Endogenous mouse huntingtin is highly abundant in cranial nerve nuclei, co-aggregates to Abeta plaques and is induced in reactive astrocytes in a transgenic mouse model of Alzheimer’s disease | Acta Neuropathologica Communications | Full Text

Endogenous mouse huntingtin is highly abundant in cranial nerve nuclei, co-aggregates to Abeta plaques and is induced in reactive astrocytes in a transgenic mouse model of Alzheimer’s disease | Acta Neuropathologica Communications | Full Text

Acta Neuropathologica Communications

Endogenous mouse huntingtin is highly abundant in cranial nerve nuclei, co-aggregates to Abeta plaques and is induced in reactive astrocytes in a transgenic mouse model of Alzheimer’s disease

• Maike Hartlage-Rübsamen,
• Veronika Ratz,
• Ulrike Zeitschel,
• Lukas Finzel,
• Lisa Machner,
• Janett Köppen,
• Anja Schulze,
• Hans-Ulrich Demuth,
• Stephan von Hörsten,
• Corinna Höfling and
• Steffen RoßnerEmail authorView ORCID ID profile

Acta Neuropathologica Communications20197:79

https://doi.org/10.1186/s40478-019-0726-2

©  The Author(s). 2019

• Received: 16 April 2019
• Accepted: 17 April 2019
• Published: 20 May 2019

Abstract

Pathogenic variants of the huntingtin (HTT) protein and their aggregation have been investigated in great detail in brains of Huntington’s disease patients and HTT-transgenic animals. However, little is known about the physiological brain region- and cell type-specific HTT expression pattern in wild type mice and a potential recruitment of endogenous HTT to other pathogenic protein aggregates such as amyloid plaques in cross seeding events. Employing a monoclonal anti-HTT antibody directed against the HTT mid-region and using brain tissue of three different mouse strains, we detected prominent immunoreactivity in a number of brain areas, particularly in cholinergic cranial nerve nuclei, while ubiquitous neuronal staining appeared faint. The region-specific distribution of endogenous HTT was found to be comparable in wild type rat and hamster brain. In human amyloid precursor protein transgenic Tg2576 mice with amyloid plaque pathology, similar neuronal HTT expression patterns and a distinct association of HTT with Abeta plaques were revealed by immunohistochemical double labelling. Additionally, the localization of HTT in reactive astrocytes was demonstrated for the first time in a transgenic Alzheimer’s disease animal model. Both, plaque association of HTT and occurrence in astrocytes appeared to be age-dependent. Astrocytic HTT gene and protein expression was confirmed in primary cultures by RT-qPCR and by immunocytochemistry. We provide the first detailed analysis of physiological HTT expression in rodent brain and, under pathological conditions, demonstrate HTT aggregation in proximity to Abeta plaques and Abeta-induced astrocytic expression of endogenous HTT in Tg2576 mice.

Keywords

• Huntingtin
• Cranial nerve nuclei
• Alzheimer’s disease
• Animal model
• Amyloid precursor protein
• Astrocytes