Candidate Alzheimer's Disease Biomarker miR-483-5p Lowers TAU Phosphorylation by Direct ERK1/2 Repression.
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ABSTRACT:
SUBMITTER: Nagaraj S
PROVIDER: S-EPMC8037306 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:MicroRNAs (miRNA) are abundant in the circulation and play a central role in diverse biologic processes; they may be useful for early diagnosis of hepatocellular carcinoma.We conducted a two-phase, case-control study (20 pairs for the discovery set and 49 pairs for the validation set) to test the hypothesis that genome-wide dysregulation of circulating miRNAs differentiates hepatocellular carcinoma cases from controls. Taqman low-density arrays were used to examine genome-wide miRNA expression for the discovery set, and quantitative real-time PCR was used to validate candidate miRNAs for both discovery and validation sets.Sixty-six miRNAs were found to be significantly overexpressed in plasma of hepatocellular carcinoma cases compared with controls after adjusting for false discovery rate (P < 0.05). A volcano plot indicated that seven miRNAs had greater than 2-fold case-control differences with P < 0.01. Four significant miRNAs (miR-150, miR-30c, miR-483-5p, and miR-520b) detectable in all samples with varied expression levels were further validated in a validation set. MiR-483-5p was statistically significantly overexpressed in hepatocellular carcinoma cases compared with controls (3.20 vs. 0.82, P < 0.0001). Hepatocellular carcinoma risk factors and clinic-pathological characteristics did not influence miR-483-5p expression. The combination of plasma miR-483-5p level and hepatitis C virus status can significantly differentiate hepatocellular carcinoma cases from controls with an area under the curve of 0.908 (P < 0.0001). The sensitivity and specificity were, respectively, 75.5% and 89.8%.These preliminary results suggest the importance of dysregulated circulating miR-483-5p as a potential hepatocellular carcinoma biomarker.Confirmation of aberrant expression of miR-483-5p in a large prospective hepatocellular carcinoma study will provide support for its application to hepatocellular carcinoma detection.
| S-EPMC3963823 | biostudies-literature
Project description:Alzheimer's disease (AD) is characterized by the presence in the brain of amyloid plaques, consisting predominately of the amyloid ? peptide (A?), and neurofibrillary tangles, consisting primarily of tau. Hyper-phosphorylated-tau (p-tau) contributes to neuronal damage, and both p-tau and total-tau (t-tau) levels are elevated in AD cerebrospinal fluid (CSF) compared to cognitively normal controls. Our hypothesis was that increased ratios of CSF phosphorylated-tau levels relative to total-tau levels correlate with regulatory region genetic variation of kinase or phosphatase genes biologically associated with the phosphorylation status of tau. Eighteen SNPs located within 5' and 3' regions of 5 kinase and 4 phosphatase genes, as well as two SNPs within regulatory regions of the MAPT gene were chosen for this analysis. The study sample consisted of 101 AD patients and 169 cognitively normal controls. Rs7768046 in the FYN kinase gene and rs913275 in the PPP2R4 phosphatase gene were both associated with CSF p-tau and t-tau levels in AD. These SNPs were also differentially associated with either CSF t-tau (rs7768046) or CSF p-tau (rs913275) relative to t-tau levels in AD compared to controls. These results suggest that rs7768046 and rs913275 both influence CSF tau levels in an AD-associated manner.
| S-EPMC3626266 | biostudies-literature
Project description:Deposition of extensively hyperphosphorylated tau in specific brain cells is a clear pathological hallmark in Alzheimer's disease and a number of other neurodegenerative disorders, collectively termed the tauopathies. Furthermore, hyperphosphorylation of tau prevents it from fulfilling its physiological role as a microtubule-stabilizing protein and leaves it increasingly vulnerable to self-assembly, suggestive of a central underlying role of hyperphosphorylation as a contributing factor in the etiology of these diseases. Via in vitro phosphorylation and regulation of kinase activity within cells and acute brain tissue, we reveal that the inflammation associated kinase, protein kinase R (PKR), directly phosphorylates numerous abnormal and disease-modifying residues within tau including Thr181, Ser199/202, Thr231, Ser262, Ser396, Ser404 and Ser409. Similar to disease processes, these PKR-mediated phosphorylations actively displace tau from microtubules in cells. In addition, PKR overexpression and knockdown, respectively, increase and decrease tau protein and mRNA levels in cells. This regulation occurs independent of noncoding transcriptional elements, suggesting an underlying mechanism involving intra-exonic regulation of the tau-encoding microtubule-associated protein tau (MAPT) gene. Finally, acute encephalopathy in wild type mice, induced by intracranial Langat virus infection, results in robust inflammation and PKR upregulation accompanied by abnormally phosphorylated full-length- and truncated tau. These findings indicate that PKR, independent of other kinases and upon acute brain inflammation, is capable of triggering pathological modulation of tau, which, in turn, might form the initial pathologic seed in several tauopathies such as Alzheimer's disease and Chronic traumatic encephalopathy where inflammation is severe.
| S-EPMC8018097 | biostudies-literature
Project description:Multiple symmetric lipomatosis (MSL) is a rare disease characterized by symmetric and abnormal distribution of subcutaneous adipose tissue (SAT); however, the etiology is largely unknown. We report here that miR-125a-3p and miR-483-5p are upregulated in the SAT of MSL patients, promoting adipogenesis through suppressing the RhoA/ROCK1/ERK1/2 pathway. TaqMan microRNA (miR) array analysis revealed that 18 miRs were upregulated in the SAT of MSL patients. Transfection of human adipose-derived mesenchymal stem cells (hADSCs) with the individual agomirs of these 18 miRs showed that miR-125a-3p and miR-483-5p significantly promoted adipogenesis. A dual-luciferase assay showed that RhoA and ERK1 were the targets of miR-125a-3p and miR-483-5p, respectively. Moreover, transfection of hADSCs with mimics of miR-125a-3p and miR-483-5p resulted in a pronounced decrease of ERK1/2 phosphorylation in the nucleus; conversely, transfection of hADSCs with inhibitors of miR-125a-3p and miR-483-5p led to a significant increase of ERK1/2 phosphorylation in the nucleus. Most importantly, we found that miR-125a-3p and miR-483-5p promoted de novo adipose tissue formation in nude mice. These results demonstrated that miR-125a-3p and miR-483-5p coordinately promoted adipogenesis through suppressing the RhoA/ROCK1/ERK1/2 pathway. Our findings may provide novel strategies for the management and treatment of MSL or obesity.
| S-EPMC4493643 | biostudies-literature
Project description:To date, there is no validated fluid biomarker for tau pathology in Alzheimer's disease, with contradictory results from studies evaluating the correlation between phosphorylated tau in CSF with tau PET imaging. Tau protein is subjected to proteolytic processing into fragments before being secreted to the CSF. A recent study suggested that tau cleavage after amino acid 368 by asparagine endopeptidase (AEP) is upregulated in Alzheimer's disease. We used immunoprecipitation followed by mass spectrometric analyses to evaluate the presence of tau368 species in CSF. A novel Simoa® assay for quantification of tau368 in CSF was developed, while total tau (t-tau) was measured by ELISA and the presence of tau368 in tangles was evaluated using immunohistochemistry. The diagnostic utility of tau368 was first evaluated in a pilot study (Alzheimer's disease = 20, control = 20), then in a second cohort where the IWG-2 biomarker criteria were applied (Alzheimer's disease = 37, control = 45), and finally in a third cohort where the correlation with 18F-GTP1 tau PET was evaluated (Alzheimer's disease = 38, control = 11). The tau368/t-tau ratio was significantly decreased in Alzheimer's disease (P < 0.001) in all cohorts. Immunohistochemical staining demonstrated that tau fragments ending at 368 are present in tangles. There was a strong negative correlation between the CSF tau368/t-tau ratio and 18F-GTP1 retention. Our data suggest that tau368 is a tangle-enriched fragment and that the CSF ratio tau368/t-tau reflects tangle pathology. This novel tau biomarker could be used to improve diagnosis of Alzheimer's disease and to facilitate the development of drug candidates targeting tau pathology. Furthermore, future longitudinal studies will increase our understanding of tau pathophysiology in Alzheimer's disease and other tauopathies.
| S-EPMC7009597 | biostudies-literature
Project description:An increasingly varied clinical spectrum of cases with amyotrophic lateral sclerosis (ALS) has been identified, and objective criteria for clinical trial eligibility are necessary.To develop a cerebrospinal fluid (CSF) biomarker sensitive and specific for the diagnosis of ALS.A case-control study including 51 individuals with ALS and 23 individuals with a disorder associated with a 4-repeat tauopathy was conducted at an academic medical center.The CSF level of tau phosphorylated at threonine 181 (ptau) and ratio of ptau to total tau (ttau).Using a cross-validation prediction procedure, we found significantly reduced CSF levels of ptau and the ptau:ttau ratio in ALS relative to 4-repeat tauopathy and to controls. In the validation cohort, the receiver operating characteristic area under the curve for the ptau:ttau ratio was 0.916, and the comparison of ALS with 4-repeat tauopathy showed 92.0% sensitivity?and 91.7% specificity. Correct classification based on a low CSF ptau:ttau ratio was confirmed in 18 of 21 cases (86%) with autopsy-proved or genetically determined disease. In patients with available measures, ptau:ttau in ALS correlated with clinical measures of disease severity, such as the Mini-Mental State Examination (n?=?51) and ALS Functional Rating Scale-Revised (n?=?42), and regression analyses related the ptau:ttau ratio to magnetic resonance imaging (n?=?10) evidence of disease in the corticospinal tract and white matter projections involving the prefrontal cortex.The CSF ptau:ttau ratio may be a candidate biomarker to provide objective support for the diagnosis of ALS.
| S-EPMC3989393 | biostudies-literature
Project description:Alzheimer's disease is characterized by accumulation of amyloid plaques and tau aggregates in several cortical brain regions. Tau phosphorylation causes formation of neurofibrillary tangles and neuropil threads. Phosphorylation at tau Ser202/Thr205 is well characterized since labeling of this site is used to assign Braak stage based on occurrence of neurofibrillary tangles. Only little is known about the spatial and temporal phosphorylation profile of other phosphorylated tau (ptau) sites. Here, we investigate total tau and ptau at residues Tyr18, Ser199, Ser202/Thr205, Thr231, Ser262, Ser396, Ser422 as well as amyloid-? plaques in human brain tissue of AD patients and controls. Allo- and isocortical brain regions were evaluated applying rater-independent automated quantification based on digital image analysis. We found that the level of ptau at several residues, like Ser199, Ser202/Thr205, and Ser422 was similar in healthy controls and Braak stages I to IV but was increased in Braak stage V/VI throughout the entire isocortex and transentorhinal cortex. Quantification of ThioS-stained plaques showed a similar pattern. Only tau phosphorylation at Tyr18 and Thr231 was already significantly increased in the transentorhinal region at Braak stage III/IV and hence showed a progressive increase with increasing Braak stages. Additionally, the increase in phosphorylation relative to controls was highest at Tyr18, Thr231 and Ser199. By contrast, Ser396 tau and Ser262 tau showed only a weak phosphorylation in all analyzed brain regions and only minor progression. Our results suggest that the ptau burden in the isocortex is comparable between all analyzed ptau sites when using a quantitative approach while levels of ptau at Tyr18 or Thr231 in the transentorhinal region are different between all Braak stages. Hence these sites could be crucial in the pathogenesis of AD already at early stages and therefore represent putative novel therapeutic targets.
| S-EPMC6027763 | biostudies-literature
Project description:Alzheimer's disease (AD) is a progressive neurodegenerative disorder characterised by neuropathological deposits of amyloid plaques and neurofibrillary tangles comprised of ?-amyloid and tau protein, respectively. In AD, tau becomes abnormally phosphorylated and aggregates to form intracellular deposits. However, the mechanisms by which tau exerts neurotoxicity in disease remain unclear. Recent studies have suggested that the presence of tau at synapses may indicate a role in neuronal signalling, which could be disrupted in pathological conditions. The non-receptor-associated tyrosine kinase fyn is located at the dendrite in neurons, where it was recently shown to interact with tau to stabilise receptor complexes at the post-synaptic density. Fyn also co-localises with tau in a proportion of neurons containing tau tangles in AD and fyn is also a tau kinase. Hence, tau-fyn interactions could play a pathogenic role in AD. Here we report the identification of critical proline residues, Pro213, Pro216, and Pro219, located within the fifth and sixth Pro-X-X-Pro motifs in the proline-rich region of tau, that are important for its binding to fyn. These residues in tau are flanked by numerous phosphorylation sites and therefore we investigated the relationship between fyn and the degree of tau phosphorylation in human post-mortem brain tissue. We found no difference in the amount of fyn present in control and AD brain. Notably, however, there was a significant correlation between fyn and phosphorylated tau at specific phospho-epitopes in control, but not in AD brain. Our results suggest that the pathological mechanisms underlying AD, that result in increased tau phosphorylation, may disrupt the physiological relationship between tau phosphorylation and fyn.
| S-EPMC4870772 | biostudies-literature
Project description:Hyperphosphorylated tau protein is a pathological hallmark of numerous neurodegenerative diseases and the level of tau pathology is correlated with the degree of cognitive impairment. Tau hyper-phosphorylation is thought to be an early initiating event in the cascade leading to tau toxicity and neuronal death. Inhibition of tau phosphorylation therefore represents an attractive therapeutic strategy. However, the widespread expression of most kinases and promiscuity of their substrates, along with poor selectivity of most kinase inhibitors, have resulted in systemic toxicities that have limited the advancement of tau kinase inhibitors into the clinic. We therefore focused on the CNS-specific tau kinase, TTBK1, and investigated whether selective inhibition of this kinase could represent a viable approach to targeting tau phosphorylation in disease. In the current study, we demonstrate that TTBK1 regulates tau phosphorylation using overexpression or knockdown of this kinase in heterologous cells and primary neurons. Importantly, we find that TTBK1-specific phosphorylation of tau leads to a loss of normal protein function including a decrease in tau-tubulin binding and deficits in tubulin polymerization. We then describe the use of a novel, selective small molecule antagonist, BIIB-TTBK1i, to study the acute effects of TTBK1 inhibition on tau phosphorylation in vivo. We demonstrate substantial lowering of tau phosphorylation at multiple sites implicated in disease, suggesting that TTBK1 inhibitors may represent an exciting new approach in the search for neurodegenerative disease therapies.
| S-EPMC7138307 | biostudies-literature
Project description:BackgroundWe aimed to investigate the tau biomarker discrepancies of Alzheimer's disease (AD) using plasma tau phosphorylated at threonine 181 (p-tau181), cerebrospinal fluid (CSF) p-tau181, and AV1451 positron emission tomography (PET).MethodsIn the Alzheimer's Disease Neuroimaging Initiative, 724 non-demented participants were categorized into plasma/CSF and plasma/PET groups. Demographic and clinical variables, amyloid-β (Aβ) burden, flortaucipir-PET binding in Braak regions of interest (ROIs), longitudinal changes in clinical outcomes, and conversion risk were compared.ResultsAcross different tau biomarker groups, the proportion of participants with a discordant profile varied (plasma+/CSF- 15.6%, plasma-/CSF+ 15.3%, plasma+/PET- 22.4%, and plasma-/PET+ 6.1%). Within the plasma/CSF categories, we found an increase from concordant-negative to discordant to concordant-positive in the frequency of Aβ pathology or cognitive impairment, rates of cognitive decline, and risk of cognitive conversion. However, the two discordant categories (plasma+/CSF- and plasma-/CSF+) showed comparable performances, resulting in similarly reduced cognitive capacities. Regarding plasma/PET categories, as expected, PET-positive individuals had increased Aβ burden, elevated flortaucipir retention in Braak ROIs, and accelerated cognitive deterioration than concordant-negative persons. Noteworthy, discordant participants with normal PET exhibited reduced flortaucipir uptake in Braak stage ROIs and slower rates of cognitive decline, relative to those PET-positive. Therefore, individuals with PET abnormality appeared to have advanced tau pathological changes and poorer cognitive function, regardless of the plasma status. Furthermore, these results were found only in individuals with Aβ pathology.ConclusionsOur results indicate that plasma and CSF p-tau181 abnormalities associated with amyloidosis occur simultaneously in the progression of AD pathogenesis and related cognitive decline, before tau-PET turns positive.
| S-EPMC8094494 | biostudies-literature