RESUMO
Misfolding and aggregation are associated with cytotoxicity in several protein folding diseases. A large network of molecular chaperones ensures protein quality control. Here, we show that within the Hsp70, Hsp110, and Hsp40 (DNAJ) chaperone families, members of a subclass of the DNAJB family (particularly DNAJB6b and DNAJB8) are superior suppressors of aggregation and toxicity of disease-associated polyglutamine proteins. The antiaggregation activity is largely independent of the N-terminal Hsp70-interacting J-domain. Rather, a C-terminal serine-rich (SSF-SST) region and the C-terminal tail are essential. The SSF-SST region is involved in substrate binding, formation of polydisperse oligomeric complexes, and interaction with histone deacetylases (HDAC4, HDAC6, SIRT2). Inhibiting HDAC4 reduced DNAJB8 function. DNAJB8 is (de)acetylated at two conserved C-terminal lysines that are not involved in substrate binding, but do play a role in suppressing protein aggregation. Combined, our data provide a functional link between HDACs and DNAJs in suppressing cytotoxic protein aggregation.
Assuntos
Proteínas de Choque Térmico HSP40/fisiologia , Histona Desacetilases/fisiologia , Animais , Linhagem Celular , Proteínas de Choque Térmico HSP40/química , Proteínas de Choque Térmico HSP40/metabolismo , Proteínas de Choque Térmico HSP70/metabolismo , Proteínas de Choque Térmico HSP70/fisiologia , Resposta ao Choque Térmico , Histona Desacetilases/química , Histona Desacetilases/metabolismo , Humanos , Peptídeos/metabolismo , Deficiências na Proteostase/metabolismo , Xenopus laevisRESUMO
We present the evidence for a direct physical association of cystic fibrosis transmembrane conductance regulator (CFTR) and epithelial sodium channel (ENaC), two major ion channels implicated in the pathophysiology of cystic fibrosis, a devastating inherited disease. We employed fluorescence resonance energy transfer, a distance-dependent imaging technique with capability to detect molecular complexes with near angstrom resolution, to estimate the proximity of CFTR and ENaC, an essential variable for possible physical interaction to occur. Fluorescence resonance energy transfer studies were complemented with a classic biochemical approach: coimmunoprecipitation. Our results place CFTR and ENaC within reach of each other, suggestive of a direct interaction between these two proteins.