measurement-mitochondrial-membrane-potential-vivo-using-genetically

Measurement of Mitochondrial Membrane Potential <em>In Vivo</em> using a Genetically Encoded Voltage Indicator

Mitochondrial membrane potential (MMP, &#916;&#936;m) is critical for mitochondrial functions, including ATP synthesis, ion transport, reactive oxygen ...

the First Affiliated Hospital of Zhengzhou University

Alzheimer's disease (AD) is a neurodegenerative disease characterized by progressive memory loss along with neuropsychiatric symptoms and a decline in activities of daily life. Its main pathological features are cerebral atrophy, amyloid plaques, and neurofibrillary tangles in the brains of patients. There are various descriptive hypotheses regarding the causes of AD, including the cholinergic hypothesis, amyloid hypothesis, tau propagation hypothesis, mitochondrial cascade hypothesis, calcium homeostasis hypothesis, neurovascular hypothesis, inflammatory hypothesis, metal ion hypothesis, and lymphatic system hypothesis. However, the ultimate etiology of AD remains obscure. In this review, we discuss the main hypotheses of AD and related clinical trials. Wealthy puzzles and lessons have made it possible to develop explanatory theories and identify potential strategies for therapeutic interventions for AD. The combination of hypometabolism and autophagy deficiency is likely to be a causative factor for AD. We further propose that fluoxetine, a selective serotonin reuptake inhibitor, has the potential to treat AD.

History and progress of hypotheses and clinical trials for Alzheimer's disease.

The effect of selective serotonin reuptake inhibitors on cognitive function in patients with Alzheimer's disease and vascular dementia: focusing on fluoxetine with long follow-up periods.

[This corrects the article DOI: 10.1038/s41392-019-0063-8.].

Erratum: Author Correction: History and progress of hypotheses and clinical trials for Alzheimer's disease.

Human herpesvirus 4 and adaptive immunity in Alzheimer's disease.

A near-infrared AIE probe and its applications for specific in vitro and in vivo two-photon imaging of lipid droplets.

pH-sensitive fluorescent proteins have revolutionized the field of cellular imaging and physiology, offering insight into the dynamic pH changes that underlie fundamental cellular processes. This comprehensive review explores the diverse applications and recent advances in the use of pH-sensitive fluorescent proteins. These remarkable tools enable researchers to visualize and monitor pH variations within subcellular compartments, especially mitochondria, shedding light on organelle-specific pH regulation. They play pivotal roles in visualizing exocytosis and endocytosis events in synaptic transmission, monitoring cell death and apoptosis, and understanding drug effects and disease progression. Recent advancements have led to improved photostability, pH specificity, and subcellular targeting, enhancing their utility. Techniques for multiplexed imaging, three-dimensional visualization, and super-resolution microscopy are expanding the horizon of pH-sensitive protein applications. The future holds promise for their integration into optogenetics and drug discovery. With their ever-evolving capabilities, pH-sensitive fluorescent proteins remain indispensable tools for unravelling cellular dynamics and driving breakthroughs in biological research. This review serves as a comprehensive resource for researchers seeking to harness the potential of pH-sensitive fluorescent proteins.

Progress in pH-Sensitive sensors: essential tools for organelle pH detection, spotlighting mitochondrion and diverse applications.

Fibroblasts were extracted from the scalp of a healthy 55-year-old male and subsequently transformed into pluripotent stem cells by introducing episomal plasmids harboring essential reprogramming factors. These induced pluripotent stem cells exhibited a normal karyotype and demonstrated the capacity to differentiate into all three germ layers, as confirmed through teratoma assays. This specific cell line serves as a valuable reference for comparative investigations alongside other induced pluripotent stem cell lines generated from somatic cells of patients afflicted by genetic neurodegenerative disorders.

Generation of induced pluripotent stem cells (ZZUCSBi001-A) from skin fibroblasts of a healthy donor.

Parkinson's disease (PD) is a mitochondria-related neurodegenerative disease characterized by locomotor deficits and loss of dopaminergic (DA) neurons in the  (SNc). Majority of PD research primarily focused on neuronal dysfunction, while the roles of astrocytes and their mitochondria remain largely unexplored. To bridge the gap and investigate the roles of astrocytic mitochondria in PD progression, we constructed a specialized optogenetic tool, mitochondrial-targeted anion channelrhodopsin, to manipulate mitochondrial membrane potential in astrocytes. Utilizing this tool, the depolarization of astrocytic mitochondria within the SNc in vivo led to the accumulation of γ-aminobutyric acid (GABA) and glutamate in SNc, subsequently resulting in excitatory/inhibitory imbalance and locomotor deficits. Consequently, in vivo calcium imaging and interventions of neurotransmitter antagonists demonstrated that GABA accumulation mediated movement deficits of mice. Furthermore, 1 h/day intermittent astrocytic mitochondrial depolarization for 2 weeks triggered spontaneous locomotor dysfunction, α-synuclein aggregation, and the loss of DA neurons, suggesting that astrocytic mitochondrial depolarization was sufficient to induce a PD-like phenotype. In summary, our findings suggest the maintenance of proper astrocytic mitochondrial function and the reinstatement of a balanced neurotransmitter profile may provide a new angle for mitigating neuronal dysfunction during the initial phases of PD.

Neurotransmitter accumulation and Parkinson's disease-like phenotype caused by anion channelrhodopsin opto-controlled astrocytic mitochondrial depolarization in substantia nigra pars compacta.

Mitochondrial membrane potential (MMP) plays a crucial role in the function of cells and organelles, involving various cellular physiological processes, including energy production, formation of reactive oxygen species (ROS), unfolded protein stress, and cell survival. Currently, there is a lack of genetically encoded fluorescence indicators (GEVIs) for MMP. In our screening of various GEVIs for their potential monitoring MMP, the Accelerated Sensor of Action Potentials (ASAP) demonstrated optimal performance in targeting mitochondria and sensitivity to depolarization in multiple cell types. However, mitochondrial ASAPs also displayed sensitivity to ROS in cardiomyocytes. Therefore, two ASAP mutants resistant to ROS were generated. A double mutant ASAP3-ST exhibited the highest voltage sensitivity but weaker fluorescence. Overall, four GEVIs capable of targeting mitochondria were obtained and named mitochondrial potential indicators 1-4 (MPI-1-4). In vivo, fiber photometry experiments utilizing MPI-2 revealed a mitochondrial depolarization during isoflurane-induced narcosis in the M2 cortex.

Development and Application of a Mitochondrial Genetically Encoded Voltage Indicator in Narcosis.

Pluripotent stem cells were generated through the electroporation of episomal plasmids, containing crucial reprogramming factors, into skin fibroblasts extracted from a female Alzheimer's patient harboring the PSEN1 709 T > C (p.Phe237Leu) heterozygous mutation. The pluripotent stem cells exhibit a normal karyotype and express pivotal stem cell markers including TRA-1-60, Nanog, SOX2, and OCT4. Furthermore, their capacity to differentiate into the three germ layers in in vivo teratoma experiments has been substantiated. The pluripotent stem cell line can serve as a cellular model for Alzheimer's disease, offering significant value in elucidating the pathogenesis and therapeutic strategies of the disease.

Generation of an induced pluripotent stem cell line (CSBZZUi001-A) from a female Alzheimer's patient carrying the PSEN1 709 T > C heterozygous mutation.

Alzheimer's disease (AD) is an intricate neurodegenerative disorder characterized by the accumulation of misfolded proteins, including beta-amyloid (Aβ) and tau, leading to cognitive decline. Despite decades of research, the precise mechanisms underlying its onset and progression remain elusive. Cathepsins are a family of lysosomal enzymes that play vital roles in cellular processes, including protein degradation and regulation of immune responses. Emerging evidence suggests that cathepsins may be involved in AD pathogenesis. Cathepsins can influence the activation of microglia and astrocytes, the resident immune cells in the brain. However, cathepsin dysfunction may lead to the accumulation of misfolded proteins, notably Aβ and tau. In addition, dysregulated cathepsin activity may induce an exaggerated immune response, promoting chronic inflammation and neuronal dysfunction in patients with AD. By unraveling the classification, functions, and roles of cathepsins in AD's pathogenesis, this review sheds light on their intricate involvement in this devastating disease. Targeting cathepsin activity could be a promising and novel approach for mitigating the pathological processes that contribute to AD, providing new avenues for its treatment and prevention.

Broadening Horizons: Exploring the Cathepsin Family as Therapeutic Targets for Alzheimer's Disease.

We recruited a healthy 44-year-old female and obtained her skin fibroblasts. Subsequently, the induced pluripotent stem cell line was successfully established using non-integrated reprogramming technology. The cell line had a normal karyotype and has been confirmed to have good pluripotency through the detection of pluripotency markers and detection of teratoma formation. This cell line can serve as an effective control for studying the cellular pathological mechanisms of other specific mutations.

Construction of induced pluripotent stem cell line (CSBZZUi002-A) from the fibroblast cells of a healthy female.

Aging is an intricate process involving interactions among multiple factors, which is one of the main risks for chronic diseases, including Alzheimer's disease (AD). As a member of cysteine protease, cathepsin S (CTSS) has been implicated in inflammation across various diseases. Here, we investigated the role of neuronal CTSS in aging and AD started by examining CTSS expression in hippocampus neurons of aging mice and identified a significant increase, which was negatively correlated with recognition abilities. Concurrently, we observed an elevation of CTSS concentration in the serum of elderly people. Transcriptome and fluorescence-activated cell sorting (FACS) results revealed that CTSS overexpression in neurons aggravated brain inflammatory milieu with microglia activation to M1 pro-inflammatory phenotype, activation of chemokine C-X3-C-motif ligand 1 (CX3CL1)-chemokine C-X3-C-motif receptor 1 (CX3CR1) axis and janus kinase 2 (JAK2)-signal transducer and activator of transcription 3 (STAT3) pathway. As CX3CL1 is secreted by neurons and acts on the CX3CR1 in microglia, our results revealed for the first time the role of neuron CTSS in neuron-microglia "crosstalk." Besides, we observed elevated CTSS expression in multiple brain regions of AD patients, including the hippocampus. Utilizing CTSS selective inhibitor, LY3000328, rescued AD-related pathological features in APP/PS1 mice. We further noticed that neuronal CTSS overexpression increased cathepsin B (CTSB) activity, but decreased cathepsin L (CTSL) activity in microglia. Overall, we provide evidence that CTSS can be used as an aging biomarker and plays regulatory roles through modulating neuroinflammation and recognition in aging and AD process.

Neuronal cathepsin S increases neuroinflammation and causes cognitive decline via CX3CL1-CX3CR1 axis and JAK2-STAT3 pathway in aging and Alzheimer's disease.

Article	Year
History and progress of hypotheses and clinical trials for Alzheimer's disease. Signal transduction and targeted therapy\| PubMed ID: 31637009	2019
The effect of selective serotonin reuptake inhibitors on cognitive function in patients with Alzheimer's disease and vascular dementia: focusing on fluoxetine with long follow-up periods. Signal transduction and targeted therapy\| PubMed ID: 31637010	2019
Erratum: Author Correction: History and progress of hypotheses and clinical trials for Alzheimer's disease. Signal transduction and targeted therapy\| PubMed ID: 31638618	2019
Human herpesvirus 4 and adaptive immunity in Alzheimer's disease. Signal transduction and targeted therapy\| PubMed ID: 32296032	2020
A near-infrared AIE probe and its applications for specific in vitro and in vivo two-photon imaging of lipid droplets. Biomaterials\| PubMed ID: 35948493	2022
Progress in pH-Sensitive sensors: essential tools for organelle pH detection, spotlighting mitochondrion and diverse applications. Frontiers in pharmacology\| PubMed ID: 38269286	2023
Generation of induced pluripotent stem cells (ZZUCSBi001-A) from skin fibroblasts of a healthy donor. Stem cell research\| PubMed ID: 38335661	2024
Neurotransmitter accumulation and Parkinson's disease-like phenotype caused by anion channelrhodopsin opto-controlled astrocytic mitochondrial depolarization in substantia nigra pars compact... MedComm\| PubMed ID: 38756440	2024
Development and Application of a Mitochondrial Genetically Encoded Voltage Indicator in Narcosis. Neuroscience bulletin\| PubMed ID: 38829505	2024
Generation of an induced pluripotent stem cell line (CSBZZUi001-A) from a female Alzheimer's patient carrying the PSEN1 709 T > C heterozygous mutation. Stem cell research\| PubMed ID: 38968760	2024
Broadening Horizons: Exploring the Cathepsin Family as Therapeutic Targets for Alzheimer's Disease. Aging and disease\| PubMed ID: 39122455	2024
Construction of induced pluripotent stem cell line (CSBZZUi002-A) from the fibroblast cells of a healthy female. Stem cell research\| PubMed ID: 39442281	2024
Neuronal cathepsin S increases neuroinflammation and causes cognitive decline via CX3CL1-CX3CR1 axis and JAK2-STAT3 pathway in aging and Alzheimer's disease. Aging cell\| PubMed ID: 39453382	2025

Pei-Pei Liu

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