Huntingtin-associated protein 1 (HAP1) interacts with the p150Glued subunit of dynactin

Abstract

Huntington's disease (HD) is an inherited neurodegenerative disease caused by expansion of a polyglutamine repeat in the HD protein huntingtin. Huntingtin's localization within the cell includes an association with cytoskeletal elements and vesicles. We previously identified a protein (HAP1) which binds to huntingtin in a glutamine repeat length-dependent manner. We now report that HAP1 interacts with cytoskeletal proteins, namely the p150 Glued subunit of dynactin and the pericentriolar protein PCM-1. Structural predictions indicate that both HAP1 and the interacting proteins have a high probability of forming coiled coils. We examined the interaction of HAP1 with p150 Glued . Binding of HAP1 to p150 Glued (amino acids 879-1150) was confirmed in vitro by binding of p150 Glued to a HAP1-GST fusion protein immobilized on glutathione-Sepharose beads. Also, HAP1 co-immunoprecipitated with p150 Glued from brain extracts, indicating that the interaction occurs in vivo . Like HAP1, p150 Glued is highly expressed in neurons in brain and both proteins are enriched in a nerve terminal vesicle-rich fraction. Double label immunofluorescence experiments in NGF-treated PC12 cells using confocal microscopy revealed that HAP1 and p150 Glued partially co-localize. These results suggest that HAP1 might function as an adaptor protein using coiled coils to mediate interactions among cytoskeletal, vesicular and motor proteins. Thus, HAP1 and huntingtin may play a role in vesicle trafficking within the cell and disruption of this function could contribute to the neuronal dysfunction and death seen in HD.

In vitro reconstitution of a highly processive recombinant human dynein complex

“…Our current study reveals that a strong candidate to mediate this stimulation is the single fly BICD protein, which is known to be one of a small number of proteins recruited to the RNA element (Dix et al , 2013). It will be important to determine in the future whether other BICD family members such as BICDR proteins (Schlager et al , 2010) and unrelated cargo adaptors for dynein (Engelender et al , 1997; Horgan et al , 2010; van der Kant et al , 2013; van Spronsen et al , 2013) also regulate motor processivity by promoting the interaction with dynactin.…”

Autophagosome dynamics in neurodegeneration at a glance

“…Autophagosome transport is regulated by huntingtin (Wong and Holzbaur, 2014a), a scaffolding protein that binds dynein directly (Caviston et al, 2007) and also interacts with dynactin (p150 Glued subunit) and kinesin through Huntingtin-associated protein 1 (HAP-1) (Engelender et al, 1997;Li et al, 1995;Li et al, 1998;McGuire et al, 2006;Twelvetrees et al, 2010). Huntingtin localizes to the outer membrane of autophagosomes (Atwal et al, 2007;Martinez-Vicente et al, 2010) and regulates autophagosome transport through its interactions with dynein and HAP-1 (Wong and Holzbaur, 2014a).…”

The retromer component SNX6 interacts with dynactin p150Glued and mediates endosome-to-TGN transport

“…Based on previous findings that some membrane proteins bind to the p150 Glued subunit of dynactin to mediate vesicular transport [10,11,13,31], we reasoned that the C-terminal tail of p150 Glued might serve as a binding platform for various adaptor proteins. In search of cargo adaptors for the dynein/dynactin motor, we performed a yeast two-hybrid screen of a human fetal brain cDNA library using the C-terminus of human p150 Glued (amino acid residues (aa) 718-1 278) as bait.…”

“…Another Golgi-associated protein, βIII spectrin, binds to the Arp1 subunit of dynactin and is believed to link the motor to membranous cargo [9]. The huntingtin protein facilitates vesicular transport of brain-derived neurotrophic factor via the interaction between huntingtin-associated protein-1 and p150 Glued [10,11]. Most recently, it was reported that the Rab7 effector RILP also binds to p150 Glued npg the dynein motor to vesicular membranes [12,13].…”