The study of intercalated cells using ex vivo techniques: primary cell culture, cell lines, kidney slices, and organoids.

This review summarizes methods to study kidney intercalated cell (IC) function ex vivo. While important for acid-base homeostasis, IC dysfunction is often not recognized clinically until it becomes severe. The advantage of using ex vivo techniques is that they allow for the differential evaluation of IC function in controlled environments. Although in vitro kidney tubular perfusion is a classical ex vivo technique to study IC, here we concentrate on primary cell cultures, immortalized cell lines, and ex vivo kidney slices. Ex vivo techniques are useful in evaluating IC signaling pathways that allow rapid responses to extracellular changes in pH, CO2, and bicarbonate (HCO3-). However, these methods for IC work can also be challenging, as cell lines that recapitulate IC do not proliferate easily in culture. Moreover, a "pure" IC population in culture does not necessarily replicate its collecting duct (CD) environment, where ICs are surrounded by the more abundant principal cells (PCs). It is reassuring that many findings obtained in ex vivo IC systems signaling have been largely confirmed in vivo. Some of these newly identified signaling pathways reveal that ICs are important for regulating NaCl reabsorption, thus suggesting new frontiers to target antihypertensive treatments. Moreover, recent single-cell characterization studies of kidney epithelial cells revealed a dual developmental origin of IC, as well as the presence of novel CD cell types with certain IC characteristics. These exciting findings present new opportunities for the study of IC ex vivo and will likely rediscover the importance of available tools in this field.NEW & NOTEWORTHY The study of kidney intercalated cells has been limited by current cell culture and kidney tissue isolation techniques. This review is to be used as a reference to select ex vivo techniques to study intercalated cells. We focused on the use of cell lines and kidney slices as potential useful models to study membrane transport proteins. We also review how novel collecting duct organoids may help better elucidate the role of these intriguing cells.

Changes in dementia treatment patterns associated with changes in the National Policy in South Korea among patients with newly diagnosed Alzheimer's disease between 2011 and 2017: results from the multicenter, retrospective CAPTAIN study.

BACKGROUND: The South Korean government has been actively involved in plans to combat dementia, implementing a series of national strategies and plans since 2008. In July 2014, eligibility for mandatory long-term care insurance (LTCI) was extended to people with dementia enabling access to appropriate long-term care including the cognitive function training program and home nursing service. This study aimed to investigate changes in treatment patterns for Alzheimer's disease (AD) between July 2011 and June 2017 which spanned the 2014 revision. METHODS: This multicenter, retrospective, observational study of patients with newly diagnosed AD analyzed electronic medical records from 17 general hospitals across South Korea. Based on their time of AD diagnosis, subjects were categorized into Cohort 1 (1 July 2011 to 30 June 2014) and Cohort 2 (1 July 2014 to 30 June 2017). RESULTS: Subjects (N=3,997) divided into Cohorts 1 (n=1,998) and 2 (n=1,999), were mostly female (66.4%) with a mean age of 84.4 years. Cohort 1 subjects were significantly older (P<0.0001) and had a lower number of comorbidities (P=0.002) compared with Cohort 2. Mean Mini-Mental State Examination (MMSE) scores in Cohorts 1 and 2 at the time of AD diagnosis or start of initial treatment were 16.9 and 17.1, respectively (P=0.2790). At 1 year, mean MMSE scores in Cohorts 1 and 2 increased to 17.9 and 17.4, respectively (P=0.1524). Donepezil was the most frequently administered medication overall (75.0%), with comparable rates between cohorts. Rates of medication persistence were ≥98% for acetylcholinesterase inhibitor or memantine therapy. Discontinuation and switch treatment rates were significantly lower (49.7% vs. 58.0%; P<0.0001), and mean duration of initial treatment significantly longer, in Cohort 2 vs. 1 (349.3 vs. 300.2 days; P<0.0001). CONCLUSIONS: Comparison of cohorts before and after revision of the national LTCI system for dementia patients found no significant difference in mean MMSE scores at the time of AD diagnosis or start of initial treatment. The reduction in the proportion of patients who discontinued or changed their initial treatment, and the significant increase in mean duration of treatment, were observed following revision of the LTCI policy which enabled increased patient access to long-term care.

Subsequent correlated changes in complement component 3 and amyloid beta oligomers in the blood of patients with Alzheimer's disease.

INTRODUCTION: Alzheimer's disease (AD) involves the complement cascade, with complement component 3 (C3) playing a key role. However, the relationship between C3 and amyloid beta (Aß) in blood is limited. METHODS: Plasma C3 and Aß oligomerization tendency (AßOt) were measured in 35 AD patients and 62 healthy controls. Correlations with cerebrospinal fluid (CSF) biomarkers, cognitive impairment, and amyloid positron emission tomography (PET) were analyzed. Differences between biomarkers were compared in groups classified by concordances of biomarkers. RESULTS: Plasma C3 and AßOt were elevated in AD patients and in CSF or amyloid PET-positive groups. Weak positive correlation was found between C3 and AßOt, while both had strong negative correlations with CSF Aß42 and cognitive performance. Abnormalities were observed for AßOt and CSF Aß42 followed by C3 changes. DISCUSSION: Increased plasma C3 in AD are associated with amyloid pathology, possibly reflecting a defense response for Aß clearance. Further studies on Aß-binding proteins will enhance understanding of Aß mechanisms in blood.

Double Mutations in a Patient with Early-Onset Alzheimer's Disease in Korea: An APP Val551Met and a PSEN2 His169Asn.

The etiology of early-onset Alzheimer's disease (EOAD) is associated with alterations in the production of amyloid beta (Aß) species caused by mutations in the APP, PSEN1, and PSEN2 genes. Mutations affect intra- or inter-molecular interactions and processes between the γ-secretase complex and amyloid precursor protein (APP), leading to the aberrant sequential cleavage of Aß species. A 64-year-old woman presented with progressive memory decline, mild right hippocampal atrophy, and a family history of Alzheimer's dementia (AD). Whole exome sequencing was performed to evaluate AD-related gene mutations, which were verified by Sanger sequencing. A mutation-caused structural alteration of APP was predicted using in silico prediction programs. Two AD-related mutations, in APP (rs761339914; c.G1651A; p.V551M) and PSEN2 (rs533813519; c.C505A; p.H169N), were identified. The APP Val551Met mutation in the E2 domain may influence APP homodimerization through changes in intramolecular interactions between adjacent amino acids, altering Aß production. The second mutation was PSEN2 His169Asn mutation, which was previously reported in five EOAD patients from Korea and China, with a relatively high frequency in the East Asian population. According to a previous report, the presenilin 2 protein was predicted to result in a major helical torsion by PSEN2 His169Asn mutation. Notably, the co-existence of APP Val551Met and PSEN2 His169Asn may induce a synergistic effect by both mutations. Future functional studies are needed to clarify the pathological effects of these double mutations.

Biglycan reduces body weight by regulating food intake in mice and improves glucose metabolism through AMPK/AKT dual pathways in skeletal muscle.

While biglycan (BGN) is suggested to direct diverse signaling cascades, the effects of soluble BGN as a ligand on metabolic traits have not been studied. Herein, we tested the effects of BGN on obesity in high-fat diet (HFD)-induced obese animals and glucose metabolism, with the underlying mechanism responsible for observed effects in vitro. Our results showed that BGN administration (1 mg/kg body weight, intraperitoneally) significantly prevented HFD-induced obesity, and this was mainly attributed to reduced food intake. Also, intracerebroventricular injection of BGN reduced food intake and body weight. The underlying mechanism includes modulation of neuropeptides gene expression involved in appetite in the hypothalamus in vitro and in vivo. In addition, BGN regulates glucose metabolism as shown by improved glucose tolerance in mice as well as AMPK/AKT dual pathway-driven enhanced glucose uptake and GLUT4 translocation in L6 myoblast cells. In conclusion, our results suggest BGN as a potential therapeutic target to treat risk factors for metabolic diseases.

Identification of the Third Case of PSEN1 Tyr389His Variant in Early-Onset Alzheimer's Disease in Korea.

Amyloid precursor protein (APP), presenilin 1 (PSEN1), and presenilin 2 (PSEN2) are associated with autosomal-dominant early-onset Alzheimer's disease (AD). Most mutations have been identified in the PSEN1 gene. We discovered a PSEN1 mutation (Tyr389His) in a Korean patient with early-onset AD who presented memory decline at 41 years of age followed by language, memory, and visuospatial dysfunctions. As this is the third such patient identified in Korea, this mutation may be involved in AD pathogenesis, suggesting that routine screening is necessary in this population. Altered intra-molecular interactions with the mutated amino acid may result in the destabilization of γ-secretase. In the future, a panel incorporating genes with relatively high-frequency rare variants, along with the APOE4 gene, may predict the onset of AD and facilitate customized treatment.

A Possible Pathogenic PSEN2 Gly56Ser Mutation in a Korean Patient with Early-Onset Alzheimer's Disease.

Early-onset Alzheimer's disease (EOAD) is characterized by the presence of neurological symptoms in patients with Alzheimer's disease (AD) before 65 years of age. Mutations in pathological genes, including amyloid protein precursor (APP), presenilin-1 (PSEN1), and presenilin-2 (PSEN2), were associated with EOAD. Seventy-six mutations in PSEN2 have been found around the world, which could affect the activity of γ-secretase in amyloid beta processing. Here, a heterozygous PSEN2 point mutation from G to A nucleotide change at position 166 (codon 56; c.166G>A, Gly56Ser) was identified in a 64-year-old Korean female with AD with progressive cognitive memory impairment for the 4 years prior to the hospital visit. Hippocampal atrophy was observed from magnetic resonance imaging-based neuroimaging analyses. Temporal and parietal cortex hypometabolisms were identified using fluorodeoxyglucose positron emission tomography. This mutation was at the N-terminal portion of the presenilin 2 protein on the cytosolic side. Therefore, the serine substitution may have promoted AD pathogenesis by perturbing to the mutation region through altered phosphorylation of presenilin. In silico analysis revealed that the mutation altered protein bulkiness with increased hydrophilicity and reduced flexibility of the mutated region of the protein. Structural changes were likely caused by intramolecular interactions between serine and other residues, which may have affected APP processing. The functional study will clarify the pathogenicity of the mutation in the future.

Effect of chitinase-3-like protein 1 on glucose metabolism: In vitro skeletal muscle and human genetic association study.

We investigated the effect of chitinase-3-like protein 1 (CHI3L1) on glucose metabolism and its underlying mechanisms in skeletal muscle cells, and evaluated whether the observed effects are relevant in humans. CHI3L1 was associated with increased glucose uptake in skeletal muscles in an AMP-activated protein kinase (AMPK)-dependent manner, and with increased intracellular calcium levels via PAR2. The improvement in glucose metabolism observed in an intraperitoneal glucose tolerance test on male C57BL/6J mice supported this association. Inhibition of the CaMKK was associated with suppression of CHI3L1-mediated glucose uptake. Additionally, CHI3L1 was found to influence glucose uptake through the PI3K/AKT pathway. Results suggested that CHI3L1 stimulated the phosphorylation of AS160 and p38 MAPK downstream of AMPK and AKT, and the resultant GLUT4 translocation. In primary myoblast cells, stimulation of AMPK and AKT was observed in response to CHI3L1, underscoring the biological relevance of CHI3L1. CHI3L1 levels were elevated in cells under conditions that mimic exercise in vitro and in exercised mice in vivo, indicating that CHI3L1 is secreted during muscle contraction. Finally, similar associations between CHI3L1 and metabolic parameters were observed in humans alongside genotype associations between CHI3L1 and diabetes at the population level. CHI3L1 may be a potential therapeutic target for the treatment of diabetes.

ATP synthase inhibitory factor 1 (IF1), a novel myokine, regulates glucose metabolism by AMPK and Akt dual pathways.

ATPase inhibitory factor 1 (IF1) is an ATP synthase-interacting protein that suppresses the hydrolysis activity of ATP synthase. In this study, we observed that the expression of IF1 was up-regulated in response to electrical pulse stimulation of skeletal muscle cells and in exercized mice and healthy men. IF1 stimulates glucose uptake via AMPK in skeletal muscle cells and primary cultured myoblasts. Reactive oxygen species and Rac family small GTPase 1 (Rac1) function in the upstream and downstream of AMPK, respectively, in IF1-mediated glucose uptake. In diabetic animal models, the administration of recombinant IF1 improved glucose tolerance and down-regulated blood glucose level. In addition, IF1 inhibits ATP hydrolysis by ß-F1-ATPase in plasma membrane, thereby increasing extracellular ATP and activating the protein kinase B (Akt) pathway, ultimately leading to glucose uptake. Thus, we suggest that IF1 is a novel myokine and propose a mechanism by which AMPK and Akt contribute independently to IF1-mediated improvement of glucose tolerance impairment. These results demonstrate the importance of IF1 as a potential antidiabetic agent.-Lee, H. J., Moon, J., Chung, I., Chung, J. H., Park, C., Lee, J. O., Han, J. A., Kang, M. J., Yoo, E. H., Kwak, S.-Y., Jo, G., Park, W., Park, J., Kim, K. M., Lim, S., Ngoei, K. R. W., Ling, N. X. Y., Oakhill, J. S., Galic, S., Murray-Segal, L., Kemp, B. E., Mantzoros, C. S., Krauss, R. M., Shin, M.-J., Kim, H. S. ATP synthase inhibitory factor 1 (IF1), a novel myokine, regulates glucose metabolism by AMPK and Akt dual pathways.

Predictors of pre-operative cognitive impairment in meningioma patients over 60 years old.

BACKGROUND: The aim of this study was to assess the cognitive function of patients over 60 years old with meningioma using a domain-specific neuropsychological test and to investigate the relevant factors affecting pre-operative cognitive decline in different subdomains. METHODS: We retrospectively investigated 46 intracranial meningioma patients between the ages of 60 and 85 years. All patients underwent brain MRI and neuropsychological test. Tumor size, location, peritumoral edema, and medial temporal atrophy (MTA) were examined to determine the association with cognitive impairment. We performed a logistic regression analysis to examine the odds ratios (ORs) for cognitive decline of four subdomains: verbal memory, language, visuospatial, and executive functions. RESULTS: Tumor size and age were associated with executive dysfunction (OR 1.083, 95% confidence interval (CI) 1.006-1.166, and OR 1.209, 95% CI 1.018-1.436, respectively). There was no statistically significant association in other cognitive domains (language, verbal memory, and visuospatial function) with variables in regression analysis. CONCLUSIONS: We conclude that tumor size and age are positively related with executive function in pre-operative meningioma patients over 60 years old.

Coping with Dementia in the Middle of the COVID-19 Pandemic.

Multiple neurological complications have been associated with the coronavirus disease-19 (COVID-19), which is caused by severe acute respiratory syndrome coronavirus 2. This is a narrative review to gather information on all aspects of COVID-19 in elderly patients with cognitive impairment. First, the following three mechanisms have been proposed to underlie the neurological complications associated with COVID-19: 1) direct invasion, 2) immune and inflammatory reaction, and 3) hypoxic brain damage by COVID-19. Next, because the elderly dementia patient population is particularly vulnerable to COVID-19, we discussed risk factors and difficulties associated with cognitive disorders in this vulnerable population. We also reviewed the effects of the patient living environment in COVID-19 cases that required intensive care unit (ICU) care. Furthermore, we analyzed the impact of stringent social restrictions and COVID-19 pandemic-mediated policies on dementia patients and care providers. Finally, we provided the following strategies for working with elderly dementia patients: general preventive methods; dementia care at home and nursing facilities according to the activities of daily living and dementia characteristics; ICU care after COVID-19 infection; and public health care system and government response. We propose that longitudinal follow-up studies are needed to fully examine COVID-19 associated neurological complications, such as dementia, and the efficacy of telemedicine/telehealth care programs.

Metformin overcomes resistance to cisplatin in triple-negative breast cancer (TNBC) cells by targeting RAD51.

BACKGROUND: Chemotherapy is a standard therapeutic regimen to treat triple-negative breast cancer (TNBC); however, chemotherapy alone does not result in significant improvement and often leads to drug resistance in patients. In contrast, combination therapy has proven to be an effective strategy for TNBC treatment. Whether metformin enhances the anticancer effects of cisplatin and prevents cisplatin resistance in TNBC cells has not been reported. METHODS: Cell viability, wounding healing, and invasion assays were performed on Hs 578T and MDA-MB-231 human TNBC cell lines to demonstrate the anticancer effects of combined cisplatin and metformin treatment compared to treatment with cisplatin alone. Western blotting and immunofluorescence were used to determine the expression of RAD51 and gamma-H2AX. In an in vivo 4T1 murine breast cancer model, a synergistic anticancer effect of metformin and cisplatin was observed. RESULTS: Cisplatin combined with metformin decreased cell viability and metastatic effect more than cisplatin alone. Metformin suppressed cisplatin-mediated RAD51 upregulation by decreasing RAD51 protein stability and increasing its ubiquitination. In contrast, cisplatin increased RAD51 expression in an ERK-dependent manner. In addition, metformin also increased cisplatin-induced phosphorylation of γ-H2AX. Overexpression of RAD51 blocked the metformin-induced inhibition of cell migration and invasion, while RAD51 knockdown enhanced cisplatin activity. Moreover, the combination of metformin and cisplatin exhibited a synergistic anticancer effect in an orthotopic murine model of 4T1 breast cancer in vivo. CONCLUSIONS: Metformin enhances anticancer effect of cisplatin by downregulating RAD51 expression, which represents a novel therapeutic target in TNBC management.

LIF, a Novel Myokine, Protects Against Amyloid-Beta-Induced Neurotoxicity via Akt-Mediated Autophagy Signaling in Hippocampal Cells.

BACKGROUND: Leukemia inhibitory factor, a novel myokine, is known to be associated with neural function, but the underlying molecular mechanism remains unclear. METHODS: HT-22 mouse hippocampal cells, primary hippocampal cells, and Drosophila Alzheimer's disease model were used to determine the effect of leukemia inhibitory factor on neurons. Immunoblot analysis and immunofluorescence method were used to analyze biological mechanism. RESULTS: Leukemia inhibitory factor increased Akt phosphorylation in a phosphoinositide-3-kinase-dependent manner in hippocampal cells. Leukemia inhibitory factor also increased the phosphorylation of the mammalian target of rapamycin and the downstream S6K. Leukemia inhibitory factor stimulated the phosphorylation of signal transducer and activator of transcription via extracellular signal-regulated kinases. Leukemia inhibitory factor increased c-fos expression through both Akt and extracellular signal-regulated kinases. Leukemia inhibitory factor blocked amyloid ß-induced neural viability suppression and inhibited amyloid ß-induced glucose uptake impairment through the block of amyloid ß-mediated insulin receptor downregulation. Leukemia inhibitory factor blocked amyloid ß-mediated induction of the autophagy marker, microtubule-associated protein 1A/1B-light chain 3. Additionally, in primary prepared hippocampal cells, leukemia inhibitory factor stimulated Akt and extracellular signal-regulated kinase, demonstrating that leukemia inhibitory factor has physiological relevance in vivo. Suppression of the autophagy marker, light chain 3II, by leukemia inhibitory factor was observed in a Drosophila model of Alzheimer's disease. CONCLUSIONS: These results demonstrate that leukemia inhibitory factor protects against amyloid ß-induced neurotoxicity via Akt/extracellular signal-regulated kinase-mediated c-fos induction, and thus suggest that leukemia inhibitory factor is a potential drug for Alzheimer's disease.

The usefulness of visual rating of posterior atrophy in predicting rapid cognitive decline in Alzheimer disease: A preliminary study.

BACKGROUND: Approximately 10% to 30% of Alzheimer disease (AD) patients progress rapidly in severity and become more dependent on caregivers. Although several studies have investigated whether imaging biomarkers such as medial temporal atrophy (MTA) and posterior atrophy (PA) are useful for predicting the rapid progression of AD, their results have been inconsistent. OBJECTIVE: The study aims to investigate the association of visually rated MTA and PA with rapid disease progression in AD. METHODS: This was a retrospective cohort study of 159 AD patients who were initially diagnosed with mild AD and were followed for 1 year to determine whether they progressed rapidly (a decrease of three points or more on the Mini-Mental State Examination over 1 year). We used 5-point and 4-point visual rating scales to assess MTA and PA, respectively. MTA and PA scores for each patient were dichotomized as normal (without atrophy) or abnormal (atrophy). We performed a logistic regression analysis to determine the odds ratios (ORs) of MTA and PA for rapid disease progression with adjustment for covariates. RESULTS: Within the study population, 47 (29.6%) patients progressed rapidly. Visual assessment of the magnetic resonance imaging (MRI) scans revealed that 112 patients (70.4%) showed MTA, whereas 80 patients (50.3%) showed PA. The ORs with 95% confidence intervals for MTA and PA were 1.825 (0.819-4.070) and 2.844 (1.378-5.835), respectively. The association of visually assessed PA, but not MTA, with rapid progression was significant after adjustment for covariates. CONCLUSION: In patients with mild AD, visual assessment of PA exhibits independent predictive value for rapid disease progression.

Prediction of cognitive impairment via deep learning trained with multi-center neuropsychological test data.

BACKGROUND: Neuropsychological tests (NPTs) are important tools for informing diagnoses of cognitive impairment (CI). However, interpreting NPTs requires specialists and is thus time-consuming. To streamline the application of NPTs in clinical settings, we developed and evaluated the accuracy of a machine learning algorithm using multi-center NPT data. METHODS: Multi-center data were obtained from 14,926 formal neuropsychological assessments (Seoul Neuropsychological Screening Battery), which were classified into normal cognition (NC), mild cognitive impairment (MCI) and Alzheimer's disease dementia (ADD). We trained a machine learning model with artificial neural network algorithm using TensorFlow (https://www.tensorflow.org) to distinguish cognitive state with the 46-variable data and measured prediction accuracies from 10 randomly selected datasets. The features of the NPT were listed in order of their contribution to the outcome using Recursive Feature Elimination. RESULTS: The ten times mean accuracies of identifying CI (MCI and ADD) achieved by 96.66 ± 0.52% of the balanced dataset and 97.23 ± 0.32% of the clinic-based dataset, and the accuracies for predicting cognitive states (NC, MCI or ADD) were 95.49 ± 0.53 and 96.34 ± 1.03%. The sensitivity to the detection CI and MCI in the balanced dataset were 96.0 and 96.0%, and the specificity were 96.8 and 97.4%, respectively. The 'time orientation' and '3-word recall' score of MMSE were highly ranked features in predicting CI and cognitive state. The twelve features reduced from 46 variable of NPTs with age and education had contributed to more than 90% accuracy in predicting cognitive impairment. CONCLUSIONS: The machine learning algorithm for NPTs has suggested potential use as a reference in differentiating cognitive impairment in the clinical setting.

The Impact of Discrepancy between Measured versus Stated Weight on Hemorrhagic Transformation and Clinical Outcomes after Intravenous Alteplase Thrombolysis.

BACKGROUND: An accurate measurement of patient weight is important in determining the dosage for intravenous alteplase thrombolysis. In most emergency rooms, however, weight is not measured. We investigated the difference between stated and measured weight and its effect on hemorrhagic transformation and clinical outcomes. METHODS: We enrolled 128 consecutive patients who had hyperacute stroke and were treated by alteplase. Alteplase dose was calculated using the weight provided by patient or guardian/caregiver, and the actual weight was measured after administration. Patients were classified into 2 groups: overused group (stated weight >measured weight) and underused group (measured weight ≥stated weight). The prevalence of hemorrhagic transformation on follow-up, determined by gradient-recalled echo MRI or non-enhanced CT, was compared between the 2 groups. The predictors for hemorrhage with progression, defined as an increase in the National Institutes of Health Stroke Scale (NIHSS) by a value of 4 or more accompanied by hemorrhage, were determined using multivariable logistic regression analysis and included the overused or underused alteplase and baseline clinical and laboratory findings. RESULTS: Sixty-six (51.6%) of 128 patients were in the underused group and 62 patients (48.4%) in the overused group. The median difference between the stated and measured weights was 1.5 (interquartile range 0.56-3.81) kg, with the largest difference being 25.6 kg. Although there were no significant difference in baseline clinical and laboratory findings between the 2 groups, the overused group showed a significantly higher prevalence of hemorrhagic transformation (p = 0.012) and hemorrhage with progression (p = 0.025). The multivariable logistic regression analysis demonstrated that overused alteplase (OR 7.26; 95% CI 1.24-42.45; p = 0.028), baseline glucose (>144 mg/dL; OR 5.03; 95% CI 1.00-25.26; p = 0.050), and initial NIHSS (OR 1.13 per 1-point NIHSS increase; 95% CI 1.00-1.27; p = 0.047) in model 1 that use alteplase overdose as a categorical variable and overused alteplase (OR 1.67 1-mg increase; 95% CI 1.05-2.66; p = 0.027) in model 2 that use an overused alteplase dose as numerical variable were significant predictors for hemorrhage with progression. CONCLUSION: More alteplase usage than actual weight led to higher hemorrhagic transformation. As one of the predictors for clinical deterioration, it is important to administrate alteplase based on an accurately measured weight.

XAF1 directs apoptotic switch of p53 signaling through activation of HIPK2 and ZNF313.

X-linked inhibitor of apoptosis (XIAP)-associated factor 1 (XAF1) is a tumor suppressor that is frequently inactivated in many human cancers. However, the molecular mechanism underlying its growth-inhibitory function remains largely unknown. Here, we report that XAF1 forms a positive feedback loop with p53 and acts as a molecular switch in p53-mediated cell-fate decisions favoring apoptosis over cell-cycle arrest. XAF1 binds directly to the N-terminal proline-rich domain of p53 and thus interferes with E3 ubiquitin ligase MDM2 binding and ubiquitination of p53. XAF1 stimulates homeodomain-interacting protein kinase 2 (HIPK2)-mediated Ser-46 phosphorylation of p53 by blocking E3 ubiquitin ligase Siah2 interaction with and ubiquitination of HIPK2. XAF1 also steps up the termination of p53-mediated cell-cycle arrest by activating zinc finger protein 313 (ZNF313), a p21(WAF1)-targeting ubiquitin E3 ligase. XAF1 interacts with p53, Siah2, and ZNF313 through the zinc finger domains 5, 6, and 7, respectively, and truncated XAF1 isoforms preferentially expressed in cancer cells fail to form a feedback loop with p53. Together, this study uncovers a novel role for XAF1 in p53 stress response, adding a new layer of complexity to the mechanisms by which p53 determines cell-fate decisions.

7SL RNA represses p53 translation by competing with HuR.

Noncoding RNAs (ncRNAs) and RNA-binding proteins are potent post-transcriptional regulators of gene expression. The ncRNA 7SL is upregulated in cancer cells, but its impact upon the phenotype of cancer cells is unknown. Here, we present evidence that 7SL forms a partial hybrid with the 3'-untranslated region (UTR) of TP53 mRNA, which encodes the tumor suppressor p53. The interaction of 7SL with TP53 mRNA reduced p53 translation, as determined by analyzing p53 expression levels, nascent p53 translation and TP53 mRNA association with polysomes. Silencing 7SL led to increased binding of HuR to TP53 mRNA, an interaction that led to the promotion of p53 translation and increased p53 abundance. We propose that the competition between 7SL and HuR for binding to TP53 3'UTR contributes to determining the magnitude of p53 translation, in turn affecting p53 levels and the growth-suppressive function of p53. Our findings suggest that targeting 7SL may be effective in the treatment of cancers with reduced p53 levels.

RNA-binding protein AUF1 represses Dicer expression.

MicroRNA (miRNA) biogenesis is tightly regulated by numerous proteins. Among them, Dicer is required for the processing of the precursor (pre-)miRNAs into the mature miRNA. Despite its critical function, the mechanisms that regulate Dicer expression are not well understood. Here we report that the RNA-binding protein (RBP) AUF1 (AU-binding factor 1) associates with the endogenous DICER1 mRNA and can interact with several segments of DICER1 mRNA within the coding region (CR) and the 3'-untranslated region (UTR). Through these interactions, AUF1 lowered DICER1 mRNA stability, since silencing AUF1 lengthened DICER1 mRNA half-life and increased Dicer expression, while overexpressing AUF1 lowered DICER1 mRNA and Dicer protein levels. Given that Dicer is necessary for the synthesis of mature miRNAs, the lowering of Dicer levels by AUF1 diminished the levels of miRNAs tested, but not the levels of the corresponding pre-miRNAs. In summary, AUF1 suppresses miRNA production by reducing Dicer production.

Assessment of acetylcholinesterase activity in CD9-positive exosomes from patients with Parkinson's disease.

Introduction: Parkinson's disease (PD) is a neurodegenerative disorder characterized by dopaminergic dysfunction and associated with abnormalities in the cholinergic system. However, the relationship between PD and cholinergic dysfunction, particularly in exosomes, is not fully understood. Methods: We enrolled 37 patients with PD and 44 healthy controls (HC) to investigate acetylcholinesterase (AChE) activity in CD9-positive and L1CAM-positive exosomes. Exosomes were isolated from plasma using antibody-coupled magnetic beads, and their sizes and concentrations were assessed using transmission electron microscopy, nanoparticle tracking analysis, and western blotting. Subsequently, the AChE activity in these exosomes was analyzed in relation to various clinical parameters. Results: A significant decrease in AChE activity was observed in CD9-positive exosomes derived from patients with PD, whereas no significant differences were found in L1CAM-positive exosomes. Further analysis with a larger sample size confirmed a substantial reduction in AChE activity in CD9-positive exosomes from the PD plasma, with moderate diagnostic accuracy. The decrease in AChE activity of CD9-positive exosomes did not show an association with cognitive impairment but displayed a trend toward correlation with PD progression. Discussion: The reduction in AChE activity in CD9-positive exosomes suggests potential peripheral cholinergic dysfunction in PD, independent of the central cholinergic system. The observed alterations in AChE activity provide valuable insights into the association between cholinergic dysfunction and the pathogenesis of PD.