All Publications
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Deregulation of ER-mitochondria contact formation and mitochondrial calcium homeostasis mediated by VDAC in fragile X syndrome.
Developmental cell
2023; 58 (7): 597-615.e10
Abstract
Loss of fragile X messenger ribonucleoprotein (FMRP) causes fragile X syndrome (FXS), the most prevalent form of inherited intellectual disability. Here, we show that FMRP interacts with the voltage-dependent anion channel (VDAC) to regulate the formation and function of endoplasmic reticulum (ER)-mitochondria contact sites (ERMCSs), structures that are critical for mitochondrial calcium (mito-Ca2+) homeostasis. FMRP-deficient cells feature excessive ERMCS formation and ER-to-mitochondria Ca2+ transfer. Genetic and pharmacological inhibition of VDAC or other ERMCS components restored synaptic structure, function, and plasticity and rescued locomotion and cognitive deficits of the Drosophila dFmr1 mutant. Expressing FMRP C-terminal domain (FMRP-C), which confers FMRP-VDAC interaction, rescued the ERMCS formation and mito-Ca2+ homeostasis defects in FXS patient iPSC-derived neurons and locomotion and cognitive deficits in Fmr1 knockout mice. These results identify altered ERMCS formation and mito-Ca2+ homeostasis as contributors to FXS and offer potential therapeutic targets.
View details for DOI 10.1016/j.devcel.2023.03.002
View details for PubMedID 37040696
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Reverse electron transfer is activated during aging and contributes to aging and age-related disease.
EMBO reports
2023: e55548
Abstract
Mechanisms underlying the depletion of NAD+ and accumulation of reactive oxygen species (ROS) in aging and age-related disorders remain poorly defined. We show that reverse electron transfer (RET) at mitochondrial complex I, which causes increased ROS production and NAD+ to NADH conversion and thus lowered NAD+ /NADH ratio, is active during aging. Genetic or pharmacological inhibition of RET decreases ROS production and increases NAD+ /NADH ratio, extending the lifespan of normal flies. The lifespan-extending effect of RET inhibition is dependent on NAD+ -dependent Sirtuin, highlighting the importance of NAD+ /NADH rebalance, and on longevity-associated Foxo and autophagy pathways. RET and RET-induced ROS and NAD+ /NADH ratio changes are prominent in human induced pluripotent stem cell (iPSC) model and fly models of Alzheimer's disease (AD). Genetic or pharmacological inhibition of RET prevents the accumulation of faulty translation products resulting from inadequate ribosome-mediated quality control, rescues relevant disease phenotypes, and extends the lifespan of Drosophila and mouse AD models. Deregulated RET is therefore a conserved feature of aging, and inhibition of RET may open new therapeutic opportunities in the context of aging and age-related diseases including AD.
View details for DOI 10.15252/embr.202255548
View details for PubMedID 36794623
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Prevention of ribosome collision-induced neuromuscular degeneration by SARS CoV-2-encoded Nsp1.
Proceedings of the National Academy of Sciences of the United States of America
2022; 119 (42): e2202322119
Abstract
An overarching goal of aging and age-related neurodegenerative disease research is to discover effective therapeutic strategies applicable to a broad spectrum of neurodegenerative diseases. Little is known about the extent to which targetable pathogenic mechanisms are shared among these seemingly diverse diseases. Translational control is critical for maintaining proteostasis during aging. Gaining control of the translation machinery is also crucial in the battle between viruses and their hosts. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of the ongoing COVID-19 pandemic. Here, we show that overexpression of SARS-CoV-2-encoded nonstructural protein 1 (Nsp1) robustly rescued neuromuscular degeneration and behavioral phenotypes in Drosophila models of Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis. These diseases share a common mechanism: the accumulation of aberrant protein species due to the stalling and collision of translating ribosomes, leading to proteostasis failure. Our genetic and biochemical analyses revealed that Nsp1 acted in a multipronged manner to resolve collided ribosomes, abort stalled translation, and remove faulty translation products causative of disease in these models, at least in part through the ribosome recycling factor ABCE1, ribosome-associated quality-control factors, autophagy, and AKT signaling. Nsp1 exhibited exquisite specificity in its action, as it did not modify other neurodegenerative conditions not known to be associated with ribosome stalling. These findings uncover a previously unrecognized mechanism of Nsp1 in manipulating host translation, which can be leveraged for combating age-related neurodegenerative diseases that are affecting millions of people worldwide and currently without effective treatment.
View details for DOI 10.1073/pnas.2202322119
View details for PubMedID 36170200
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Dendritic Inhibition by Shh Signaling-Dependent Stellate Cell Pool Is Critical for Motor Learning
JOURNAL OF NEUROSCIENCE
2022; 42 (26): 5130-5143
Abstract
Cerebellar inhibitory interneurons are important regulators of neural circuit activity for diverse motor and nonmotor functions. The molecular layer interneurons (MLIs), consisting of basket cells (BCs) and stellate cells (SCs), provide dendritic and somatic inhibitory synapses onto Purkinje cells, respectively. They are sequentially generated in an inside-out pattern from Pax2+ immature interneurons, which migrate from the prospective white matter to the ML of the cortex. However, little is known about how MLI subtype identities and pool sizes are determined, nor are their contributions to motor learning well understood. Here, we show that GABAergic progenitors fated to generate both BCs and SCs respond to the Sonic hedgehog (Shh) signal. Conditional abrogation of Shh signaling of either sex inhibited proliferation of GABAergic progenitors and reduced the number of Pax2+ cells, whereas persistent Shh pathway activation increased their numbers. These changes, however, did not affect early born BC numbers but selectively altered the SC pool size. Moreover, genetic depletion of GABAergic progenitors when BCs are actively generated also resulted in a specific reduction of SCs, suggesting that the specification of MLI subtypes is independent of Shh signaling and their birth order and likely occurs after Pax2+ cells settle into their laminar positions in an inside-out sequence. Mutant mice with reduced SC numbers displayed decreased dendritic inhibitory synapses and neurotransmission onto Purkinje cells, resulting in an impaired acquisition of eyeblink conditioning. These findings also reveal an essential role of Shh signaling-dependent SCs in regulating inhibitory dendritic synapses and motor learning.SIGNIFICANCE STATEMENT The cerebellar circuit that enables fine motor learning involves MLIs of BCs and SCs, which provide dendritic and somatic inhibitory synapses onto Purkinje cells. Little is known about how their identities and numbers are determined, nor are their specific contributions to motor learning well understood. We show that MLI subtypes are specified independent of Shh signaling and their birth orders but appear to occur in their terminal laminar positions according to the inside-out sequence. This finding challenges the current view that MLI subtypes are specified sequentially at the progenitor level. We also demonstrate that dendritic inhibition by Shh signaling-dependent SC pool is necessary for motor learning.
View details for DOI 10.1523/JNEUROSCI.2073-21.2022
View details for Web of Science ID 000821965900002
View details for PubMedID 35589396
View details for PubMedCentralID PMC9236294
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Autophagy is required for human umbilical cord mesenchymal stem cells to improve spatial working memory in APP/PS1 transgenic mouse model
STEM CELL RESEARCH & THERAPY
2018; 9: 9
Abstract
Recent studies have shown that autophagy plays a central role in mesenchymal stem cells (MSCs), and many studies have shown that human umbilical cord MSCs (huMSCs) can treat Alzheimer's disease (AD) through a variety of mechanisms. However, no studies have looked at the effects of autophagy on neuroprotective function of huMSCs in the AD mouse model. Thus, in this study we investigated whether inhibition of autophagy could weaken or block the function of huMSCs through in vitro and in vivo experiments.In vitro we examined huMSC migration and neuronal differentiation by inhibiting or activating autophagy; in vivo autophagy of huMSCs was inhibited by knocking down Beclin 1, and these huMSCs were transplanted into the APP/PS1 transgenic mouse. A series of related indicators were detected by T-maze task, electrophysiological experiments, immunofluorescence staining, enzyme-linked immunosorbent assay (ELISA), and Western blotting.We demonstrated that regulation of autophagy can affect huMSC migration and their neuronal differentiation. Moreover, inhibition of autophagy in huMSCs could not realize neuroprotective effects via anti-apoptosis or promoting neurogenesis and synapse formation compared with those of control huMSCs.These findings indicate that autophagy is required for huMSCs to maintain their function and improve cognition impairment in APP/PS1 transgenic mice.
View details for DOI 10.1186/s13287-017-0756-2
View details for Web of Science ID 000419962400001
View details for PubMedID 29335016
View details for PubMedCentralID PMC5769333
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Autophagy is involved in mouse kidney development and podocyte differentiation regulated by Notch signalling
JOURNAL OF CELLULAR AND MOLECULAR MEDICINE
2017; 21 (7): 1315-1328
Abstract
Podocyte dysfunction results in glomerular diseases accounted for 90% of end-stage kidney disease. The evolutionarily conserved Notch signalling makes a crucial contribution in podocyte development and function. However, the underlying mechanism of Notch pathway modulating podocyte differentiation remains less obvious. Autophagy, reported to be related with Notch signalling pathways in different animal models, is regarded as a possible participant during podocyte differentiation. Here, we found the dynamic changes of Notch1 were coincided with autophagy: they both increased during kidney development and podocyte differentiation. Intriguingly, when Notch signalling was down-regulated by DAPT, autophagy was greatly diminished, and differentiation was also impaired. Further, to better understand the relationship between Notch signalling and autophagy in podocyte differentiation, rapamycin was added to enhance autophagy levels in DAPT-treated cells, and as a result, nephrin was recovered and DAPT-induced injury was ameliorated. Therefore, we put forward that autophagy is involved in kidney development and podocyte differentiation regulated by Notch signalling.
View details for DOI 10.1111/jcmm.13061
View details for Web of Science ID 000404367800007
View details for PubMedID 28158917
View details for PubMedCentralID PMC5487928
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Icariin combined with human umbilical cord mesenchymal stem cells significantly improve the impaired kidney function in chronic renal failure
MOLECULAR AND CELLULAR BIOCHEMISTRY
2017; 428 (1-2): 203-212
Abstract
At present, the main therapy for chronic renal failure (CRF) is dialysis and renal transplantation, but neither obtains satisfactory results. Human umbilical cord mesenchymal stem cells (huMSCs) are isolated from the fetal umbilical cord which has a high self-renewal and multi-directional differentiation potential. Icariin (ICA), a kidney-tonifying Chinese Medicine can enhance the multipotency of huMSCs. Therefore, this work seeks to employ the use of ICA-treated huMSCs for the treatment of chronic renal failure. Blood urea nitrogen and creatinine (Cr) analyses showed amelioration of functional parameters in ICA-treated huMSCs for the treatment of CRF rats at 3, 7, and 14 days after transplantation. ICA-treated huMSCs can obviously increase the number of cells in injured renal tissues at 3, 7, and 14 days after transplantation by optical molecular imaging system. Hematoxylin-eosin staining demonstrated that ICA-treated huMSCs reduced the levels of fibrosis in CRF rats at 14 days after transplantation. Superoxide dismutase and Malondialdehyde analyses showed that ICA-treated huMSCs reduced the oxidative damage in CRF rats. Moreover, transplantation with ICA-treated huMSCs decreased inflammatory responses, promoted the expression of growth factors, and protected injured renal tissues. Taken together, our findings suggest that ICA-treated huMSCs could improve the kidney function in CRF rats.
View details for DOI 10.1007/s11010-016-2930-8
View details for Web of Science ID 000399249400019
View details for PubMedID 28116543
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Etidronate rescues cognitive deficits through improving synaptic transmission and suppressing apoptosis in 2-vessel occlusion model rats
JOURNAL OF NEUROCHEMISTRY
2017; 140 (3): 476-484
Abstract
Vascular dementia is a neurodegenerative disorder caused by the reduction of cerebral blood flow. It shows a progressive cognitive impairment. In our previous study, we found that etidronate (ET) showed neuroprotective effects against glutamate-injured PC12 cells. Thus, in this study, we aimed to observe the effects of ET on learning and memory impairment and the related mechanism in 2-vessel occlusion (2VO) model rats. Rats were administered a permanent bilateral common carotid artery occlusion to induce vascular dementia model. Two weeks later, 2VO model rats were treated with ET (20 mg/kg/day i.p.) for 1 week. Results showed that ET improved the spatial learning and memory function in 2VO rats detected by Morris water maze experiment. A reduced long-term potentiation was also rescued by ET treatment in 2VO rats. Moreover, the long-term potentiation-related proteins, calcium/calmodulin-dependent protein kinase II (CaMKII), NMDAR 2B and PSD95 were up-regulated after treatment with ET. By testing the levels of malondialdehyde and superoxide dismutase in 2VO rats, we discovered that ET lowered oxidative stress. Furthermore, ET displayed a better anti-apoptosis ability through detecting the levels of Bcl-2 and Bax protein and terminal deoxynucleotidyl transferase dUTP nick-end labeling-positive cells. In conclusion, ET shows neuroprotective effects on 2VO rats through rescuing spatial working memory deficits, and a possible mechanism may be related to the increased synaptic transmission and the inhibition of oxidative stress and apoptosis.
View details for DOI 10.1111/jnc.13904
View details for Web of Science ID 000394641200011
View details for PubMedID 27874976
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Neuroprotective Effects of Etidronate and 2,3,3-Trisphosphonate Against Glutamate-Induced Toxicity in PC12 Cells
NEUROCHEMICAL RESEARCH
2016; 41 (4): 844-854
Abstract
Etidronate is one of the best known bisphosphonates (BP) derivatives. It is often used as a reference drug in research related to hypercalcaemia and other common bone diseases. 2,3,3-trisphosphonate (TrisPP) is brand new analogue of BP, that also contains a 'germinal bisphosphonate' unit with an additional phosphoryl group attached in proximity to the BP unit. It is known that BPs bind to calcium by chemisorptions to form Ca-BP complexes through (O)P-C-P(O) moiety and hydrogen coordinations, and so they suppress calcium flow by interfering with Ca(2+) channel operations. The mechanistic actions of BP, involving interactions and regulations of Ca(2+), are somewhat similar to the pathogenesis of well-known neurodegenerative disorders, such as Alzheimer's disease, Parkinson's disease and Huntington's disease. To investigate if neuroprotective effects are exhibited by the compounds of interests, we used a rat adrenal pheochromocytoma cell line (PC12) as our in vitro model to observe any occurrence of neuron inter-reflection. We pre-treated these PC12 cells with etidronate and TrisPP before challenging the cells with a high concentration of the neurotoxin, glutamate. Our data showed that pre-treatment with 100 μM etidronate partially ameliorated the glutamate-induced decrease in cell viability (47 %), whereas pre-treating cells with 10-100 μM TrisPP showed remarkable cell protection (78-86 %). Moreover, pre-treatments of the cells with etidronate or TrisPP attenuated cell apoptosis, reactive oxygen species generation, Ca(2+) overloading and caspase-3 protein expression, which were associated with a remarkable increase in superoxide dismutase activity in our glutamate-injured PC12 cells. Therefore, this study supports the notion that etidronate and TrisPP may be promising neuroprotective agents.
View details for DOI 10.1007/s11064-015-1761-4
View details for Web of Science ID 000373860300023
View details for PubMedID 26559687
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Toxicology of nanosized titanium dioxide: an update
ARCHIVES OF TOXICOLOGY
2015; 89 (12): 2207-2217
Abstract
Nanosized titanium dioxide (nano-TiO2) has tremendous potential for a host of applications, and TiO2 nanoparticles (NP) possess different physicochemical properties compared to their fine particle analogs, which might alter their bioactivity. Their adverse effects on living cells have raised serious concerns recently for their use in health care and consumer sectors such as sunscreens, cosmetics, pharmaceutical additives and implanted biomaterials. Many researches have demonstrated that the physicochemical properties including shape, size, surface characteristics and inner structure of nano-TiO2 particles have different degrees of toxicity to different organism groups under different conditions. Some former reports have demonstrated that nano-TiO2 materials could enter into human body through different routes such as inhalation, dermal penetration and ingestion. After being taken by human body, NP might induce oxidative stress, cytotoxicity, genotoxicity, inflammation and cell apoptosis ultimately in mammal organs and systems. Here, we summarized the update about toxicity of nano-TiO2 and aimed to supply a safety usage guideline of this nanomaterial.
View details for DOI 10.1007/s00204-015-1594-6
View details for Web of Science ID 000366155200002
View details for PubMedID 26391178
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Nucleus-staining with biomolecule-mimicking nitrogen-doped carbon dots prepared by a fast neutralization heat strategy
CHEMICAL COMMUNICATIONS
2015; 51 (95): 16956-16959
Abstract
Biomolecule-mimicking nitrogen-doped carbon dots (N-Cdots) were synthesized from dopamine by a neutralization heat strategy. Fluorescence imaging of various cells validated their nucleus-staining efficiency. The dopamine-mimicking N-Cdots "trick" nuclear membranes to achieve nuclear localization and imaging.
View details for DOI 10.1039/c5cc06304c
View details for Web of Science ID 000367468300016
View details for PubMedID 26445735