Cytoplasmic dynein/dynactin mediates the assembly of aggresomes

Abstract

Aggresomes are pericentrosomal cytoplasmic structures into which aggregated, ubiquitinated, misfolded proteins are sequestered. Misfolded proteins accumulate in aggresomes when the capacity of the intracellular protein degradation machinery is exceeded. Previously, we demonstrated that an intact microtubule cytoskeleton is required for the aggresome formation [Johnston et al., 1998: J. Cell Biol. 143:1883-1898]. In this study, we have investigated the involvement of microtubules (MT) and MT motors in this process. Induction of aggresomes containing misfolded DeltaF508 CFTR is accompanied by a redistribution of the retrograde motor cytoplasmic dynein that colocalizes with aggresomal markers. Coexpression of the p50 (dynamitin) subunit of the dynein/dynactin complex prevents the formation of aggresomes, even in the presence of proteasome inhibitors. Using in vitro microtubule binding assays in conjunction with immunogold electron microscopy, our data demonstrate that misfolded DeltaF508 CFTR associate with microtubules. We conclude that cytoplasmic dynein/dynactin is responsible for the directed transport of misfolded protein into aggresomes. The implications of these findings with respect to the pathogenesis of neurodegenerative disease are discussed.

Histone deacetylase inhibitors: molecular mechanisms of action

“…Direction of misfolded proteins to aggresomes is essential for cell survival, since these proteins are susceptible to forming cytotoxic aggregates that can interfere with normal cell function. Aggresome formation requires the microtubule network and the microtubule-associated motor, dynein (Johnston et al, 2002). HDAC6 can bind p150, a component of dynein motor complex, and act as a bridge between the dynein motors and the ubiquitination process, directing the polyubiquitinated proteins to aggresome.…”

The benefits of local depletion: The centrosome as a scaffold for ubiquitin-proteasome-mediated degradation

“…22 These structures, dubbed 'aggresomes', are composed of electron-dense protein aggregates that depend on minus-enddirected microtubule trafficking for accumulation at centrosomes. 26 Aggresome formation depends on the histone deacetylase HDAC6 which simultaneously binds polyubiquitinated unfolded proteins and dynein motors to participate in active trafficking of aggregate particles to the centrosome. 27 Aggresomes are rich in ubiquitin, 19S and 20S proteasome subunits, and the chaperones Hsp70 and Hsp90.…”

Thiopurine S-methyltransferase pharmacogenetics: insights, challenges and future directions

“…Aggresomes are pericentriolar cytoplasmic structures in which aggregated, polyubiquinated misfolded proteins can be sequestered (Johnston et al, 1998;Kopita, 2000;Garcia-Mata et al, 2002). Aggresome formation is microtubule dependent, with the involvement of histone deacytalase 6 (HDAC6) and motor proteins such as dynein (Johnston et al, 2002;Kawaguchi et al, 2003). The fact that TPMT*3A is targeted for accelerated proteasome-mediated degradation, with the involvement of molecular chaperones, raised the possibility that the two common polymorphisms in TPMT*3A might result in misfolding.…”