Biology subjects

Le, W.

Publications and source records attributed to Le, W..

7 recordsLinked to original sources

bioRxiv2025

Subtype-Specific Roles of Nigrostriatal Dopaminergic Neurons in Motor and Associative Learning

Nigrostriatal dopaminergic neurons (DANs) in the substantia nigra pars compacta (SNc) comprise distinct subtypes defined by unique gene expression profiles and anatomical characteristics. However, their specific contributions to motor and non-motor functions remain elusive. Using Calbindin 1 (Calb1) and Aldehyde dehydrogenase 1a1 (Aldh1a1) as molecular markers, we investigated the functions of these nigrostriatal DAN subtypes in mice. Through intersectional genetics and chemogenetic manipulation, we selectively inhibited Calb1+ or Aldh1a1+ DANs by stereotactically delivering an adeno-associated viral vector (AAV-CreOn-FlpOn-hM4Di-P2A-mCherry) into the SNc of ThFlp; Calb1IRESCre or ThFlp; Aldh1a1CreERT2 double knock-in (KI) mice. This approach enabled subtype-specific neuronal inhibition via designer receptors exclusively activated by designer drugs (DREADD). Following DREADD ligand administration, both Calb1+ and Aldh1a1+ DAN-inhibited mice exhibited significant reduction in voluntary movement and impaired motor skill learning, demonstrating their essential roles in motor function. However, only Calb1+ DAN inhibition affected early associative-learning behavior, suggesting a unique role in reinforcement learning. These findings establish Calb1+ and Aldh1a1+ nigrostriatal DANs as key regulators of movement and motor learning, with Calb1+ neurons additionally modulating reward-based associative learning. This study advances our understanding of the functional heterogeneity of nigrostriatal DAN subtypes and identifies potential therapeutic targets for addressing motor and non-motor deficits in Parkinsons disease.

neuroscience↗

bioRxiv2024

Patch and matrix striatonigral neurons differentially regulate locomotion

Spiny projection neurons (SPNs) in the dorsal striatum play crucial roles in locomotion control and value-based decision-making. SPNs, which include both direct-pathway striatonigral and indirect-pathway striatopallidal neurons, can be further classified into subtypes based on distinct transcriptomic profiles and cell body distribution patterns. However, how these SPN subtypes regulate spontaneous locomotion in the context of environmental valence remains unclear. Using Sepw1-Cre transgenic mice, which label a specific SPN subtype characterized by a patchy distribution of cell bodies in the dorsal striatum, we found that these patchy striatonigral neurons constrain motor vigor in response to valence differentials. In a modified light/dark box test, mice exhibited differential walking speeds between the light and dark zones. Genetic ablation of these patchy SPNs disrupted restful slowing in the dark zone and increased zone discrimination by speed. In vivo recordings linked the activity of these neurons to zone occupancy, speed, and deceleration, with a specific role in mediating deceleration. Furthermore, chemogenetic activation of patchy SPNs--and optical activation of striatonigral neurons in particular--reduced locomotion and attenuated speed-based zone discrimination. These findings reveal that a subtype of patchy striatonigral neurons regulates implicit walking speed selection based on innate valence differentials.

neuroscience↗

bioRxiv2024

Protein disulfide isomerase disassembles stress granules and blocks cytoplasmic aggregation of TDP-43 in ALS

Cytoplasmic aggregation of the transactive response DNA-binding protein-43 (TDP-43) in neurons, a pathological feature common to amyotrophic lateral sclerosis (ALS) and frontotemporal lobar degeneration, has been found in some Alzheimers patients. Protein disulfide isomerase (PDI) functions as both an enzyme and a molecular chaperone to correct or eliminate misfolded proteins under pathological conditions. Here, we report that TDP-43 is mislocalized to the cytoplasm and colocalizes with PDI in the brain and spinal cord of two ALS patients and the brain of six Alzheimers patients compared to controls. TDP-43 selectively recruits wild-type PDI into its phase-separated condensate, which in turn slows down in vitro liquid-liquid phase separation of TDP-43, shifting the equilibrium phase boundary to higher protein concentrations. Importantly, wild-type PDI decreases oxidative stress-induced interaction between TDP-43 and G3BP1 to disassemble stress granules containing TDP-43 in neuronal cells. Wild-type PDI blocks the oxidative stress-induced mislocalization of TDP-43 to the cytoplasm, and blocks subsequent pathological phosphorylation and aggregation of TDP-43. We demonstrate that under pathological stress conditions, wild-type PDI disassembles stress granules, blocks cytoplasmic mislocalization and aggregation of TDP-43, and suppresses mitochondrial damage and TDP-43 toxicity. In the presence of abnormal forms of PDI, however, PDI loses its activity, and stress granules containing TDP-43 are assembled into amyloid fibrils, resulting in mitochondrial impairment and neuronal cell death in ALS patients and some Alzheimers patients. TeaserPDI disassembles SGs, blocks cytoplasmic mislocalization and aggregation of TDP-43, and suppress TDP-43 toxicity in ALS.

biochemistry↗

bioRxiv2023

ALS-causing SOD1 mutations H46R and G85R form similar novel amyloid fibril structures and promote ferroptosis in cells

More than two hundred genetic mutations of Cu, Zn-superoxide dismutase (SOD1) have been identified in amyotrophic lateral sclerosis (ALS), a neurodegenerative disease characterized by the selective death of motor neurons through ferroptosis. Two ALS-causing SOD1 mutations, H46R and G85R, are metal-binding region mutants with reduced affinity for metal ions. Here, we generated amyloid fibrils from the apo forms of H46R and G85R under reducing conditions and determined their structures using cryo-EM. We built models for the fibril cores, comprising residues 85-153 for H46R and 82-153 for G85R. These mutations disrupt crucial interactions in the wild-type SOD1 fibril, resulting in amyloid fibrils with distinct structures compared to the wild-type fibril. Remarkably, H46R and G85R form similar novel amyloid fibril structures. The fibril cores display a serpentine fold containing seven or eight {beta}-strands, which are stabilized by a hydrophobic cavity. In the G85R fibril core, Arg85 and Asp101 form a salt bridge for stabilization. We demonstrate that fibril seeds from H46R and G85R cause more severe mitochondrial impairment and significantly promote ferroptosis in neuronal cells, compared with those from wild-type SOD1. Our findings reveal how different SOD1 mutations can result in similar amyloid fibril structures and contribute to ALS pathology.

biochemistry↗

bioRxiv2022

JMJD3 is a Key Regulator of Dopamine Synthesis in Ventral Tegmental Area Dopamine Neurons.

Chronic pain is associated with midbrain dopamine levels. The molecules and mechanisms modulating this association remain to be elucidated. By using conditional knockout mice, we report that JMJD3 deficiency in midbrain dopamine neurons causes prolonged mechanical hyperalgesia regardless of sex and age. Both genetic defect and pharmaceutical inhibition of JMJD3 decrease dopamine level in midbrain and striatum, resulting from reduced tyrosine hydroxylase expression in midbrain dopamine neurons. Furthermore, epigenetic experiments reveal that JMJD3 is indispensable for the transcription of tyrosine hydroxylase through direct and indirect manners. These findings suggest JMJD3 and midbrain dopamine neurons as novel players and pharmaceutical targets for chronic pain regulation.

neuroscience↗

bioRxiv2021

Deficiency in endocannabinoid synthase DAGLB contributes to Parkinson's disease and dopaminergic neuron dysfunction

2-arachidonoyl-glycerol (2-AG), the most abundant endocannabinoid (eCB) in the brain, regulates diverse neural functions. However, whether 2-AG deficiency contributes to Parkinsons disease (PD) and nigral dopaminergic neurons (DANs) dysfunction is unclear. Diacylglycerol lipase and {beta} (DAGLA and DAGLB) mediate the biosynthesis of 2-AG. Using homozygosity mapping and whole-exome sequencing, we linked multiple homozygous loss-of-function mutations in DAGLB to a form of early-onset autosomal recessive PD. We then used RNA sequencing and fiber photometry with genetically encoded eCB sensors to demonstrate that DAGLB is the main 2-AG synthase in nigral DANs. Genetic knockdown of Daglb by CRISPR/Cas9 in mouse nigral DANs substantially reduces 2-AG levels in the substantia nigra (SN). The SN 2-AG levels are markedly correlated with the vigor of movement during the acquisition of motor skills, while Daglb-deficiency impairs motor learning. Conversely, pharmacological enhancement of 2-AG levels increases nigral DAN activity and dopamine release and improves motor learning. Together, we demonstrate that DAGLB-deficiency contributes to the etiopathogenesis of PD, reveal the importance of DAGLB-mediated 2-AG biosynthesis in nigral DANs in regulating neural activity and dopamine release, and provide preclinical evidence for the beneficial effects of 2-AG augmentation in PD treatment.

neuroscience↗

bioRxiv2019

Highly Efficient Repair of the ΔF508 Mutation in Airway Stem Cells of Cystic Fibrosis Patients with Functional Rescue of the Differentiated Epithelia

Cystic fibrosis (CF) is a monogenic autosomal recessive disorder caused by mutations in the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) Cl- channel. CF results in multiorgan dysfunction and ultimately mortality from respiratory sequelae. Although pharmacologic approaches have demonstrated efficacy in reducing symptoms and respiratory decline, a curative treatment modality remains elusive. Gene therapy, a promising curative strategy, has been limited due to poor correction efficiencies both in vitro and in vivo. Here, we use Cas9 and adeno-associated virus 6 (AAV6) to correct the {Delta}F508 mutation (found in [~]70% of CF alleles and [~]90% of CF patients in North America) in upper airway basal stem cells (UABCs) obtained from CF and non-CF patients undergoing functional endoscopic sinus surgery (FESS). In UABCs from homozygous ({Delta}F508/{Delta}F508) and compound heterozygous ({Delta}F508/Other) CF patients, we achieved 28 {+/-} 5 % and 42 {+/-} 15% correction, respectively. In homozygous human bronchial epithelial cells (HBECs), we achieved 41{+/-} 4 % correction. Upon differentiation in air-liquid interface (ALI), cultures of corrected CF cells displayed partial restoration of CFTRinh-172 sensitive Cl- currents relative to non-CF controls: 31{+/-} 5 % in UABCs and 51 {+/-} 3 % in HBECs (both from subjects homozygous for {Delta}F508 CFTR). Finally, gene edited cells embedded successfully and retained expression of cytokeratin 5 (KRT5), a basal cell marker, on a FDA-approved porcine small intestinal submucosal (pSIS) membrane previously shown to improve re-mucosalization after FESS. In summary, we present an efficient, feeder-free, selection-free and clinically compatible approach to generate cell-based therapies for CF from autologous airway stem cells. This approach represents a first step towards developing patient-specific autologous airway stem cell transplant as a curative treatment for CF.

bioengineering↗