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Latest articles published on PNAS

Published on: 19 Jan 2022 Viewed: 304

Our staff editors continue to share exciting, interesting, and thought-provoking reading material in the recommended articles series.

This week, we would like to share several latest articles published on PNAS.

Title: Discovery of a dual-action small molecule that improves neuropathological features of Alzheimer’s disease mice
Authors: Min Hee Park, Kang Ho Park, Byung Jo Choi, Wan Hui Han, Hee Ji Yoon, Hye Yoon Jung, Jihoon Lee, Im-Sook Song, Dong Yu Lim, Min-Koo Choi, Yang-Ha Lee, Cheol-Min Park, Ming Wang, Jihoon Jo, Hee-Jin Kim, Seung Hyun Kim, Edward H. Schuchman, Hee Kyung Jin, Jae-sung Bae
Type: Research Article of PNAS
Abstract
Alzheimer’s disease (AD) is characterized by complex, multifactorial neuropathology, suggesting that small molecules targeting multiple neuropathological factors are likely required to successfully impact clinical progression. Acid sphingomyelinase (ASM) activation has been recognized as an important contributor to these neuropathological features in AD, leading to the concept of using ASM inhibitors for the treatment of this disorder. Here we report the identification of KARI 201, a direct ASM inhibitor evaluated for AD treatment. KARI 201 exhibits highly selective inhibition effects on ASM, with excellent pharmacokinetic properties, especially with regard to brain distribution. Unexpectedly, we found another role of KARI 201 as a ghrelin receptor agonist, which also has therapeutic potential for AD treatment. This dual role of KARI 201 in neurons efficiently rescued neuropathological features in AD mice, including amyloid beta deposition, autophagy dysfunction, neuroinflammation, synaptic loss, and decreased hippocampal neurogenesis and synaptic plasticity, leading to an improvement in memory function. Our data highlight the possibility of potential clinical application of KARI 201 as an innovative and multifaceted drug for AD treatment.
Access this article: https://doi.org/10.1073/pnas.2115082119


Title: Integrated genome and transcriptome analyses reveal the mechanism of genome instability in ataxia with oculomotor apraxia 2
Authors: Radhakrishnan Kanagaraj, Richard Mitter, Theodoros Kantidakis, Matthew M. Edwards, Anaid Benitez, Probir Chakravarty, Beiyuan Fu, Olivier Becherel, Fengtang Yang, Martin F. Lavin, Amnon Koren, Aengus Stewart, Stephen C. West
Type: Research Article of PNAS
Abstract
Mutations in the SETX gene, which encodes Senataxin, are associated with the progressive neurodegenerative diseases ataxia with oculomotor apraxia 2 (AOA2) and amyotrophic lateral sclerosis 4 (ALS4). To identify the causal defect in AOA2, patient-derived cells and SETX knockouts (human and mouse) were analyzed using integrated genomic and transcriptomic approaches. A genome-wide increase in chromosome instability (gains and losses) within genes and at chromosome fragile sites was observed, resulting in changes to gene-expression profiles. Transcription stress near promoters correlated with high GCskew and the accumulation of R-loops at promoter-proximal regions, which localized with chromosomal regions where gains and losses were observed. In the absence of Senataxin, the Cockayne syndrome protein CSB was required for the recruitment of the transcription-coupled repair endonucleases (XPG and XPF) and RAD52 recombination protein to target and resolve transcription bubbles containing R-loops, leading to genomic instability. These results show that transcription stress is an important contributor to SETX mutation-associated chromosome fragility and AOA2. 
Access this article: https://doi.org/10.1073/pnas.2114314119


Title: Association of improved air quality with lower dementia risk in older women
Authors: Xinhui Wang, Diana Younan, Joshua Millstein, Andrew J. Petkus, Erika Garcia, Daniel P. Beavers, Mark A. Espeland, Helena C. Chui, Susan M. Resnick, Margaret Gatz, Joel D. Kaufman, Gregory A. Wellenius, Eric A. Whitsel, JoAnn E. Manson, Stephen R. Rapp, Jiu-Chiuan Chen
Type: Research Article of PNAS
Abstract:
Late-life ambient air pollution is a risk factor for brain aging, but it remains unknown if improved air quality (AQ) lowers dementia risk. We studied a geographically diverse cohort of older women dementia free at baseline in 2008 to 2012 (n = 2,239, aged 74 to 92). Incident dementia was centrally adjudicated annually. Yearly mean concentrations of fine particulate matter (PM2.5) and nitrogen dioxide (NO2) were estimated using regionalized national universal kriging models and averaged over the 3-y period before baseline (recent exposure) and 10 y earlier (remote exposure). Reduction from remote to recent exposures was used as the indicator of improved AQ. Cox proportional hazard ratios (HRs) for dementia risk associated with AQ measures were estimated, adjusting for sociodemographic, lifestyle, and clinical characteristics. We identified 398 dementia cases during follow up (median = 6.1 y). PM2.5 and NO2 reduced significantly over the 10 y before baseline. Larger AQ improvement was associated with reduced dementia risks (HRPM2.5 0.80 per 1.78 μg/m3, 95% CI 0.71–0.91; HRNO2 0.80 per 3.91 parts per billion, 95% CI 0.71–0.90), equivalent to the lower risk observed in women 2.4 y younger at baseline. Higher PM2.5 at baseline was associated with higher dementia risk (HRPM2.5 1.16 per 2.90 μg/m3, 95% CI 0.98–1.38), but the lower dementia risk associated with improved AQ remained after further adjusting for recent exposure. The observed associations did not substantially differ by age, education, geographic region, Apolipoprotein E e4 genotypes, or cardiovascular risk factors. Long-term AQ improvement in late life was associated with lower dementia risk in older women.
Access this article: https://doi.org/10.1073/pnas.2107833119


Title: Biased M1 muscarinic receptor mutant mice show accelerated progression of prion neurodegenerative disease
Authors: Miriam Scarpa, Colin Molloy, Laura Jenkins, Bethany Strellis, Rebecca F. Budgett, Sarah Hesse, Louis Dwomoh, Sara Marsango, Gonzalo S. Tejeda, Mario Rossi, Zeshan Ahmed, Graeme Milligan, Brian D. Hudson, Andrew B. Tobin, Sophie J. Bradley
Type: Research Article of PNAS
Abstract:
There are currently no treatments that can slow the progression of neurodegenerative diseases, such as Alzheimer’s disease (AD). There is, however, a growing body of evidence that activation of the M1 muscarinic acetylcholine receptor (M1-receptor) can not only restore memory loss in AD patients but in preclinical animal models can also slow neurodegenerative disease progression. The generation of an effective medicine targeting the M1-receptor has however been severely hampered by associated cholinergic adverse responses. By using genetically engineered mouse models that express a G protein–biased M1-receptor, we recently established that M1-receptor mediated adverse responses can be minimized by ensuring activating ligands maintain receptor phosphorylation/arrestin-dependent signaling. Here, we use these same genetic models in concert with murine prion disease, a terminal neurodegenerative disease showing key hallmarks of AD, to establish that phosphorylation/arrestin-dependent signaling delivers neuroprotection that both extends normal animal behavior and prolongs the life span of prion-diseased mice. Our data point to an important neuroprotective property inherent to the M1-receptor and indicate that next generation M1-receptor ligands designed to drive receptor phosphorylation/arrestin-dependent signaling would potentially show low adverse responses while delivering neuroprotection that will slow disease progression.
Access this article: https://doi.org/10.1073/pnas.2107389118


Title: IP3R-driven increases in mitochondrial Ca2+ promote neuronal death in NPC disease
Authors: Scott A. Tiscione, Maria Casas, Jonathan D. Horvath, Vincent Lam, Keiko Hino, Daniel S. Ory, L. Fernando Santana, Sergi Simó, Rose E. Dixon, Eamonn J. Dickson
Type: Research Article of PNAS
Abstract:
Ca2+ is the most ubiquitous second messenger in neurons whose spatial and temporal elevations are tightly controlled to initiate and orchestrate diverse intracellular signaling cascades. Numerous neuropathologies result from mutations or alterations in Ca2+ handling proteins; thus, elucidating molecular pathways that shape Ca2+ signaling is imperative. Here, we report that loss-of-function, knockout, or neurodegenerative disease–causing mutations in the lysosomal cholesterol transporter, Niemann-Pick Type C1 (NPC1), initiate a damaging signaling cascade that alters the expression and nanoscale distribution of IP3R type 1 (IP3R1) in endoplasmic reticulum membranes. These alterations detrimentally increase Gq-protein coupled receptor–stimulated Ca2+ release and spontaneous IP3R1 Ca2+ activity, leading to mitochondrial Ca2+ cytotoxicity. Mechanistically, we find that SREBP-dependent increases in Presenilin 1 (PS1) underlie functional and expressional changes in IP3R1. Accordingly, expression of PS1 mutants recapitulate, while PS1 knockout abrogates Ca2+ phenotypes. These data present a signaling axis that links the NPC1 lysosomal cholesterol transporter to the damaging redistribution and activity of IP3R1 that precipitates cell death in NPC1 disease and suggests that NPC1 is a nanostructural disease.
Access this article: https://doi.org/10.1073/pnas.2110629118


Title: Bach1 derepression is neuroprotective in a mouse model of Parkinson’s disease
Authors: Manuj Ahuja, Navneet Ammal Kaidery, Otis C. Attucks, Erin McDade, Dmitry M. Hushpulian, Arsen Gaisin, Irina Gaisina, Young Hoon Ahn, Sergey Nikulin, Andrey Poloznikov, Irina Gazaryan, Masayuki Yamamoto, Mitsuyo Matsumoto, Kazuhiko Igarashi, Sudarshana M. Sharma, Bobby Thomas
Type: Research Article of PNAS
Abstract:
Parkinson’s disease (PD) is a progressive neurodegenerative movement disorder characterized by the loss of nigrostriatal dopaminergic neurons. Mounting evidence suggests that Nrf2 is a promising target for neuroprotective interventions in PD. However, electrophilic chemical properties of the canonical Nrf2-based drugs cause irreversible alkylation of cysteine residues on cellular proteins resulting in side effects. Bach1 is a known transcriptional repressor of the Nrf2 pathway. We report that Bach1 levels are up-regulated in PD postmortem brains and preclinical models. Bach1 knockout (KO) mice were protected against 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced dopaminergic neurotoxicity and associated oxidative damage and neuroinflammation. Functional genomic analysis demonstrated that the neuroprotective effects in Bach1 KO mice was due to up-regulation of Bach1-targeted pathways that are associated with both Nrf2-dependent antioxidant response element (ARE) and Nrf2-independent non-ARE genes. Using a proprietary translational technology platform, a drug library screen identified a substituted benzimidazole as a Bach1 inhibitor that was validated as a nonelectrophile. Oral administration of the Bach1 inhibitor attenuated MPTP neurotoxicity in pre- and posttreatment paradigms. Bach1 inhibitor–induced neuroprotection was associated with the up-regulation of Bach1-targeted pathways in concurrence with the results from Bach1 KO mice. Our results suggest that genetic deletion as well as pharmacologic inhibition of Bach1 by a nonelectrophilic inhibitor is a promising therapeutic approach for PD.
Access this article: https://doi.org/10.1073/pnas.2111643118

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