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

Smitha Pillai,Susanne Hartmann,Bernd H Kalinna,Richard Lucius,Franz Theuring,Eva Liebau

doi:10.1186/1475-2883-4-9

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.

Highlights

Filarial nematodes reside among others in the lymphatic vessels or the subcutis of their vertebrate hosts, where they often persist for many years in spite of an array of immune effector mechanisms
Since studies on cystatin of other parasitic nematodes such as the rodent filaria Acanthocheilonema viteae [4], Brugia malayi [5,6], Litomosoides sigmodontis [7], Nippostrongylus brasiliensis [8] and O. volvulus [9] have revealed that it is a modulator of the host immune response
We further demonstrated that the Av17 promoter is functional in C elegans and compared the expression of the cDNA and the genomic sequence of Av17 in C. elegans

Summary

Introduction

Filarial nematodes reside among others in the lymphatic vessels or the subcutis of their vertebrate hosts, where they often persist for many years in spite of an array of immune effector mechanisms. One of the parasitederived molecules described in this context is the filarial excretory/secretory protein cystatin. Cystatin of Onchocerca volvulus was first described by Lustigmann et al [3]. Since studies on cystatin of other parasitic nematodes such as the rodent filaria Acanthocheilonema viteae [4], Brugia malayi [5,6], Litomosoides sigmodontis [7], Nippostrongylus brasiliensis [8] and O. volvulus [9] have revealed that it is a modulator of the host immune response. Cystatins of parasitic nematodes have (page number not for citation purposes)

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