Interactome network analysis identifies multiple caspase-6 interactors involved in the pathogenesis of HD

Caspase-6 (CASP6) has emerged as an important player in Huntington disease (HD), Alzheimer disease (AD) and cerebral ischemia, where it is activated early in the disease process. CASP6 also plays a key role in axonal degeneration, further underscoring the importance of this protease in neurodegenerative pathways. As a protein's function is modulated by its protein-protein interactions we performed a high throughput yeast-2-hybrid (Y2H) screen against ∼17,000 human proteins to gain further insight into the function of CASP6. We identified a high confidence list of 87 potential CASP6 interactors. From this list, 61% are predicted to contain a CASP6 recognition site. Of nine candidate substrates assessed, six are cleaved by CASP6. Proteins that did not contain a predicted CASP6 recognition site were assessed using a LUMIER assay approach and 51% were further validated as interactors by this method. Of note, 54% of the high-confidence interactors identified show alterations in human HD brain at the mRNA level, and there is a significant enrichment for previously validated huntingtin (HTT) interactors. One protein of interest, STK3, a proapoptotic kinase, was validated biochemically to be a CASP6 substrate. Furthermore, our results demonstrate that in striatal cells expressing mutant huntingtin (mHTT) an increase in full length and fragment levels of STK3 are observed. We further show that caspase-3 is not essential for the endogenous cleavage of STK3. Characterization of the interaction network provides important new information regarding key pathways of interactors of CASP6 and highlights potential novel therapeutic targets for HD, AD and cerebral ischemia

Loss-of-function mutations in UDP-Glucose 6-Dehydrogenase cause recessive developmental epileptic encephalopathy

Developmental epileptic encephalopathies are devastating disorders characterized by intractable epileptic seizures and developmental delay. Here, we report an allelic series of germline recessive mutations in UGDH in 36 cases from 25 families presenting with epileptic encephalopathy with developmental delay and hypotonia. UGDH encodes an oxidoreductase that converts UDP-glucose to UDP-glucuronic acid, a key component of specific proteoglycans and glycolipids. Consistent with being loss-of-function alleles, we show using patients’ primary fibroblasts and biochemical assays, that these mutations either impair UGDH stability, oligomerization, or enzymatic activity. In vitro, patient-derived cerebral organoids are smaller with a reduced number of proliferating neuronal progenitors while mutant ugdh zebrafish do not phenocopy the human disease. Our study defines UGDH as a key player for the production of extracellular matrix components that are essential for human brain development. Based on the incidence of variants observed, UGDH mutations are likely to be a frequent cause of recessive epileptic encephalopathy

Inhibition of Excessive Monoamine Oxidase A/B Activity Protects Against Stress-induced Neuronal Death in Huntington Disease

10.1007/s12035-014-8974-4Molecular Neurobiology5231850-186

Histone modifications and p53 binding poise the p21 promoter for activation in human embryonic stem cells

10.1038/srep28112Scientific Reports62811

Modeling Doxorubicin-Induced Cardiotoxicity in Human Pluripotent Stem Cell Derived-Cardiomyocytes

10.1038/srep25333Scientific Reports62533

Novel mutation in HTRA1 in a family with diffuse white matter lesions and inflammatory features

10.1212/NXG.0000000000000345Neurology: Genetics5434

Cholesterol defect is marked across multiple rodent models of Huntington's disease and is manifest in astrocytes

Brain cholesterol, which is synthesized locally, is a major component of myelin and cell membranes and participates in neuronal functions, such as membrane trafficking, signal transduction, neurotransmitter release, and synaptogenesis. Here we show that brain cholesterol biosynthesis is reduced in multiple transgenic and knock-in Huntington's disease (HD) rodent models, arguably dependent on deficits in mutant astrocytes. Mice carrying a progressively increased number of CAG repeats show a more evident reduction in cholesterol biosynthesis. In postnatal life, the cholesterol-dependent activities of neurons mainly rely on the transport of cholesterol from astrocytes on ApoE-containing particles. Our data show that mRNA levels of cholesterol biosynthesis and efflux genes are severely reduced in primary HD astrocytes, along with impaired cellular production and secretion of ApoE. Consistently, in CSF of HD mice, ApoE is mostly associated with smaller lipoproteins, indicating reduced cholesterol transport on ApoE-containing lipoproteins circulating in the HD brain. These findings indicate that cholesterol defect is robustly marked in HD animals, implying that strategies aimed at selectively modulating brain cholesterol metabolism might be of therapeutic significanc

Partial rescue of some features of Huntington Disease in the genetic absence of caspase-6 in YAC128 mice

10.1016/j.nbd.2014.12.030Neurobiology of Disease7624-3

Unbiased Profiling of Isogenic Huntington Disease hPSC-Derived CNS and Peripheral Cells Reveals Strong Cell-Type Specificity of CAG Length Effects

10.1016/j.celrep.2019.02.008Cell Reports2692494-2508000000

pS421 huntingtin modulates mitochondrial phenotypes and confers neuroprotection in an HD hiPSC model

10.1038/s41419-020-02983-zCell Death and Disease11980