Biology subjects

Chughtai, U.

Publications and source records attributed to Chughtai, U..

3 recordsLinked to original sources

bioRxiv2026

Phenotypic screening in Parkinson's iPSC-dopamine neurons identifies the FASN-SREBP1 axis as a potential therapeutic target

Parkinson's disease (PD) remains highly challenging to model in vitro, particularly when seeking robust functional phenotypes for target discovery. Patient-derived induced pluripotent stem cell dopaminergic neurons (iPSC-DANs) offer a promising platform to address this challenge. Because calcium dyshomeostasis is well-described in PD pathophysiology, it offers a platform for phenotypic screening. We have previously shown that GBA-N370S iPSC-DANs display impaired intracellular calcium release. Here, we used this disease-relevant phenotype to undertake a 4,108-compound phenotypic screen in GBA-N370S (GBA-NS) iPSC-DANs. This screen identified fatty acid synthase (FASN) as the most enriched protein target. The ability of compounds to rescue calcium release correlated with biochemical potency against FASN across multiple chemical series. We confirmed that FASN knockdown increased intracellular calcium release, supporting an on-target effect. Untargeted lipidomics demonstrated broad remodelling of the neuronal lipidome after FASN inhibition, confirming target engagement. FASN inhibition also increased active a-glucocerebrosidase (GCase), reduced extracellular a-synuclein release and ER stress, and altered RASGRF1 expression. Mechanistically, FASN inhibition activated sterol regulatory element-binding protein 1 (SREBP1), and SREBP1 overexpression alone was sufficient to increase intracellular calcium release, identifying a FASN-SREBP1-calcium homeostasis axis in human neurons. Finally, the FASN inhibitor BI 99179 achieved brain exposure and reduced brain fatty acid levels while inducing an SRE-associated transcriptional response in a Parkinson's mouse model, providing evidence of in vivo target engagement. These findings establish patient iPSC-neuron functional screening as a tractable discovery platform to identify targets which can be taken in vivo and nominate the FASN-SREBP1 axis as a candidate therapeutic pathway in PD.

neuroscience↗

bioRxiv2021

A novel post-translational proteomics platform identifies neurite outgrowth impairments in Parkinson's disease GBA-N370S dopamine neurons

The causes of Parkinsons disease (PD) likely involve complex interactions between environmental factors and susceptibility genes with variants at the GBA locus encoding the glucocerebrosidase (GCase) enzyme being the strongest common genetic risk factor for PD. To understand GBA-related disease mechanisms, we used a novel multipart-enrichment proteomics and post-translational modification workflow to simultaneously identify peptides with phosphorylation, reversible cysteine-modifications or sialylated N-linked glycosylation, alongside unmodified proteins. We identified large numbers of dysregulated proteins and post-translational modifications (PTMs) in heterozygous GBA-N370S PD patient induced pluripotent stem cells (iPSC)-derived dopamine neurons. Alterations in glycosylation status of lysosomal proteins identified disturbances in the autophagy-lysosomal pathway, concurrent with upstream perturbations in mTOR phosphorylation and activity in GBA-N370S iPSC-dopamine neurons. In addition, the strategy revealed several native and modified proteins encoded by PD-associated genes to be dysregulated in GBA-N370S neurons, enhancing our understanding of the wider role of GBA mutations on the neuronal proteome. Integrated pathway analysis of all datasets revealed impaired neuritogenesis in GBA-N370S PD iPSC-dopamine neurons and identified tau (MAPT) as a key mediator of this process. Using a functional assay, we confirmed neurite outgrowth deficits in GBA-N370S PD neurons and a central role for tau in this process. Furthermore, pharmacological restoration of GCase activity in GBA-N370S PD patient neurons rescued the neurite outgrowth deficit. Overall, this study demonstrates the potential of PTMomics to elucidate novel neurodegeneration-associated pathways and identify phenotypes and potential drug targets in complex disease models.

neuroscience↗

bioRxiv2021

FAN1 nuclease activity affects CAG expansion and age at onset of Huntington's disease

The age at onset of motor symptoms in Huntingtons disease (HD) is driven by HTT CAG repeat length but modified by other genes. We used exome sequencing of 683 HD patients with extremes of onset or phenotype relative to CAG length to identify rare variants associated with clinical effect. We identified damaging coding variants in candidate modifier genes from prior genome-wide association studies associated with altered HD onset or severity. Variants in FAN1 clustered in its DNA-binding and nuclease domains and were associated predominantly with earlier onset HD. Nuclease activities of these variants correlated with residual age at motor onset of HD. Mutating endogenous FAN1 to a nuclease-inactive form in an induced pluripotent stem cell model of HD led to rates of CAG expansion comparable to those observed with complete FAN1 knock out. Together, these data implicate FAN1 nuclease activity in slowing somatic repeat expansion and hence onset of HD.

neuroscience↗