A novel small molecule HSP90 inhibitor, NXD30001, differentially induces heat shock proteins in nervous tissue in culture and in vivo

Abstract

Heat shock proteins (HSPs) are attractive therapeutic targets for neurodegenerative diseases, such as amyotrophic lateral sclerosis (ALS), characterized by aberrant formation of protein aggregates. Although motor neurons have a high threshold for activation of HSP genes, HSP90 inhibitors are effective inducers. This study evaluated NXD30001, a novel, small molecule HSP90 inhibitor based on the radicicol backbone, for its ability to induce neuronal HSPs and for efficacy in an experimental model of ALS based on mutations in superoxide-dismutase 1 (SOD1). In motor neurons of dissociated murine spinal cord cultures, NXD30001-induced expression of HSP70/HSPA1 (iHSP70) and its co-chaperone HSP40/DNAJ through activation of HSF1 and exhibited a protective profile against SOD1 G93A similar to geldanamycin, but with less toxicity. Treatment prevented protein aggregation, mitochondrial fragmentation, and motor neuron death, important features of mutant SOD1 toxicity, but did not effectively prevent aberrant intracellular Ca 2+ accumulation. NXD30001 distributed to brain and spinal cord of wild-type and SOD1G93A transgenic mice following intraperitoneal injection; however, unlike in culture, in vivo levels of SOD1 were not reduced. NXD30001-induced expression of iHSP70 in skeletal and cardiac muscle and, to a lesser extent, in kidney, but not in liver, spinal cord, or brain, with either single or repeated administration. NXD30001 is a very useful experimental tool in culture, but these data point to the complex nature of HSP gene regulation in vivo and the necessity for early evaluation of the efficacy of novel HSP inducers in target tissues in vivo.

Development-dependent regulation of molecular chaperones after hypoxia–ischemia

“…Previous studies have shown that increased expression of even a single molecular chaperone can offer neuroprotection in animal ischemia or ischemia-like cell culture models (Zhan et al, 2010; Kim et al, 2012; Stetler et al, 2012). Consistently, drug activation of HSF1 confers robust cell protection in cellular, worm, fly, and mouse or rat protein misfolding stress models including brain ischemia animal models (Lu et al, 2002; Harrison et al, 2008; Batulan et al, 2006; Neef et al, 2010; Liu et al, 2011; Verma et al, 2014; Ambade et al, 2014; Cha et al, 2014). This study shows that the levels of HSR and HSF1 activation are high in mature, but low in neonatal brain after HI.…”

“…Activation of HSF1 leads to its nuclear translocation and induction of more than 3000 genes; including the classical molecular chaperone genes such as HSP70, Hdj1, Hdj4, Hdj6, HSP27 and HSP25, as well as the non-classical heat shock genes (Song et al, 2010; Islam et al, 2013). For that reason, drug-induced activation of HSR has been used as an experimental strategy to show that induction of HSR offers strong cell protection in cellular, worm, fly, and mouse or rat models (e.g., Lu et al, 2002; Harrison et al, 2008; Batulan et al, 2006; Neef et al, 2010; Liu et al, 2011; Verma et al, 2014; Ambade et al, 2014; Cha et al, 2014). However, activation of HSF1 may also have undesired effects.…”

Role of HSP70 in motoneuron survival after excitotoxic stress in a rat spinal cord injury model in vitro

“…To evaluate the specificity of HSP70 0 s role in excitotoxicity, we also investigated the effects of inhibition of HSP90 with geldanamycin (GA) at 10-20 nM concentration (Zinkie et al, 2013;Cha et al, 2014). For each GA treatment at least three spinal cords were employed.…”

Molecular chaperones and neuronal proteostasis

“…Reduction of tau pathology and tau phosphorylation in mice [126,27]; polyQ in flies [123] [127] but in mice effect was only temporary due to epigenetic changes [128]; SBMA mouse model [129]; SCA3 mouse model [130] effective on mutant SOD1 cells but effect in mice questionable [131]; α-synuclein toxicity in flies [132] [17]; rhodopsin RP in rats [133].…”