Introduction The huntingtin protein (HTT) has 3144 amino acids and undergoes numerous post-translational modifications. Its amino-terminal end is highly conserved and seems to be involved in huntingtin-huntingtin interactions. Several antibodies have been developed for detecting the amino-terminal domain of HTT (including N17, the CAG tract and the polyProline region), but few have been shown to detect endogeneous HTT expression using histological means.

Objectives To develop “custom-made” aptamers that can be used to detect HTT in neuritic aggregates in human and rodent histological material.

Methods Aptamers are synthetic DNA-based polymers selected in vitrofrom random-nucleotide combination libraries. For this project, we used single-chain oligonucleotides due to their flexible nature. These oligonucleotides have been selected against a synthetic albumin-bound peptide and with a polypeptide corresponding to the first exon of HTT (67-amino acid-long polypeptide plus a poly-Q stretch of 23 glutamine residues) bound to glutathione-S-transferase (GST) protein.

Results The aptamers obtained varied in the recognition of the recombinant and the native protein in Western-Blots and immunocytochemical analysis of histological sections. An aptamer against the first 12 AA of HTT (termed HTT5) was obtained, which is able to recognise not only normal HTT in control brain sections but also mutant HTT in neuritic aggregates and intranuclear inclusions in histological brain sections from Huntington’s disease patients.

Conclusions Aptamer HTT5 is a new tool for the detection of normal and mutant HTT that can be used for the specific recognition of this protein in cells and tissues from animal models and HD-affected patients.