MARK, a novel family of protein kinases that phosphorylate microtubule-associated proteins and trigger microtubule disruption

Research progress on anti-tumor mechanism of TAOK kinases

Thousand and one amino-acid protein kinases(TAOKs), as a key member of the mitogen-activated protein kinase (MAPK) cascade, has recently attracted widespread attention in the field of anti-cancer research. There are three members of this subfamily: TAOK1, TAOK2, and TAOK3. Studies have shown that members of the TAOK family participate in regulating cell proliferation, apoptosis, migration, and invasion through various pathways, thereby playing an important role in tumorigenesis and progression. This review summarizes the functions of TAOK kinases in tumor cell signal transduction, cell cycle regulation, and the tumor microenvironment, with a particular emphasis on its potential as a target for anti-cancer drugs. Future research will further elucidate the specific mechanisms of action of TAOK kinase in different types of tumors and explore its clinical application prospects.

Updates in Alzheimer's disease: from basic research to diagnosis and therapies

Alzheimer's disease (AD) is the most common neurodegenerative disorder, characterized pathologically by extracellular deposition of β-amyloid (Aβ) into senile plaques and intracellular accumulation of hyperphosphorylated tau (pTau) as neurofibrillary tangles. Clinically, AD patients show memory deterioration with varying cognitive dysfunctions. The exact molecular mechanisms underlying AD are still not fully understood, and there are no efficient drugs to stop or reverse the disease progression. In this review, we first provide an update on how the risk factors, including APOE variants, infections and inflammation, contribute to AD; how Aβ and tau become abnormally accumulated and how this accumulation plays a role in AD neurodegeneration. Then we summarize the commonly used experimental models, diagnostic and prediction strategies, and advances in periphery biomarkers from high-risk populations for AD. Finally, we introduce current status of development of disease-modifying drugs, including the newly officially approved Aβ vaccines, as well as novel and promising strategies to target the abnormal pTau. Together, this paper was aimed to update AD research progress from fundamental mechanisms to the clinical diagnosis and therapies.

α-Tocotrienol Protects Neurons by Preventing Tau Hyperphosphorylation via Inhibiting Microtubule Affinity-Regulating Kinase Activation

In the pathological process of Alzheimer's disease, neuronal cell death is closely related to the accumulation of reactive oxygen species. Our previous studies have found that oxidative stress can activate microtubule affinity-regulating kinases, resulting in elevated phosphorylation levels of tau protein specifically at the Ser262 residue in N1E-115 cells that have been subjected to exposure to hydrogen peroxide. This process may be one of the pathogenic mechanisms of Alzheimer's disease. Vitamin E is a fat-soluble, naturally occurring antioxidant that plays a crucial role in biological systems. This study aimed to examine the probable processes that contribute to the inhibiting effect on the abnormal phosphorylation of tau protein and the neuroprotective activity of a particular type of vitamin E, α-tocotrienol. The experimental analysis revealed that α-tocotrienol showed significant neuroprotective effects in the N1E-115 cell line. Our data further suggest that one of the mechanisms underlying the neuroprotective effects of α-tocotrienol may be through the inhibition of microtubule affinity-regulated kinase activation, which significantly reduces the oxidative stress-induced aberrant elevation of p-Tau (Ser262) levels. These results indicate that α-tocotrienol may represent an intriguing strategy for treating or preventing Alzheimer's disease.

DEAD box RNA helicases are pervasive protein kinase interactors and activators

DEAD box (DDX) RNA helicases are a large family of ATPases, many of which have unknown functions. There is emerging evidence that besides their role in RNA biology, DDX proteins may stimulate protein kinases. To investigate if protein kinase-DDX interaction is a more widespread phenomenon, we conducted three orthogonal large-scale screens, including proteomics analysis with 32 RNA helicases, protein array profiling, and kinome-wide in vitro kinase assays. We retrieved Ser/Thr protein kinases as prominent interactors of RNA helicases and report hundreds of binary interactions. We identified members of ten protein kinase families, which bind to, and are stimulated by, DDX proteins, including CDK, CK1, CK2, DYRK, MARK, NEK, PRKC, SRPK, STE7/MAP2K, and STE20/PAK family members. We identified MARK1 in all screens and validated that DDX proteins accelerate the MARK1 catalytic rate. These findings indicate pervasive interactions between protein kinases and DEAD box RNA helicases, and provide a rich resource to explore their regulatory relationships.

SARS-CoV-2-derived protein Orf9b enhances MARK2 activity via interaction with the autoinhibitory KA1 domain

Microtubule affinity-regulating kinase 2 (MARK2) is a Ser/Thr protein kinase that regulates cell polarity and immune responses. Here, we report that Orf9b, one of the accessory proteins encoded in the SARS-CoV-2 genome, increases MARK2 activity via interaction with the autoinhibitory KAI domain. We found that co-expression of Orf9b enhances the kinase activity of MARK2 in HEK293 cells. Orf9b does not bind to or enhance the activity of the mutant form of MARK2 lacking the KA1 domain. Orf9b lowers inhibitory phosphorylation of MARK2 at T595 while mutation experiments indicate that this site is dispensable for Orf9b-mediated enhancement of MARK2 activity. Our results suggest that Orf9b enhances MARK2 activity by binding the autoinhibitory KA1 domain, which closely interacts with the kinase domain.

Mendelian Randomization Identifies Genetically Supported Drug Targets for Amyotrophic Lateral Sclerosis and Frontotemporal Dementia

Currently, amyotrophic lateral sclerosis (ALS) and frontotemporal dementia (FTD) have no effective treatments. Drug repurposing offers a rapid method to meet therapeutic need for ALS and FTD. To identify therapeutic targets associated with ALS and FTD, Mendelian randomization (MR) analysis and colocalization were performed. Genetic instruments were based on transcriptomic and proteomic data for 422 actionable proteins targeted by approved drugs or clinical drug candidates. The publicly available ALS GWAS summary data (including a total of 20,806 ALS cases and 59,804 controls) and FTD GWAS summary data (including a total of 2154 patients with FTD and 4308 controls) were used. Using cis-expression quantitative trait loci and cis-protein quantitative trait loci genetic instruments, we identified several drug targets for repurposing (ALS: MARK3, false-discovery rate (FDR) = 0.043; LTBR, FDR = 0.068) (FTD: HLA-DRB1, FDR = 0.083; ADH5, FDR = 0.056). Our MR study analyzed the actionable druggable proteins and provided potential therapeutic targets for ALS and FTD. Future studies should further elucidate the underlying mechanism of corresponding drug targets in the pathogenesis of ALS and FTD.

A novel role for microtubule affinity-regulating kinases in neuropathic pain

BACKGROUND AND PURPOSE

Neuropathic pain affects millions of patients, but there are currently few viable therapeutic options available. Microtubule affinity-regulating kinases (MARKs) regulate the dynamics of microtubules and participate in synaptic remodelling. It is unclear whether these changes are involved in the central sensitization of neuropathic pain. This study examined the role of MARK1 or MARK2 in regulating neurosynaptic plasticity induced by neuropathic pain.

EXPERIMENTAL APPROACH

A rat spinal nerve ligation (SNL) model was established to induce neuropathic pain. The role of MARKs in nociceptive regulation was assessed by genetically knocking down MARK1 or MARK2 in amygdala and systemic administration of PCC0105003, a novel small molecule MARK inhibitor. Cognitive function, anxiety-like behaviours and motor coordination capability were also examined in SNL rats. Synaptic remodelling-associated signalling changes were detected with electrophysiological recording, Golgi-Cox staining, western blotting and qRT-PCR.

KEY RESULTS

MARK1 and MARK2 expression levels in amygdala and spinal dorsal horn were elevated in SNL rats. MARK1 or MARK2 knockdown in amygdala and PCC0105003 treatment partially attenuated pain-like behaviours along with improving cognitive deficit, anxiogenic-like behaviours and motor coordination in SNL rats. Inhibition of MARKs signalling reversed synaptic plasticity at the functional and structural levels by suppressing NR2B/GluR1 and EB3/Drebrin signalling pathways both in amygdala and spinal dorsal horn.

CONCLUSION AND IMPLICATIONS

These results suggest that MARKs-mediated synaptic remodelling plays a key role in the pathogenesis of neuropathic pain and that pharmacological inhibitors of MARKs such as PCC0105003 could represent a novel therapeutic strategy for the management of neuropathic pain.

Molecular mechanisms linking type 2 diabetes mellitus and late-onset Alzheimer's disease: A systematic review and qualitative meta-analysis

Research evidence indicating common metabolic mechanisms through which type 2 diabetes mellitus (T2DM) increases risk of late-onset Alzheimer's dementia (LOAD) has accumulated over recent decades. The aim of this systematic review is to provide a comprehensive review of common mechanisms, which have hitherto been discussed in separate perspectives, and to assemble and evaluate candidate loci and epigenetic modifications contributing to polygenic risk linkages between T2DM and LOAD. For the systematic review on pathophysiological mechanisms, both human and animal studies up to December 2023 are included. For the qualitative meta-analysis of genomic bases, human association studies were examined; for epigenetic mechanisms, data from human studies and animal models were accepted. Papers describing pathophysiological studies were identified in databases, and further literature gathered from cited work. For genomic and epigenomic studies, literature mining was conducted by formalised search codes using Boolean operators in search engines, and augmented by GeneRif citations in Entrez Gene, and other sources (WikiGenes, etc.). For the systematic review of pathophysiological mechanisms, 923 publications were evaluated, and 138 gene loci extracted for testing candidate risk linkages. 3 57 publications were evaluated for genomic association and descriptions of epigenomic modifications. Overall accumulated results highlight insulin signalling, inflammation and inflammasome pathways, proteolysis, gluconeogenesis and glycolysis, glycosylation, lipoprotein metabolism and oxidation, cell cycle regulation or survival, autophagic-lysosomal pathways, and energy. Documented findings suggest interplay between brain insulin resistance, neuroinflammation, insult compensatory mechanisms, and peripheral metabolic dysregulation in T2DM and LOAD linkage. The results allow for more streamlined longitudinal studies of T2DM-LOAD risk linkages.

LKB1 biology: assessing the therapeutic relevancy of LKB1 inhibitors

Liver Kinase B1 (LKB1), encoded by Serine-Threonine Kinase 11 (STK11), is a master kinase that regulates cell migration, polarity, proliferation, and metabolism through downstream adenosine monophosphate-activated protein kinase (AMPK) and AMPK-related kinase signalling. Since genetic screens identified STK11 mutations in Peutz-Jeghers Syndrome, STK11 mutants have been implicated in tumourigenesis labelling it as a tumour suppressor. In support of this, several compounds reduce tumour burden through upregulating LKB1 signalling, and LKB1-AMPK agonists are cytotoxic to tumour cells. However, in certain contexts, its role in cancer is paradoxical as LKB1 promotes tumour cell survival by mediating resistance against metabolic and oxidative stressors. LKB1 deficiency has also enhanced the selectivity and cytotoxicity of several cancer therapies. Taken together, there is a need to develop LKB1-specific pharmacological compounds, but prior to developing LKB1 inhibitors, further work is needed to understand LKB1 activity and regulation. However, investigating LKB1 activity is strenuous as cell/tissue type, mutations to the LKB1 signalling pathway, STE-20-related kinase adaptor protein (STRAD) binding, Mouse protein 25-STRAD binding, splicing variants, nucleocytoplasmic shuttling, post-translational modifications, and kinase conformation impact the functional status of LKB1. For these reasons, guidelines to standardize experimental strategies to study LKB1 activity, associate proteins, spliced isoforms, post-translational modifications, and regulation are of upmost importance to the development of LKB1-specific therapies. Therefore, to assess the therapeutic relevancy of LKB1 inhibitors, this review summarizes the importance of LKB1 in cell physiology, highlights contributors to LKB1 activation, and outlines the benefits and risks associated with targeting LKB1.

MARK4 aggravates cardiac dysfunction in mice with STZ-induced diabetic cardiomyopathy by regulating ACSL4-mediated myocardial lipid metabolism

Diabetic cardiomyopathy is a specific type of cardiomyopathy. In DCM, glucose uptake and utilization are impaired due to insulin deficiency or resistance, and the heart relies more heavily on fatty acid oxidation for energy, resulting in myocardial lipid toxicity-related injury. MARK4 is a member of the AMPK-related kinase family, and improves ischaemic heart failure through microtubule detyrosination. However, the role of MARK4 in cardiac regulation of metabolism is unclear. In this study, after successful establishment of a diabetic cardiomyopathy model induced by streptozotocin and a high-fat diet, MARK4 expression was found to be significantly increased in STZ-induced DCM mice. After AAV9-shMARK4 was administered through the tail vein, decreased expression of MARK4 alleviated diabetic myocardial damage, reduced oxidative stress and apoptosis, and facilitated cardiomyocyte mitochondrial fusion, and promoted myocardial lipid oxidation metabolism. In addition, through the RNA-seq analysis of differentially expressed genes, we found that MARK4 deficiency promoted lipid decomposition and oxidative metabolism by downregulating the expression of ACSL4, thus reducing myocardial lipid accumulation in the STZ-induced DCM model.

MicroRNA miR-7-5p targets MARK2 to control metamorphosis in Galeruca daurica

The MARK2 gene, coding microtubule affinity-regulating kinase or serine/threonine protein kinase, is an important modulator in organism microtubule generation and cell polarity. However, its role in the metamorphosis of insects remains unknown. In this study, we found a conserved miRNA, miR-7-5p, which targets MARK2 to participate in the regulation of the larval-pupal metamorphosis in Galeruca daurica. The dual luciferase reporter assay showed that miR-7-5p interacted with the 3' UTR of MARK2 and repressed its expression. The expression profiling of miR-7-5p and MARK2 displayed an opposite trend during the larval-adult development process. In in-vivo experiments, overexpression of miR-7-5p by injecting miR-7-5p agomir in the final instar larvae down-regulated MARK2 and up-regulated main ecdysone signaling pathway genes including E74, E75, ECR, FTZ-F1 and HR3, which was similar to the results from knockdown of MARK2 by RNAi. In contrast, repression of miR-7-5p by injecting miR-7-5p antagomir obtained opposite effects. Notably, both overexpression and repression of miR-7-5p in the final instar larvae caused abnormal molting and high mortality during the larval-pupal transition, and high mortality during the pupal-adult transition. The 20-hydroxyecdysone (20E) injection experiment showed that 20E up-regulated miR-7-5p whereas down-regulated MARK2. This study reveals that the accurate regulation of miRNAs and their target genes is indispensable for insect metamorphosis.

Multi-omics analysis revealed that the protein kinase MoKin1 affected the cellular response to endoplasmic reticulum stress in the rice blast fungus, Magnaporthe oryzae

BACKGROUND

Previous studies have shown that protein kinase MoKin1 played an important role in the growth, conidiation, germination and pathogenicity in rice blast fungus, Magnaporthe oryzae. ΔMokin1 mutant showed significant phenotypic defects and significantly reduced pathogenicity. However, the internal mechanism of how MoKin1 affected the development of physiology and biochemistry remained unclear in M. oryzae.

RESULT

This study adopted a multi-omics approach to comprehensively analyze MoKin1 function, and the results showed that MoKin1 affected the cellular response to endoplasmic reticulum stress (ER stress). Proteomic analysis revealed that the downregulated proteins in ΔMokin1 mutant were enriched mainly in the response to ER stress triggered by the unfolded protein. Loss of MoKin1 prevented the ER stress signal from reaching the nucleus. Therefore, the phosphorylation of various proteins regulating the transcription of ER stress-related genes and mRNA translation was significantly downregulated. The insensitivity to ER stress led to metabolic disorders, resulting in a significant shortage of carbohydrates and a low energy supply, which also resulted in severe phenotypic defects in ΔMokin1 mutant. Analysis of MoKin1-interacting proteins indicated that MoKin1 really took participate in the response to ER stress.

CONCLUSION

Our results showed the important role of protein kinase MoKin1 in regulating cellular response to ER stress, providing a new research direction to reveal the mechanism of MoKin1 affecting pathogenic formation, and to provide theoretical support for the new biological target sites searching and bio-pesticides developing.

Hiding in plain sight: Complex interaction patterns between Tau and 14-3-3ζ protein variants

Tau protein is an intrinsically disordered protein that plays a key role in Alzheimer's disease (AD). In brains of AD patients, Tau occurs abnormally phosphorylated and aggregated in neurofibrillary tangles (NFTs). Together with Tau, 14-3-3 proteins - abundant cytosolic dimeric proteins - were found colocalized in the NFTs. However, so far, the molecular mechanism of the process leading to pathological changes in Tau structure as well as the direct involvement of 14-3-3 proteins are not well understood. Here, we aimed to reveal the effects of phosphorylation by protein kinase A (PKA) on Tau structural preferences and provide better insight into the interaction between Tau and 14-3-3 proteins. We also addressed the impact of monomerization-inducing phosphorylation of 14-3-3 at S58 on the binding to Tau protein. Using multidimensional nuclear magnetic resonance spectroscopy (NMR), chemical cross-linking analyzed by mass spectrometry (MS) and PAGE, we unveiled differences in their binding affinity, stoichiometry, and interfaces with single-residue resolution. We revealed that the interaction between 14-3-3 and Tau proteins is mediated not only via the 14-3-3 amphipathic binding grooves, but also via less specific interactions with 14-3-3 protein surface and, in the case of monomeric 14-3-3, also partially via the exposed dimeric interface. In addition, the hyperphosphorylation of Tau changes its affinity to 14-3-3 proteins. In conclusion, we propose quite complex interaction mode between the Tau and 14-3-3 proteins.

Mark4 ablation attenuates pathological phenotypes in a mouse model of tauopathy

Accumulation of abnormally phosphorylated tau proteins is linked to various neurodegenerative diseases, including Alzheimer's disease and frontotemporal dementia. Microtubule affinity-regulating kinase 4 (MARK4) has been genetically and pathologically associated with Alzheimer's disease and reported to enhance tau phosphorylation and toxicity in Drosophila and mouse traumatic brain-injury models but not in mammalian tauopathy models. To investigate the role of MARK4 in tau-mediated neuropathology, we crossed P301S tauopathy model (PS19) and Mark4 knockout mice. We performed behaviour, biochemical and histology analyses to evaluate changes in PS19 pathological phenotype with and without Mark4. Here, we demonstrated that Mark4 deletion ameliorated the tau pathology in a mouse model of tauopathy. In particular, we found that PS19 with Mark4 knockout showed improved mortality and memory compared with those bearing an intact Mark4 gene. These phenotypes were accompanied by reduced neurodegeneration and astrogliosis in response to the reduction of pathological forms of tau, such as those phosphorylated at Ser356, AT8-positive tau and thioflavin S-positive tau. Our data indicate that MARK4 critically contributes to tau-mediated neuropathology, suggesting that MARK4 inhibition may serve as a therapeutic avenue for tauopathies.

A novel multi-omics mendelian randomization method for gene set enrichment and its application to psychiatric disorders

Genome-wide association studies (GWAS) of psychiatric disorders (PD) yield numerous loci with significant signals, but often do not implicate specific genes. Because GWAS risk loci are enriched in expression/protein/methylation quantitative loci (e/p/mQTL, hereafter xQTL), transcriptome/proteome/methylome-wide association studies (T/P/MWAS, hereafter XWAS) that integrate xQTL and GWAS information, can link GWAS signals to effects on specific genes. To further increase detection power, gene signals are aggregated within relevant gene sets (GS) by performing gene set enrichment (GSE) analyses. Often GSE methods test for enrichment of "signal" genes in curated GS while overlooking their linkage disequilibrium (LD) structure, allowing for the possibility of increased false positive rates. Moreover, no GSE tool uses xQTL information to perform mendelian randomization (MR) analysis. To make causal inference on association between PD and GS, we develop a novel MR GSE (MR-GSE) procedure. First, we generate a "synthetic" GWAS for each MSigDB GS by aggregating summary statistics for x-level (mRNA, protein or DNA methylation (DNAm) levels) from the largest xQTL studies available) of genes in a GS. Second, we use synthetic GS GWAS as exposure in a generalized summary-data-based-MR analysis of complex trait outcomes. We applied MR-GSE to GWAS of nine important PD. When applied to the underpowered opioid use disorder GWAS, none of the four analyses yielded any signals, which suggests a good control of false positive rates. For other PD, MR-GSE greatly increased the detection of GO terms signals (2,594) when compared to the commonly used (non-MR) GSE method (286). Some of the findings might be easier to adapt for treatment, e.g., our analyses suggest modest positive effects for supplementation with certain vitamins and/or omega-3 for schizophrenia, bipolar and major depression disorder patients. Similar to other MR methods, when applying MR-GSE researchers should be mindful of the confounding effects of horizontal pleiotropy on statistical inference.

Map-1a regulates Sertoli cell BTB dynamics through the cytoskeletal organization of microtubule and F-actin

Microtubule-associated protein 1a (Map1a) is a microtubule (MT) regulatory protein that binds to the MT protofilaments in mammalian cells to promote MT stabilization. Maps work with MT cleavage proteins and other MT catastrophe-inducing proteins to confer MT dynamics to support changes in the Sertoli cell shape to sustain spermatogenesis. However, no functional studies are found in the literature to probe its role in spermatogenesis. Using an RNAi approach, coupled with the use of toxicant-induced testis (in vivo)- and Sertoli cell (in vitro)-injury models, RNA-Seq analysis, transcriptome profiling, and relevant bioinformatics analysis, immunofluorescence analysis, and pertinent biochemical assays for cytoskeletal organization, we have delineated the functional role of Map1a in Sertoli cells and testes. Map1a was shown to support MT structural organization, and its knockdown (KD) also perturbed the structural organization of actin, vimentin, and septin cytoskeletons as these cytoskeletons are intimately related, working in concert to support spermatogenesis. More importantly, cadmium-induced Sertoli cell injury that perturbed the MT structural organization across the cell cytoplasm was associated with disruptive changes in the distribution of Map1a and a surge in p-p38-MAPK (phosphorylated p38-mitogen-activated protein kinase) expression but not total p38-MAPK. These findings thus support the notion that p-p38-MAPK activation is involved in cadmium-induced Sertoli cell injury. This conclusion was supported by studies using doramapimod, a specific p38-MAPK phosphorylation (activation) inhibitor, which was capable of restoring the cadmium-induced disruptive structural organization of MTs across the Sertoli cell cytoplasm. In summary: this study provides mechanistic insights regarding restoration of toxicant-induced Sertoli cell and testis injury and male infertility.

Role of MARK2 in the nervous system and cancer

Microtubule-Affinity Regulating Kinase 2 (MARK2), a member of the serine/threonine protein kinase family, phosphorylates microtubule-associated proteins, playing a crucial role in cancer and neurodegenerative diseases. This kinase regulates multiple signaling pathways, including the WNT, PI3K/AKT/mTOR (PAM), and NF-κB pathways, potentially linking it to cancer and the nervous system. As a crucial regulator of the PI3K/AKT/mTOR pathway, the loss of MARK2 inhibits the growth and metastasis of cancer cells. MARK2 is involved in the excessive phosphorylation of tau, thus influencing neurodegeneration. Therefore, MARK2 emerges as a promising drug target for the treatment of cancer and neurodegenerative diseases. Despite its significance, the development of inhibitors for MARK2 remains limited. In this review, we aim to present detailed information on the structural features of MARK2 and its role in various signaling pathways associated with cancer and neurodegenerative diseases. Additionally, we further characterize the therapeutic potential of MARK2 in neurodegenerative diseases and cancer, and hope to facilitate basic research on MARK2 and the development of inhibitors targeting MARK2.

Microtubule-affinity regulating kinase family members distinctively affect tau phosphorylation and promote its toxicity in a Drosophila model

Accumulation of abnormally phosphorylated tau and its aggregation constitute a significant hallmark of Alzheimer's disease (AD). Tau phosphorylation at Ser262 and Ser356 in the KXGS motifs of microtubule-binding repeats plays a critical role in its physiological function and AD disease progression. Major tau kinases to phosphorylate tau at Ser262 and Ser356 belong to the Microtubule Affinity Regulating Kinase family (MARK1-4), which are considered one of the major contributors to tau abnormalities in AD. However, whether and how each member affects tau toxicity in vivo is unclear. We used transgenic Drosophila as a model to compare the effect on tau-induced neurodegeneration among MARKs in vivo. MARK4 specifically promotes tau accumulation and Ser396 phosphorylation, which yields more tau toxicity than was caused by other MARKs. Interestingly, MARK1, 2, and 4 increased tau phosphorylation at Ser262 and Ser356, but only MARK4 caused tau accumulation, indicating that these sites alone did not cause pathological tau accumulation. Our results revealed MARKs are different in their effect on tau toxicity, and also in tau phosphorylation at pathological sites other than Ser262 and Ser356. Understanding the implementation of each MARK into neurodegenerative disease helps to develop more target and safety therapies to overcome AD and related tauopathies.

Heterozygous truncating variant of TAOK1 in a boy with periventricular nodular heterotopia: a case report and literature review of TAOK1-related neurodevelopmental disorders

BACKGROUND

Thousand and one amino-acid kinase 1 (TAOK1) encodes the MAP3K protein kinase TAO1, which has recently been displayed to be essential for neuronal maturation and cortical differentiation during early brain development. Heterozygous variants in TAOK1 have been reported in children with neurodevelopmental disorders, with or without macrocephaly, hypotonia and mild dysmorphic traits. Literature reports lack evidence of neuronal migration disorders in TAOK1 patients, although studies in animal models suggest this possibility.

CASE PRESENTATION

We provide a clinical description of a child with a neurodevelopmental disorder due to a novel TAOK1 truncating variant, whose brain magnetic resonance imaging displays periventricular nodular heterotopia.

CONCLUSIONS

To our knowledge, this is the first report of a neuronal migration disorder in a patient with a TAOK1-related neurodevelopmental disorder, thus supporting the hypothesized pathogenic mechanisms of TAOK1 defects.

Harnessing memantine in Alzheimer's disease therapy through inhibition of microtubule affinity-regulating kinase: Mechanistic insights

Alzheimer's disease (AD) is one of the neurodegenerative disorder that primarily affects memory, thinking, and behavior, eventually leading to severe cognitive impairment. Therapeutic management of AD is urgently needed to improve the quality and lifestyle of patients. Tau phosphorylating kinases are considered attractive therapeutic targets. Microtubule affinity-regulating kinase 4 (MARK4) is directly linked with pathological phosphorylations of tau, highlighting its role in the therapeutic targeting of AD. The current manuscript shows the MARK4 inhibitory effect of Memantine (MEM), a drug used in treating AD. We have performed fluorescence based binding measurements, enzyme inhibition assay, docking and molecular dynamics (MD) simulations to understand the binding of of MARK4 and MEM and subsequent inhibition in the kinase activity. A 100 ns MD simulations provided a detailed analysis of MARK4-MEM complex and the role of potential critical residues in the binding. Finally, this study provides molecular insights into the therapeutic implication of MEM in AD therapeutics. We propose MEM effectively inhibits MARK4, it may be implicated in the development of targeted and efficient treatments for AD.

Studying Microtubule Dynamics in Human Neurons: Two-Dimensional Microtubule Tracing and Kymographs in iPSC- and SH-SY5Y-Derived Neurons for Tau Research

The study of microtubule (MT) dynamics is essential for the understanding of cellular transport, cell polarity, axon formation, and other neurodevelopmental mechanisms. All these processes rely on the constant transition between assembly and disassembly of tubulin polymers to/from MTs, known as dynamic instability. This process is well-regulated, among others, by phosphorylation of microtubule-associated proteins (MAP), including the Tau protein. Protein kinases, in particular the microtubule affinity regulating kinase (MARK), regulate the MT-Tau interaction, inducing Tau dissociation by phosphorylation. Phosphorylated Tau dissociates from microtubules forming insoluble aggregates known as neurofibrillary tangles. These accumulations of hyperphosphorylated Tau in the neurons disrupt the physiological MT-based transport machinery within the cell and can potentially lead to the development of neurodegenerative disorders, such as Alzheimer's disease (AD) and related tauopathies. Further investigations on the MT cytoskeleton dynamics are essential as they may elucidate pathomechanisms of neurodegenerative diseases - particularly tauopathies - as well as fundamental neurodevelopmental processes.The study of the dynamic assembly and disassembly of the MT network requires live-cell imaging rather than conventional immunocytochemistry based on fixed samples. To investigate MT dynamics, we perform live-cell imaging of neurons transfected with a fluorescently tagged version of the microtubule plus-end tracking protein (+TIP) EB3. This protein associates with the growing ends of MTs and thus visualizes MT growth in real time. Our imaging analysis protocol allows the determination of quantity, orientation, and velocity of MT growth in the soma and neurites of transfected neurons, using ImageJ-based tracking software and kymographs. Furthermore, functional effects of Tau and MARK kinases on the MT cytoskeleton can be assessed by overexpression or downregulation experiments of the respective protein prior to the live imaging assay. We use two different human neuronal cell models, naive and differentiated SH-SY5Y neuroblastoma cells, and neurons derived from induced pluripotent stem cells (iPSCs), both of which have shown success as models to study Tau-related pathologies.This protocol describes an optimized method for analysis of microtubule dynamics using fluorescent tagged EB3 protein as microtubule plus end marker. In this chapter, we outline the process of neuronal transfection, live-cell imaging, and necessary time-lapse image analysis based on ImageJ in two human-derived neuronal systems, which are suitable for the analysis of Tau trafficking and sorting studies.

Post-Translational Modifications in Tau and Their Roles in Alzheimer's Pathology

Microtubule-Associated Protein Tau (also known as tau) has been shown to accumulate into paired helical filaments and neurofibrillary tangles, which are known hallmarks of Alzheimer's disease (AD) pathology. Decades of research have shown that tau protein undergoes extensive post-translational modifications (PTMs), which can alter the protein's structure, function, and dynamics and impact the various properties such as solubility, aggregation, localization, and homeostasis. There is a vast amount of information describing the impact and role of different PTMs in AD pathology and neuroprotection. However, the complex interplay between these PTMs remains elusive. Therefore, in this review, we aim to comprehend the key post-translational modifications occurring in tau and summarize potential connections to clarify their impact on the physiology and pathophysiology of tau. Further, we describe how different computational modeling methods have helped in understanding the impact of PTMs on the structure and functions of the tau protein. Finally, we highlight the tau PTM-related therapeutics strategies that are explored for the development of AD therapy.

Alterations in DNA methylation associate with reduced migraine and headache days after medication withdrawal treatment in chronic migraine patients: a longitudinal study

BACKGROUND

Chronic migraine, a highly disabling migraine subtype, affects nearly 2% of the general population. Understanding migraine chronification is vital for developing better treatment and prevention strategies. An important factor in the chronification of migraine is the overuse of acute headache medication. However, the mechanisms behind the transformation of episodic migraine to chronic migraine and vice versa have not yet been elucidated. We performed a longitudinal epigenome-wide association study to identify DNA methylation (DNAm) changes associated with treatment response in patients with chronic migraine and medication overuse as part of the Chronification and Reversibility of Migraine clinical trial. Blood was taken from patients with chronic migraine (n = 98) at baseline and after a 12-week medication withdrawal period. Treatment responders, patients with ≥ 50% reduction in monthly headache days (MHD), were compared with non-responders to identify DNAm changes associated with treatment response. Similarly, patients with ≥ 50% versus < 50% reduction in monthly migraine days (MMD) were compared.

RESULTS

At the epigenome-wide significant level (p < 9.42 × 10-8), a longitudinal reduction in DNAm at an intronic CpG site (cg14377273) within the HDAC4 gene was associated with MHD response following the withdrawal of acute medication. HDAC4 is highly expressed in the brain, plays a major role in synaptic plasticity, and modulates the expression and release of several neuroinflammation markers which have been implicated in migraine pathophysiology. Investigating whether baseline DNAm associated with treatment response, we identified lower baseline DNAm at a CpG site (cg15205829) within MARK3 that was significantly associated with MMD response at 12 weeks.

CONCLUSIONS

Our findings of a longitudinal reduction in HDAC4 DNAm status associated with treatment response and baseline MARK3 DNAm status as an early biomarker for treatment response, provide support for a role of pathways related to chromatin structure and synaptic plasticity in headache chronification and introduce HDAC4 and MARK3 as novel therapeutic targets.

Arsenic and Tau Phosphorylation: a Mechanistic Review

Arsenic poisoning can affect the peripheral nervous system and cause peripheral neuropathy. Despite different studies on the mechanism of intoxication, the complete process is not explained yet, which can prevent further intoxication and produce effective treatment. In the following paper, we would like to consider the idea that arsenic might cause some diseases via inflammation induction, and tauopathy in neurons. Tau protein, one of the microtubule-associated proteins expressed in neurons, contributes to neuronal microtubules structure. Arsenic may be involved in cellular cascades involved in modulating tau function or hyperphosphorylation of tau protein, which ultimately leads to nerve destruction. For proof of this assumption, some investigations have been planned to measure the association between arsenic and quantities of phosphorylation of tau protein. Additionally, some researchers have investigated the association between microtubule trafficking in neurons and the levels of tau protein phosphorylation. It should be noticed that changing tau phosphorylation in arsenic toxicity may add a new feature to understanding the mechanism of poisonousness and aid in discovering novel therapeutic candidates such as tau phosphorylation inhibitors for drug development.

Traditional Chinese Medicine studies for Alzheimer's disease via network pharmacology based on entropy and random walk

Alzheimer's disease (AD) is a common neurodegenerative disease having complex pathogenesis, approved drugs can only alleviate symptoms of AD for a period of time. Traditional Chinese medicine (TCM) contains multiple active ingredients that can act on multiple targets simultaneously. In this paper, a novel algorithm based on entropy and random walk with the restart of heterogeneous network (RWRHE) is proposed for predicting active ingredients for AD and screening out the effective TCMs for AD. First, Six TCM compounds containing 20 herbs from the AD drug reviews in the CNKI (China National Knowledge Internet) are collected, their active ingredients and targets are retrieved from different databases. Then, comprehensive similarity networks of active ingredients and targets are constructed based on different aspects and entropy weight, respectively. A comprehensive heterogeneous network is constructed by integrating the known active ingredient-target association information and two comprehensive similarity networks. Subsequently, bi-random walks are applied on the heterogeneous network to predict active ingredient-target associations. AD related targets are selected as the seed nodes, a random walk is carried out on the target similarity network to predict the AD-target associations, and the associations of AD-active ingredients are inferred and scored. The effective herbs and compounds for AD are screened out based on their active ingredients' scores. The results measured by machine learning and bioinformatics show that the RWRHE algorithm achieves better prediction accuracy, the top 15 active ingredients may act as multi-target agents in the prevention and treatment of AD, Danshen, Gouteng and Chaihu are recommended as effective TCMs for AD, Yiqitongyutang is recommended as effective compound for AD.

A cell-penetrating peptide derived from SARS-CoV-2 protein Orf9b allosterically inhibits MARK4 activity and mitigates tau toxicity

Abnormal activation of microtubule affinity-regulating kinase 4 (MARK4) and its phosphorylation of the microtubule-associated protein tau are believed to play a role in the pathogenesis of Alzheimer's disease, and MARK4 inhibition can be a strategy to develop disease-modifying therapy. Here we report the development of a membrane-permeable peptide that inhibits MARK4 activity in an allosteric manner. The SARS-CoV-2-derived protein Orf9b inhibited MARK4-mediated tau phosphorylation in primary neurons and Drosophila. Orf9b inhibited MARK4 activity in an allosteric manner and did not inhibit the activity of MARK2, which is another MARK family member and is closely related to MARK4. Co-expression of Orf9b in the fly retina expressing human tau and MARK4 suppressed phosphorylation of tau at the microtubule-binding repeats and tau-induced neurodegeneration. We identified the minimal sequence of Orf9b required to suppress MARK4 activity and fused it to a cell-permeable sequence (TAT-Orf9b10-18_78-95). Extracellular supplementation of TAT-Orf9b10-18_78-95 inhibited MARK4 activity in primary neurons, and feeding TAT-Orf9b10-18_78-95 to a fly model of tauopathy lowered phospho-tau levels and suppressed neurodegeneration. These results suggest that TAT-Orf9b10-18_78-95 is a unique class of MARK4 inhibitor and can be used to modify tau toxicity.

Preparation of nanoformulation of 5-fluorouracil to improve anticancer efficacy: integrated spectroscopic, docking, and MD simulation approaches

Nanoformulations (NFs) can be used as a novel drug delivery system to treat all cancer types. One of the major drawbacks of conventional anticancer drugs is that they have poor specificity and higher toxicity towards normal cells. 5-fluorouracil (5-FU) is a well-studied anticancer drug that has a significant role in various cancers, specifically colorectal cancer therapy. This study was performed to determine the functional groups, particle size, surface charge, heterogeneity, and stability of the NF. The NFs of 5-FU were prepared through the ultrasonication technique by increasing the surfactant (Tween-80) concentrations. Among all three NFs, nanoformulated 5-FU (n5-FU) showed the most effective particle size (10.72 nm) with a zeta potential of (-4.57 mV). The cytotoxicity and apoptosis profiles confirmed that n5-FU enhanced the anticancer effect of the pure drug in HCT-116 cells, as evident from MTT assay, fluorescence microscopy, and FACS analysis. In HCT-116 cells, the IC50 values of pure and n5-FU were obtained as 41.3 μM and 18.8 μM, respectively, indicating that n5-FU was more effective against the cancer cell line. The cellular uptake study was performed to check the intake of NF in cancer cells. However, the microtubule-affinity regulating kinase-4 (MARK-4), a cancer-target protein, was purified to study the inhibition and interaction studies. The inhibition assay confirmed the inhibitory potential of 5-FU against MARK-4 protein. the multi-spectroscopic, molecular docking and MD simulation studies were performed to analyse the conformational changes, binding studies, intermolecular interactions, and stability of MARK-4 protein upon binding 5-FU. This demonstrates that NF can enhance the effectiveness of anticancer drugs.Communicated by Ramaswamy H. Sarma.

Role of lisinopril in the therapeutic management of cardiovascular disease by targeting microtubule affinity regulating kinase 4: molecular docking and molecular dynamics simulation approaches

Cardiovascular diseases (CVDs) are a major cause of premature adult death. Various factors contribute to the development of CVDs, such as atherosclerosis leading to myocardial infarction (MI), and compromised cardiac function after MI leads to chronic heart failure with systemic health complications and a high mortality rate. Microtubule detyrosination has rapidly evolved as an essential mechanism to regulate cardiomyocyte contractility. Microtubule affinity regulating kinase 4 (MARK4) regulates cardiomyocyte contractility in a way that it promotes phosphorylation of microtubule-associated protein 4, thereby facilitating the access of vasohibin 2-a tubulin carboxypeptidase-to microtubules for the detyrosination of α-tubulin. Lisinopril, a drug belonging to the class of angiotensin-converting enzyme inhibitors, is used to treat high blood pressure. This is also used to treat heart failure, which plays a vital role in improving the survival rate post-heart attack. In this study, we will evaluate the MARK4 inhibitory potential of lisinopril employing molecular docking and molecular dynamics (MD) simulation approaches. Molecular docking analysis suggested that lisinopril binds to MARK4 with a significant binding affinity forming interactions with functionally essential residues of MARK4. Additionally, MD simulation deciphered the structural dynamics and stability of the MARK4-lisinopril complex. The findings of MD studies established that minimal structural deviations are observed during simulation, affirming the stability of the MARK4-lisinopril complex. Altogether, this study demonstrates lisinopril's crucial role in the therapeutic management of CVD by targeting MARK4.Communicated by Ramaswamy H. Sarma.

Stem cells-derived exosomes alleviate neurodegeneration and Alzheimer's pathogenesis by ameliorating neuroinflamation, and regulating the associated molecular pathways

Amyloid beta (Aβ) aggregation and tau hyper phosphorylation (p-tau) are key molecular factors in Alzheimer's disease (AD). The abnormal formation and accumulation of Aβ and p-tau lead to the formation of amyloid plaques and neurofibrillary tangles (NFTs) which ultimately leads to neuroinflammation and neurodegeneration. β- and γ-secretases produce Aβ peptides via the amyloidogenic pathway, and several kinases are involved in tau phosphorylation. Exosomes, a recently developed method of intercellular communication, derived from neuronal stem cells (NSC-exos), are intriguing therapeutic options for AD. Exosomes have ability to cross the BBB hence highly recommended for brain related diseases and disorders. In the current study, we examined how NSC-exos could protect human neuroblastoma cells SH-SY5Y (ATCC CRL-2266). NSC-exos were derived from Human neural stem cells (ATCC-BYS012) by ultracentrifugation and the therapeutic effects of the NSC-exos were then investigated in vitro. NSC-exos controlled the associated molecular processes to drastically lower Aβ and p-tau. A dose dependent reduction in β- and γ-secretase, acetylcholinesterase, GSK3β, CDK5, and activated α-secretase activities was also seen. We further showed that BACE1, PSEN1, CDK5, and GSK-3β mRNA expression was suppressed and downregulated, while ADAM10 mRNA was increased. NSC- Exos downregulate NF-B/ERK/JNK-related signaling pathways in activated glial cells HMC3 (ATCC-CRL-3304) and reduce inflammatory mediators such iNOS, IL-1β, TNF-α, and IL-6, which are associated with neuronal inflammation. The NSC-exos therapy ameliorated the neurodegeneration of human neuroblastoma cells SH-SY5Y by enhancing viability. Overall, these findings support that exosomes produced from stem cells can be a neuro-protective therapy to alleviate AD pathology.

Mechanistic insights into MARK4 inhibition by galantamine toward therapeutic targeting of Alzheimer's disease

Introduction: Hyperphosphorylation of tau is an important event in Alzheimer's disease (AD) pathogenesis, leading to the generation of "neurofibrillary tangles," a histopathological hallmark associated with the onset of AD and related tauopathies. Microtubule-affinity regulating kinase 4 (MARK4) is an evolutionarily conserved Ser-Thr (S/T) kinase that phosphorylates tau and microtubule-associated proteins, thus playing a critical role in AD pathology. The uncontrolled neuronal migration is attributed to overexpressed MARK4, leading to disruption in microtubule dynamics. Inhibiting MARK4 is an attractive strategy in AD therapeutics. Methods: Molecular docking was performed to see the interactions between MARK4 and galantamine (GLT). Furthermore, 250 ns molecular dynamic studies were performed to investigate the stability and conformational dynamics of the MARK4-GLT complex. We performed fluorescence binding and isothermal titration calorimetry studies to measure the binding affinity between GLT and MARK4. Finally, an enzyme inhibition assay was performed to measure the MARK4 activity in the presence and absence of GLT. Results: We showed that GLT, an acetylcholinesterase inhibitor, binds to the active site cavity of MARK4 with an appreciable binding affinity. Molecular dynamic simulation for 250 ns demonstrated the stability and conformational dynamics of the MARK4-GLT complex. Fluorescence binding and isothermal titration calorimetry studies suggested a strong binding affinity. We further show that GLT inhibits the kinase activity of MARK4 significantly (IC50 = 5.87 µM). Conclusion: These results suggest that GLT is a potential inhibitor of MARK4 and could be a promising therapeutic target for AD. GLT's inhibition of MARK4 provides newer insights into the mechanism of GLT's action, which is already used to improve cognition in AD patients.

Therapeutic targeting of microtubule affinity-regulating kinase 4 in cancer and neurodegenerative diseases

Microtubule affinity-regulating kinase 4 (MARK4) is a member of the Ser/Thr protein kinase family, phosphorylates the microtubule-connected proteins and plays a vital role in causing cancers and neurodegenerative diseases. This kinase modulates multiple signaling pathways, including mammalian target of rapamycin, nuclear factor-κB, and Hippo-signaling, presumably responsible for cancer and Alzheimer's. MARK4 acts as a negative controller of the Hippo-kinase cassette for promoting YAP/TAZ action, and the loss of MARK4 detains the tumorigenic properties of cancer cells. MARK4 is involved in tau hyperphosphorylation that consequently affects neurodegeneration. MARK4 is a promising drug target for cancer, diabetes, and Alzheimer's. Developing the potent and selective inhibitors of MAKR4 are promising in the therapeutic management of associated diseases. Despite its great significance, a few reviews are available to discuss its structure, function and clinical significance. In the current review, we aimed to provide detailed information on the structural features of MARK4 targeted in drug development and its role in various signaling pathways related to cancer and neurodegenerative diseases. We further described the therapeutic potential of MARK4 inhibitors in preventing numerous diseases. Finally, the updated information on MARK4 will be helpful in the further development of effective therapeutic molecules.

Elucidating Fibroblast Growth Factor-Induced Kinome Dynamics Using Targeted Mass Spectrometry and Dynamic Modeling

Fibroblast growth factors (FGFs) are paracrine or endocrine signaling proteins that, activated by their ligands, elicit a wide range of health and disease-related processes, such as cell proliferation and the epithelial-to-mesenchymal transition. The detailed molecular pathway dynamics that coordinate these responses have remained to be determined. To elucidate these, we stimulated MCF-7 breast cancer cells with either FGF2, FGF3, FGF4, FGF10, or FGF19. Following activation of the receptor, we quantified the kinase activity dynamics of 44 kinases using a targeted mass spectrometry assay. Our system-wide kinase activity data, supplemented with (phospho)proteomics data, reveal ligand-dependent distinct pathway dynamics, elucidate the involvement of not earlier reported kinases such as MARK, and revise some of the pathway effects on biological outcomes. In addition, logic-based dynamic modeling of the kinome dynamics further verifies the biological goodness-of-fit of the predicted models and reveals BRAF-driven activation upon FGF2 treatment and ARAF-driven activation upon FGF4 treatment.

Synthesis, Structural Modification, and Bioactivity Evaluation of Substituted Acridones as Potent Microtubule Affinity-Regulating Kinase 4 Inhibitors

Acridones present numerous pharmacological activities, including inhibition of microtubule affinity-regulating kinase 4 (MARK4) kinase activity. To investigate structure-activity relationships and develop potent MARK4 inhibitors, derivatives of 2-methylacridone were synthesized and tested for their activity against MARK4 kinase. Selective substitutions at the nitrogen atom were accomplished by treating 2-methylacridone with alkyl halides in the presence of K2CO3. In addition, amidation of acridone acetic acid 11 with piperazine or tryptophan methyl ester followed by derivatization with various amines gave a series of new acridone derivatives. Among the tested compounds, six were identified as possessing high inhibitory activity against MARK4. The molecular modeling studies showed that the derivatives bearing piperazine or tryptophan bind well to the ATP-binding site of MARK4. The antiproliferative activity of six active compounds was evaluated against HeLa and U87MG cancer cells. Tryptophan derivatives 23a, 23b, and 23c showed significant cytotoxicity against both cell lines with EC50 values ranging from 2.13 to 4.22 μM, while derivatives bearing piperazine were found to be not cytotoxic. Additionally, compound 23a decreased the proliferation of human MDA-MB-435 and U251 cancer cells in the low micromolar range; however, it also affects the non-cancerous HGF cells. Due to their high binding affinity against MARK4, the synthesized compounds could be potential agents to target MARK4 against cancer and tauopathies.

Oxidative stress induces tau hyperphosphorylation via MARK activation in neuroblastoma N1E-115 cells

Reactive oxygen species are considered a cause of neuronal cell death in Alzheimer's disease (AD). Abnormal tau phosphorylation is a proven pathological hallmark of AD. Microtubule affinity-regulating kinases (MARKs) regulate tau-microtubule binding and play a crucial role in neuronal survival. In this study, we hypothesized that oxidative stress increases the phosphorylation of Ser262 of tau protein through activation of MARKs, which is the main reason for the development of AD. We investigated the relationship between tau hyperphosphorylation on Ser262 and MARKs in N1E-115 cells subjected to oxidative stress by exposure to a low concentration of hydrogen peroxide. This work builds on the observation that hyperphosphorylation of tau is significantly increased by oxidative stress. MARKs activation correlated with tau hyperphosphorylation at Ser262, a site that is essential to maintain microtubule stability and is the initial phosphorylation site in AD. These results indicated that MARKs inhibitors might serve a role as therapeutic tools for the treatment of AD.

Unraveling Molecular and Genetic Insights into Neurodegenerative Diseases: Advances in Understanding Alzheimer's, Parkinson's, and Huntington's Diseases and Amyotrophic Lateral Sclerosis

Neurodegenerative diseases are, according to recent studies, one of the main causes of disability and death worldwide. Interest in molecular genetics has started to experience exponential growth thanks to numerous advancements in technology, shifts in the understanding of the disease as a phenomenon, and the change in the perspective regarding gene editing and the advantages of this action. The aim of this paper is to analyze the newest approaches in genetics and molecular sciences regarding four of the most important neurodegenerative disorders: Alzheimer's disease, Parkinson's disease, Huntington's disease, and amyotrophic lateral sclerosis. We intend through this review to focus on the newest treatment, diagnosis, and predictions regarding this large group of diseases, in order to obtain a more accurate analysis and to identify the emerging signs that could lead to a better outcome in order to increase both the quality and the life span of the patient. Moreover, this review could provide evidence of future possible novel therapies that target the specific genes and that could be useful to be taken into consideration when the classical approaches fail to shed light.

Effects of three microtubule-associated proteins (MAP2, MAP4, and Tau) on microtubules' physical properties and neurite morphology

The physical properties of cytoskeletal microtubules have a multifaceted effect on the expression of their cellular functions. A superfamily of microtubule-associated proteins, MAP2, MAP4, and tau, promote the polymerization of microtubules, stabilize the formed microtubules, and affect the physical properties of microtubules. Here, we show differences in the effects of these three MAPs on the physical properties of microtubules. When microtubule-binding domain fragments of MAP2, tau, and three MAP4 isoforms were added to microtubules in vitro and observed by fluorescence microscopy, tau-bound microtubules showed a straighter morphology than the microtubules bound by MAP2 and the three MAP4 isoforms. Flexural rigidity was evaluated by the shape of the teardrop pattern formed when microtubules were placed in a hydrodynamic flow, revealing that tau-bound microtubules were the least flexible. When full-length MAPs fused with EGFP were expressed in human neuroblastoma (SH-SY5Y) cells, the microtubules in apical regions of protrusions expressing tau were straighter than in cells expressing MAP2 and MAP4. On the other hand, the protrusions of tau-expressing cells had the fewest branches. These results suggest that the properties of microtubules, which are regulated by MAPs, contribute to the morphogenesis of neurites.

In silico investigation and potential therapeutic approaches of isoquinoline alkaloids for neurodegenerative diseases: computer-aided drug design perspective

Microtubule affinity regulating kinase (MARK4) has been proposed as a potential therapeutic target for diabetes, cancer, and neurological diseases. We used a variety of computational studies techniques to examine the binding affinity and MARK4 inhibitory potential of several isoquinoline alkaloids. MARK4 has been associated with tau protein phosphorylation and, consequently, Alzheimer's disease. The three molecules with the highest binding affinities inside the 5ES1 receptor, according to molecular docking experiments, are isoliensinine, liensinine, and methylcorypalline. Isoliensinine had the highest drug score and drug likeness, coming in at 1.17, while Liensinine and Methylcorypalline came in at 1.15 and 1.07, respectively. The thesis claims that three compounds have a better chance than the others of being identified as therapeutic leads. The bulk of the compounds under investigation didn't break any of Lipinski's five rules, especially methylcorypalline, which did and is probably orally active. The majority of the compounds under investigation, particularly Isoliensinine, Liensinine, and Methylcorypalline, show the potential to exhibit drug-like behaviour, which is strongly confirmed by ADMET characteristics estimates. The chemicals Isoliensinine, Liensinine, and Methylcorypalline, especially Methylcorypalline, form the most stable combination with the 5ES1, according to a 100 ns molecular dynamics simulation of these compounds docked inside 5ES1 complexes. Methylcorypalline has a higher binding affinity inside 5ES1, according to additional MM/GBSA experiments using MD trajectories. Overall, research supports the use of the drug development tool methylcolipalin for its ability to inhibit MARK4, which may have implications for the treatment of neurodegenerative diseases.Communicated by Ramaswamy H. Sarma.

Lfc subcellular localization and activity is controlled by αv-class integrin

Fibronectin (FN)-binding integrins control a variety of cellular responses through Rho GTPases. The FN-binding integrins, αvβ3 and α5β1, are known to induce different effects on cell morphology and motility. Here, we report that FN-bound αvβ3 integrin, but not FN-bound α5β1 integrin, triggers the dissociation of the RhoA GEF Lfc (also known as GEF-H1 and ARHGEF2 in humans) from microtubules (MTs), leading to the activation of RhoA, formation of stress fibres and maturation of focal adhesions (FAs). Conversely, loss of Lfc expression decreases RhoA activity, stress fibre formation and FA size, suggesting that Lfc is the major GEF downstream of FN-bound αvβ3 that controls RhoA activity. Mechanistically, FN-engaged αvβ3 integrin activates a kinase cascade involving MARK2 and MARK3, which in turn leads to phosphorylation of several phospho-sites on Lfc. In particular, S151 was identified as the main site involved in the regulation of Lfc localization and activity. Our findings indicate that activation of Lfc and RhoA is orchestrated in FN-adherent cells in an integrin-specific manner.

Gut Microbiota in Autophagy Regulation: New Therapeutic Perspective in Neurodegeneration

Gut microbiota and the brain are related via a complex bidirectional interconnective network. Thus, intestinal homeostasis is a crucial factor for the brain, as it can control the environment of the central nervous system and play a significant role in disease progression. The link between neuropsychological behavior or neurodegeneration and gut dysbiosis is well established, but many involved pathways remain unknown. Accumulating studies showed that metabolites derived from gut microbiota are involved in the autophagy activation of various organs, including the brain, one of the major pathways of the protein clearance system that is essential for protein aggregate clearance. On the other hand, some metabolites are evidenced to disrupt the autophagy process, which can be a modulator of neurodegeneration. However, the detailed mechanism of autophagy regulation by gut microbiota remains elusive, and little research only focused on that. Here we tried to evaluate the crosstalk between gut microbiota metabolites and impaired autophagy of the central nervous system in neurodegeneration and the key to future research regarding gut dysbiosis and compromised autophagy in neurodegenerative diseases.

Chemical Genetic Identification of PKC Epsilon Substrates in Mouse Brain

PKC epsilon (PKCε) plays important roles in behavioral responses to alcohol and in anxiety-like behavior in rodents, making it a potential drug target for reducing alcohol consumption and anxiety. Identifying signals downstream of PKCε could reveal additional targets and strategies for interfering with PKCε signaling. We used a chemical genetic screen combined with mass spectrometry to identify direct substrates of PKCε in mouse brain and validated findings for 39 of them using peptide arrays and in vitro kinase assays. Prioritizing substrates with several public databases such as LINCS-L1000, STRING, GeneFriends, and GeneMAINA predicted interactions between these putative substrates and PKCε and identified substrates associated with alcohol-related behaviors, actions of benzodiazepines, and chronic stress. The 39 substrates could be broadly classified in three functional categories: cytoskeletal regulation, morphogenesis, and synaptic function. These results provide a list of brain PKCε substrates, many of which are novel, for future investigation to determine the role of PKCε signaling in alcohol responses, anxiety, responses to stress, and other related behaviors.

Lanthanum Chloride Induces Axon Abnormality Through LKB1-MARK2 and LKB1-STK25-GM130 Signaling Pathways

Lanthanum (La) is a natural rare-earth element that can damage the central nervous system and impair learning and memory. However, its neurotoxic mechanism remains unclear. In this study, adult female rats were divided into 4 groups and given distilled water solution containing 0%, 0.125%, 0.25%, and 0.5% LaCl₃, respectively, and this was done from conception to the end of the location. Their offspring rats were used to establish animal models to investigate LaCl₃ neurotoxicity. Primary neurons cultured in vitro were treated with LaCl₃ and infected with LKB1 overexpression lentivirus. The results showed that LaCl₃ exposure resulted in abnormal axons in the hippocampus and primary cultured neurons. LaCl₃ reduced the expression of LKB1, p-LKB1, STRAD and MO25 proteins, and directly or indirectly affected the expression of LKB1, leading to decreased activity of LKB1-MARK2 and LKB1-STK25-GM130 pathways. This study indicated that LaCl₃ exposure could interfere with the normal effects of LKB1 in the brain and downregulate LKB1-MARK2 and LKB1-STK25-GM130 signaling pathways, resulting in abnormal axon in offspring rats.

Inhibition of microtubule affinity regulating kinase 4 by an acetylcholinesterase inhibitor, Huperzine A: Computational and experimental approaches

Microtubule affinity regulating kinase 4 (MARK4), 752 amino acids long, belonging to the AMPK superfamily, plays a vital role in regulating microtubules due to its potential to phosphorylate microtubule-associated proteins (MAP's) and thus, MARK4 plays a key role in Alzheimer's disease (AD) pathology. MARK4 is a druggable target for cancer, neurodegenerative diseases, and metabolic disorders. In this study, we have evaluated the MARK4 inhibitory potential of Huperzine A (HpA), an acetylcholinesterase inhibitor (AChEI), a potential AD drug. Molecular docking revealed the key residues governing the MARK4-HpA complex formation. The structural stability and conformational dynamics of the MARK4-HpA complex was assessed by employing Molecular dynamics (MD) simulation. The results suggested that the binding of HpA with MARK4 leads to minimal structural alterations in the native conformation of MARK4, implying the stability of the MARK4-HpA complex. Isothermal titration calorimetry (ITC) studies deciphered that HpA binds to MARK4 spontaneously. Moreover, the kinase assay depicted significant inhibition of MARK by HpA (IC₅₀ = 4.91 μM), implying it to be a potent MARK4 inhibitor that can be implicated in the treatment of MARK4-directed diseases.

MARK3 kinase: Regulation and physiologic roles

Microtubule affinity-regulating kinase 3 (MARK3), a member of the MARK family, regulates several essential pathways, including the cell cycle, ciliated cell differentiation, and osteoclast differentiation. It is important to understand the control of their activities as MARK3 contains an N-terminal serine/threonine kinase domain, ubiquitin-associated domain, and C-terminal kinase-associated domain, which perform multiple regulatory functions. These functions include post-translational modification (e.g., phosphorylation) and interaction with scaffolding and other proteins. Differences in the amino acid sequence and domain position result in different three-dimensional protein structures and affect the function of MARK3, which distinguish it from the other MARK family members. Recent data indicate a potential role of MARK3 in several pathological conditions, including congenital blepharophimosis syndrome, osteoporosis, and tumorigenesis. The present review focuses on the physiological and pathological role of MARK3, its regulation, and recent developments in the small molecule inhibitors of the MARK3 signalling cascade.

Effects of Exercise Training on the Phosphoproteomics of the Medial Prefrontal Cortex in Rats With Autism Spectrum Disorder Induced by Valproic Acid

BACKGROUND

The key neural pathological characteristics of autism spectrum disorder (ASD) include abnormal synaptic plasticity of the medial prefrontal cortex (mPFC). Exercise therapy is widely used to rehabilitate children with ASD, but its neurobiological mechanism is unclear.

METHODS

To clarify whether the structural and molecular plasticity of synapses in the mPFC are related to improvement in ASD behavioral deficits after continuous exercise rehabilitation training, we applied phosphoproteomic, behavioral, morphological, and molecular biological methods to investigate the impact of exercise on the phosphoprotein expression profile and synaptic structure of the mPFC in valproic acid (VPA)-induced ASD rats.

RESULTS

Exercise training differentially regulated the density, morphology, and ultrastructure of synapses in mPFC subregions in the VPA-induced ASD rats. In total, 1031 phosphopeptides were upregulated and 782 phosphopeptides were downregulated in the mPFC in the ASD group. After exercise training, 323 phosphopeptides were upregulated, and 1098 phosphopeptides were downregulated in the ASDE group. Interestingly, 101 upregulated and 33 downregulated phosphoproteins in the ASD group were reversed after exercise training, and these phosphoproteins were mostly involved in synapses. Consistent with the phosphoproteomics data, the total and phosphorylated levels of the proteins MARK1 and MYH10 were upregulated in the ASD group and reversed after exercise training.

CONCLUSIONS

The differential structural plasticity of synapses in mPFC subregions may be the basic neural architecture of ASD behavioral abnormalities. The phosphoproteins involved in mPFC synapses, such as MARK1 and MYH10, may play important roles in the exercise rehabilitation effect on ASD-induced behavioral deficits and synaptic structural plasticity, which requires further investigation.

AMPK-like proteins and their function in female reproduction and gynecologic cancer

Serine-threonine kinase (STK11), also known as liver kinase B1 (LKB1), is a regulator of cellular homeostasis through regulating the cellular ATP-to-ADP ratio. LKB1 is classified as a tumor suppressor and functions as the key activator of AMP-activated protein kinase (AMPK) and a family of serine-threonine kinases called AMPK-like proteins. These proteins include novel (nua) kinase family 1 (NUAK1 and 2), salt inducible kinase (SIK1), QIK (known as SIK2), QSK (known as SIK3 kinase), and maternal embryonic leuzine zipper kinase (MELK) on tightly controlled and specific residual sites. LKB1 also regulates brain selective kinases 1 and 2 (BRSK1 and 2), additional members of AMPK-like protein family, which functions are probably less studied. AMPK-like proteins play a role in variety of reproductive physiology functions such as follicular maturation, menopause, embryogenesis, oocyte maturation, and preimplantation development. In addition, dysfunctional activity of AMPK-like proteins contributes to apoptosis blockade in cancer cells and induction of the epithelial-mesenchymal transition required for metastasis. Dysregulation of these proteins occurs in ovarian, endometrial, and cervical cancers. AMPK-like proteins are still undergoing further classification and may represent novel targets for targeted gynecologic cancer therapies. In this chapter, we describe the AMPK-like family of proteins and their roles in reproductive physiology and gynecologic cancers.

Cell polarity in the protist-to-animal transition

A signature feature of the animal kingdom is the presence of epithelia: sheets of polarized cells that both insulate the organism from its environment and mediate interactions with it. Epithelial cells display a marked apico-basal polarity, which is highly conserved across the animal kingdom, both in terms of morphology and of molecular regulators. How did this architecture first evolve? Although the last eukaryotic common ancestor almost certainly possessed a simple form of apico-basal polarity (marked by the presence of one or several flagella at a single cellular pole), comparative genomics and evolutionary cell biology reveal that the polarity regulators of animal epithelial cells have a surprisingly complex and stepwise evolutionary history. Here, we retrace their evolutionary assembly. We suggest that the "polarity network" that polarized animal epithelial cells evolved by integration of initially independent cellular modules that evolved at distinct steps of our evolutionary ancestry. The first module dates back to the last common ancestor of animals and amoebozoans and involved Par1, extracellular matrix proteins, and the integrin-mediated adhesion complex. Other regulators, such as Cdc42, Dlg, Par6 and cadherins evolved in ancient unicellular opisthokonts, and might have first been involved in F-actin remodeling and filopodial dynamics. Finally, the bulk of "polarity proteins" as well as specialized adhesion complexes evolved in the metazoan stem-line, in concert with the newly evolved intercellular junctional belts. Thus, the polarized architecture of epithelia can be understood as a palimpsest of components of distinct histories and ancestral functions, which have become tightly integrated in animal tissues.

Treatment of epilepsy using a targeted p38γ kinase gene therapy

Hyperphosphorylated microtubule-associated protein tau has been implicated in dementia, epilepsy, and other neurological disorders. In contrast, site-specific phosphorylation of tau at threonine 205 (T205) by the kinase p38γ was shown to disengage tau from toxic pathways, serving a neuroprotective function in Alzheimer's disease. Using a viral-mediated gene delivery approach in different mouse models of epilepsy, we show that p38γ activity-enhancing treatment reduces seizure susceptibility, restores neuronal firing patterns, reduces behavioral deficits, and ameliorates epilepsy-induced deaths. Furthermore, we show that p38γ-mediated phosphorylation of tau at T205 is essential for this protection in epilepsy, as a lack of this critical interaction reinstates pathological features and accelerates epilepsy in vivo. Hence, our work provides a scope to harness p38γ as a future therapy applicable to acute neurological conditions.

Drosophila GSK3β promotes microtubule disassembly and dendrite pruning in sensory neurons

The evolutionarily conserved Glycogen Synthase Kinase 3β (GSK3β), a negative regulator of microtubules, is crucial for neuronal polarization, growth and migration during animal development. However, it remains unknown whether GSK3β regulates neuronal pruning, which is a regressive process. Here, we report that the Drosophila GSK3β homologue Shaggy (Sgg) is cell-autonomously required for dendrite pruning of ddaC sensory neurons during metamorphosis. Sgg is necessary and sufficient to promote microtubule depolymerization, turnover and disassembly in the dendrites. Although Sgg is not required for the minus-end-out microtubule orientation in dendrites, hyperactivated Sgg can disturb the dendritic microtubule orientation. Moreover, our pharmacological and genetic data suggest that Sgg is required to promote dendrite pruning at least partly via microtubule disassembly. We show that Sgg and Par-1 kinases act synergistically to promote microtubule disassembly and dendrite pruning. Thus, Sgg and Par-1 might converge on and phosphorylate a common downstream microtubule-associated protein(s) to disassemble microtubules and thereby facilitate dendrite pruning.

Exome-wide association study to identify rare variants influencing COVID-19 outcomes: Results from the Host Genetics Initiative

Host genetics is a key determinant of COVID-19 outcomes. Previously, the COVID-19 Host Genetics Initiative genome-wide association study used common variants to identify multiple loci associated with COVID-19 outcomes. However, variants with the largest impact on COVID-19 outcomes are expected to be rare in the population. Hence, studying rare variants may provide additional insights into disease susceptibility and pathogenesis, thereby informing therapeutics development. Here, we combined whole-exome and whole-genome sequencing from 21 cohorts across 12 countries and performed rare variant exome-wide burden analyses for COVID-19 outcomes. In an analysis of 5,085 severe disease cases and 571,737 controls, we observed that carrying a rare deleterious variant in the SARS-CoV-2 sensor toll-like receptor TLR7 (on chromosome X) was associated with a 5.3-fold increase in severe disease (95% CI: 2.75-10.05, p = 5.41x10-7). This association was consistent across sexes. These results further support TLR7 as a genetic determinant of severe disease and suggest that larger studies on rare variants influencing COVID-19 outcomes could provide additional insights.

Tau Protein as Therapeutic Target for Cancer? Focus on Glioblastoma

Despite being extensively studied for several decades, the microtubule-associated protein Tau has not finished revealing its secrets. For long, Tau has been known for its ability to promote microtubule assembly. A less known feature of Tau is its capability to bind to cancer-related protein kinases, suggesting a possible role of Tau in modulating microtubule-independent cellular pathways that are associated with oncogenesis. With the intention of finding new therapeutic targets for cancer, it appears essential to examine the interaction of Tau with these kinases and their consequences. This review aims at collecting the literature data supporting the relationship between Tau and cancer with a particular focus on glioblastoma tumors in which the pathological significance of Tau remains largely unexplored. We will first treat this subject from a mechanistic point of view showing the pivotal role of Tau in oncogenic processes. Then, we will discuss the involvement of Tau in dysregulating critical pathways in glioblastoma. Finally, we will outline promising strategies to target Tau protein for the therapy of glioblastoma.