Meeting Abstract

31.4  Jan. 5  Molecular Cloning and Expression of Heat Shock Protein 90 and Heat Shock Factor from the Shrimp Metapenaeus ensis WU, L.*; CHU, K. H.; The Chinese University of Hong Kong; The Chinese University of Hong Kong kahouchu@cuhk.edu.hk

During vitellogenesis of oviparous animals, the transcription of vitellogenin, the major source of nutrients during embryogenesis, is under the regulation of heat shock protein 90 (Hsp90), which is regulated by the heat shock factor (Hsf). In vertebrates, Hsp90 competes with estrogen hormones for estrogen receptor, the main transcription activator of vitellogenin, but the regulatory role of Hsp and Hsf in vitellogenesis of invertebrates is largely unknown. In a recent study on shrimp vitellogenin, multiple binding elements of Hsf have been identified in the promoter of the gene, suggesting the participation of Hsf in regulating vitellogenin transcription in crustaceans. To study the possible regulatory role of Hsp90 and Hsf, we cloned the full length mRNA of Hsp90 and Hsf from the ovary of the shrimp Metapenaeus ensis. Amino acid sequences of Hsp90 show 87% and 70-80% homology with homologs in a crab and insects, respectively. Hsp90 shows consistently high level expression in ovary, gut, muscle and central nerve system of shrimps at different ovarian maturation stages, but is differentially expressed in eyestalk and hepatopancreas. While Hsp90 expression in the eyestalk increases during ovarian development, it shows an opposite trend in the hepatopancreas. The decrease of Hsp90 expression is accompanied by the up-regulation of vitellogenin transcription in the hepatopancreas, indicating the possible inhibitory action of Hsp90 on vitellogenesis. Further studies on the functioning of Hsp90 and Hsf in shrimp are in progress. The result would provide insights on the control of vitellogenesis in invertebrates.