title: Repression of Proteases and Hsp90 Chaperone Expression Induced by an Antiretroviral in Virulent Environmental Strains of Cryptococcus neoformans.
abstract: This study evaluated the effect of the antiretroviral ritonavir on protease secretion in different strains of Cryptococcus neoformans isolated from the environment and investigated the expression of heat shock protein (Hsp90), classically described virulence factors in other yeast in the presence of the same antiretroviral. The presence of the enzyme was detected by the formation of a degradation of the halo around the colonies. The results were classified as follows: level 1 (without proteases), level 2 (positive for proteases), and level 3 (strongly positive for proteases). Total protein extract isolated from the cell walls of the 12 strains incubated in the absence and presence of ritonavir (0.3125 mg mL-1) were resolved by SDS-PAGE and analyzed by Western blot assays using an antiserum against Hsp90 from Blastocladiella emersonii. All strains tested showed inhibition of proteinase activity in the presence of ritonavir at 0.3125 to 1.25 mg mL-1. High levels of Hsp90 were observed in the absence of ritonavir (0.3125 mg mL-1), except for the non-virulent control cells. In contrast, in the presence of the antiretroviral, a drastic reduction in the expression of the chaperone was observed. The data suggest that ritonavir, in addition to containing viral replication, could inhibit the expression of virulence factors in opportunistic yeast, as proteases and Hsp90. According to our current knowledge, this is the first time that the inhibition of Hsp90 by an antiretroviral was reported for environmental isolates of C. neoformans.
authors.affiliation: Hospital Universitário do Oeste do Paraná, Universidade Estadual do Oeste do Paraná - UNIOESTE, Av Tancredo Neves, 3224, Cascavel, PR, Brazil.
authors.forename: Cleber Fernando
authors.initials: CF
authors.lastname: Serafin
authors.affiliation: Hospital Universitário do Oeste do Paraná, Universidade Estadual do Oeste do Paraná - UNIOESTE, Av Tancredo Neves, 3224, Cascavel, PR, Brazil.
authors.forename: Ana Paula
authors.initials: AP
authors.lastname: Paris
authors.affiliation: Intituto de Ciências Biomédicas, Universidade de São Paulo, USP, São Paulo, SP, Brazil.
authors.forename: Claudete Rodrigues
authors.initials: CR
authors.lastname: Paula
authors.affiliation: Laboratório de Bioquímica Molecular, Centro de Ciências Médicas e Farmacêuticas, Universidade Estadual do Oeste do Paraná, UNIOESTE, Cascavel, PR, Brazil.
authors.forename: Rita Cássia Garcia
authors.initials: RC
authors.lastname: Simão
authors.affiliation: Hospital Universitário do Oeste do Paraná, Universidade Estadual do Oeste do Paraná - UNIOESTE, Av Tancredo Neves, 3224, Cascavel, PR, Brazil. rinaldo.gandra@unioeste.br.
authors.forename: Rinaldo Ferreira
authors.initials: RF
authors.lastname: Gandra
mesh_terms: D000818:Animals; D044966:Anti-Retroviral Agents / Q000494:pharmacology*; D010856:Columbidae / Q000382:microbiology; D003455:Cryptococcus neoformans / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D018841:HSP90 Heat-Shock Proteins / Q000096:biosynthesis*; D010447:Peptide Hydrolases / Q000096:biosynthesis*; D011480:Protease Inhibitors / Q000378:metabolism*; D019438:Ritonavir / Q000494:pharmacology*
chemical_list: D044966:Anti-Retroviral Agents; D018841:HSP90 Heat-Shock Proteins; D011480:Protease Inhibitors; D010447:Peptide Hydrolases; D019438:Ritonavir
keywords: AIDS; Antiretroviral; Cryptococcus neoformans; Hsp90; Proteases; Virulence factors