Biology subjects

Lee, Y.

Publications and source records attributed to Lee, Y..

At least 271 records · Page 15Linked to original sources

bioRxiv2020

Non-canonical immune response to the inhibition of DNA methylation via stabilization of endogenous retrovirus dsRNAs

5-Aza-2'-deoxycytidine, also known as decitabine, is a DNA-methyltransferase inhibitor (DNMTi) used to treat acute myeloid leukemia (AML). Decitabine activates the transcription of endogenous retroviruses (ERV), which can induce an immune response by acting as cellular double-stranded RNAs (dsRNAs). Here, we employ an image-based screening platform to identify dsRNA-binding factors that mediate the downstream effect of ERV induction. We find that Staufen1 (Stau1) knockdown decreases the interferon signature and rescues decitabine-mediated cell death. Moreover, Stau1 directly binds to ERV RNAs and stabilizes them, together with a long non-coding RNA TINCR. We further show that TINCR enhances the interaction between Stau1 and ERV RNAs. Analysis of a clinical patient cohort reveals that AML patients with low Stau1 and TINCR expressions exhibits inferior treatment outcomes to the DNMTi therapy. Our study reveals that decitabine-mediated cell death is a consequence of complex interactions among different dsRNA-binding proteins for access to their common dsRNA targets. HIGHLIHGTSO_LIImage-based RNAi screening reveals multiple dsRBPs regulate response to decitabine C_LIO_LIStau1 binds to ERV RNAs and affects their stability and subcellular localization C_LIO_LITINCR binds to Stau1 and enhances Stau1-ERV interactions C_LIO_LIAML/MDS patients with low Stau1 and TINCR expressions show poor response to DNMTis C_LI

molecular biology↗

bioRxiv2020

High-order mutants reveal an essential requirement for peroxidases but not laccases in Casparian strip lignification

The invention of lignin has been at the heart of plants capacity to colonize land, allowing them to grow tall, transport water within their bodies and protect themselves against various stresses. Consequently, this polyphenolic polymer, that impregnates the cellulosic plant cell walls, now represents the second most abundant polymer on Earth, after cellulose itself. Yet, despite its great physiological, ecological and economical importance, our knowledge of lignin biosynthesis in vivo, especially the crucial last steps of polymerization within the cell wall, remains vague. Specifically, the respective roles and importance of the two main polymerizing enzymes classes, laccases and peroxidases have remained obscure. One reason for this lies in the very high numbers of laccases and peroxidases encoded by 17 and 73 homologous genes, respectively, in the Arabidopsis genome. Here, we have focused on a specific lignin structure, the ring-like Casparian strips (CS) within the endodermis of Arabidopsis roots. By reducing the number of possible candidate genes using cellular resolution expression and localization data and by boosting the levels of mutants that can be stacked using CRISPR/Cas9, we were able to knock-out more than half of all laccases in the Arabidopsis genome in a nonuple mutant - abolishing the vast majority of laccases with detectable endodermal-expression. Yet, we were unable to detect even slight defects in CS formation. By contrast, we were able to induce a complete absence of CS formation in a quintuple peroxidase mutant. Our findings are in stark contrast to the strong requirement of xylem vessels for laccase action and indicate that lignin in different cell types can be polymerized in very distinct ways. We speculate that cells lignify differently depending on whether they deposit lignin in a localized or ubiquitous fashion, whether they stay alive during and after lignification as well as the composition of the cell wall.

plant biology↗

bioRxiv2020

A hybrid Embden-Meyerhof-Parnas pathway provides a synthetic link between sugar and phosphate metabolism

The fundamental Embden–Meyerhoff–Paranas (EMP) pathway for sugar catabolism, anabolism, and energy metabolism has been reconstituted with non-oxidative glycolysis (NOG). Although carbon conservation was achieved via NOG, the energy metabolism was significantly limited. Herein, we showed the construction of a hybrid EMP that replaced the first phase of the EMP in Corynebacterium glutamicum with NOG and revealed a metabolic link of carbon and phosphorus metabolism. In accordance with synthetic glucose kinase activity and phosphoketolase on the hybrid EMP, cell growth was completely recovered in the C. glutamicum pfkA mutant strain where the first phase of EMP was eliminated. Notably, we have revealed a phosphate-replenishing pathway that involved trehalose biosynthesis for the generation of inorganic phosphate (Pi) sources in the hybrid EMP when external Pi supply was limited. Thus, the re-designed hybrid EMP pathway with balanced carbon and phosphorus states provides an efficient microbial platform for biochemical production.Competing Interest StatementThe authors have declared no competing interest.View Full Text

synthetic biology↗

bioRxiv2020

Protein structure search to support the development of protein structure prediction methods

Protein structure prediction is a long-standing unsolved problem in molecular biology that has seen renewed interest with the recent success of deep learning with AlphaFold at CASP13. While developing and evaluating protein structure prediction methods, researchers may want to identify the most similar known structures to their predicted structures. These predicted structures often have low sequence and structure similarity to known structures. We show how RUPEE, a purely geometric protein structure search, is able to identify the structures most similar to structure predictions, regardless of how they vary from known structures, something existing protein structure searches struggle with. RUPEE accomplishes this through the use of a novel linear encoding of protein structures as a sequence of residue descriptors. Using a fast Needleman-Wunsch algorithm, RUPEE is able to perform alignments on the sequences of residue descriptors for every available structure. This is followed by a series of increasingly accurate structure alignments from TM-align alignments initialized with the Needleman-Wunsch residue descriptor alignments to standard TM-align alignments of the final results. By using alignment normalization effectively at each stage, RUPEE also can execute containment searches in addition to full-length searches to identify structural motifs within proteins. We compare the results of RUPEE to mTM-align, SSM, CATHEDRAL and VAST using a benchmark derived from the protein structure predictions submitted to CASP13. RUPEE identifies better alignments on average with respect to RMSD and TM-score as well as Q-score and SSAP-score, scores specific to SSM and CATHEDRAL, respectively. Finally, we show a sample of the top-scoring alignments that RUPEE identified that none of the other protein structure searches we compared to were able to identify. The RUPEE protein structure search is available at https://ayoubresearch.com. Code and data are available at https://github.com/rayoub/rupee.

bioinformatics↗

bioRxiv2020

An endocrine-hepato-muscular metabolic cycle links skeletal muscle atrophy and hyperglycemia in type 2 diabetes

Both obesity and sarcopenia are frequently associated in ageing, and together may promote the progression of related conditions such as diabetes and frailty. However, little is known about the pathophysiological mechanisms underpinning this association. Here we uncover dysregulated systemic alanine metabolism and hyper-expression of the alanine transaminases (ALT) in the liver of obese/diabetic mice and humans. Hepatocyte-selective silencing of both ALT enzymes revealed a clear role in systemic alanine clearance which related to glycemic control. In obese/diabetic mice, not only did silencing both ALT enzymes retard hyperglycemia, but also reversed skeletal muscle atrophy. This was due to a rescue of depressed skeletal muscle protein synthesis, with a liver-skeletal muscle amino acid metabolic crosstalk exemplified by ex vivo experiments. Mechanistically, chronic liver glucocorticoid and glucagon signaling driven liver alanine catabolism promoted hyperglycemia and skeletal muscle wasting. Taken together, here we reveal an endocrine-hepato-muscular metabolic cycle linking hyperglycemia and skeletal muscle atrophy in type 2 diabetes.

physiology↗

bioRxiv2020

Impaired hand dexterity function in a non-human primate model with chronic Parkinson's disease

Symptoms of Parkinsons disease (PD) caused by loss of dopaminergic neurons are accompanied by movement disorders, including tremors, rigidity, bradykinesia, and akinesia. Non-human primate (NHP) models with PD play an essential role in the analysis of PD pathophysiology and behavior symptoms. As impairments of hand dexterity function can affect activities of daily living in patients with PD, research on hand dexterity function in NHP models with chronic PD is essential. Traditional rating scales previously used in the evaluation of animal spontaneous behavior were insufficient due to factors related to subjectivity and passivity. Thus, experimentally designed applications for an appropriate apparatus are necessary. In this study, we aimed to longitudinally assess hand dexterity function using hand dexterity task (HDT) in NHP-PD models. To validate this assessment, we analyzed an alteration in Parkinsonian tremor symptoms, loss of dopaminergic neuron, and positron emission tomography (PET) imaging of dopamine transporters (DAT) in these models. HDT latency significantly increased in NHP-PD models. In addition, a significant inverse correlation between HDT and DAT was identified, but no local bias was found. The correlation with intention tremor symptoms was lower than the resting tremor. In conclusion, the evaluation of HDT may reflect behavioral symptoms of NHP-PD models. Furthermore, HDT was effectively used to experimentally distinguish intention tremors from other tremors.

neuroscience↗

bioRxiv2020

Gait analysis of healthy rhesus monkeys using a pressure-sensing walkway system

Gait analysis in non-human primate models has been performed to elucidate the neural systems involved in controlling quadrupedal locomotor behavior. This study aimed to use a pressure-sensing walkway to identify characteristics of species-specific quadrupedal locomotion in rhesus monkeys. A total of nine healthy adult female rhesus monkeys (Macaca mulatta) were used for gait analysis. We measured the temporo-spatial and kinetic parameters of quadrupedal gait using a custom-built pressure-sensing walkway and compared the left- and right-side parameters to assess the symmetry of the gait pattern. All temporo-spatial and kinetic parameter values showed no significant differences among the nine rhesus monkeys for both the forelimbs and hindlimbs. However, significant differences were observed between forelimb and hindlimb kinetic parameters such as peak vertical force, vertical impulse, and the percentage of body weight distribution. All kinetic parameter values were higher for the forelimbs than for the hindlimbs. These data indicated that the center of gravity in healthy rhesus monkeys is located at the forelimbs rather than at the hindlimbs while walking. Furthermore, the symmetry indices considered for symmetric gait pattern showed a low variability. Most median symmetry index values were nearly zero, indicating no difference between the right and left sides. This study described valid methods for assessing gait parameters and demonstrated rhesus-specific characteristics of quadrupedal locomotion, providing a basis for the assessment of gait normality in rhesus monkeys.

animal behavior and cognition↗

bioRxiv2020

Molecular determinants of β-arrestin coupling to formoterol-bound β1-adrenoceptor

The {beta}1-adrenoceptor ({beta}1AR) is a G protein-coupled receptor (GPCR) activated by the hormone noradrenaline, resulting in the coupling of the heterotrimeric G protein Gs1. G protein-mediated signalling is terminated by phosphorylation of the receptor C-terminus and coupling of {beta}-arrestin 1 ({beta}arr1, also known as arrestin-2), which displaces Gs and induces signalling through the MAP kinase pathway2. The ability of synthetic agonists to induce signalling preferentially through either G proteins or arrestins (biased agonism)3 is important in drug development, as the therapeutic effect may arise from only one signalling cascade, whilst the other pathway may mediate undesirable side effects4. To understand the molecular basis for arrestin coupling, we determined the electron cryo-microscopy (cryo-EM) structure of the {beta}1AR-{beta}arr1 complex in lipid nanodiscs bound to the biased agonist formoterol5, and the crystal structure of formoterol-bound {beta}1AR coupled to the G protein mimetic nanobody Nb806. {beta}arr1 couples to {beta}1AR in a distinct manner to how Gs couples to {beta}2AR7, with the finger loop of {beta}arr1 occupying a narrower cleft on the intracellular surface closer to transmembrane helix H7 than the C-terminal 5 helix of Gs. The conformation of the finger loop in {beta}arr1 is different from that adopted by the finger loop in visual arrestin when it couples to rhodopsin8, and its {beta}-turn configuration is reminiscent of the loop in Nb80 that inserts at the same position. {beta}1AR coupled to {beta}arr1 showed significant differences in structure compared to {beta}1AR coupled to Nb80, including an inward movement of extracellular loop 3 (ECL3) and the cytoplasmic ends of H5 and H6. In the orthosteric binding site there was also weakening of interactions between formoterol and the residues Ser2115.42 and Ser2155.46, and a reduction in affinity of formoterol for the {beta}1AR-{beta}arr1 complex compared to {beta}1AR coupled to mini-Gs. These differences provide a foundation for the development of small molecules that could bias signalling in the {beta}-adrenoceptors.

molecular biology↗

bioRxiv2020

Engineered Heterochronic Parabiosis in 3D Microphysiological System for Identification of Muscle Rejuvenating Factors

Exposure of aged mice to a young systemic milieu revealed remarkable rejuvenation effects on aged tissues, including skeletal muscle. Although some candidate factors have been identified, the exact identity and the underlying mechanisms of putative rejuvenating factors remain elusive, mainly due to the complexity of in vivo parabiosis. Here, we present an in vitro muscle parabiosis system that integrates young- and old-muscle stem cell vascular niche on a three-dimensional microfluidic platform designed to recapitulate key features of native muscle stem cell microenvironment. This innovative system enables mechanistic studies of cellular dynamics and molecular interactions within the muscle stem cell niche, especially in response to conditional extrinsic stimuli of local and systemic factors. We demonstrate that vascular endothelial growth factor (VEGF) signaling from endothelial cells and myotubes synergistically contribute to the rejuvenation of the aged muscle stem cell function. Moreover, with the adjustable on-chip system, we can mimic both blood transfusion and parabiosis and detect the time-varying effects of anti-geronic and pro-geronic factors in a single organ or multi-organ systems. Our unique approach presents a complementary in vitro model to supplement in vivo parabiosis for identifying potential anti-geronic factors responsible for revitalizing aging organs.

cell biology↗

bioRxiv2020

ThiL is a valid antibacterial target that is essential for both thiamine biosynthesis and salvage pathway in Pseudomonas aeruginosa

Thiamine pyrophosphate (TPP) is an essential cofactor for various pivotal cellular processes in all living organisms, including bacteria. As thiamine biosynthesis occurs in bacteria but not humans, bacterial thiamine biosynthesis is an attractive target for antibiotic development. Among enzymes in the thiamine biosynthetic pathway, thiamine monophosphate kinase (ThiL) catalyzes the final step of the pathway, phosphorylating thiamine monophosphate (TMP) to produce TPP. In this work, we extensively investigated ThiL in Pseudomonas aeruginosa, a major pathogen of hospital-acquired infections. We demonstrated that thiL deletion abolishes not only thiamine biosynthesis but also thiamine salvage capability, showing growth defects of the {Delta}thiL mutant even in the presence of thiamine derivatives except TPP. Most importantly, the pathogenesis of the {Delta}thiL mutant was markedly attenuated compared to wild-type bacteria, with lower inflammatory cytokine induction and 103~104 times decreased bacterial load in an in vivo infection model where the intracellular TPP level is in the submicromolar range. In order to validate P. aeruginosa ThiL (PaThiL) as a new drug target, we further characterized its biochemical properties determining a Vmax of 4.0{+/-}0.2 nomol{middle dot}min-1 and KM values of 111{+/-}8 and 8.0{+/-}3.5M for ATP and TMP, respectively. A subsequent in vitro small molecule screening identified PaThiL inhibitors including WAY213613 that is a noncompetitive inhibitor with a Ki value of 13.4{+/-}2.3 M and a potential antibacterial activity against P. aeruginosa. This study proved that PaThiL is a new drug target against P. aeruginosa providing comprehensive biological and biochemical data that could facilitate to develop a new repertoire of antibiotics.

microbiology↗

bioRxiv2020

CRISPR Screen in Regulatory T Cells Reveals Ubiquitination Modulators of Foxp3

Regulatory T cells (Tregs) are required to control immune responses and maintain homeostasis but are a significant barrier to anti-tumor immunity1. Conversely, Treg instability, characterized by loss of the master transcription factor Foxp3 and acquisition of pro-inflammatory properties2, can promote autoimmunity and/or facilitate more effective tumor immunity3,4. A comprehensive understanding of the pathways that regulate Foxp3 could lead to more effective Treg therapies for autoimmune disease and cancer. Despite improved functional genetic tools that now allow for systematic interrogation, dissection of the gene regulatory programs that modulate Foxp3 expression has not yet been reported. In this study, we developed a CRISPR-based pooled screening platform for phenotypes in primary mouse Tregs and applied this technology to perform a targeted loss-of-function screen of [~]490 nuclear factors to identify gene regulatory programs that promote or disrupt Foxp3 expression. We discovered several novel modulators including ubiquitin-specific peptidase 22 (Usp22), Ataxin 7 like 3 (Atxn7l3) and ring finger protein 20 (Rnf20). Members of the deubiquitination module of the SAGA chromatin modifying complex, Usp22 and Atxn7l3, were discovered to be positive regulators that stabilized Foxp3 expression; whereas the screen suggested Rnf20, an E3 ubiquitin ligase, is a negative regulator of Foxp3. Treg-specific ablation of Usp22 in mice reduced Foxp3 protein and created defects in their suppressive function that led to spontaneous autoimmunity but protected against tumor growth in multiple cancer models. Foxp3 destabilization in Usp22-deficient Tregs could be rescued by ablation of Rnf20, revealing a reciprocal ubiquitin switch in Tregs. These results reveal novel modulators of Foxp3 and demonstrate a screening method that can be broadly applied to discover new targets for Treg immunotherapies for cancer and autoimmune disease.

immunology↗

bioRxiv2020

Is FAM19A5 an adipokine? Peripheral FAM19A5 in wild-type, FAM19A5 knock-out, and LacZ knock-in mice.

FAM19A5 is a novel secretory protein primarily expressed in the brain. However, a recent study reported that FAM19A5 is an adipocyte-derived adipokine that regulates vascular smooth muscle function through sphingosine-1-phosphate receptor 2 (S1PR2). In our study, we investigated FAM19A5 transcript and protein levels in peripheral tissues, including adipose tissues, from wild-type, FAM19A5 knockout, and FAM19A5 LacZ knockin mice. We found that FAM19A5 transcript levels in the central nervous system were much greater than those in any of the peripheral tissues, including adipose tissues. Furthermore, the FAM19A5 protein levels in adipose and reproductive tissues were below detectable limits for Western blot analysis. Additionally, we found that the FAM19A5 protein did not interact with S1PR2 in terms of G protein-mediated signal transduction, {beta}-arrestin recruitment, or ligand-mediated internalization. Taken together, our findings revealed basal levels of FAM19A5 transcripts and proteins in peripheral tissues, confirming its primary expression in the central nervous system and lack of significant interaction with S1PR2.

genetics↗

bioRxiv2020

Improvement of glymphatic-lymphatic drainage of beta-amyloid by focused ultrasound in Alzheimer's disease model

Drainage of parenchymal waste through the lymphatic system maintains brain homeostasis. Age-related changes of glymphatic-lymphatic clearance lead to the accumulation beta-amyloid (A{beta}) in dementia models. In this study, focused ultrasound treatment in combination with microbubbles (FUS-MB) improved A{beta} drainage in early dementia model mice, 5XFAD. FUS-MB enhanced solute A{beta} clearance from brain, but not plaques, to cerebrospinal fluid (CSF) space and then deep cervical lymph node (dCLN). dCLN ligation exaggerated memory impairment and progress of plaque formation and also the beneficial effects of FUS-MB upon A{beta} removal through CSF-lymphatic routes. In this ligation model, FUS-MB improved memory despite accumulation of A{beta} in CSF. In conclusion, FUS-MB enhances glymphatic-lymphatic clearance of A{beta} mainly by increasing brain-to-CSF A{beta} drainage. We suggest that FUS-MB can delay dementia progress in early period and benefits of FUS-MB depend on the effect of A{beta} disposal through CSF-lymphatics.

neuroscience↗

bioRxiv2020

Roles of sarcoplasmic reticulum Ca2+ ATPase pump in the impairments of lymphatic contractile activity in a metabolic syndrome rat model

The intrinsic lymphatic contractile activity is necessary for proper lymph transport. Mesenteric lymphatic vessels from high-fructose diet-induced metabolic syndrome (MetSyn) rats exhibited impairments in its intrinsic phasic contractile activity; however, the molecular mechanisms responsible for the weaker lymphatic pumping activity in MetSyn conditions are unknown. Several metabolic disease models have shown that dysregulation of sarcoplasmic reticulum Ca2+ ATPase (SERCA) pump is one of the key determinants of the phenotypes seen in various muscle tissues. Hence, we hypothesized that a decrease in SERCA pump expression and/or activity in lymphatic muscle influences the diminished lymphatic vessel contractions in MetSyn animals. Results demonstrated that SERCA inhibitor, thapsigargin, significantly reduced lymphatic phasic contractile frequency and amplitude in control vessels, whereas, the reduced MetSyn lymphatic contractile activity was not further diminished by thapsigargin. While SERCA2a expression was significantly decreased in MetSyn lymphatic vessels, myosin light chain 20, MLC20 phosphorylation was increased in these vessels. Additionally, insulin resistant lymphatic muscle cells exhibited elevated intracellular calcium and decreased SERCA2a expression and activity. The SERCA activator, CDN 1163 increased phasic contractile frequency in the vessels from MetSyn, thereby, partially restored lymph flow. Thus, our data provide the first evidence that SERCA2a modulates the lymphatic pumping activity by regulating phasic contractile amplitude and frequency, but not the lymphatic tone. Diminished lymphatic contractile activity in the vessels from the MetSyn animal is associated with the decreased SERCA2a expression and impaired SERCA2 activity in lymphatic muscle.

physiology↗

bioRxiv2019

An instrument to assess HIV-related knowledge and adjustment to HIV+ status, and their association with anti-retroviral adherence

BackgroundFindings on the association between health literacy and anti-retroviral (ARV) adherence are inconsistent. Health literacy is usually operationalized with simple tests of basic literacy, but more complex conceptions of health literacy include content knowledge. People living with chronic illness also conceptualize and experience illness in ways other than biomedical or mechanistic models of disease. ObjectiveThere are no instruments that comprehensively assess knowledge of people living with HIV concerning HIV disease and treatment; or psychological adjustment to being HIV+. Little is known about the relationship between factual knowledge, or positive identification as HIV+, and anti-retroviral (ARV) adherence. MethodsFormative work with in-depth semi-structured interviews, and cognitive testing, to develop a structured instrument assessing HIV-related knowledge, and personal meanings of living with HIV. Pilot administration of the instrument to a convenience sample of 101 respondents. Key ResultsRespondents varied considerably in their expressed need for in-depth knowledge, the accuracy of their understanding of relevant scientific concepts and facts about ARV treatment, and psychological adjustment and acceptance of HIV+ status. Most knowledge domains were not significantly related to self-reported ARV adherence, but accurate knowledge specifically about ARV treatment was (r=0.25, p=.02), as was an adapted version of the Need for Cognition scale (r=.256, p=.012). Negative feelings about living with HIV (r=.33, p=.0012), and medication taking (r=.276, p=.008) were significantly associated with non-adherence. ConclusionThe instrument may be useful in diagnosing addressable reasons for non-adherence, as a component of psychoeducational interventions, and for evaluation of such interventions. PLAIN LANGUAGE SUMMARYWe developed a questionnaire for people with HIV. General knowledge about HIV wasnt related to whether people took their medications, but specific information about treatment was. People with lots of bad feelings about living with HIV were less likely to take medications as prescribed. People who liked to think more about their decisions were more likely to take their medications.

scientific communication and education↗

bioRxiv2019

Individual differences in dopamine function underlying the balance between model-based and model-free control

Reinforcement learning involves a balance between model-free (MF) and model-based (MB) systems. Recent studies suggest that individuals with either pharmacologically enhanced levels of dopamine (DA) or higher baseline levels of DA exhibit more MB control. However, it remains unknown whether such pharmacological effects depend on baseline DA. Here, we investigated whether effects of L-DOPA on the balance of MB/MF control depend on ventral striatal baseline DA. Sixty participants had two functional magnetic resonance imaging (fMRI) scans while performing a two-stage sequential decision-making task under 150 mg L-DOPA or placebo (counterbalanced), followed by a 4-hour 18F-DOPA positron emission tomography (PET) scan (on a separate occasion). We found an interaction between baseline DA levels and L-DOPA induced changes in MB control. Individuals with higher baseline DA levels showed a greater L-DOPA induced enhancement in MB control. Surprisingly, we found a corresponding drug-by-baseline DA interaction on MF, but not MB learning signals in the ventromedial prefrontal cortex. We did not find a significant interaction between baseline DA levels and L-DOPA effects on MF control or MB/MF balance. In sum, our findings point to a baseline dependency of L-DOPA effects on differential aspects of MB and MF control. Individual differences in DA washout may be an important moderator of L-DOPA effects. Overall, our findings complement the general notion where higher DA levels is related to a greater reliance on MB control. Although the relationship between phasic DA firing and MF learning is conventionally assumed in the animal literature, the relationship between DA and MF control is not as straightforward and requires further clarification.

neuroscience↗

bioRxiv2019

GSK-3β regulates the synaptic expression of NMDA receptors via phosphorylation of phosphatidylinositol 4 kinase type IIα

Understanding the normal functions of GSK-3{beta} in the central nervous system is of major interest because deregulation of this kinase is strongly implicated in a variety of serious brain conditions, such as Alzheimer disease, bipolar disorder and schizophrenia. GSK-3{beta} plays a role in the induction of NMDA receptor-dependent long-term depression (LTD) and several substrates for GSK-3{beta} have been identified in this form of synaptic plasticity, including KLC-2, PSD-95 and tau. Stabilization of NMDA receptors at synapses has also been shown to involve GSK-3{beta}, but the substrates involved are currently unknown. Recent work has identified phosphatidylinositol 4 kinase type II (PI4KII) as a neuronal GSK-3{beta} substrate that can potentially regulate the surface expression of AMPA receptors. In the present study, we investigated the synaptic role of PI4KII in organotypic rat hippocampal slices. We found that knockdown of PI4KII had no effect on synaptic AMPA receptors but substantially inhibited synaptic NMDA receptors. Furthermore, the ability of the selective GSK-3 inhibitor, CT99021, to inhibit synaptic NMDA receptors was occluded in shRNA-PI4KII transfected neurons. The effects of knocking down PI4KII knockdown were fully rescued by a shRNA-resistant wild type construct but could not be rescued by a mutant construct that was unable to be phosphorylated by GSK-3{beta}. The data suggest that GSK-3{beta} phosphorylates PI4KII to stabilize the expression of synaptic NMDA receptors.

neuroscience↗

bioRxiv2019

Translationally relevant transcriptomic alterations in mouse ischemic cerebral microvessels

Increasing evidence implicates cerebral microvascular dysfunction in the pathophysiology of numerous central nervous system pathologies, including stroke. Understanding the molecular alterations in cerebral microvessels in these conditions will provide original opportunities for scientific investigation at the pre-clinical and clinical levels. In this study, we conducted a novel genome-wide transcriptomic analysis of microvessels in a mouse model of transient focal cerebral ischemia. Using a publicly available human ischemic stroke dataset, we identified shared alterations in our microvessel dataset with implications for human pathophysiology. From this unbiased analysis, we report predicted alterations in inter- and intra-cellular signaling, emphasizing perturbations in genes involved in blood brain barrier function, endothelial cell activation and metabolism. Furthermore, our study unveiled previously unreported gene expression changes associated with altered sphingolipid metabolism. Altogether, our results have identified microvessel-specific transcriptomic changes in a number of translationally relevant pathways that support the targeting of these pathways in preclinical studies. The data shared here provide a resource for future investigation of translationally relevant pathways in ischemic stroke.

neuroscience↗