Wild-type sTREM2 blocks Aß aggregation and neurotoxicity, but the Alzheimer's R47H mutant increases Aß aggregation.

TREM2 is a pattern recognition receptor, expressed on microglia and myeloid cells, detecting lipids and Aß and inducing an innate immune response. Missense mutations (e.g., R47H) of TREM2 increase risk of Alzheimer's disease (AD). The soluble ectodomain of wild-type TREM2 (sTREM2) has been shown to protect against AD in vivo, but the underlying mechanisms are unclear. We show that Aß oligomers bind to cellular TREM2, inducing shedding of the sTREM2 domain. Wild-type sTREM2 bound to Aß oligomers (measured by single-molecule imaging, dot blots, and Bio-Layer Interferometry) inhibited Aß oligomerization and disaggregated preformed Aß oligomers and protofibrils (measured by transmission electron microscopy, dot blots, and size-exclusion chromatography). Wild-type sTREM2 also inhibited Aß fibrillization (measured by imaging and thioflavin T fluorescence) and blocked Aß-induced neurotoxicity (measured by permeabilization of artificial membranes and by loss of neurons in primary neuronal-glial cocultures). In contrast, the R47H AD-risk variant of sTREM2 is less able to bind and disaggregate oligomeric Aß but rather promotes Aß protofibril formation and neurotoxicity. Thus, in addition to inducing an immune response, wild-type TREM2 may protect against amyloid pathology by the Aß-induced release of sTREM2, which blocks Aß aggregation and neurotoxicity. In contrast, R47H sTREM2 promotes Aß aggregation into protofibril that may be toxic to neurons. These findings may explain how wild-type sTREM2 apparently protects against AD in vivo and why a single copy of the R47H variant gene is associated with increased AD risk.

Amyloid-ß toxicity modulates tau phosphorylation through the PAX6 signalling pathway.

The molecular link between amyloid-ß plaques and neurofibrillary tangles, the two pathological hallmarks of Alzheimer's disease, is still unclear. Increasing evidence suggests that amyloid-ß peptide activates multiple regulators of cell cycle pathways, including transcription factors CDKs and E2F1, leading to hyperphosphorylation of tau protein. However, the exact pathways downstream of amyloid-ß-induced cell cycle imbalance are unknown. Here, we show that PAX6, a transcription factor essential for eye and brain development which is quiescent in adults, is increased in the brains of patients with Alzheimer's disease and in APP transgenic mice, and plays a key role between amyloid-ß and tau hyperphosphorylation. Downregulation of PAX6 protects against amyloid-ß peptide-induced neuronal death, suggesting that PAX6 is a key executor of the amyloid-ß toxicity pathway. Mechanistically, amyloid-ß upregulates E2F1, followed by the induction of PAX6 and c-Myb, while Pax6 is a direct target for both E2F1 and its downstream target c-Myb. Furthermore, PAX6 directly regulates transcription of GSK-3ß, a kinase involved in tau hyperphosphorylation and neurofibrillary tangles formation, and its phosphorylation of tau at Ser356, Ser396 and Ser404. In conclusion, we show that signalling pathways that include CDK/pRB/E2F1 modulate neuronal death signals by activating downstream transcription factors c-Myb and PAX6, leading to GSK-3ß activation and tau pathology, providing novel potential targets for pharmaceutical intervention.

Generation of a whole-brain atlas for the cholinergic system and mesoscopic projectome analysis of basal forebrain cholinergic neurons.

The cholinergic system in the brain plays crucial roles in regulating sensory and motor functions as well as cognitive behaviors by modulating neuronal activity. Understanding the organization of the cholinergic system requires a complete map of cholinergic neurons and their axon arborizations throughout the entire brain at the level of single neurons. Here, we report a comprehensive whole-brain atlas of the cholinergic system originating from various cortical and subcortical regions of the mouse brain. Using genetically labeled cholinergic neurons together with whole-brain reconstruction of optical images at 2-µm resolution, we obtained quantification of the number and soma volume of cholinergic neurons in 22 brain areas. Furthermore, by reconstructing the complete axonal arbors of fluorescently labeled single neurons from a subregion of the basal forebrain at 1-µm resolution, we found that their projections to the forebrain and midbrain showed neuronal subgroups with distinct projection specificity and diverse arbor distribution within the same projection area. These results suggest the existence of distinct subtypes of cholinergic neurons that serve different regulatory functions in the brain and illustrate the usefulness of complete reconstruction of neuronal distribution and axon projections at the mesoscopic level.

The inexpensive additive N-methylmorpholine effectively decreases the equivalents of nucleophiles in the catalytic highly enantioselective arylation of aryl aldehydes.

Highly enantioselective arylation of aryl aldehydes catalyzed by (S)-H8 -BINOL-Ti(Oi-Pr)2 complex in the presence of N-methylmorpholine (NMM) as an effective and inexpensive additive is described for the first time. We found high enantioselectivity and yield but successfully reduced the equivalents of nucleophiles triarylaluminums by 50% compared with our previous report. The practicability of the process was thereby greatly increased.

Coding mutations in SORL1 and Alzheimer disease.

OBJECTIVE: Common single nucleotide polymorphisms in the SORL1 gene have been associated with late onset Alzheimer disease (LOAD), but causal variants have not been fully characterized nor has the mechanism been established. The study was undertaken to identify functional SORL1 mutations in patients with LOAD. METHODS: This was a family- and cohort-based genetic association study. Caribbean Hispanics with familial and sporadic LOAD and similarly aged controls were recruited from the United States and the Dominican Republic, and patients with sporadic disease of Northern European origin were recruited from Canada. Prioritized coding variants in SORL1 were detected by targeted resequencing and validated by genotyping in additional family members and unrelated healthy controls. Variants transfected into human embryonic kidney 293 cell lines were tested for Aß40 and Aß42 secretion, and the amount of the amyloid precursor protein (APP) secreted at the cell surface was determined. RESULTS: Seventeen coding exonic variants were significantly associated with disease. Two rare variants (rs117260922-E270K and rs143571823-T947M) with minor allele frequency (MAF) < 1% and 1 common variant (rs2298813-A528T) with MAF = 14.9% segregated within families and were deemed deleterious to the coding protein. Transfected cell lines showed increased Aß40 and Aß42 secretion for the rare variants (E270K and T947M) and increased Aß42 secretion for the common variant (A528T). All mutants increased the amount of APP at the cell surface, although in slightly different ways, thereby failing to direct full-length APP into the retromer-recycling endosome pathway. INTERPRETATION: Common and rare variants in SORL1 elevate the risk of LOAD by directly affecting APP processing, which in turn can result in increased Aß40 and Aß42 secretion.

Isolation and Characterization of Yunnan Variants of the Pseudorabies Virus and Their Pathogenicity in Rats.

Porcine pseudorabies has long existed in China and is a serious threat to the Chinese farming industry. To understand the prevalence and genetic variation of the porcine pseudorabies virus (PRV) and its pathogenicity in Yunnan Province, China, we collected 560 serum samples across seven Yunnan Province regions from 2020 to 2021 and detected anti-gE antibodies in these samples. Sixty-one clinical tissue samples were also collected from pigs with suspected PRV that were vaccinated with Bartha-K61. PRV-gE antibodies were found in 29.6% (166/560) of the serum samples. The PRV positivity rate in clinical tissue samples was 13.1% (8/61). Two isolates, PRV-KM and PRV-QJ, were obtained. The identity of the gB, gD, and gE genes between these isolates and the Chinese mutants exceeded 99.5%. These isolates and the classical Fa strain were used to infect 4-week-old rats intranasally to assess their pathogenicity. All infected rats showed the typical clinical and pathological features of PRV two days post-infection. The viral loads in the organs differed significantly among the infected groups. Viruses were detected in the saliva and feces at 12 h. Significant dynamic changes in total white blood cell counts (WBC), lymphocyte counts (Lym), and neutrophil counts (Gran) occurred in the blood of the infected groups at 24 and 48 h. These results show that mutant PRV strains are prevalent in Bartha-K61-vaccinated pigs in Yunnan Province, China. Moreover, rats shed PRV in their saliva and feces during early infection, indicating the need for rodent control in combatting PRV infections in Yunnan Province, China.

MicroRNA-128 suppresses tau phosphorylation and reduces amyloid-beta accumulation by inhibiting the expression of GSK3ß, APPBP2, and mTOR in Alzheimer's disease.

INTRODUCTION AND AIMS: Alzheimer's disease (AD) is characterized by the abnormal accumulation of hyperphosphorylated tau proteins and amyloid-beta (Aß) peptides. Recent studies have shown that many microRNAs (miRNAs) are dysregulated in AD, and modulation of these miRNAs can influence the development of tau and Aß pathology. The brain-specific miRNA miR-128, encoded by MIR128-1 and MIR128-2, is important for brain development and dysregulated in AD. In this study, the role of miR-128 in tau and Aß pathology as well as the regulatory mechanism underlying its dysregulation were investigated. METHODS: The effect of miR-128 on tau phosphorylation and Aß accumulation was examined in AD cellular models through miR-128 overexpression and inhibition. The therapeutic potential of miR-128 in AD mouse model was assessed by comparing phenotypes of 5XFAD mice administered with miR-128-expressing AAVs with 5XFAD mice administered with control AAVs. Phenotypes examined included behavior, plaque load, and protein expression. The regulatory factor of miR-128 transcription was identified through luciferase reporter assay and validated by siRNA knockdown and ChIP analysis. RESULTS: Both gain-of-function and loss-of-function studies in AD cellular models reveal that miR-128 represses tau phosphorylation and Aß secretion. Subsequent investigations show that miR-128 directly inhibits the expression of tau phosphorylation kinase GSK3ß and Aß modulators APPBP2 and mTOR. Upregulation of miR-128 in the hippocampus of 5XFAD mice ameliorates learning and memory impairments, decreases plaque deposition, and enhances autophagic flux. We further demonstrated that C/EBPα transactivates MIR128-1 transcription, while both C/EBPα and miR-128 expression are inhibited by Aß. CONCLUSION: Our findings suggest that miR-128 suppresses AD pathogenesis, and could be a promising therapeutic target for AD. We also find a possible mechanism underlying the dysregulation of miR-128 in AD, in which Aß reduces miR-128 expression by inhibiting C/EBPα.

Recognition and Classification of Ship Images Based on SMS-PCNN Model.

In the field of ship image recognition and classification, traditional algorithms lack attention to the differences between the grain of ship images. The differences in the hull structure of different categories of ships are reflected in the coarse-grain, whereas the differences in the ship equipment and superstructures of different ships of the same category are reflected in the fine-grain. To extract the ship features of different scales, the multi-scale paralleling CNN oriented on ships images (SMS-PCNN) model is proposed in this paper. This model has three characteristics. (1) Extracting image features of different sizes by parallelizing convolutional branches with different receptive fields. (2) The number of channels of the model is adjusted two times to extract features and eliminate redundant information. (3) The residual connection network is used to extend the network depth and mitigate the gradient disappearance. In this paper, we collected open-source images on the Internet to form an experimental dataset and conduct performance tests. The results show that the SMS-PCNN model proposed in this paper achieves 84.79% accuracy on the dataset, which is better than the existing four state-of-the-art approaches. By the ablation experiments, the effectiveness of the optimization tricks used in the model is verified.

Neolignans and amide alkaloids from the stems of Piper kadsura and their neuroprotective activity.

Four undescribed neolignans and three undescribed amide alkaloids, along with twelve known compounds, were isolated from the stems of Piper kadsura (Choisy) Ohwi. The structures of the new compounds were determined by spectroscopic analysis, quantum-chemical calculations, and Mo2(OAc)4-induced ECD analysis. The neuroprotective effects of these compounds against Aß25-35-induced cell damage in PC12 cells were investigated, and eight compounds exhibited significant neuroprotective effects against Aß25-35-induced PC12 cell damage, with the EC50 values of 3.06-29.3 µM. Three of these compounds were selected for further experiments, and they appear to reduce apoptosis and enhance autophagy against Aß25-35-induced PC12 cell damage.

Signals classification based on IA-optimal CNN.

The versatility of the existing A-optimal-based CNN for solving multiple types of signals classification problems has not been verified by different signals datasets. Moreover, the existing A-optimal-based CNN uses a simplified approximate function as the optimization objective function instead of precise analytical function, which affects the signals classification accuracy to a certain extent. In this paper, a classification method called IA-optimal CNN is proposed. To improve the stability of the classifier, the trace of the covariance matrix of the weights of the fully connected layer is used as the optimization objective function, and the parameter optimization model is established without any simplification of the optimization objective function. In addition, to avoid the difficulty of not being able to obtain the analytical expression formula of the partial derivative of the inverse matrix with regard to the networks parameters, a novel dual function is introduced to transform the optimization problem into an equivalent binary function optimization problem. Furthermore, based on the above analytical solution results, the parameters are updated using the alternate iterative optimization method and the accurate weight update formula is deduced in detail. Five signals datasets are used to test the universality of the IA-optimal CNN in signals classification fields. The performance of IA-optimal CNN is showed, and the experimental results are compared with the existing A-optimal-based classification algorithm. Lastly, the following conclusion is proved theoretically: For the A-optimal-based CNN, the trace of the covariance matrix will continue to decrease and approach a convergence value in the iterative process, but it is impossible for the networks to strictly reach the A-optimal state.

Comparison of Essential Oils of Houttuynia cordata Thunb. from Different Processing Methods and Harvest Seasons Based on GC-MS and Chemometric Analysis.

Houttuyniae Herba (HH) refers to the dried aerial part of Houttuynia cordata Thunb. (DHC) or the fresh whole grass of Houttuynia cordata Thunb. (FHC), where DHC are harvested in summer and FHC around the year. However, harvest seasons and processing methods (i.e., medicinal parts and drying process) might affect the quality of HH. To compare the essential oils (EOs) of DHC and FHC and their two harvest seasons, GC-MS analysis combined with chemometric analysis was applied. The results showed that the oil yield of FHC (0.076 ± 0.030%) was higher than that of DHC (0.038 ± 0.029%), and oil yield was higher in summer than in autumn (0.044 ± 0.029% for DHC1, 0.036 ± 0.028% for DHC2, 0.084 ± 0.026% for FHC1, and 0.067 ± 0.033% for FHC2, respectively). Moreover, hierarchical cluster analysis (HCA) and principal component analysis (PCA) successfully distinguished the chemical constituents of DHC and FHC oils. Additionally, according to orthogonal partial least squares discriminant analysis (OPLS-DA), eleven components were selected as chemical markers for discriminating DHC and FHC, and two and four chemical markers for discriminating two harvest seasons of DHC and FHC, respectively. Among these markers, the average contents of α-pinene, limonene, ß-phellandrene, α-terpineol, 4-tridecanone, and ethyl decanoate were higher in FHC oils. In contrast, the average contents of nonanal, 1-nonanol, ß-cyclocitral, n-hexadecanoic acid, and octadecanol were higher in DHC oils. Additionally, the contents of 4-tridecanone and ethyl decanoate were both higher in DHC1 oils than in DHC2 oils. Moreover, the contents of ß-myrcene and ß-phellandrene were higher in FHC1 oils, while the contents of 2,6-octadien-1-ol, 3,7-dimethyl-, acetate, and (z)-phytol were higher in FHC2 oils. For these reasons, this study provides a scientific basis for quality control and clinical medication.

Objective Recognition of Tinnitus Location Using Electroencephalography Connectivity Features.

Purpose: Tinnitus is a common but obscure auditory disease to be studied. This study will determine whether the connectivity features in electroencephalography (EEG) signals can be used as the biomarkers for an efficient and fast diagnosis method for chronic tinnitus. Methods: In this study, the resting-state EEG signals of tinnitus patients with different tinnitus locations were recorded. Four connectivity features [including the Phase-locking value (PLV), Phase lag index (PLI), Pearson correlation coefficient (PCC), and Transfer entropy (TE)] and two time-frequency domain features in the EEG signals were extracted, and four machine learning algorithms, included two support vector machine models (SVM), a multi-layer perception network (MLP) and a convolutional neural network (CNN), were used based on the selected features to classify different possible tinnitus sources. Results: Classification accuracy was highest when the SVM algorithm or the MLP algorithm was applied to the PCC feature sets, achieving final average classification accuracies of 99.42 or 99.1%, respectively. And based on the PLV feature, the classification result was also particularly good. And MLP ran the fastest, with an average computing time of only 4.2 s, which was more suitable than other methods when a real-time diagnosis was required. Conclusion: Connectivity features of the resting-state EEG signals could characterize the differentiation of tinnitus location. The connectivity features (PCC and PLV) were more suitable as the biomarkers for the objective diagnosing of tinnitus. And the results were helpful for clinicians in the initial diagnosis of tinnitus.

Histopathology of brain functional areas in pigs infected by porcine pseudorabies virus.

Porcine pseudorabies virus (PRV) infection is a major disease in swine. It is challenging to eradicate the virus entirely after it has invaded Chinese farms, resulting in significant economic losses. This study aimed to explore the histopathological correlation of brain regions in PRV-infected pigs. Twenty pigs were randomly divided into two experimental groups (the PRV-infected and sham-inoculated groups; n = 10 per group). The pigs were then observed for clinical signs at specified time points. Brain tissue samples were collected for histopathological examination on days 3, 10, and 14. The correlation analysis was based on clinical observation, lesion characterization, and pathogen location. Clinical observation showed that the severity of clinical neurological signs increased with time. Pathological dissection and microscopic observation revealed gross pathological changes such as degeneration and necrosis of nerve cells, increase in microglia, eosinophilic inclusion body, lymphocyte infiltration, and loose cortical tissue structure. Immunohistochemistry showed that the virus was mainly localized in neurons, microglia, nerve fibers, cerebellar granular layer, and Purkinje cell layer. The virus invasion route was from the cerebrum to the cerebellum and eventually to the brainstem, and the severity of brain damage increased with time. The route of virus infection was from the olfactory bulb to the hippocampus and eventually to the medulla oblongata, and the viral expression increased with time. Of note, brain injury, viral expression, and clinical neurological signs were positively correlated with the infection period; similarly, the severity and degrees of their changes were positively correlated.

Identification and quantification of cassava starch adulteration in different food starches by droplet digital PCR.

We report a rapid and accurate quantitative detection method using droplet digital PCR (ddPCR) technology to identify cassava adulteration in starch products. The ddPCR analysis showed that the weight of cassava (M) and cassava-extracted DNA content had a significant linear relationship-the correlation coefficient was R2 = 0.995, and the maximum coefficient of variation of replicates was 7.48%. The DNA content and DNA copy number (C) measured by ddPCR also had a linear relationship with R2 = 0.992; the maximum coefficient of variation of replicates was 8.85%. The range of cassava ddPCR DNA content was 25 ng/µL, and the formula M = (C + 32.409)/350.579 was obtained by converting DNA content into the median signal. The accuracy and application potential of the method were verified using the constructed adulteration model.

Anatomically revealed morphological patterns of pyramidal neurons in layer 5 of the motor cortex.

Neuronal cell types are essential to the comprehensive understanding of the neuronal function and neuron can be categorized by their anatomical property. However, complete morphology data for neurons with a whole brain projection, for example the pyramidal neurons in the cortex, are sparse because it is difficult to trace the neuronal fibers across the whole brain and acquire the neuron morphology at the single axon resolution. Thus the cell types of pyramidal neurons have yet to be studied at the single axon resolution thoroughly. In this work, we acquire images for a Thy1 H-line mouse brain using a fluorescence micro-optical sectioning tomography system. Then we sample 42 pyramidal neurons whose somata are in the layer 5 of the motor cortex and reconstruct their morphology across the whole brain. Based on the reconstructed neuronal anatomy, we analyze the axonal and dendritic fibers of the neurons in addition to the soma spatial distributions, and identify two axonal projection pattern of pyramidal tract neurons and two dendritic spreading patterns of intratelencephalic neurons. The raw image data are available upon request as an additional asset to the community. The morphological patterns identified in this work can be a typical representation of neuron subtypes and reveal the possible input-output function of a single pyramidal neuron.

Pinpointing Morphology and Projection of Excitatory Neurons in Mouse Visual Cortex.

The excitatory neurons in the visual cortex are of great significance for us in understanding brain functions. However, the diverse neuron types and their morphological properties have not been fully deciphered. In this paper, we applied the brain-wide positioning system (BPS) to image the entire brain of two Thy1-eYFP H-line male mice at 0.2 µm × 0.2 µm × 1 µm voxel resolution. A total of 103 neurons were reconstructed in layers 5 and 6 of the visual cortex with single-axon-level resolution. Based on the complete topology of neurons and the inherent positioning function of the imaging method, we classified the observed neurons into six types according to their apical dendrites and somata location: star pyramidal cells in layer 5 (L5-sp), slender-tufted pyramidal cells in layer 5 (L5-st), tufted pyramidal cells in layer 5 (L5-tt), spiny stellate-like cells in layer 6 (L6-ss), star pyramidal cells in layer 6 (L6-sp), and slender-tufted pyramidal cells in layer 6 (L6-st). By examining the axonal projection patterns of individual neurons, they can be categorized into three modes: ipsilateral circuit connection neurons, callosal projection neurons and corticofugal projection neurons. Correlating the two types of classifications, we have found that there are at least two projection modes comprised in the former defined neuron types except for L5-tt. On the other hand, each projection mode may consist of four dendritic types defined in this study. The axon projection mode only partially correlates with the apical dendrite feature. This work has demonstrated a paradigm for resolving the visual cortex through single-neuron-level quantification and has shown potential to be extended to reveal the connectome of other defined sensory and motor systems.

A corticopontine circuit for initiation of urination.

Urination (also called micturition) is thought to be regulated by a neural network that is distributed in both subcortical and cortical regions. Previously, urination-related neurons have been identified in subcortical structures such as the pontine micturition center (also known as Barrington's nucleus). However, the origin of the descending cortical pathway and how it interfaces with this subcortical circuit to permit voluntary initiation of urination remain elusive. Here we identified a small cluster of layer 5 neurons in the primary motor cortex whose activities tightly correlate with the onset of urination in freely behaving mice and increase dramatically during territorial marking. Optogenetically activating these neurons elicits contraction of the bladder and initiates urination, through their projections to the pontine micturition center, while silencing or ablating them impairs urination and causes retention of urine. Together these results reveal a novel cortical component upstream of the pontine micturition center that is critically involved in urination.

Mutations in Hnrnpa1 cause congenital heart defects.

Incomplete penetrance of congenital heart defects (CHDs) was observed in a mouse model. We hypothesized that the contribution of a major genetic locus modulates the manifestation of the CHDs. After genome-wide linkage mapping, fine mapping, and high-throughput targeted sequencing, a recessive frameshift mutation of the heterogeneous nuclear ribonucleoprotein A1 (Hnrnpa1) gene was confirmed (Hnrnpa1ct). Hnrnpa1 was expressed in both the first heart field (FHF) and second heart field (SHF) at the cardiac crescent stage but was only maintained in SHF progenitors after heart tube formation. Hnrnpa1ct/ct homozygous mutants displayed complete CHD penetrance, including truncated and incomplete looped heart tube at E9.5, ventricular septal defect (VSD) and persistent truncus arteriosus (PTA) at E13.5, and VSD and double outlet right ventricle at P0. Impaired development of the dorsal mesocardium and sinoatrial node progenitors was also observed. Loss of Hnrnpa1 expression leads to dysregulation of cardiac transcription networks and multiple signaling pathways, including BMP, FGF, and Notch in the SHF. Finally, two rare heterozygous mutations of HNRNPA1 were detected in human CHDs. These findings suggest a role of Hnrnpa1 in embryonic heart development in mice and humans.

A rare variant in MLKL confers susceptibility to ApoE ɛ4-negative Alzheimer's disease in Hong Kong Chinese population.

Alzheimer's disease (AD) is the most common neurodegenerative disorders in the elderly. To identify rare genetic factors other than apolipoprotein E ɛ4 allele (ApoE ɛ4) contributing to the pathogenesis of late-onset AD (LOAD), we conducted a whole-exome analysis of 246 ApoE ɛ4-negative LOAD cases and 172 matched controls in Hong Kong Chinese population. LOAD patients showed a significantly higher burden of rare loss-of-function variants in genes related to immune function than healthy controls. Among the genes involved in immune function, we identified a rare stop-gain variant (p.Q48X) in mixed lineage kinase domain like pseudokinase (MLKL) gene present exclusively in 6 LOAD cases. MLKL is expressed in neurons, and the its expression levels in the p.Q48X carriers were significantly lower than that in age-matched wild-type controls. The ratio of Aß42 to Aß40 significantly increased in MLKL knockdown cells compared to scramble controls. MLKL loss-of-function mutation might contribute to late-onset ApoE ɛ4-negative AD in the Hong Kong Chinese population.

[Involvement of Caspase-3 and p38 mitogen-activated protein kinase in MMT-induced apoptosis in PC-3M cells].

OBJECTIVE: To explore the function of Caspase-3 and p38 MAPK in MMT-induced apoptosis in PC-3M cells. METHODS: After incubation of PC-3M cells with 1 mmol/L MMT, the activity of Caspase-3 was examined. The influence on cells viability of Z-DEVD-FMK, a Caspase-3-specific peptide inhibitor, was also examined. Western blot was used to examine the change of p38 MAPK. The effect on cells viability and Caspase-3 activity of SB203580, a specific inhibitor of p38 MAPK, were also examined. RESULTS: The activity of Caspase-3 increased significantly in MMT-induced apoptosis in PC-3M cells /9P < 0.01), and Z-DEVD-FMK could protect cells from apoptosis (P < 0.01). In this course, the phosphorylation of p38 MAPK could be observed. SB203580 inhibited Caspase-3 activity (P < 0.05) and prevented PC-3M cells from MMT-induced apoptosis (P < 0.05). CONCLUSION: Caspase-3 and p38 MAPK are involved in MMT-induced PC-3M cells apoptosis.