Biology subjects

Zhi, L.

Publications and source records attributed to Zhi, L..

7 recordsLinked to original sources

bioRxiv2025

The Human LRRK2-R1441G Mutation Drives Age-Dependent Oxidative Stress and Mitochondrial Dysfunction in Dopaminergic Neurons

Mitochondrial dysfunction and oxidative stress are central to Parkinsons disease (PD) pathogenesis, particularly affecting substantia nigra pars compacta (SNc) dopamine (DA) neurons. Here, we investigate how the R1441G mutation in leucine-rich repeat kinase 2 (LRRK2), a key genetic contributor to familial and sporadic PD, impacts mitochondrial function in midbrain DA neurons. Using a BAC transgenic mouse model overexpressing human LRRK2-R1441G, we crossed these mice with TH-mito-roGFP mice, enabling mitochondria-targeted redox imaging in DA neurons. The two-photon imaging of acute brain slices from 3-, 6-, and 10-month-old mice revealed a progressive elevated oxidative stress in SNc DA neurons and their striatal projections, accompanied with reduced respiratory complex activity and decline in mitochondrial health. Spatial transcriptomics via GeoMx Digital Spatial Profiler identified molecular changes linked to dysregulated mitochondrial uncoupling protein function and calcium homeostasis. These findings demonstrate age-dependent mitochondrial dysfunction in LRRK2-mutant SNc DA neurons, highlighting calcium channels and uncoupling proteins as potential therapeutic targets to slow PD progression.

neuroscience↗

bioRxiv2025

Human blood vessel organoids recapitulate key mechanisms of transition from vasculopathy to fibrosis in systemic sclerosis

Systemic sclerosis (SSc) is an autoimmune disease that transitions from vasculopathy as an initiating pathogenic event to tissue fibrosis. The mechanisms of these transitions remain, however, poorly understood, mainly because complex multicellular human models of SSc vasculopathy are lacking. Here we characterized blood vessel organoids (BVOs) as a novel model system of vasculopathy in SSc. We demonstrate that exposure of SSc-BVOs to SSc serum triggers changes on epigenetic, mRNA and protein levels and recapitulates key pathogenic features of SSc vasculopathy, with shifts from angiogenic endothelial cell subsets to those undergoing endothelial-to-mesenchymal transition, loss of endothelial cells-pericytes interactions and profound angiogenic defects. The genetic predisposition of SSc donors and serum IgGs are required for the deleterious effects of SSc serum. We further validate SSc-BVOs as a human model system to evaluate candidate therapies targeting SSc microvasculopathy and use this system to provide evidence that {gamma}-secretase inhibition is a potential therapeutic approach.

biophysics↗

bioRxiv2024

Loss of PINK1 causes age-dependent mitochondrial trafficking deficits in nigrostriatal dopaminergic neurons through aberrant activation of p38 MAPK

Mutations in PTEN-induced putative kinase 1 (PINK1) cause early-onset, autosomal-recessive Parkinsons disease (PD). While previous studies showed age-related declines in dopamine release and ATP levels in Pink1-/- mice, the mechanisms remain unclear. Using a novel TH-Mito-Dendra2 transgenic mouse model to label dopaminergic neuron mitochondria, it is found that PINK1 loss leads to age-dependent deficits in mitochondrial axonal trafficking, characterized by reduced anterograde movement and increased static mitochondria in acute brain slices, which more closely mimic in vivo conditions. Pharmacological induction of reactive oxygen species (ROS) and calcium release impaired mitochondrial mobility. Pink1 knockout mice exhibited elevated mitochondrial calcium, ROS levels, and p38 MAPK hyperactivation. Treatment with p38 inhibitor SB202190 restored mitochondrial motility and increased anterograde transport. Our findings suggest that PINK1 loss disrupts mitochondrial trafficking by disturbing calcium homeostasis and ROS production via the p38 pathway, contributing to PD pathogenesis. Table of Contents O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=181 SRC="FIGDIR/small/602426v3_ufig1.gif" ALT="Figure 1"> View larger version (68K): org.highwire.dtl.DTLVardef@1352742org.highwire.dtl.DTLVardef@a48086org.highwire.dtl.DTLVardef@1f209daorg.highwire.dtl.DTLVardef@164ed23_HPS_FORMAT_FIGEXP M_FIG C_FIG Using a novel mouse model with labeled dopaminergic neuron mitochondria, Zhao J. et al. discovered age dependent disruptions in mitochondrial transport. Their research showed progressive deterioration of mitochondrial movement, characterized by reduced anterograde movement and increased static mitochondria. These changes were associated with higher oxidative stress and hyperactivation of p38 MAPK in Parkinsons disease.

neuroscience↗

bioRxiv2023

Adaptive immunity: from CRISPR to CRIHSP?

Clustered regularly interspaced short palindromic repeats (CRISPR) confer adaptive immunity in prokaryotes against viral infection and plasmid transformation. Here, we identified abundant clustered regularly interspaced homologous stem-loop pairs (CRIHSP) within human adaptive immunity-related genes, such as antigen receptor germline genes. By examining genomic stability under activation-induced cytidine deaminase (AID) overexpression, we found that CRIHSP structures are preferred targets for AID. Through collecting and analyzing cancer cell genomic mutation databases, we discovered that these mutation sites tend to cluster toward stem-loop structures. Importantly, the frequency of stem-loop sequences within immunoglobulin heavy chain variable (IGHV) gene segments was over 3-fold higher compared to that within other regions. We concurrently observed stem-loop structures frequently flanking RSS motifs. Conservative estimates indicate a 74.07% probability of immunoglobulin heavy chain diversity (IGHD) gene segment enclosure within stem-loop. These RSS-proximal stem-loops may assemble into homologous stem-loop pair (HSP)-like intermediates and subsequent CRIHSP arrays. Our results implicate CRIHSP architectures as critical enhancer of antigen receptor gene recombination and diversification. Further molecular dissection of these processes could potentially elucidate mechanisms underlying cancer cell genomic instability, chromatin folding and dynamic regulation, gene expression control, etc.

immunology↗

bioRxiv2021

Lentiviral vector optimization enhances the expression and cytotoxicity of chimeric antigen receptors

Adoptive chimeric antigen receptor (CAR)-modified T or NK cells (CAR-T/NK) have emerged as a novel form of disease treatment. Lentiviral vectors (LVs) are commonly employed to engineer T/NK cells for the efficient expression of CARs. This study reported for the first time the influence of single-promoter and dual-promoter LVs on the CAR expression and cytotoxicity of engineered NK cells. Our results demonstrated that the selected CAR exhibits both a higher expression level and a higher coexpression concordance with the GFP reporter in HEK-293T or NK92 cells by utilizing the optimized single-promoter pCDHsp rather than the original dual-promoter pCDHdp. After puromycin selection, the pCDHsp produces robust CAR expression and enhanced in vitro cytotoxicity of engineered NK cells. Therefore, infection with a single-promoter pCDHsp lentivector is recommended to prepare CAR-engineered cells. This research will help to optimize the production of CAR-NK cells and improve their functional activity, to provide CAR-NK cell products with better and more uniform quality.

cell biology↗

bioRxiv2020

Telmisartan potentiates insulin secretion via ion channels, independent of the AT1 receptor and PPARγ

Angiotensin II type 1 receptor blockers (ARBs), as antihypertensive drugs, have drawn attention for their benefits to individuals with diabetes and prediabetes. However, the effects of ARBs on insulin secretion remain unclear. Here, we investigated the insulinotropic effects of ARBs (telmisartan, valsartan, and irbesartan) and the underlying electrophysiological mechanism in rat islets. We found that only telmisartan among the three ARBs exhibited an insulin secretagogue role. Distinct from other ARBs, telmisartan exerted effects on ion channels including voltage-gated potassium (Kv) channels and voltage-gated Ca2+ channels to promote extracellular Ca2+ influx, thereby potentiating insulin secretion in a glucose-dependent manner. We observed that the peroxisome proliferator-activated receptor {gamma} pathway was not involved in these telmisartan-induced effects. Furthermore, we identified that telmisartan at least directly inhibited Kv2.1 channel through construction of a Chinese hamster ovary cell line with Kv2.1 channel overexpression. Acute exposure of type 2 diabetes model (db/db) mice to a telmisartan dose equivalent to therapeutic doses in humans resulted in lower blood glucose and increased plasma insulin concentration in the oral glucose tolerance test. We further observed the telmisartan-induced insulinotropic and electrophysiological effects on pathological pancreatic islets isolated from db/db mice. Collectively, our results establish an important function of telmisartan distinct from other ARBs in the treatment of diabetes.

cell biology↗

bioRxiv2020

Predictions for the binding domain and potential new drug targets of 2019-nCoV

An outbreak of new SARS-like viral in Wuhan, China has been named 2019-nCoV. The current state of the epidemic is increasingly serious, and there has been the urgent necessity to develop an effective new drug. In previous studies, it was found that the conformation change in CTD1 was the region where SARS-CoV bound to human ACE2. Although there are mutations of the 2019-nCoV, the binding energy of ACE2 remains high. The surface glycoprotein of 2019-nCoV was coincident with the CTD1 region of the S-protein by comparing the I-TASSER prediction model with the actual SARS model, which suggests that 2019-nCoV may bind to the ACE2 receptor through conformational changes. Furthermore, site prediction on the surface glycoprotein of 2019-nCoV suggests some core amino acid area may be a novel drug target against 2019-nCoV.

bioinformatics↗