An “Exacerbate-reverse” Strategy in Yeast Identifies Histone Deacetylase Inhibition as a Correction for Cholesterol and Sphingolipid Transport Defects in Human Niemann-Pick Type C Disease
ABSTRACT Niemann-Pick type C (NP-C) disease is a fatal lysosomal lipid storage disorder for which no effective therapy exists. A genome-wide, conditional synthetic lethality screen was performed using the yeast model of NP-C disease during anaerobiosis, an auxotrophic condition that requires yeast to utilize exogenous sterol. We identified 12 pathways and 13 genes as modifiers of the absence of the yeast NPC1 ortholog (NCR1) and quantified the impact of loss of these genes on sterol metabolism in ncr1Δ strains grown under viable aerobic conditions. Deletion of components of the yeast NuA4 histone acetyltransferase complex in ncr1Δ strains conferred anaerobic inviability and accumulation of multiple sterol intermediates. Thus, we hypothesize an imbalance in histone acetylation in human NP-C disease. Accordingly, we show that the majority of the 11 histone deacetylase (HDAC) genes are transcriptionally up-regulated in three genetically distinct fibroblast lines derived from patients with NP-C disease. A clinically approved HDAC inhibitor (suberoylanilide hydroxamic acid) reverses the dysregulation of the majority of the HDAC genes. Consequently, three key cellular diagnostic criteria of NP-C disease are dramatically ameliorated as follows: lysosomal accumulation of both cholesterol and sphingolipids and defective esterification of LDL-derived cholesterol. These data suggest HDAC inhibition as a candidate therapy for NP-C disease. We conclude that pathways that exacerbate lethality in a model organism can be reversed in human cells as a novel therapeutic strategy. This "exacerbate-reverse" approach can potentially be utilized in any model organism for any disease.
- SourceAvailable from: Steve Meaney
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- "There is compelling evidence that both of these genes are regulated by histone acetylation status and treatment of cells with a variety of different HDACi leads to a significant increase in the expression of these genes (Gévry et al., 2003; Kim et al., 2007; Pipalia et al., 2011; Helquist et al., 2013; Maceyka et al., 2013). The increase in the expression of the mutated NPC proteins, which have some by not sufficient activity, resulted in a quantitative increase in activity which was sufficient to correct the cellular defect (Munkacsi et al., 2011; Pipalia et al., 2011; Yang et al., 2014). Due the success of the HDACi treatment in pre-clinical models, HDACi therapy is currently being trialed in a small group of NPC patients. "
ABSTRACT: Although best known as a risk factor for cardiovascular disease, cholesterol is a vital component of all mammalian cells. In addition to key structural roles, cholesterol is a vital biochemical precursor for numerous biologically important compounds including oxysterols and bile acids, as well as acting as an activator of critical morphogenic systems (e.g., the Hedgehog system). A variety of sophisticated regulatory mechanisms interact to coordinate the overall level of cholesterol in cells, tissues and the entire organism. Accumulating evidence indicates that in additional to the more "traditional" regulatory schemes, cholesterol homeostasis is also under the control of epigenetic mechanisms such as histone acetylation and DNA methylation. The available evidence supporting a role for these mechanisms in the control of cholesterol synthesis, elimination, transport and storage are the focus of this review.Frontiers in Genetics 09/2014; 5:311. DOI:10.3389/fgene.2014.00311
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- "The only step in the pathogenic cascade targeted by an approved therapy is miglustat, an orally available inhibitor of glycosphingolipid biosynthesis that reduces GSL storage (Patterson et al., 2007; Platt et al., 1994). Several other therapeutic targets downstream of the NPC1 protein have been validated using small molecule monotherapies in the NPC1 mouse model (Alvarez et al., 2008; Davidson et al., 2009; Liu et al., 2009; Lloyd-Evans et al., 2008; Munkacsi et al., 2011; Pipalia et al., 2011; Smith et al., 2009; Zervas et al., 2001; reviewed by Davidson and Walkley, 2010; Madra and Sturley, 2010). In previous studies, we tested three therapeutics that target unique aspects of the pathogenic cascade, all of which results in survival benefit in a mouse model of NPC1 disease when evaluated as monotherapies; miglustat (Zervas et al., 2001), the non-steroidal anti-inflammatory drug (NSAID) ibuprofen (Smith et al., 2009) and the intracellular calcium modulator curcumin (Lloyd-Evans et al., 2008). "
ABSTRACT: Objectives Niemann-Pick disease type C (NPC) is a neurodegenerative lysosomal storage disorder characterised by the storage of multiple lipids, reduced lysosomal calcium levels, impaired late endosome:lysosome fusion and neuroinflammation. NPC is caused by mutations in either of two genes, NPC1 or NPC2, which are believed to function in a common cellular pathway, the function of which remain unclear. The complexity of the pathogenic cascade in NPC disease provides a number of potential clinical intervention points. To date, drugs that target pivotal stages in the pathogenic cascade have been tested as monotherapies or in combination with a second agent, showing additive or synergistic benefit. In this study, we have investigated whether we can achieve greater therapeutic benefit in the Npc1-/- mouse by combining three therapies that each target unique aspects of the pathogenic cascade. Methods We have treated Npc1-/- mice with miglustat that targets sphingolipid synthesis and storage, curcumin that compensates for the lysosomal calcium defect by elevating cytosolic calcium, and the non-steroidal anti-inflammatory drug ibuprofen to reduce central nervous system inflammation. Results/interpretation We have found that triple combination therapy has a greater neuroprotective benefit compared with single and dual therapies, increasing the time period Npc1-/- mice maintained body weight and motor function and maximally delaying the onset of Purkinje cell loss. In addition, ibuprofen selectively reduced microglial activation, while curcumin had no anti-inflammatory effects, indicating differential mechanisms of action for these two therapies. When taken together, these results demonstrate that targeting multiple unique steps in the pathogenic cascade maximises clinical benefit in a mouse model of NPC1 disease.Neurobiology of Disease 07/2014; 67. DOI:10.1016/j.nbd.2014.03.001 · 5.08 Impact Factor
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- "Despite lacking a nervous system, yeast is a powerful single-cell model organism for genome-wide analysis of biological functions (Fig. 5). Unfortunately, loss of the yeast NPC1 ortholog Ncr1 does not cause a phenotype that can be easily explored by high-throughput screening assays to gain insight into NPC1 cellular pathways (Munkacsi et al., 2011). By contrast, the filamentous fungus Fusarium graminearum does have a discernible NPC storage phenotype upon deletion of the NPC1 ortholog (Breakspear et al., 2011). "
ABSTRACT: Understanding neurodegenerative disease progression and its treatment requires the systematic characterization and manipulation of relevant cell types and molecular pathways. The neurodegenerative lysosomal storage disorder Niemann-Pick disease type C (NPC) is highly amenable to genetic approaches that allow exploration of the disease biology at the organismal, cellular and molecular level. Although NPC is a rare disease, genetic analysis of the associated neuropathology promises to provide insight into the logic of disease neural circuitry, selective neuron vulnerability and neural-glial interactions. The ability to control the disorder cell-autonomously and in naturally occurring spontaneous animal models that recapitulate many aspects of the human disease allows for an unparalleled dissection of the disease neurobiology in vivo. Here, we review progress in mouse-model-based studies of NPC disease, specifically focusing on the subtype that is caused by a deficiency in NPC1, a sterol-binding late endosomal membrane protein involved in lipid trafficking. We also discuss recent findings and future directions in NPC disease research that are pertinent to understanding the cellular and molecular mechanisms underlying neurodegeneration in general.Disease Models and Mechanisms 08/2013; 6(5). DOI:10.1242/dmm.012385 · 4.97 Impact Factor