Biology subjects

Maiuri, T.

Publications and source records attributed to Maiuri, T..

4 recordsLinked to original sources

bioRxiv2025

Direct Measure of DNA Damage in Huntington Disease Reveals Elevated Oxidative Genotoxic Stress and Dysfunctional DNA Repair

DNA damage repair (DDR) pathway proteins are genetic modifiers of Huntington disease (HD) age of onset and severity. Deficient DDR in HD at the first steps of poly ADP-ribosylation makes DNA damage quantification by traditional downstream DNA damage response markers inaccurate. Repair Assisted Damage Detection (RADD) allows for an accurate direct assessment of oxidative DNA damage, a DDR pathway in which huntingtin protein directly participates. Using RADD, we show that human HD-derived cells have elevated oxidative DNA damage and assess the effect of relevant HD therapeutic targets in rescuing this phenotype. Using huntingtin protein level lowering, we define a dysfunctional role of mutant huntingtin in oxidative DDR. We show that ataxia-telangiectasia mutated (ATM) signaling is deficient and that ATM inhibition rescues elevated oxidative DNA damage in HD cells. In contrast, we show that N6-furfuryladenine (N6FFA) treatment, to increase huntingtin phosphorylation within the amino terminal N17 domain (p-N17), is not effective at restoring HD DDR but reveals dysfunctional N6FFA mediated DDR signaling. We propose a model in which elevated DNA damage arises from both aberrant mutant huntingtin involvement in oxidative DDR and the impairment of oxidative DDR pathways, such as ATM kinase activity, N6FFA processing, and poly ADP-ribose signaling in HD. This highlights the importance of using direct measures of DNA damage such as RADD, rather than measures of a DNA damage response pathway.

cell biology↗

bioRxiv2022

Poly ADP-Ribose Signaling is Dysregulated in Huntington Disease Patients

Huntington disease (HD) is a genetic neurodegenerative disease caused by CAG expansion in the Huntingtin (HTT) gene, translating to an expanded polyglutamine tract in the huntingtin (HTT) protein. Age at disease onset correlates to CAG repeat length but varies by decades between individuals with identical repeat lengths. Genome-wide association studies link HD modification to DNA repair and mitochondrial health pathways. Clinical studies show elevated DNA damage in HD, even at the premanifest stage. A major DNA repair node influencing neurodegenerative disease is the PARP pathway. Accumulation of poly ADP-ribose (PAR) has been implicated in Alzheimer and Parkinson diseases, as well as cerebellar ataxia. We report that HD mutation carriers have lower cerebrospinal fluid PAR levels than healthy controls, starting at the premanifest stage. Human HD iPSC-derived neurons and patient- derived fibroblasts have diminished PAR response in the context of elevated DNA damage. We have defined a PAR-binding motif in huntingtin, detected huntingtin complexed with PARylated proteins in human cells during stress, and localized huntingtin to mitotic chromosomes upon inhibition of PAR degradation. Direct huntingtin PAR binding was measured by fluorescence polarization and visualized by atomic force microscopy at the single molecule level. While wild type and mutant huntingtin did not differ in their PAR binding ability, purified wild type huntingtin protein increased in vitro PARP1 activity while mutant huntingtin did not. These results provide insight into an early molecular mechanism of HD, suggesting possible targets for the design of early preventive therapies. Significance statementA consensus on dysfunctional DNA repair has emerged in neurodegenerative disease research, with elevated poly ADP-ribose (PAR) signaling more recently implicated. In contrast, we have identified a deficient PAR response in Huntingtons disease (HD) patient spinal fluid samples and cells. This may be explained by the inability of huntingtin protein bearing the HD-causing mutation to stimulate production of PAR the way the wild type protein does. Since drugs that target PAR production and degradation have already been developed, these findings present an exciting avenue for therapeutic intervention for HD.

neuroscience↗

bioRxiv2019

Spinocerebellar Ataxia Type 1 protein Ataxin-1 is signalled to DNA damage by Ataxia Telangiectasia Mutated kinase

Spinocerebellar Ataxia Type 1 (SCA1) is an autosomal dominant neurodegenerative disorder caused by a polyglutamine expansion in the ataxin-1 protein. Recent genetic correlational studies have implicated DNA damage repair pathways in modifying the age at onset of disease symptoms in SCA1 and Huntingtons Disease, another polyglutamine expansion disease. We demonstrate that both endogenous and transfected ataxin-1 localizes to sites of DNA damage, which is impaired by polyglutamine expansion. This response is dependent on ataxia telangiectasia mutated (ATM) kinase activity. Further, we characterize an ATM phosphorylation motif within ataxin-1 at serine 188. We show reduction of the Drosophila ATM homolog levels in a ATXN1[82Q] Drosophila model through shRNA or genetic cross ameliorates motor symptoms. These findings offer a possible explanation as to why DNA repair was implicated in SCA1 pathogenesis by past studies. The similarities between the ataxin-1 and the huntingtin responses to DNA damage provide further support for a shared pathogenic mechanism for polyglutamine expansion diseases.

cell biology↗

bioRxiv2018

A Patient-Derived Cellular Model for Huntington Disease Reveals Phenotypes at Clinically Relevant CAG Lengths

The huntingtin protein participates in several cellular processes that are disrupted when the polyglutamine tract is expanded beyond a threshold of 37 CAG DNA repeats in Huntingtons disease (HD). Cellular biology approaches to understand these functional disruptions in HD have primarily focused on cell lines with synthetically long CAG length alleles that clinically represent outliers in this disease and a more severe form of HD that lacks age-onset. Patient-derived fibroblasts are limited to a finite number of passages before succumbing to cellular senescence. We used human telomerase reverse transcriptase (hTERT) to immortalize fibroblasts taken from individuals of varying age, sex, disease onset and CAG repeat length, which we have termed TruHD cells. TruHD cells display classic HD phenotypes of altered morphology, size and growth rate, increased sensitivity to oxidative stress, aberrant ADP/ATP ratios and hypophosphorylated huntingtin protein. We additionally observed dysregulated ROS-dependent huntingtin localization to nuclear speckles in HD cells. We report the generation and characterization of a human, clinically relevant cellular model for investigating disease mechanisms in HD at the single cell level, which, unlike transformed cell lines, maintains TP53 function critical for huntingtin transcriptional regulation and genomic integrity.

cell biology↗