Evidence for a repressive function of the long polyglutamine tract in the human androgen receptor: Possible pathogenetic relevance for the (CAG)n-expanded neuronopathies

Abstract

We have reported that polyglutamine (polyGln)-expanded human androgen receptors (hAR) have reduced transactivational competence in transfected cells. We presumed that maximal hAR transactivation requires a normal-size polyGln tract. Here we report, however, that hAR transactivity and polyGln-tract length are related inversely: n=0>12>20>40>50. Thus, a normal-size polyGln tract represses the transactivational competence of a polyGln-free hAR, and polyGln expansion increases that negative effect. This observation has pathogenetic implications for X-linked spinobulbar muscular atrophy (Kennedy syndrome), and possibly for the autosomal dominant central neuronopathies associated with (CAG)n expansion in the translated portion of four different genes. / 1995 Oxford University Press.