Autophagy and Polyglutamine Disease

Polyglutamine (polyQ) disease is a type of fatal neurodegenerative disease caused by an expansion of CAG repeats in a specific gene, resulting in a protein with an abnormal polyQ fragment. The age of onset and the degree of pathological deterioration are related to the length of the polyQ fragment. At least 9 kinds of polyglutamine diseases have been discovered, including Huntington disease (HD), dentatorubral pallidoluysian atrophy (DRPLA), spinobulbar muscular atrophy (SBMA) and six spinocerebellar ataxia (SCA) such as SCA1, 2, 3, 6, 7 and 17 subtypes (Table 9.1). Previous studies suggest that autophagy plays a major role in the quality control of disease proteins in polyQ diseases. In this chapter, we majorly focused on three representative polyQ diseases, including spinocerebellar Ataxia type 3 (SCA3), spinocerebellar ataxia type 7 (SCA7) and Huntington's disease (HD). The relationship of the ubiquitin-proteasome system and autophagy involved in disease protein accumulation were summarized.