title: Rmcystatin3, a cysteine protease inhibitor from Rhipicephalus microplus hemocytes involved in immune response.
abstract: 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.
authors: Department of Biochemistry, Escola Paulista de Medicina, Universidade Federal de São Paulo, 04044-020 São Paulo, SP, Brazil.
authors: Stephen
authors: S
authors: Lu
authors: Department of Biochemistry, Escola Paulista de Medicina, Universidade Federal de São Paulo, 04044-020 São Paulo, SP, Brazil.
authors: Tatiane S
authors: TS
authors: Soares
authors: Centro de Biotecnologia do Estado do Rio Grande do Sul, UFRGS, Porto Alegre, Brazil.
authors: Itabajara S
authors: IS
authors: Vaz Junior
authors: Department of Biochemistry, Escola Paulista de Medicina, Universidade Federal de São Paulo, 04044-020 São Paulo, SP, Brazil.
authors: Diogo V
authors: DV
authors: Lovato
authors: Department of Biochemistry, Escola Paulista de Medicina, Universidade Federal de São Paulo, 04044-020 São Paulo, SP, Brazil. Electronic address: tanaka.bioq@epm.br.
authors: Aparecida S
authors: AS
authors: Tanaka
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D002401:Cathepsin B / Q000037:antagonists & inhibitors / Q000378:metabolism; D056668:Cathepsin L / Q000037:antagonists & inhibitors / Q000378:metabolism; D015853:Cysteine Proteinase Inhibitors / Q000276:immunology* / Q000378:metabolism / Q000494:pharmacology; D060467:Disease Resistance / Q000235:genetics / Q000276:immunology*; D004926:Escherichia coli / Q000276:immunology / Q000502:physiology; D005216:Fat Body / Q000276:immunology / Q000378:metabolism; D015870:Gene Expression / Q000276:immunology; D006434:Hemocytes / Q000276:immunology* / Q000378:metabolism; D054884:Host-Pathogen Interactions / Q000276:immunology; D008969:Molecular Sequence Data; D034622:RNA Interference / Q000276:immunology; D011994:Recombinant Proteins / Q000494:pharmacology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D048494:Rhipicephalus / Q000235:genetics / Q000276:immunology* / Q000382:microbiology; D012469:Salivary Glands / Q000276:immunology / Q000378:metabolism; D017386:Sequence Homology, Amino Acid
chemical_list: D015853:Cysteine Proteinase Inhibitors; D011994:Recombinant Proteins; D002401:Cathepsin B; D056668:Cathepsin L
keywords: Cystatin; Innate immunity; RNAi; Rhipicephalus microplus; Ticks