Background The discovery of the huntingtin gene enabled the creation of transgenic HD models including the transgenic minipigs (TgHD) used in this study. The advantages of minipigs as models of HD disease are that their brains are very similar to humans in terms of anatomy, histology, lifespan and genetics. The brain, especially its parts such as striatum and cortex, are considered to be mostly affected by HD.
Aim To investigate the expression of selected HD markers: mutated huntingtin (mtHtt) and their aggregates, Golgi resistant protein GCP60 and microgliosis in the brain (cortex and striatum) of transgenic minipigs for the human mtHtt and compare them with brains of wild type (WT) minipigs.
Methods In this study we used WT and TgHD minipigs for N-terminal part of the human mtHtt (548aaHTT-145Q, both F2 generation, age 24 months). HD markers were examined immunohistochemically (IHC) on cryostat sections or biochemically by western blotting (WB) using the following primary antibodies: anti-polyglutamines, anti-polyglutamine-expansion diseases marker, aggregated huntingtin (S829), anti-ACBD3 (GPC60), anti-IBA1.
Results The IHC examination showed increased expression of polyglutamines, GCP60 and IBA1 proteins in the brain tissue of TgHD minipigs. The WB examination confirmed massive polyglutamine expression and increased accumulation of Golgi resistant protein GCP60 in the TgHD brain tissue. Also we revealed higher number of activated microglia in nucleus caudate of TgHD in comparison with WT minipigs. No mtHtt aggregates were detected in TgHD brains.
Conclusion Using IHC and WB methods we were able to characterise early changes in the brain tissue of TgHD animals of F2 generation. This animal study of initial stages of HD development at the cellular and molecular level can contribute to better understanding of human disease pathology.
Support CHDI Foundation (A-5378), TACR (TA01011466), European Regional Development FundCZ.1.05/2.1.00/03.0124, RVO 67985904.