Research

Studies on Acanthocheilonema viteae cystatin: Genomic organization, promoter studies and expression in Caenorhabditis elegans

Smitha Pillai^1* , Bernd H Kalinna^1* , Eva Liebau², Susanne Hartmann¹, Franz Theuring³ and Richard Lucius¹

¹  Department of Molecular Parasitology, Institute of Biology, Humboldt University Berlin, 10115 Berlin, Germany

²  Department of Biochemistry, Bernhard Nocht Institute for Tropical Medicine, 20359 Hamburg, Germany

³  Institute for Pharmacology and Toxicology, Charitée, 10115 Berlin, Germany

Filaria Journal 2005, 4:9doi:10.1186/1475-2883-4-9

Published:	9 August 2005

Abstract

Cystatins are reversible, tightly binding inhibitors of cysteine proteases. Filarial cystatins have been ascribed immunomodulatory properties and have been implicated in protective immunity. To continue exploration of this potential, here we have determined the sequence, structure and genomic organization of the cystatin gene locus of A. viteae. The gene is composed of 4 exons separated by 3 introns and spans ~2 kb of genomic DNA. The upstream genomic sequence contains transcriptional factor binding sites such as AP-1 and NF-Y, an inverted CCAAT sequence, and a TATA box. To investigate sites of cystatin expression, Caenorhabditis elegans worms were transformed by microinjection with the putative promoter region and the first exon of the A. viteae cystatin gene fused to the reporter GFP. In transgenic worms fluorescence was observed in the pharyngeal and rectal gland cells suggesting that cystatin is secreted. Additionally, A. viteae cystatin was expressed in C. elegans to explore its potential as an expression system for filarial genes.