Biology subjects

Gaertner, A.

Publications and source records attributed to Gaertner, A..

4 recordsLinked to original sources

bioRxiv2026

The DES-p.A120P mutation associated with biventricular arrhythmogenic cardiomyopathy has a dominant-negative effect on desmin filament assembly

Desmin is a muscle-specific intermediate filament protein, which connects different cell organelles and is highly relevant for the structural integrity of cardiomyocytes. Mutations in the DES gene, cause different cardiomyopathies including arrhythmogenic cardiomyopathy. In this study, we functionally investigate the novel genetic variant DES-p.A120P using cell transfection experiments including cardiomyocytes derived from induced pluripotent stem cells in combination with confocal microscopy. These experiments reveal that the filament assembly of desmin-p.A120P is disturbed - even when co-expressed with wild-type desmin. In conclusion, the functional characterization of desmin-p.A120P supports the classification as a pathogenic variant associated with arrhythmogenic cardiomyopathy.

genetics↗

bioRxiv2024

Suppression of Huntington's Disease Somatic Instability by Transcriptional Repression and Direct CAG Repeat Binding

Huntingtons disease (HD) arises from a CAG expansion in the huntingtin (HTT) gene beyond a critical threshold. A major thrust of current HD therapeutic development is lowering levels of mutant HTT mRNA (mHTT) and protein (mHTT) with the aim of reducing the toxicity of these product(s). Human genetic data also support a key role for somatic instability (SI) in HTTs CAG repeat - whereby it lengthens with age in specific somatic cell types - as a key driver of age of motor dysfunction onset. Thus, an attractive HD therapy would address both mHTT toxicity and SI, but to date the relationship between SI and HTT lowering remains unexplored. Here, we investigated multiple therapeutically-relevant HTT-lowering modalities to establish the relationship between HTT lowering and SI in HD knock-in mice. We find that repressing transcription of mutant Htt (mHtt) provides robust protection from SI, using diverse genetic and pharmacological approaches (antisense oligonucleotides, CRISPR-Cas9 genome editing, the Lac repressor, and virally delivered zinc finger transcriptional repressor proteins, ZFPs). However, we find that small interfering RNA (siRNA), a potent HTT-lowering treatment, lowers HTT levels without influencing SI and that SI is also normal in mice lacking 50% of total HTT levels, suggesting HTT levels, per se, do not modulate SI in trans. Remarkably, modified ZFPs that bind the mHtt locus, but lack a repressive domain, robustly protect from SI, despite not reducing HTT mRNA or protein levels. These results have important therapeutic implications in HD, as they suggest that DNA-targeted HTT-lowering treatments may have significant advantages compared to other HTT-lowering approaches, and that interaction of a DNA-binding protein and HTTs CAG repeats may provide protection from SI while sparing HTT expression.

neuroscience↗

bioRxiv2023

Atlas of DES (desmin) variants: Impact of variants located within the head domain on filament assembly

Desmin is a muscle-specific intermediate filament protein, which plays a significant role in providing structural integrity of cardiomyocytes by connecting different cell organelles and multi-protein complexes. DES mutations cause cardiomyopathies and skeletal myopathies. Most of these pathogenic mutations are localized in the highly conserved rod domain and affect the filament assembly. However, the impact of DES variants within the N-terminal head domain on the filament assembly process is widely unknown. Therefore, we inserted a set of 85 different head domain variants with unknown significance from human genetic databases in expression constructs and investigated their impact on filament formation in cell culture in combination with confocal microscopy. The majority of these desmin variants do not affect the filament assembly. However, the desmin variants -p.S13P, -p.N107D, -p.E108G and -p.K109E significantly inhibit the filament assembly. Additionally, we expressed and purified recombinant desmin and investigated the filament assembly defects by atomic force microscopy verifying these findings at the single molecular level. Furthermore, we truncated systematically the head domain to investigate which general parts of this domain are necessary for filament assembly. In summary, our functional investigations might be relevant for the classification of novel DES variants and the genetic counselling of patients carrying desmin head variants.

cell biology↗

bioRxiv2021

A novel imaging ligand as a biomarker for mutant huntingtin-lowering in Huntington's disease

Huntingtons disease (HD) is a dominantly inherited neurodegenerative disorder caused by a CAG trinucleotide expansion in the huntingtin (HTT) gene that encodes the pathologic mutant HTT (mHTT) protein with an expanded polyglutamine (PolyQ) tract. While several therapeutic programs targeting mHTT expression have advanced to clinical evaluation, no method is currently available to visualize mHTT levels in the living brain. Here we demonstrate the development of a positron emission tomography (PET) imaging radioligand with high affinity and selectivity for mHTT aggregates. This small molecule radiolabeled with 11C ([11C]CHDI-180R) enables non-invasive monitoring of mHTT pathology in the brain and can track region-and time-dependent suppression of mHTT in response to therapeutic interventions targeting mHTT expression. We further show that therapeutic agents that lower mHTT in the striatum have a functional restorative effect that can be measured by preservation of striatal imaging markers, enabling a translational path to assess the functional effect of mHTT lowering.

neuroscience↗