Biology subjects

Marchionini, D.

Publications and source records attributed to Marchionini, D..

3 recordsLinked to original sources

bioRxiv2026

Hepatic huntingtin loss drives an acute phase response and liver injury in multiple mouse models

Multiple therapeutic strategies are being developed to slow Huntingtons disease (HD) progression through targeted reduction of huntingtin (HTT) protein or mRNA. Despite HTTs discovery over 30 years ago, its cellular functions remain incompletely understood, and the long-term consequences of HTT-lowering therapies remain unclear. We previously demonstrated that hepatic HTT loss in mice disrupts hepatocyte zonation and metabolism. Here, we investigate the physiological consequences of hepatic Htt loss. Across multiple models of Htt loss--including ubiquitous and hepatocyte-specific genetic knockouts and a therapeutically relevant Htt-targeting siRNA--there was elevated expression of IL-6/STAT3-driven acute phase response genes. Single-nucleus RNA sequencing reveals a zonal pattern of hepatocyte stress, most highly upregulated in pericentral hepatocytes, and identifies a distinct pericentral cluster of stressed hepatocytes that was enriched [~]9.6-fold following Htt knockout. Histological examination reveals that Htt loss results in increased hepatic pathology, including hepatic intranuclear inclusions, apoptosis, and necrosis, as well as prevalence of granulomas. Transcriptomic analysis reveals significant upregulation of metallothionein genes following Htt loss, as confirmed by elevated plasma metallothionein-1 (MT1) levels in knockout mice. These findings underscore important safety considerations for HTT-lowering therapies and suggest candidate biomarkers for monitoring hepatic off-target effects in clinical trials.

molecular biology↗

bioRxiv2023

Early whole-body mutant huntingtin lowering preserves proteins and lipids important for synapse function and white matter maintenance in the LacQ140 mouse model

BackgroundExpansion of a triplet repeat tract in exon1 of the HTT gene causes Huntingtons disease (HD). The mutant HTT protein (mHTT) has numerous aberrant interactions with diverse, pleiomorphic effects. No disease modifying treatments exist but lowering mutant huntingtin (mHTT) by gene therapy is a promising approach to treat Huntingtons disease (HD). It is not clear when lowering should be initiated, how much lowering is necessary and for what duration lowering should occur to achieve benefits. Furthermore, the effects of mHTT lowering on brain lipids have not been assessed. MethodsUsing a mHtt-inducible mouse model we analyzed whole body mHtt lowering initiated at different ages and sustained for different time-periods. Subcellular fractionation (density gradient ultracentrifugation), protein chemistry (gel filtration, western blot, and capillary electrophoresis immunoassay), liquid chromatography and mass spectrometry of lipids, and bioinformatic approaches were used to test effects of mHTT transcriptional lowering. ResultsmHTT protein in cytoplasmic and synaptic compartments of the caudate putamen, which is most affected in HD, was reduced 38-52%. Little or no lowering of mHTT occurred in nuclear and perinuclear regions where aggregates formed at 12 months of age. mHtt transcript repression partially or fully preserved select striatal proteins (SCN4B, PDE10A). Total lipids in striatum were reduced in LacQ140 mice at 9 months and preserved by early partial mHtt lowering. The reduction in total lipids was due in part to reductions in subclasses of ceramide (Cer), sphingomyelin (SM), and monogalactosyldiacylglycerol (MGDG), which are known to be important for white matter structure and function. Lipid subclasses phosphatidylinositol (PI), phosphatidylserine (PS), and bismethyl phosphatidic acid (BisMePA) were also changed in LacQ140 mice. Levels of all subclasses other than ceramide were preserved by early mHtt lowering. Pathway enrichment analysis of RNAseq data imply a transcriptional mechanism is responsible in part for changes in myelin lipids, and some but not all changes can be rescued by mHTT lowering. ConclusionsOur findings suggest that early and sustained reduction in mHtt can prevent changes in levels of select striatal proteins and most lipids but a misfolded, degradation-resistant form of mHTT hampers some benefits in the long term.

neuroscience↗

bioRxiv2020

HAP40 is a conserved central regulator of Huntingtin and a specific modulator of mutant Huntingtin toxicity

Perturbation of Huntingtin (HTT)s physiological function is one postulated pathogenic factor in Huntingtons disease (HD). However, little is known how HTT is regulated in vivo. In a proteomic study, we isolated a novel [~]40kDa protein as a strong binding partner of Drosophila HTT and demonstrated it was the functional ortholog of HAP40, an HTT associated protein shown recently to modulate HTTs conformation but with unclear physiological and pathologic roles. We showed that in both flies and human cells, HAP40 maintained conserved physical and functional interactions with HTT, loss of HAP40 resulted in similar phenotypes as HTT knockout, including animal viability and autophagy, and more strikingly, HAP40 depletion significantly reduced the levels of endogenous HTT, while HAP40 was mostly degraded via the proteasome in the absence of HTT. Interestingly, polyglutamine expansion in HTT did not affect its affinity for HAP40. However, HAP40 modulated HD pathogenesis in Drosophila model by regulating the overall protein levels and the toxicity of full-length mutant HTT. Together, our study uncovers a conserved mechanism governing the stability and in vivo functions of HTT, and demonstrates that HAP40 is a central and positive regulator of HTT, a potential modulator of HD pathogenesis and a promising candidate for "HTT-lowering" strategy against HD.

neuroscience↗