Huntingtin phosphorylation on serine 421 is significantly reduced in the striatum and by polyglutamine expansion in vivo

• Published in: Human molecular genetics Vol. 14; no. 11; pp. 1569 - 1577
• Main Authors: Warby, Simon C., Chan, Edmond Y., Metzler, Martina, Gan, Lu, Singaraja, Roshni R., Crocker, Susan F., Robertson, Harold A., Hayden, Michael R.
• Format: Journal Article
• Language: English
• Published: Oxford Oxford University Press 01-06-2005; Oxford Publishing Limited (England)
• Subjects: Amino Acid Sequence; Base Sequence; Biological and medical sciences; Corpus Striatum - metabolism; DNA Primers; Fundamental and applied biological sciences. Psychology; Genetics of eukaryotes. Biological and molecular evolution; Humans; Huntingtin Protein; Molecular and cellular biology; Molecular Sequence Data; Nerve Tissue Proteins - chemistry; Nerve Tissue Proteins - metabolism; Nuclear Proteins - chemistry; Nuclear Proteins - metabolism; Peptides - metabolism; Phosphorylation; Sequence Homology, Amino Acid; Serine - metabolism; In vivo; Genetics; Phosphorylation; Huntingtin; Serine
• ISSN: 0964-6906; 1460-2083
• DOI: 10.1093/hmg/ddi165

Huntington disease (HD) results from polyglutamine expansion in the huntingtin protein (htt). Despite the widespread tissue expression pattern of htt, neuronal loss is highly selective to medium spiny neurons of the striatum. Huntingtin is phosphorylated on serine-421 (S421) by the pro-survival signaling protein kinase Akt (PKB) and this has been previously shown to be protective against the toxicity of polyglutamine-expanded htt in cell culture. Using an antibody specific for htt phosphorylated on S421, we now demonstrate that htt phosphorylation is present at significant levels under normal physiological conditions in human and mouse brain. Furthermore, htt phosphorylation shows a regional distribution with the highest levels in the cerebellum, less in the cortex, and least in the striatum. In cell cultures and in YAC transgenic mice, the endogenous phosphorylation of polyglutamine-expanded htt is significantly reduced relative to wild-type htt. The presence and pattern of significant htt phosphorylation in the brain indicates that this dynamic post-translational modification is important for the regulation of htt and may contribute to the selective neurodegeneration seen in HD.