BAG-1 associates with the polyglutamine-expanded huntingtin aggregates.

Huntington's disease (HD) is characterised by the proteolytic production of N-terminal fragments of huntingtin containing polyglutamine repeats that forms intracellular ubiquitinated aggregates in the affected neurons. Using cellular and transgenic mice model of HD, we report here that BAG-1 co-immunoprecipitates with the polyglutamine-expanded truncated N-terminal huntingtin (tNhtt) and associates with their aggregates through its interaction with the chaperones Hsc70/Hsp70. We further demonstrate that the over expression of BAG-1 protects polyglutamine-expanded tNhtt induced cell death. Since, BAG-1 is essential for cell survival, its association with tNhtt aggregates might disrupt its normal function and thereby promote polyglutamine-expanded tNhtt-induced cell death.