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The study of variations in human neurodevelopment and cognition is limited by the availability of experimental models. While animal models only partially recapitulate the human brain development, genetics, and heterogeneity, human-induced pluripotent stem cells can provide an attractive experimental alternative. However, cellular reprogramming and further differentiation techniques are costly and time-consuming and therefore, studies using this approach are often limited to a small number of samples. In this study, we describe a rapid and cost-effective method to reprogram somatic cells and the direct generation of cortical organoids in a 96-well format. Our data are a proof-of-principle that a large cohort of samples can be generated for experimental assessment of the human neural development.

Macroautophagy (hereafter autophagy) is a key pathway in neurodegeneration. Despite protective actions, autophagy may contribute to neuron demise when dysregulated. Here we consider X-linked spinal and bulbar muscular atrophy (SBMA), a repeat disorder caused by polyglutamine-expanded androgen receptor (polyQ-AR). We found that polyQ-AR reduced long-term protein turnover and impaired autophagic flux in motor neuron-like cells. Ultrastructural analysis of SBMA mice revealed a block in autophagy pathway progression. We examined the transcriptional regulation of autophagy and observed a functionally significant physical interaction between transcription factor EB (TFEB) and AR. Normal AR promoted, but polyQ-AR interfered with, TFEB transactivation. To evaluate physiological relevance, we reprogrammed patient fibroblasts to induced pluripotent stem cells and then to neuronal precursor cells (NPCs). We compared multiple SBMA NPC lines and documented the metabolic and autophagic flux defects that could be rescued by TFEB. Our results indicate that polyQ-AR diminishes TFEB function to impair autophagy and promote SBMA pathogenesis.

Spinal bulbar muscular atrophy (SBMA) is a motor neuron disease caused by toxic gain of function of the androgen receptor (AR). Previously, we found that co-regulator binding through the activation function-2 (AF2) domain of AR is essential for pathogenesis, suggesting that AF2 may be a potential drug target for selective modulation of toxic AR activity. We screened previously identified AF2 modulators for their ability to rescue toxicity in a Drosophila model of SBMA. We identified two compounds, tolfenamic acid (TA) and 1-[2-(4-methylphenoxy)ethyl]-2-[(2-phenoxyethyl)sulfanyl]-1H-benzimidazole (MEPB), as top candidates for rescuing lethality, locomotor function and neuromuscular junction defects in SBMA flies. Pharmacokinetic analyses in mice revealed a more favorable bioavailability and tissue retention of MEPB compared with TA in muscle, brain and spinal cord. In a preclinical trial in a new mouse model of SBMA, MEPB treatment yielded a dose-dependent rescue from loss of body weight, rotarod activity and grip strength. In addition, MEPB ameliorated neuronal loss, neurogenic atrophy and testicular atrophy, validating AF2 modulation as a potent androgen-sparing strategy for SBMA therapy., Author(s): Nisha M Badders [1]; Ane Korff [1, 2]; Helen C Miranda [3]; Pradeep K Vuppala [4]; Rebecca B Smith [1]; Brett J Winborn [1]; Emmanuelle R Quemin [1]; Bryce [...]

Huntington's disease (HD) is a progressive neurodegenerative disorder caused by a CAG trinucleotide repeat expansion in the huntingtin (HTT) gene, which encodes a polyglutamine tract in the HTT protein. We found that peroxisome proliferator- activated receptor delta (PPAR-δ) interacts with HTT and that mutant HTT represses PPAR-δ-mediated transactivation. Increased PPAR-δ transactivation ameliorated mitochondrial dysfunction and improved cell survival of neurons from mouse models of HD. Expression of dominant-negative PPAR-δ in the central nervous system of mice was sufficient to induce motor dysfunction, neurodegeneration, mitochondrial abnormalities and transcriptional alterations that recapitulated HD-like phenotypes. Expression of dominant-negative PPAR-δ specifically in the striatum of medium spiny neurons in mice yielded HD- like motor phenotypes, accompanied by striatal neuron loss. In mouse models of HD, pharmacologic activation of PPAR-δ using the agonist KD3010 improved motor function, reduced neurodegeneration and increased survival. PPAR-δ activation also reduced HTT-induced neurotoxicity in vitro and in medium spiny-like neurons generated from stem cells derived from individuals with HD, indicating that PPAR-δ activation may be beneficial in HD and related disorders., The PPARs are ligand-activated transcription factors that belong to the nuclear hormone receptor superfamily. The three subtypes--termed PPAR-α, PPAR-δ and PPAR-γ--serve as lipid sensors in response to increased energy requirements [...]