Rmcystatin3, a cysteine protease inhibitor from Rhipicephalus microplus hemocytes involved in immune response

• Autor(a) principal: Lu, Stephen [UNIFESP]
• Data de Publicação: 2014
• Outros Autores: Soares, Tatiane Sanches [UNIFESP], Vaz Junior, Itabajara S., Lovato, Diogo Ventura [UNIFESP], Tanaka, Aparecida Sadae [UNIFESP]
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da UNIFESP
• Texto Completo: http://repositorio.unifesp.br/handle/11600/38351; http://dx.doi.org/10.1016/j.biochi.2014.07.012
• topic: Cystatin; RNAi; Rhipicephalus microplus; Ticks; Innate immunity

The Rhipicephalus microplus tick is responsible for losses in the livestock production estimated in 2 billions USD. Despite its economical importance the knowledge in tick's physiology is sparse. in order to contribute to this scenario we describe the characterization of a cysteine proteinase inhibitor named Rmcystatin-3. Purified recombinant Rmcystatin-3 was able to inhibit cathepsin L (Ki = 2.5 nM), BmCl1 (Ki = 1.8 nM) and cathepsin B (Ki = 136 nM). Western blot and quantitative PCR analysis revealed the presence of Rmcystatin-3 in fat body, salivary gland but mainly in hemocytes. the mRNA levels of Rmcystatin-3 during bacterial challenge are drastically down-regulated. in order to define the Rmcystatin-3 possible role in tick immunity, the cystatin gene was knockdown by RNA interference with and without Escherichia coli infection. Our results showed that the Rmcystatin-3 silenced group was more immune competent to control bacterial infection than the group injected with non-related dsRNA. Taking together, our data strongly suggested an important role of Rmcystatin-3 in tick immunity. (C) 2014 Elsevier B.V. and Societe francaise de biochimie et biologie Moleculaire (SFBBM). All rights reserved.