulatory Effects on Δ6 Fad Transcription

摘要

Peroxisome proliferator activated receptors(PPAR)are kinds of key transcriptional factors in regulating LC-PUFA biosynthesis.Until now,little is known about PPAR in marine molluscs as well as in other invertebrates.Sinonovacula constricta is the first marine mollusc that is proved to possess the complete LC-PUFA biosynthetic pathway,and it can be a perfect representative to clarify this situation.In this study,the molecular properties of S.constricta PPAR were characterized,and corresponding potential regulatory roles in S.constrictaΔ6 fatty acyl desaturase(Fad)transcription were estimated by dual luciferase assay.Results showed that two PPAR homologs(PPAR_a and_b)were identified in S.constricta.They both contain typical features of vertebrate PPAR,suggesting highly conserved functional regions in PPAR.By phylogenetic comparison,they are clearly different with vertebrate PPAR and can be divided into two distinctive sub-groups.Moreover,they show a high expression level in gill,labial palps,mantle and intestine.Their down-regulated expressions in trochophore larva and veliger larva might be attributed to food-deprivation.Additionally,the transcriptional activity of S.constrictaΔ6 Fad promoter was significantly activated by both PPAR_a and_b,indicating that S.constricta PPAR might play a role in the regulation of LC-PUFA biosynthesis.To our knowledge,this is the first systematic analysis of PPAR in a marine mollusc.The results will provide a valuable reference for further researches on the function of marine molluscan PPAR and their underlying mechanisms in regulating LC-PUFA biosynthesis.