Biology subjects

Sanders, L. H.

Publications and source records attributed to Sanders, L. H..

3 recordsLinked to original sources

bioRxiv2023

Nuclease-dead S. aureus Cas9 downregulates alpha-synuclein and reduces mtDNA damage and oxidative stress levels in patient-derived stem cell model of Parkinson's disease

Parkinsons disease (PD) is one of the most common neurodegenerative diseases, but no disease modifying therapies have been successful in clinical translation presenting a major unmet medical need. A promising target is alpha-synuclein or its aggregated form, which accumulates in the brain of PD patients as Lewy bodies. While it is not entirely clear which alpha-synuclein protein species is disease relevant, mere overexpression of alpha-synuclein in hereditary forms leads to neurodegeneration. To specifically address gene regulation of alpha-synuclein, we developed a CRISPR interference (CRISPRi) system based on the nuclease dead S. aureus Cas9 (SadCas9) fused with the transcriptional repressor domain Krueppel-associated box to controllably repress alpha-synuclein expression at the transcriptional level. We screened single guide (sg)RNAs across the SNCA promoter and identified several sgRNAs that mediate downregulation of alpha-synuclein at varying levels. CRISPRi downregulation of alpha-synuclein in iPSC-derived neuronal cultures from a patient with an SNCA genomic triplication showed functional recovery by reduction of oxidative stress and mitochondrial DNA damage. Our results are proof-of-concept in vitro for precision medicine by targeting the SNCA gene promoter. The SNCA CRISPRi approach presents a new model to understand safe levels of alpha-synuclein downregulation and a novel therapeutic strategy for PD and related alpha-synucleinopathies.

neuroscience↗

bioRxiv2022

G2019S selective LRRK2 kinase inhibitor abrogates mitochondrial DNA damage

Pathogenic mutations in LRRK2 cause Parkinsons disease (PD). The G2019S variant is the most common, which results in abnormally high kinase activity. Compounds that target LRRK2 kinase activity are currently being developed and tested in clinical trials. We recently found that G2019S LRRK2 causes mitochondrial DNA (mtDNA) damage and treatment with multiple classes of LRRK2 kinase inhibitors at concentrations associated with dephosphorylation of LRRK2 reversed mtDNA damage to healthy control levels. Because maintaining the normal function of LRRK2 in heterozygous G2019S LRRK2 carriers while specifically targeting the G2019S LRRK2 activity could have an advantageous safety profile, we explored the efficacy of a G2019S mutant selective LRRK2 inhibitor to reverse mtDNA damage in G2019S LRRK2 models and patient cells relative to non-selective LRRK2 inhibitors. Potency of LRRK2 kinase inhibition by EB-42168, a G2019S mutant LRRK2 kinase inhibitor, and MLi-2, a nonselective inhibitor, was determined by measuring phosphorylation of LRRK2 at Ser935 and/or Ser1292 using quantitative western immunoblot analysis. The Mito DNADX assay, a novel system that allows for the accurate real-time quantification of mtDNA damage in a 96-well platform, was performed in parallel. We confirmed that EB-42168 selectively inhibits LRRK2 phosphorylation on G2019S LRRK2 relative to wild-type LRRK2. On the other hand, MLi-2 was equipotent for wild-type and G2019S LRRK2. Acute treatment with EB-42168 inhibited LRRK2 phosphorylation and also restored mtDNA damage to healthy control levels. Precision medicine is a common approach in modern day cancer research that is not yet routinely applied to neurodegenerative diseases. Abrogation of mtDNA damage with mutant selective tool inhibitor EB-42168 demonstrates the promise of a precision medicine approach for LRRK2 G2019S PD. Levels of mtDNA damage may serve as a potential pharmacodynamic biomarker of altered kinase activity that could be useful for small molecule development and clinical trials.

neuroscience↗

bioRxiv2022

A mitochondrial blood-based patient stratification candidate biomarker for Parkinson's disease

Parkinsons disease (PD) is the most common neurodegenerative movement disorder and neuroprotective interventions remain elusive. High throughput biomarkers aimed to stratify patients based on shared etiology is one critical path to the success of disease-modifying therapies in clinical trials. Mitochondrial dysfunction plays a prominent role in the pathogenesis of PD. Previously, we found brain region-specific mitochondrial DNA (mtDNA) damage accumulation in neuronal and in vivo PD models, as well as human PD postmortem brain tissue. In this study, to investigate mtDNA damage as a potential blood biomarker for PD, we describe a novel Mito DNADX assay that allows for the accurate real-time quantification of mtDNA damage in a 96-well platform, compatible with assessing large cohorts of patient samples. We found that levels of mtDNA damage were increased in blood derived from early-stage idiopathic PD patients or those harboring the pathogenic LRRK2 G2019S mutation compared to age-matched healthy controls. Given that increased mtDNA damage was also found in non-manifesting LRRK2 mutation carriers, mtDNA damage may begin to accumulate prior to a clinical PD diagnosis. LRRK2 kinase inhibition mitigated mtDNA damage in idiopathic PD models and patient-derived cells. The latter observations further substantiate a mechanistic role for wild-type LRRK2 kinase activity in idiopathic PD and support mtDNA damage reversal as a suitable approach to slow PD-related pathology. In light of recent advances in the field of precision medicine, the analysis of mtDNA damage as a blood-based patient stratification biomarker should be included in future clinical trials. One Sentence SummaryBlood test identifies Parkinsons patients most likely to respond to mitochondria-targeted therapeutics facilitating a precision medicine approach.

neuroscience↗