Insulin-like growth factor binding protein 5 (IGFBP5) mediates methamphetamine-induced dopaminergic neuron apoptosis

Mir-204-5p alleviates mitochondrial dysfunction by targeting IGFBP5 in diabetic cataract

BACKGROUND

Cataract contributes to visual impairment worldwide, and diabetes mellitus accelerates the formation and progression of cataract. Here we found that the expression level of miR-204-5p was diminished in the lens epithelium with anterior lens capsule of cataract patients compared to normal donors, and decreased more obviously in those of diabetic cataract (DC) patients. However, the contribution and mechanism of miR-204-5p during DC development remain elusive.

METHODS AND RESULT

The mitochondrial membrane potential (MMP) was reduced in the lens epithelium with anterior lens capsule of DC patients and the H2O2-induced human lens epithelial cell (HLEC) cataract model, suggesting impaired mitochondrial functional capacity. Consistently, miR-204-5p knockdown by the specific inhibitor also attenuated the MMP in HLECs. Using bioinformatics and a luciferase assay, further by immunofluorescence staining and Western blot, we identified IGFBP5, an insulin-like growth factor binding protein, as a direct target of miR-204-5p in HLECs. IGFBP5 expression was upregulated in the lens epithelium with anterior lens capsule of DC patients and in the HLEC cataract model, and IGFBP5 knockdown could reverse the mitochondrial dysfunction in the HLEC cataract model.

CONCLUSIONS

Our results demonstrate that miR-204-5p maintains mitochondrial functional integrity through repressing IGFBP5, and reveal IGFBP5 may be a new therapeutic target and prognostic factor for DC.

The neuroprotective effects of caffeic acid phenethyl ester against methamphetamine-induced neurotoxicity

Methamphetamine (METH) is a highly abused substance on a global scale and has the capacity to elicit toxicity within the central nervous system. The neurotoxicity induced by METH encompasses neuronal degeneration and cellular demise within the substantia nigra-striatum and hippocampus. Caffeic acid phenethyl ester (CAPE), a constituent of propolis, is a diminutive compound that demonstrates antioxidative and anti-inflammatory characteristics. Numerous investigations have demonstrated the safeguarding effects of CAPE in various neurodegenerative ailments. Our hypothesis posits that CAPE may exert a neuroprotective influence on METH-induced neurotoxicity via specific mechanisms. In order to validate the hypothesis, a series of experimental techniques including behavioral tests, immunofluorescence labeling, RNA sequencing, and western blotting were employed to investigate the neurotoxic effects of METH and the potential protective effects of CAPE. The results of our study demonstrate that CAPE effectively ameliorates cognitive memory deficits and anxiety symptoms induced by METH in mice. Furthermore, CAPE has been observed to attenuate the upregulation of neurotoxicity-associated proteins that are induced by METH exposure and also reduced the loss of hippocampal neurons in mice. Moreover, transcriptomics analysis was conducted to determine alterations in gene expression within the hippocampus of mice. Subsequently, bioinformatics analysis was employed to investigate the divergent outcomes and identify potential key genes. Interferon-stimulated gene 15 (ISG15) was successfully identified and confirmed through RT-qPCR, western blotting, and immunofluorescence techniques. Our research findings unequivocally demonstrated the neuroprotective effect of CAPE against METH-induced neurotoxicity, with ISG15 may have an important role in the underlying protective mechanism. These results offer novel perspectives on the treatment of METH-induced neurotoxicity.

IGFBP5 Promotes Neuronal Apoptosis in a 6-OHDA-Toxicant Model of Parkinson's Disease by Inhibiting the Sonic Hedgehog Signaling Pathway

INTRODUCTION

Parkinson's disease (PD) is the most common neurodegenerative disease worldwide. Studies have shown that insulin-like growth factor-binding protein 5 (IGFBP5) may contribute to methamphetamine-induced neurotoxicity and neuronal apoptosis in PC-12 cells and rat striatum. Here, we studied the expression and role of IGFBP5 in the 6-OHDA-toxicant model of PD.

METHODS

PC-12 and SH-SY5Y cells were exposed to 50 μm 6-OHDA for 24 h. qRT-PCR, western blotting, CCK-8 assay, EdU staining, annexin V staining, and immunofluorescence were performed to study the effects of IGFBP5-specific siRNAs. The effects of IGFBP5 on a rat 6-OHDA model of PD were confirmed by performing behavioral tests, tyrosine hydroxylase (TH) immunofluorescence staining, and western blotting.

RESULTS

In the GSE7621 dataset, IGFBP5 was highly expressed in the substantia nigra tissues of PD patients compared to healthy controls. In PC-12 and SH-SY5Y cells, IGFBP5 was upregulated following 6-OHDA exposure in a dose-dependent manner. Silencing of IGFBP5 promoted PC-12 and SH-SY5Y proliferation and inhibited apoptosis under 6-OHDA stimulation. Silencing of IGFBP5 relieved 6-OHDA-induced TH-positive neuron loss. Hedgehog signaling pathway was predicted as a downstream signaling pathway of IGFBP5. Negative regulation between IGFBP5 and sonic hedgehog (SHH) signaling pathway was confirmed in vitro. The effects of IGFBP5 silencing on SH-SY5Y cells were partially reversed using cyclopamine, a direct inhibitor of the SHH signaling pathway. In addition, silencing of IGFBP5 attenuated motor deficits and neuronal damage in 6-OHDA-induced PD rats.

CONCLUSION

Elevated IGFBP5 expression may be involved in 6-OHDA-induced neurotoxicity through regulation of the SHH signaling pathway.

Dynamic dysregulation of transcriptomic networks in brainstem autonomic nuclei during hypertension development in the female spontaneously hypertensive rat

Neurogenic hypertension stems from an imbalance in autonomic function that shifts the central cardiovascular control circuits toward a state of dysfunction. Using the female spontaneously hypertensive rat and the normotensive Wistar-Kyoto rat model, we compared the transcriptomic changes in three autonomic nuclei in the brainstem, nucleus of the solitary tract (NTS), caudal ventrolateral medulla, and rostral ventrolateral medulla (RVLM) in a time series at 8, 10, 12, 16, and 24 wk of age, spanning the prehypertensive stage through extended chronic hypertension. RNA-sequencing data were analyzed using an unbiased, dynamic pattern-based approach that uncovered dominant and several subtle differential gene regulatory signatures. Our results showed a persistent dysregulation across all three autonomic nuclei regardless of the stage of hypertension development as well as a cascade of transient dysregulation beginning in the RVLM at the prehypertensive stage that shifts toward the NTS at the hypertension onset. Genes that were persistently dysregulated were heavily enriched for immunological processes such as antigen processing and presentation, the adaptive immune response, and the complement system. Genes with transient dysregulation were also largely region-specific and were annotated for processes that influence neuronal excitability such as synaptic vesicle release, neurotransmitter transport, and an array of neuropeptides and ion channels. Our results demonstrate that neurogenic hypertension is characterized by brainstem region-specific transcriptomic changes that are highly dynamic with significant gene regulatory changes occurring at the hypertension onset as a key time window for dysregulation of homeostatic processes across the autonomic control circuits.NEW & NOTEWORTHY Hypertension is a major disease and is the primary risk factor for cardiovascular complications and stroke. The gene expression changes in the central nervous system circuits driving hypertension are understudied. Here, we show that coordinated and region-specific gene expression changes occur in the brainstem autonomic circuits over time during the development of a high blood pressure phenotype in a rat model of human essential hypertension.

POLE2 Regulates Apoptosis of Oral Squamous Cell Carcinoma Cells through the PI3K/AKT Signaling Pathway

OBJECTIVE

Oral squamous cell carcinoma (OSCC) is the most common malignant tumor of the head and neck, but its occurrence and progression mechanisms remain unclear. In addition-there is a lack of effective targeting drugs. The second major subunit of DNA polymerase (POLE2) catalyzes the prolongation of new strand replication and modifies exonuclease domain activity. Our previous study found that POLE2 was associated with OSCC progression, but the mechanism remains unclear.

METHODS

The expression of POLE2 in OSCC tissues was detected using immunological assays. Mann-Whitney U analysis was used to investigate the relationship between POLE2 gene expression and tumor classification and prognosis of OSCC. POLE2 expression was inhibited in OSCC cells, and the effects of gene and protein expression were detected using RT-PCR and Western blotting. The POLE2 knockout model was constructed by transfecting a lentiviral vector. Cell proliferation, apoptosis, and migration were detected using various assays including colony formation, MTT, flow cytometry, wound healing assay, Transwell assay, and the Human Apoptosis Antibody Array. The animal model of OSCC was established by subcutaneous injection of transfected HN6 into 4-week-old female nude mice. After 30 days, tumors were removed under anesthesia and tumor weight and dimension were recorded. Tumor cell proliferation was analyzed using Ki67 staining.

RESULTS

POLE2 gene levels were significantly higher in the OSCC tissues than in the normal tissues. In addition, POLE2 gene levels were statistically correlated with tumor classification and prognosis. Silencing POLE2 inhibited the proliferation of oral cancer cells and promoted apoptosis in vitro. Animal experiments also supported a positive correlation between POLE2 and OSCC tumor formation. We further demonstrated that POLE2 could upregulate the expression of apoptosis-related proteins such as caspase-3, CD40, CD40L, DR6, Fas, IGFBP-6, p21, and SMAC. In addition, POLE2 regulated OSCC development by inhibiting the PI3K/AKT signaling pathway.

CONCLUSION

POLE2 is closely related to the progression of OSCC. Thus, POLE2 may be a potential target for OSCC treatment.

Silencing POLE2 promotes apoptosis and inhibits proliferation of oral squamous cell carcinomas by inhibiting PI3K/AKT signaling pathway

Oral squamous cell carcinoma is the most common malignant tumor in the head and neck at present, but the mechanism of its occurrence and development is still unclear, and there is still a lack of effective targeting drugs. The second major subunit of DNA polymerase (POLE2) has exonuclease activity and can catalyze the replication and modification of new chains. Our previous studies have found that it is associated with OSCC progression, but the mechanism is unclear.The expression of POLE2 in OSCC was detected by immunological method. The expression of POLE2 was inhibited in OSCC cells, and the biological function of the cells was detected by RT-PCR and Western Blot. Cell proliferation, apoptosis and migration were detected by colony formation, MTT, flow cytometry, wound healing and Transwell. The expression level of POLE2 gene in OSCC was significantly higher than that in normal tissues. In addition, the expression level of POLE2 gene was significantly different from the tumor type and prognosis. During the development of oral squamous cell carcinoma, silencing POLE2 inhibits the proliferation of oral cancer cells and promotes apoptosis. The results of animal experiments also support the positive correlation between POLE2 and OSCC progression. We further demonstrated that POLE2 can up-regulate the downregulation of apoptosis-related proteins such as Caspase3, CD40, CD40L, DR6, Fas, IGFBP-6, P21, and SMAC. In addition, POLE2 regulates OSCC progression by inhibiting the PI3K/AKT pathway. POLE2 is closely related to the progression of OSCC, and POLE2 may be a potential target for OSCC treatment.

Endothelial Cell Response in Kawasaki Disease and Multisystem Inflammatory Syndrome in Children

Although Kawasaki disease (KD) and multisystem inflammatory syndrome in children (MIS-C) share some clinical manifestations, their cardiovascular outcomes are different, and this may be reflected at the level of the endothelial cell (EC). We performed RNA-seq on cultured ECs incubated with pre-treatment sera from KD (n = 5), MIS-C (n = 7), and healthy controls (n = 3). We conducted a weighted gene co-expression network analysis (WGCNA) using 935 transcripts differentially expressed between MIS-C and KD using relaxed filtering (unadjusted p < 0.05, >1.1-fold difference). We found seven gene modules in MIS-C, annotated as an increased TNFα/NFκB pathway, decreased EC homeostasis, anti-inflammation and immune response, translation, and glucocorticoid responsive genes and endothelial-mesenchymal transition (EndoMT). To further understand the difference in the EC response between MIS-C and KD, stringent filtering was applied to identify 41 differentially expressed genes (DEGs) between MIS-C and KD (adjusted p < 0.05, >2-fold-difference). Again, in MIS-C, NFκB pathway genes, including nine pro-survival genes, were upregulated. The expression levels were higher in the genes influencing autophagy (UBD, EBI3, and SQSTM1). Other DEGs also supported the finding by WGCNA. Compared to KD, ECs in MIS-C had increased pro-survival transcripts but reduced transcripts related to EndoMT and EC homeostasis. These differences in the EC response may influence the different cardiovascular outcomes in these two diseases.

Exosome-Encapsulated microRNA-140-5p Alleviates Neuronal Injury Following Subarachnoid Hemorrhage by Regulating IGFBP5-Mediated PI3K/AKT Signaling Pathway

Recent literature has highlighted the therapeutic implication of exosomes (Exos) released by adipose tissue-originated stromal cells (ADSCs) in regenerative medicine. Herein, the current study sought to examine the potential protective effects of ADSC-Exos on neuronal injury following subarachnoid hemorrhage (SAH) by delivering miR-140-5p. Firstly, isolated primary neurons were co-cultured together with well-identified ADSC-Exos. TDP-43-treated neurons were subsequently treated with PKH67-ADSC-Exos and Cy3-miR-140-5p to assess whether ADSC-Exos could transmit miR-140-5p to the recipient neurons to affect their behaviors. Moreover, a luciferase assay was carried out to identify the presumable binding of miR-140-5p to IGFBP5. IGFBP5 rescue experimentation was also performed to testify whether IGFBP5 conferred the impact of miR-140-5p on neuronal damage. The role of PI3K/AKT signaling pathway was further analyzed with the application of its inhibitor miltefosine. Lastly, SAH rat models were developed for in vivo validation. It was found that ADSC-Exos conferred protection against TDP-43-caused neuronal injury by augmenting viability and suppressing cell apoptosis. In addition, miR-140-5p was transmitted from ADSC-Exos to neurons and post-transcriptionally downregulated the expression of IGFBP5. As a result, by means of suppressing IGFBP5 and activating the PI3K/AKT signaling pathway, miR-140-5p from ADSC-Exos induced a neuroprotective effect. Furthermore, in vivo findings substantiated the aforementioned protective role of ADSC-Exos-miR-140-5p, contributing to protection against SAH-caused neurological dysfunction. Collectively, our findings indicated that ADSC-Exos-miR-140-5p could inhibit TDP-43-induced neuronal injury and attenuate neurological dysfunction of SAH rats by inhibiting IGFBP5 and activating the PI3K/Akt signaling pathway.

Cannabidiol prevents methamphetamine-induced neurotoxicity by modulating dopamine receptor D1-mediated calcium-dependent phosphorylation of methyl-CpG-binding protein 2

In the past decade, methamphetamine (METH) abuse has sharply increased in the United States, East Asia, and Southeast Asia. METH abuse not only leads to serious drug dependence, but also produces irreversible neurotoxicity. Currently, there are no approved pharmacotherapies for the treatment of METH use disorders. Cannabidiol (CBD), a major non-psychoactive (and non-addictive) cannabinoid from the cannabis plant, shows neuroprotective, antioxidative, and anti-inflammatory properties under METH exposure. At present, however, the mechanisms underlying these properties remain unclear, which continues to hinder research on its therapeutic potential. In the current study, computational simulations showed that CBD and METH may directly bind to the dopamine receptor D1 (DRD1) via two overlapping binding sites. Moreover, CBD may compete with METH for the PHE-313 binding site. We also found that METH robustly induced apoptosis with activation of the caspase-8/caspase-3 cascade in-vitro and in-vivo, while CBD pretreatment prevented these changes. Furthermore, METH increased the expression of DRD1, phosphorylation of Methyl-CpG-binding protein 2 (MeCP2) at serine 421 (Ser421), and level of intracellular Ca2+in-vitro and in-vivo, but these effects were blocked by CBD pretreatment. The DRD1 antagonist SCH23390 significantly prevented METH-induced apoptosis, MeCP2 phosphorylation, and Ca2+ overload in-vitro. In contrast, the DRD1 agonist SKF81297 markedly increased apoptosis, MeCP2 phosphorylation, and Ca2+ overload, which were blocked by CBD pretreatment in-vitro. These results indicate that CBD prevents METH-induced neurotoxicity by modulating DRD1-mediated phosphorylation of MeCP2 and Ca2+ signaling. This study suggests that CBD pretreatment may resist the effects of METH on DRD1 by competitive binding.

microRNA-181a Promotes Mitochondrial Dysfunction and Inflammatory Reaction in a Rat Model of Intensive Care Unit-Acquired Weakness by Inhibiting IGFBP5 Expression

This study investigated mechanisms by which microRNA (miR)-181a orchestrates mitochondrial dysfunction and inflammation in a rat model of intensive care unit-acquired weakness (ICU-AW). Expression of miR-181a and insulin-like growth factor binding protein 5 (IGFBP5) was detected and then miR-181a was overexpressed or inhibited and IGFBP5 was overexpressed in the ICU-AW rats. The expression of UCP-3, metaphase chromosome protein 1 (MCP1), mitochondrial DNA (mtDNA), inflammatory factors, phosphorylation (p)-JAK1, p-STAT1, and p-STAT2 were measured in skeletal muscle tissues; binding of miR-181a to IGFBP5 was evaluated by a dual-luciferase reporter assay. The results demonstrated high expression of miR-181a and low expression of IGFBP5 in ICU-AW versus control rats; IGFBP5 was identified as a target gene of miR-181a. Further experiments demonstrated that ICU-AW rats suffered from marked loss of grip strength and decreased adenosine triphosphate production, mtDNA content, and UCP-3 mRNA expression in skeletal muscles; this was accompanied by elevated TNF-α, IL-6, IL-1β, MCP1, p-JAK1, p-STAT1, and p-STAT2 levels. Importantly, miR-181a suppression alleviated strength loss, inflammatory reaction, and mitochondrial dysfunction and diminished the phosphorylation levels of JAK1, STAT1, and STAT2 whereas IGFBP5 upregulation rescued the effect of miR-181a overexpression in ICU-AW rats. These results indicate that miR-181a promotes mitochondrial dysfunction and inflammation by activating the JAK/STAT pathway via IGFBP5 in ICU-AW model rats.

Methamphetamine mediates apoptosis of vascular smooth muscle cells via the chop-related endoplasmic reticulum stress pathway

Methamphetamine (METH) is a highly addictive amphetamine-type drug that has caused persistent harm to society and human health in recent years. Most studies have shown that METH severely damages the central nervous system, and this drug has been found to be toxic to the cardiovascular system in recent years. Therefore, we hypothesized that METH may also damage vascular smooth muscle. We examined the expression of the apoptosis-related proteins Caspase 3 and PARP after METH treatment in vivo and in vitro and detected the expression of endoplasmic reticulum stress-related proteins. After treatment with the endoplasmic reticulum stress inhibitor 4-PBA, changes in the above indicators were examined. C/EBP homologous protein (Chop) expression was also detected, and the relationship between endoplasmic reticulum stress and apoptosis was further determined by siRNA silencing of Chop. The results indicated that METH can induce apoptosis of vascular smooth muscle cells (VSMCs) and upregulate the expression of Chop and endoplasmic reticulum stress-related proteins. Chop inhibits protein kinase B phosphorylation and further inhibits forkhead box class O3a (Foxo3a) dephosphorylation, resulting in increased p53 upregulated molecular of apoptosis (PUMA) transcription. Increased PUMA induces apoptosis through the mitochondrial pathway. These results indicate that Chop is involved in the METH-induced endoplasmic reticulum stress and apoptosis in VSMCs and may be a potential therapeutic target for METH-induced VSMC injury.

Inhibition of Methamphetamine-Induced Cytotoxicity in the U87-Cell Line by Atorvastatin-Conjugated Carbon Nanotubes

In biological systems, carbon nanotubes can enhance the biological effects of drugs and reduce their side effects. Methamphetamine (METH) is a stimulant drug that induces cell death in various cell types, primarily neural cells. On the other hand, specific doses of atorvastatin (ATO) can stimulate cell growth and inhibit cell death in different cell lines. This study aimed to investigate the improvement effect of ATO@single-walled carbon nanotube (SWCNT) on METH-induced cell cytotoxicity in the U87 glioblastoma cell line. In this study, cells were cultured in 10 mM of METH during the cell treatment with 0-10 nM of ATO and ATO@SWCNT. The conjugated drugs to SWCNT as Van der Waals were detected using field emission scanning electron microscopy, Fourier transform-infrared spectroscopy, and other analyses. Then, the in vitro proliferating of ATO@SWCNT was explored against glioblastoma cells compared to pure ATO. This examine was performed using methyl thiazole tetrazolium approach, terminal deoxynucleotidyl transferase deoxy uridine-triphosphate nick end labeling assay, caspase-3 method, lactate dehydrogenase assay, and RH-123 assay with 10 mM METH. The results obtained from transmission electron microscopy analysis showed the average size of 50 nm for ATO@SWCNT. This study indicated that U87 cells, which were exposed to METH and suffered cell death, were severely reduced in the presence of ATO, especially ATO@SWCNT (for its anti-apoptotic effect), but they survived. This study suggests that ATO, which was primarily used to reduce blood lipids, can significantly reduce brain cell death. The findings of this study indicate that by using SWCNT, more drugs can reach the target cells. This method reduces the total amount of required medication and shows a more beneficial therapeutic effect.

Oxytocin Attenuates Methamphetamine-Induced Apoptosis via Oxytocin Receptor in Rat Hippocampal Neurons

Methamphetamine (METH) is a highly neurotoxic psychoactive substance that can directly damage the central nervous system through prolonged use. Oxytocin (OT) has attracted much attention because of its neuroprotective effect. The purpose of this study was to investigate whether OT is neuroprotective against METH-induced damage in rat hippocampal neurons. Our results revealed that pre-incubation with OT significantly prevented the damage of METH to hippocampal neurons, including the decrease of mitochondrial membrane potential and the increase of ROS (reactive oxygen species). OT pre-incubation attenuated the up-regulation of Cleaved-Caspase-3 expression and the down-regulation of Bcl-2/Bax expression induced by METH. Pre-incubation with OT prevented the decrease in oxytocin receptor density and P-CREB (phosphorylation of cAMP-response element binding) expression induced by METH in rat hippocampal neurons. Moreover, Pre-incubation of atosiban (ATO) significantly prevented these changes. In conclusion, our study proved that pre-administration of OT could significantly attenuate hippocampal neuron apoptosis induced by METH. Oxytocin receptor activation is involved in the preventive effect of OT on METH-induced apoptosis in rat hippocampal neurons.

Methamphetamine-induced dopaminergic neurotoxicity as a model of Parkinson's disease

Parkinson's disease (PD) is a progressive neurodegenerative disease with a high prevalence, approximately 1 % in the elderly population. Numerous studies have demonstrated that methamphetamine (MA) intoxication caused the neurological deficits and nigrostriatal damage seen in Parkinsonian conditions, and subsequent rodent studies have found that neurotoxic binge administration of MA reproduced PD-like features, in terms of its symptomatology and pathology. Several anti-Parkinsonian medications have been shown to attenuate the motor impairments and dopaminergic damage induced by MA. In addition, it has been recognized that mitochondrial dysfunction, oxidative stress, pro-apoptosis, proteasomal/autophagic impairment, and neuroinflammation play important roles in inducing MA neurotoxicity. Importantly, MA neurotoxicity has been shown to share a common mechanism of dopaminergic toxicity with that of PD pathogenesis. This review describes the major findings on the neuropathological features and underlying neurotoxic mechanisms induced by MA and compares them with Parkinsonian pathogenesis. Taken together, it is suggested that neurotoxic binge-type administration of MA in rodents is a valid animal model for PD that may provide knowledge on the neuropathogenesis of PD.

Neurotoxicity of methamphetamine: Main effects and mechanisms

Methamphetamine (METH) is an illicit psychostimulant that is abused throughout the world. METH addiction is also a major public health concern and the abuse of large doses of the drug is often associated with serious neuropsychiatric consequences that may include agitation, anxiety, hallucinations, paranoia, and psychosis. Some human methamphetamine users can also suffer from attention, memory, and executive deficits. METH-associated neurological and psychiatric complications might be related, in part, to METH-induced neurotoxic effects. Those include altered dopaminergic and serotonergic functions, neuronal apoptosis, astrocytosis, and microgliosis. Here we have endeavored to discuss some of the main effects of the drug and have presented the evidence supporting certain of the molecular and cellular bases of METH neurotoxicity. The accumulated evidence suggests the involvement of transcription factors, activation of dealth pathways that emanate from mitochondria and endoplasmic reticulum (ER), and a role for neuroinflammatory mechanisms. Understanding the molecular processes involved in METH induced neurotoxicity should help in developing better therapeutic approaches that might also serve to attenuate or block the biological consequences of use of large doses of the drug by some humans who meet criteria for METH use disorder.

Homocysteine downregulates cardiac homeobox transcription factor NKX2.5 via IGFBP5

Homocysteine (Hcy) is an independent risk factor of congenital heart disease (CHD), but its exact underlying mechanism is unclear. In this study, we collected amniotic fluid (AF) supernatant samples from pregnant women carrying CHD-affected (n = 16) or normal (n = 16) fetuses. We found that Hcy concentrations were higher in the AF of the CHD group when compared with normal pregnancies. Also, Western blot showed that NK2 homeobox 5 (NKX2.5) was decreased and insulin-like growth factor binding protein 5 (IGFBP5) was increased in the AF of the CHD group. In the H9C2 cell culture experiment, 500 μmol/L Hcy downregulated NKX2.5 and upregulated IGFBP5. Real-time PCR and Western blot showed that NKX2.5 expression was reduced in H9C2 cells treated with IGFBP5. Luciferase reporter gene demonstrated that IGFBP5 decreased the transcription of the NKX2.5 promoter. Chromatin immunoprecipitation and electrophoretic mobility shift assay suggested that IGFBP5 binds to the NKX2.5 promoter region. Thus, the data indicated that one of the possible mechanisms by which Hcy is involved in CHD may be that Hcy inhibits NKX2.5 expression partly through IGFBP5.NEW & NOTEWORTHY We found that Hcy and IGFBP5 were increased, whereas NKX2.5 was decreased, in AF of CHD. Meanwhile, Hcy could upregulate IGFBP5 but downregulate NKX2.5, and IGFBP5 inhibited NKX2.5 expression in vitro. Moreover, IGFBP5 can bind to the NKX2.5 promoter region and reduce NKX2.5 transcriptional activity.

POLE2 knockdown reduce tumorigenesis in esophageal squamous cells

Background

Esophageal squamous cell carcinoma (ESCC) is one of the most frequent malignant tumors originated from digestive system around the world and the treatment was limited by the unclear mechanism. DNA polymerase epsilon 2, accessory subunit (POLE2) is involved in DNA replication, repair, and cell cycle control, whose association with ESCC is still not clear.

Methods

In this study, the expression level of POLE2 in ESCC tissues was detected by IHC. The POLE2 knockdown cell line was constructed, identified by qPCR and western blot and used for detecting cellular functions and constructing xenotransplantation mice model. MTT Assay, colony formation assay, flow cytometry, wound-healing assay and Transwell assay were used to detected cell proliferation, apoptosis and migration.

Results

We firstly identified that the expression of POLE2 was overexpressed in ESCC. Moreover, the high expression of POLE2 can predict the tumor deterioration and poor prognosis of ESCC patients. Additionally, downregulation of POLE2 was involved in ESCC progression by promoting proliferation, migration, and inhibiting apoptosis in vitro. In vivo studies proved that POLE2 was positively correlated with ESCC tumor formation, which was consistent with the results in vitro. We also illuminated that POLE2 knockdown upregulated pro-apoptotic proteins (Bax, Caspase3, CD40L, FasL, IGFBP-5 and P21) and downregulated anti-apoptotic proteins (CLAP-2, IGF-I and sTNF-R2). In addition, POLE2 was involved in ESCC via targeting PI3K/Akt, Cyclin D1 signaling pathway.

Conclusions

Therefore, POLE2 was proved to be involved in the development of ESCC, which may be a potential therapeutic target and bring new breakthroughs in the treatment of ESCC.

Astrocyte-Derived Lipocalin-2 Is Involved in Mitochondrion-Related Neuronal Apoptosis Induced by Methamphetamine

Methamphetamine (METH) is a widely abused and highly addictive psychoactive stimulant that can induce neuronal apoptosis. Lipocalin-2 (LCN2) is a member of the lipocalin family, and its upregulation is involved in cell death in the adult brain. However, the role of LCN2 in METH-induced neurotoxicity has not been reported. In this study, we found that LCN2 was predominantly expressed in hippocampal astrocytes after METH exposure and that recombinant LCN2 (Re LCN2) can induce neuronal apoptosis in vitro and in vivo. The inhibition of LCN2 and LCN2R, a cell surface receptor for LCN2, reduced METH- and Re LCN2-induced mitochondrion-related neuronal apoptosis in cultures of primary rat neurons and animal models. Our study supports the role of reactive oxygen species (ROS) generation and the PRKR-like ER kinase (PERK)-mediated signaling pathway in the upregulation of astrocyte-derived LCN2 after METH exposure. Additionally, the serum and cerebrospinal fluid (CSF) levels of LCN2 were significantly upregulated after METH exposure. These results indicate that upregulation of astrocyte-derived LCN2 binding to LCN2R is involved in METH-induced mitochondrion-related neuronal apoptosis.

Insulin-Like Growth Factor Binding Protein-5 in Physiology and Disease

Insulin-like growth factor (IGF) signaling is regulated by a conserved family of IGF binding proteins (IGFBPs) in vertebrates. Among the six distinct types of IGFBPs, IGFBP-5 is the most highly conserved across species and has the broadest range of biological activities. IGFBP-5 is expressed in diverse cell types, and its expression level is regulated by a variety of signaling pathways in different contexts. IGFBP-5 can exert a range of biological actions including prolonging the half-life of IGFs in the circulation, inhibition of IGF signaling by competing with the IGF-1 receptor for ligand binding, concentrating IGFs in certain cells and tissues, and potentiation of IGF signaling by delivery of IGFs to the IGF-1 receptor. IGFBP-5 also has IGF-independent activities and is even detected in the nucleus. Its broad biological activities make IGFBP-5 an excellent representative for understanding IGFBP functions. Despite its evolutionary conservation and numerous biological activities, knockout of IGFBP-5 in mice produced only a negligible phenotype. Recent research has begun to explain this paradox by demonstrating cell type-specific and physiological/pathological context-dependent roles for IGFBP-5. In this review, we survey and discuss what is currently known about IGFBP-5 in normal physiology and human disease. Based on recent in vivo genetic evidence, we suggest that IGFBP-5 is a multifunctional protein with the ability to act as a molecular switch to conditionally regulate IGF signaling.

The role of chaperone-mediated autophagy in neurotoxicity induced by alpha-synuclein after methamphetamine exposure

INTRODUCTION

Chaperone-mediated autophagy (CMA) is an autophagy-lysosome pathway (ALP) that is different from the other two lysosomal pathways, namely, macroautophagy and microautophagy, and can selectively degrade cytosolic proteins in lysosomes without vesicle formation. CMA activity declines in neurodegenerative diseases such as Parkinson's disease, and similar neurotoxicity can occur after methamphetamine (METH) treatment. The relationship between CMA and METH-induced neurotoxicity is not clear.

METHODS

We detected changes in the chaperone protein Hsc70 and the lysosomal surface receptor Lamp-2a after METH treatment and then regulated these two proteins by small interfering RNA and DNA plasmid transfection to investigate how CMA influences METH-induced neurotoxicity.

RESULTS

We found that CMA activity is decreased after METH exposure in neurons and downregulated Lamp-2a can aggravate the neurotoxicity induced by α-Syn after METH exposure and that Hsc70 overexpression can relieve the abnormal levels of alpha-synuclein and its aggregate forms and the increase in cell apoptosis induced by METH.

CONCLUSIONS

The results provide in vivo evidence for CMA plays a pivotal role in METH-induced neurotoxicity, and upregulation of Hsc70 expression significantly protects neuronal cells against METH-induced toxicity. This research may pave the way for potential therapeutic approaches targeting CMA for METH abuse and neurodegenerative disorders.

Involvement of C/EBPβ-related signaling pathway in methamphetamine-induced neuronal autophagy and apoptosis

Methamphetamine (METH) is a widely abused illicit psychoactive drug. Our previous study has shown that CCAAT-enhancer binding protein β (C/EBPβ) is an important regulator in METH-induced neuronal autophagy and apoptosis. However, the detailed molecular mechanisms underlying this process remain poorly understood. Previous studies have demonstrated that DNA damage-inducible transcript 4 (DDIT4), Trib3 (tribbles pseudo kinase 3), alpha-synuclein (α-syn) are involved in METH-induced dopaminergic neurotoxicity. We hypothesized that C/EBPβ is involved in METH-induced DDIT4-mediated neuronal autophagy and Trib3-mediated neuronal apoptosis. We tested our hypothesis by examining the effects of silencing C/EBPβ, DDIT4, Trib3 or α-syn with small interfering ribonucleic acid (siRNA) on METH-induced autophagy and apoptosis in the human neuroblastoma SH-SY5Y cells. We also measured the levels of phosphorylated tuberous sclerosis complex 2 (TSC2) protein and Parkin protein level in SH-SY5Y cells. Furthermore, we demonstrated the effect of silencing C/EBPβ on METH-caused neurotoxicity in the striatum of rats by injecting LV-shC/EBPβ lentivirus using a stereotaxic positioning system. The results showed that METH exposure increased C/EBPβ, DDIT4 protein expression. Elevated DDIT4 expression raised up p-TSC2/TSC2 protein expression ratio, inhibited mTOR signaling pathway, activating cell autophagy. We also found that METH exposure increased the expression of Trib3, α-syn, decreased the Parkin protein expression. Lowering levels of Parkin raised up α-syn expression, which initiated mitochondrial apoptosis by down-regulating anti-apoptotic Bcl-2, followed by up-regulation of pro-apoptotic Bax, resulting in translocation of cytochrome c (cyto c), an apoptogenic factor, from the mitochondria to cytoplasm and activation of caspase-dependent pathways. These findings were supported by data showing METH-induced autophagy and apoptosis was significantly inhibited by silencing C/EBPβ, DDIT4, Trib3 or α-syn, or by Parkin over-expression. Based on the present data, a novel of mechanism on METH-induced cell toxicity is proposed, METH exposure increased C/EBPβ protein expression, triggered DDIT4/TSC2/mTOR signaling pathway, and evoked Trib3/Parkin/α-syn-related mitochondrial apoptotic signaling pathway. Collectively, these results suggest that C/EBPβ plays an important role in METH-triggered autophagy and apoptosis and it may be a potential target for therapeutics in METH-caused neurotoxicity.

Methamphetamine produces cardiac damage and apoptosis by decreasing melusin

Methamphetamine (METH) is an amphetamine-type drug that is highly addictive and widely abused. Many studies have shown that METH exposure causes severe damage not only to the nervous system but also to the cardiovascular system. Melusin protein is a mechanotransducer that plays an important role in maintaining normal heart function. However, the role of melusin in METH-induced cardiotoxicity has not yet been reported. We hypothesized that methamphetamine can produce cardiac damage and apoptosis by decreasing the quantity of melusin. To test this hypothesis, we determined the protein expression of melusin and apoptosis markers in METH-treated rats and primary rat cardiomyocytes. We also established a melusin-overexpressing cell model to assess the importance of melusin in maintaining antiapoptotic pathways. To confirm our findings from the in vitro and animal models, we also evaluated the apoptotic index of cardiomyocytes and the protein expression of apoptotic markers in postmortem heart tissues from deceased METH abusers and age-matched control subjects. The results showed that the apoptosis of cardiomyocytes was increased significantly and that the protein expression of melusin was decreased after exposure to METH in primary rat cardiomyocytes, in rats and in humans. METH treatment also decreased the expression of the downstream proteins FAK, IQGAP1, p-AKT, p-GSK3β, and p-ERK in primary rat cardiomyocytes and in vivo. After overexpression of melusin, the above effects were partially reversed in primary rat cardiomyocytes. We conclude that METH can produce cardiac damage and apoptosis by decreasing melusin, while melusin-activated signaling by phosphorylated AKT, phosphorylated GSK3β, and ERK may be resistant to methamphetamine-induced myocardial apoptosis.

SUMOylation of Alpha-Synuclein Influences on Alpha-Synuclein Aggregation Induced by Methamphetamine

Methamphetamine (METH) is an illegal and widely abused psychoactive stimulant. METH abusers are at high risk of neurodegenerative disorders, including Parkinson’s disease (PD). Previous studies have demonstrated that METH causes alpha-synuclein (α-syn) aggregation in the both laboratory animal and human. In this study, exposure to high METH doses increased the expression of α-syn and the small ubiquitin-related modifier 1 (SUMO-1). Therefore, we hypothesized that SUMOylation of α-syn is involved in high-dose METH-induced α-syn aggregation. We measured the levels of α-syn SUMOylation and these enzymes involved in the SUMOylation cycle in SH-SY5Y human neuroblastoma cells (SH-SY5Y cells), in cultures of C57 BL/6 primary mouse neurons and in brain tissues of mice exposure to METH. We also demonstrated the effect of α-syn SUMOylation on α-syn aggregation after METH exposure by overexpressing the key enzyme of the SUMOylation cycle or silencing SUMO-1 expression in vitro. Then, we make introduced mutations in the major SUMOylation acceptor sites of α-syn by transfecting a lentivirus containing the sequence of WT α-syn or K96/102R α-syn into SH-SY5Y cells and injecting an adenovirus containing the sequence of WT α-syn or K96/102R α-syn into the mouse striatum. Levels of the ubiquitin-proteasome system (UPS)-related makers ubiquitin (Ub) and UbE1, as well as the autophagy-lysosome pathway (ALP)-related markers LC3, P62 and lysosomal associated membrane protein 2A (LAMP2A), were also measured in SH-SY5Y cells transfected with lentivirus and mice injected with adenovirus. The results showed that METH exposure decreases the SUMOylation level of α-syn, although the expression of α-syn and SUMO-1 are increased. One possible cause is the reduction of UBC9 level. The increase in α-syn SUMOylation by UBC9 overexpression relieves METH-induced α-syn overexpression and aggregation, whereas the decrease in α-syn SUMOylation by SUMO-1 silencing exacerbates the same pathology. Furthermore, mutations in the major SUMOylation acceptor sites of α-syn also aggravate α-syn overexpression and aggregation by impairing degradation through the UPS and the ALP in vitro and in vivo. These results suggest that SUMOylation of α-syn plays a fundamental part in α-syn overexpression and aggregation induced by METH and could be a suitable target for the treatment of neurodegenerative diseases.

Role of CXCR1 and Interleukin-8 in Methamphetamine-Induced Neuronal Apoptosis

Methamphetamine (METH), an extremely and widely abused illicit drug, can cause serious nervous system damage and social problems. Previous research has shown that METH use causes dopaminergic neuron apoptosis and astrocyte-related neuroinflammation. However, the relationship of astrocytes and neurons in METH-induced neurotoxicity remains unclear. We hypothesized that chemokine interleukin (IL) eight released by astrocytes and C-X-C motif chemokine receptor 1 (CXCR1) in neurons are involved in METH-induced neuronal apoptosis. We tested our hypothesis by examining the changes of CXCR1 in SH-SY5Y cells and in the brain of C57BL/6 mice exposed to METH by western blotting and immunolabeling. We also determined the effects of knocking down CXCR1 expression with small interfering ribonucleic acid (siRNA) on METH-exposed SH-SY5Y cells. Furthermore, we detected the expression levels of IL-8 and the nuclear factor-kappa B (NF-κB) pathway in U87MG cells and then co-cultured the two cell types to determine the role of CXCR1 and IL-8 in neuronal apoptosis. Our results indicated that METH exposure increased CXCR1 expression both in vitro and in vivo, with the effects obtained in vitro being dose-dependent. Silencing of CXCR1 expression with siRNAs reduced the expression of cleaved caspase-3, cleaved poly (ADP-ribose) polymerase (PARP), and other related proteins. In addition, IL-8 expression and release were increased in METH-exposed U87MG cells, which is regulated by NF-κB pathway. Neuronal apoptosis was attenuated by siCXCR1 after METH treatment in the co-cultured cells, which can be reversed after exposure to recombinant IL-8. These results demonstrate that CXCR1 plays an important role in neuronal apoptosis induced by METH and may be a potential target for METH-induced neurotoxicity therapy. Highlights -Methamphetamine exposure upregulated the expression of CXCR1.-Methamphetamine exposure increased the expression of interleukin-8 through nuclear factor-kappa B pathway.-Activation of CXCR1 by interleukin-8 induces an increase in methamphetamine-related neuronal apoptosis.

Methamphetamine exposure triggers apoptosis and autophagy in neuronal cells by activating the C/EBPβ-related signaling pathway

Methamphetamine (Meth) is a widely abused psychoactive drug that primarily damages the nervous system, notably causing dopaminergic neuronal apoptosis. CCAAT-enhancer binding protein (C/EBPβ) is a transcription factor and an important regulator of cell apoptosis and autophagy. Insulin-like growth factor binding protein (IGFBP5) is a proapoptotic factor that mediates Meth-induced neuronal apoptosis, and Trib3 (tribbles pseudokinase 3) is an endoplasmic reticulum (ER) stress-inducible gene involved in autophagic cell death through the mammalian target of rapamycin (mTOR) signaling pathway. To test the hypothesis that C/EBPβ is involved in Meth-induced IGFBP5-mediated neuronal apoptosis and Trib3-mediated neuronal autophagy, we measured the protein expression of C/EBPβ after Meth exposure and evaluated the effects of silencing C/EBPβ, IGFBP5, or Trib3 on Meth-induced apoptosis and autophagy in neuronal cells and in the rat striatum after intrastriatal Meth injection. We found that, at relatively high doses, Meth exposure increased C/EBPβ protein expression, which was accompanied by increased neuronal apoptosis and autophagy; triggered the IGFBP5-mediated, p53-up-regulated modulator of apoptosis (PUMA)-related mitochondrial apoptotic signaling pathway; and stimulated the Trib3-mediated ER stress signaling pathway through the Akt-mTOR signaling axis. We also found that autophagy is an early response to Meth-induced stress upstream of apoptosis and plays a detrimental role in Meth-induced neuronal cell death. These results suggest that Meth exposure induces C/EBPβ expression, which plays an essential role in the neuronal apoptosis and autophagy induced by relatively high doses of Meth; however, relatively low concentrations of Meth did not change the expression of C/EBPβ in vitro. Further studies are needed to elucidate the role of C/EBPβ in low-dose Meth-induced neurotoxicity.-Xu, X., Huang, E., Luo, B., Cai, D., Zhao, X., Luo, Q., Jin, Y., Chen, L., Wang, Q., Liu, C., Lin, Z., Xie, W.-B., Wang, H. Methamphetamine exposure triggers apoptosis and autophagy in neuronal cells by activating the C/EBPβ-related signaling pathway.

The Main Molecular Mechanisms Underlying Methamphetamine- Induced Neurotoxicity and Implications for Pharmacological Treatment

Methamphetamine (METH) is a popular new-type psychostimulant drug with complicated neurotoxicity. In spite of mounting evidence on METH-induced damage of neural cell, the accurate mechanism of toxic effect of the drug on central nervous system (CNS) has not yet been completely deciphered. Besides, effective treatment strategies toward METH neurotoxicity remain scarce and more efficacious drugs are to be developed. In this review, we summarize cellular and molecular bases that might contribute to METH-elicited neurotoxicity, which mainly include oxidative stress, excitotoxicity, and neuroinflammation. We also discuss some drugs that protect neural cells suffering from METH-induced neurotoxic consequences. We hope more in-depth investigations of exact details that how METH produces toxicity in CNS could be carried out in future and the development of new drugs as natural compounds and immunotherapies, including clinic trials, are expected.

Quinacrine pretreatment reduces microwave-induced neuronal damage by stabilizing the cell membrane

Quinacrine, widely used to treat parasitic diseases, binds to cell membranes. We previously found that quinacrine pretreatment reduced microwave radiation damage in rat hippocampal neurons, but the molecular mechanism remains poorly understood. Considering the thermal effects of microwave radiation and the protective effects of quinacrine on heat damage in cells, we hypothesized that quinacrine would prevent microwave radiation damage to cells in a mechanism associated with cell membrane stability. To test this, we used retinoic acid to induce PC12 cells to differentiate into neuron-like cells. We then pretreated the neurons with quinacrine (20 and 40 mM) and irradiated them with 50 mW/cm² microwaves for 3 or 6 hours. Flow cytometry, atomic force microscopy and western blot assays revealed that irradiated cells pretreated with quinacrine showed markedly less apoptosis, necrosis, and membrane damage, and greater expression of heat shock protein 70, than cells exposed to microwave irradiation alone. These results suggest that quinacrine stabilizes the neuronal membrane structure by upregulating the expression of heat shock protein 70, thus reducing neuronal injury caused by microwave radiation.

Toll-Like Receptor 4 Mediates Methamphetamine-Induced Neuroinflammation through Caspase-11 Signaling Pathway in Astrocytes

Methamphetamine (METH) is an amphetamine-typed stimulant drug that is increasingly being abused worldwide. Previous studies have shown that METH toxicity is systemic, especially targeting dopaminergic neurons in the central nervous system (CNS). However, the role of neuroinflammation in METH neurotoxicity remains unclear. We hypothesized that Toll-like receptor 4 (TLR4) and Caspase-11 are involved in METH-induced astrocyte-related neuroinflammation. We tested our hypothesis by examining the changes of TLR4 and Caspase-11 protein expression in primary cultured C57BL/6 mouse astrocytes and in the midbrain and striatum of mice exposed to METH with western blot and double immunofluorescence labeling. We also determined the effects of blocking Caspase-11 expression with wedelolactone (a specific inhibitor of Caspase-11) or siRNA on METH-induced neuroinflammation in astrocytes. Furthermore, we determined the effects of blocking TLR4 expression with TAK-242 (a specific inhibitor of TLR4) or siRNA on METH-induced neuroinflammation in astrocytes. METH exposure increased Caspase-11 and TLR4 expression both in vitro and in vivo, with the effects in vitro being dose-dependent. Inhibition of Caspase-11 expression with either wedelolactone or siRNAs reduced the expression of inflammasome NLRP3 and pro-inflammatory cytokines. In addition, blocking TLR4 expression inhibited METH-induced activation of NF-κB and Caspase-11 in vitro and in vivo, suggesting that TLR4-Caspase-11 pathway is involved in METH-induced neuroinflammation. These results indicate that Caspase-11 and TLR4 play an important role in METH-induced neuroinflammation and may be potential gene targets for therapeutics in METH-caused neurotoxicity.

cfa-miR-143 Promotes Apoptosis via the p53 Pathway in Canine Influenza Virus H3N2-Infected Cells

MicroRNAs regulate multiple aspects of the host response to viral infection. This study verified that the expression of cfa-miR-143 was upregulated in vivo and in vitro by canine influenza virus (CIV) H3N2 infection. To understand the role of cfa-miR-143 in CIV-infected cells, the target gene of cfa-miR-143 was identified and assessed for correlations with proteins involved in the apoptosis pathway. A dual luciferase reporter assay showed that cfa-miR-143 targets insulin-like growth factor binding protein 5 (Igfbp5). Furthermore, a miRNA agomir and antagomir of cfa-miR-143 caused the downregulation and upregulation of Igfbp5, respectively, in CIV-infected madin-darby canine kidney (MDCK) cells. This study demonstrated that cfa-miR-143 stimulated p53 and caspase3 activation and induced apoptosis via the p53 pathway in CIV H3N2-infected cells. In conclusion, CIV H3N2 induced the upregulation of cfa-miR-143, which contributes to apoptosis via indirectly activating the p53-caspase3 pathway.

Nupr1 Modulates Methamphetamine-Induced Dopaminergic Neuronal Apoptosis and Autophagy through CHOP-Trib3-Mediated Endoplasmic Reticulum Stress Signaling Pathway

Methamphetamine (METH) is an illegal and widely abused psychoactive stimulant. METH exposure causes detrimental effects on multiple organ systems, primarily the nervous system, especially dopaminergic pathways, in both laboratory animals and humans. In this study, we hypothesized that Nuclear protein 1 (Nupr1/com1/p8) is involved in METH-induced neuronal apoptosis and autophagy through endoplasmic reticulum (ER) stress signaling pathway. To test this hypothesis, we measured the expression levels of Nupr1, ER stress protein markers CHOP and Trib3, apoptosis-related protein markers cleaved-caspase3 and PARP, as well as autophagy-related protein markers LC3 and Beclin-1 in brain tissues of adult male Sprague-Dawley (SD) rats, rat primary cultured neurons and the rat adrenal pheochromocytoma cells (PC12 cells) after METH exposure. We also determined the effects of METH exposure on the expression of these proteins after silencing Nupr1, CHOP, or Trib3 expression with synthetic small hairpin RNA (shRNA) or siRNA in vitro, and after silencing Nupr1 in the striatum of rats by injecting lentivirus containing shRNA sequence targeting Nupr1 gene to rat striatum. The results showed that METH exposure increased Nupr1 expression that was accompanied with increased expression of ER stress protein markers CHOP and Trib3, and also led to apoptosis and autophagy in rat primary neurons and in PC12 cells after 24 h exposure (3.0 mM), and in the prefrontal cortex and striatum of rats after repeated intraperitoneal injections (15 mg/kg × 8 injections at 12 h intervals). Silencing of Nupr1 expression partly reduced METH-induced apoptosis and autophagy in vitro and in vivo. These results suggest that Nupr1 plays an essential role in METH-caused neuronal apoptosis and autophagy at relatively higher doses and may be a potential therapeutic target in high-dose METH-induced neurotoxicity.

Overview of long non-coding RNA and mRNA expression in response to methamphetamine treatment in vitro

Long non-coding RNAs (lncRNAs) display multiple functions including regulation of neuronal injury. However, their impact in methamphetamine (METH)-induced neurotoxicity has rarely been reported. Here, using microarray analysis, we investigated the expression profiling of lncRNAs and mRNAs in primary cultured prefrontal cortical neurons after METH treatment. We observed a difference in lncRNA and mRNA expression between the experimental and sham control groups. Using bioinformatics, we analyzed the highest enriched gene ontology (GO) terms of biological process, cellular component, and molecular function, and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway and pathway network analysis. Furthermore, an lncRNA-mRNA co-expression sub-network for aberrantly expressed terms revealed possible interactions of lncRNA NR_110713 and NR_027943 with their related genes. Afterwards, three lncRNAs (NR_110713, NR_027943, GAS5) and two mRNAs (Ddit3, Casp12) were targeted to validate the microarray data by qRT-PCR. This presented an overview of lncRNA and mRNA expression profiling and indicated that lncRNA might participate in METH-induced neuronal apoptosis by regulating the coding genes of neurons.

Role of Mitochondria in Methamphetamine-Induced Dopaminergic Neurotoxicity: Involvement in Oxidative Stress, Neuroinflammation, and Pro-apoptosis-A Review

Methamphetamine (MA), an amphetamine-type psychostimulant, is associated with dopaminergic toxicity and has a high abuse potential. Numerous in vivo and in vitro studies have suggested that impaired mitochondria are critical in dopaminergic toxicity induced by MA. Mitochondria are important energy-producing organelles with dynamic nature. Evidence indicated that exposure to MA can disturb mitochondrial energetic metabolism by inhibiting the Krebs cycle and electron transport chain. Alterations in mitochondrial dynamic processes, including mitochondrial biogenesis, mitophagy, and fusion/fission, have recently been shown to contribute to dopaminergic toxicity induced by MA. Furthermore, it was demonstrated that MA-induced mitochondrial impairment enhances susceptibility to oxidative stress, pro-apoptosis, and neuroinflammation in a positive feedback loop. Protein kinase Cδ has emerged as a potential mediator between mitochondrial impairment and oxidative stress, pro-apoptosis, or neuroinflammation in MA neurotoxicity. Understanding the role and underlying mechanism of mitochondrial impairment could provide a molecular target to prevent or alleviate dopaminergic toxicity induced by MA.

Methamphetamine induces hepatotoxicity via inhibiting cell division, arresting cell cycle and activating apoptosis: In vivo and in vitro studies

Methamphetamine (METH) resulted in acute hepatic injury. However, the underlying mechanisms have not been fully clarified. In the present study, rats were treated with METH (15 mg/kg B.W.) for 8 injections (i.p.), and the levels of alanine transaminase, asparatate transaminase and ammonia in serum were significantly elevated over those in the control group, suggesting hepatic injury, which was evidenced by histopathological observation. Analysis of the liver tissues with microarray revealed differential expressions of a total of 332 genes in METH-treated rats. According to the GO and KEGG annotations, a large number of down-regulated cell cycle genes were screened out, suggesting that METH induced cell cycle arrest and deficient of cell cycle checkpoint. Related genes and proteins were confirmed by RT-qPCR and western blotting in rat livers, respectively. Moreover, treatment of Brl-3A cells with METH caused significant cytotoxic response and marked cell cycle arrest. Furthermore, overexpressions of Cidea, cleaved caspase 3 and PARP 1 in METH-treated rats indicated activation of apoptosis, while its inhibition alleviated cell death in Brl-3A cells, suggesting that activation of apoptosis took an important role in METH-induced hepatotoxicity. Taken together, the present study demonstrates that METH induced hepatotoxicity via inducing cell cycle arrest and activating apoptosis.

Neonatal rotenone lesions cause onset of hyperactivity during juvenile and adulthood in the rat

Attention deficit hyperactivity disorder (ADHD) is characterized by behavioral and cognitive symptoms. Longitudinal studies demonstrated that the symptoms remains clinically significant for the majority of ADHD children into adulthood. Furthermore, a population-based birth cohort provided the initial evidence of adult ADHD that lacks a history of childhood ADHD. We previously demonstrated that neonatal exposure to bisphenol A, an environmental chemical caused hyperactivity in the juvenile. Here, we extend to examine other chemical such as rotenone, a dopaminergic toxins. Oral administration of rotenone (3mg/kg) into 5-day-old male Wistar rats significantly caused hyperactivity at adulthood (8∼11 weeks old; p<0.05). It was about 1.3∼1.4-fold more active in the nocturnal phase after administration of rotenone than control rats. Higher dose (16mg/kg) or repeated lower dose of rotenone (1mg/kg/day for 4days) caused hyperactivity in the juvenile. Furthermore, DNA array analyses showed that neonatal exposure to rotenone altered the levels of gene expression of several molecules related to apoptosis/cell cycle, ATPase, skeletal molecule, and glioma. Bivariate normal distribution analysis indicates no correlation in gene expression between a hyperactivity disorder model and a Parkinson's disease model by rotenone. Thus, we demonstrate a rotenone models of ADHD whose onset varies during juvenile and adulthood.

Nupr1/Chop signal axis is involved in mitochondrion-related endothelial cell apoptosis induced by methamphetamine

Methamphetamine (METH) abuse has been a serious global public health problem for decades. Previous studies have shown that METH causes detrimental effects on the nervous and cardiovascular systems. METH-induced cardiovascular toxicity has been, in part, attributed to its destructive effect on vascular endothelial cells. However, the underlying mechanism of METH-caused endothelium disruption has not been investigated systematically. In this study, we identified a novel pathway involved in endothelial cell apoptosis induced by METH. We demonstrated that exposure to METH caused mitochondrial apoptosis in human umbilical vein endothelial cells and rat cardiac microvascular endothelial cells in vitro as well as in rat cardiac endothelial cells in vivo. We found that METH mediated endothelial cell apoptosis through Nupr1–Chop/P53–PUMA/Beclin1 signaling pathway. Specifically, METH exposure increased the expression of Nupr1, Chop, P53 and PUMA. Elevated p53 expression raised up PUMA expression, which initiated mitochondrial apoptosis by downregulating antiapoptotic Bcl-2, followed by upregulation of proapoptotic Bax, resulting in translocation of cytochrome c (cyto c), an apoptogenic factor, from the mitochondria to cytoplasm and activation of caspase-dependent pathways. Interestingly, increased Beclin1, upregulated by Chop, formed a ternary complex with Bcl-2, thereby decreasing the dissociative Bcl-2. As a result, the ratio of dissociative Bcl-2 to Bax was also significantly decreased, which led to translocation of cyto c and initiated more drastic apoptosis. These findings were supported by data showing METH-induced apoptosis was significantly inhibited by silencing Nupr1, Chop or P53, or by PUMA or Beclin1 knockdown. Based on the present data, a novel mechanistic model of METH-induced endothelial cell toxicity is proposed. Collectively, these results highlight that the Nupr1–Chop/P53–PUMA/Beclin1 pathway is essential for mitochondrion-related METH-induced endothelial cell apoptosis and may be a potential therapeutic target for METH-caused cardiovascular toxicity. Future studies using knockout animal models are warranted to substantiate the present findings.

Effects of DDIT4 in Methamphetamine-Induced Autophagy and Apoptosis in Dopaminergic Neurons

Methamphetamine (METH) is an illicit psychoactive drug that can cause a variety of detrimental effects to the nervous system, especially dopaminergic pathways. We hypothesized that DNA damage-inducible transcript 4 (DDIT4) is involved in METH-induced dopaminergic neuronal autophagy and apoptosis. To test the hypothesis, we determined changes of DDIT4 protein expression and the level of autophagy in rat catecholaminergic PC12 cells and human dopaminergic SH-SY5Y cells, and in the hippocampus, prefrontal cortex, and striatum of Sprague Dawley rats exposed to METH. We also examined the effects of silencing DDIT4 expression on METH-induced dopaminergic neuronal autophagy using fluorescence microscopy and electron microscopy. Flow cytometry and Western blot were used to determine apoptosis and the expression of apoptotic markers (cleaved caspase-3 and cleaved PARP) after blocking DDIT4 expression in PC12 cells and SH-SY5Y cells with synthetic siRNA, as well as in the striatum of rats by injecting LV-shDDIT4 lentivirus using a stereotaxic positioning system. Our results showed that METH exposure increased DDIT4 expression that was accompanied with increased autophagy and apoptosis in PC12 cells (3 mM) and SH-SY5Y cells (2 mM), and in the hippocampus, prefrontal cortex, and striatum of rats. Inhibition of DDIT4 expression reduced METH-induced autophagy and apoptosis in vitro and in vivo. However, DDIT4-related effects were not observed at a low concentration of METH (1 μM). These results suggest that DDIT4 plays an essential role in METH-induced dopaminergic neuronal autophagy and apoptosis at higher doses and may be a potential gene target for therapeutics in high-dose METH-induced neurotoxicity.

DNA damage-inducible transcript 4 (DDIT4) mediates methamphetamine-induced autophagy and apoptosis through mTOR signaling pathway in cardiomyocytes

Methamphetamine (METH) is an amphetamine-like psychostimulant that is commonly abused. Previous studies have shown that METH can induce damages to the nervous system and recent studies suggest that METH can also cause adverse and potentially lethal effects on the cardiovascular system. Recently, we demonstrated that DNA damage-inducible transcript 4 (DDIT4) regulates METH-induced neurotoxicity. However, the role of DDIT4 in METH-induced cardiotoxicity remains unknown. We hypothesized that DDIT4 may mediate METH-induced autophagy and apoptosis in cardiomyocytes. To test the hypothesis, we examined DDIT4 protein expression in cardiomyocytes and in heart tissues of rats exposed to METH with Western blotting. We also determined the effects on METH-induced autophagy and apoptosis after silencing DDIT4 expression with synthetic siRNA with or without pretreatment of a mTOR inhibitor rapamycin in cardiomyocytes using Western blot analysis, fluorescence microscopy and TUNEL staining. Our results showed that METH exposure increased DDIT4 expression and decreased phosphorylation of mTOR that was accompanied with increased autophagy and apoptosis both in vitro and in vivo. These effects were normalized after silencing DDIT4. On the other hand, rapamycin promoted METH-induced autophagy and apoptosis in DDIT4 knockdown cardiomyocytes. These results suggest that DDIT4 mediates METH-induced autophagy and apoptosis through mTOR signaling pathway in cardiomyocytes.

Identification of Differentially Expressed IGFBP5-Related Genes in Breast Cancer Tumor Tissues Using cDNA Microarray Experiments

IGFBP5 is an important regulatory protein in breast cancer progression. We tried to identify differentially expressed genes (DEGs) between breast tumor tissues with IGFBP5 overexpression and their adjacent normal tissues. In this study, thirty-eight breast cancer and adjacent normal breast tissue samples were used to determine IGFBP5 expression by qPCR. cDNA microarrays were applied to the highest IGFBP5 overexpressed tumor samples compared to their adjacent normal breast tissue. Microarray analysis revealed that a total of 186 genes were differentially expressed in breast cancer compared with normal breast tissues. Of the 186 genes, 169 genes were downregulated and 17 genes were upregulated in the tumor samples. KEGG pathway analyses showed that protein digestion and absorption, focal adhesion, salivary secretion, drug metabolism-cytochrome P450, and phenylalanine metabolism pathways are involved. Among these DEGs, the prominent top two genes (MMP11 and COL1A1) which potentially correlated with IGFBP5 were selected for validation using real time RT-qPCR. Only COL1A1 expression showed a consistent upregulation with IGFBP5 expression and COL1A1 and MMP11 were significantly positively correlated. We concluded that the discovery of coordinately expressed genes related with IGFBP5 might contribute to understanding of the molecular mechanism of the function of IGFBP5 in breast cancer. Further functional studies on DEGs and association with IGFBP5 may identify novel biomarkers for clinical applications in breast cancer.

Role of PUMA in methamphetamine-induced neuronal apoptosis

Exposure to methamphetamine (METH), a widely used illicit drug, has been shown to cause neuron apoptosis. p53 upregulated modulator of apoptosis (PUMA) is a key mediator in neuronal apoptosis. This study aimed to examine the effects of PUMA in METH-induced neuronal apoptosis. We determined PUMA protein expression in PC12 cells and SH-SY5Y cells after METH exposure using western blot. We also observed the effect of METH on neuronal apoptosis after silencing PUMA expression with siRNA using TUNEL staining and flow cytometry. Additionally, to investigate possible mechanisms of METH-induced PUMA-mediated neuronal apoptosis, we measured the protein expression of apoptotic markers, including cleaved caspase-3, cleaved PARP, Bax, B-cell leukemia/lymphoma-2 (Bcl-2) and cytochrome c (cyto c), after METH treatment with or without PUMA knockdown. Results showed that METH exposure induced cell apoptosis, increased PUMA protein levels, activated caspase-3 and PARP, elevated Bax and reduced Bcl-2 expression, as well as increased the release of cyto c from mitochondria to the cytoplasm in both PC12 and SH-SY5Y cells. All these effects were attenuated or reversed after silencing PUMA. A schematic depicting the role of PUMA in METH-induced mitochondrial apoptotic pathway was proposed. Our results suggest that PUMA plays an important role in METH-triggered apoptosis and it may be a potential target for ameliorating neuronal injury and apoptosis caused by METH.

Amphetamine-related drugs neurotoxicity in humans and in experimental animals: Main mechanisms

Amphetamine-related drugs, such as 3,4-methylenedioxymethamphetamine (MDMA) and methamphetamine (METH), are popular recreational psychostimulants. Several preclinical studies have demonstrated that, besides having the potential for abuse, amphetamine-related drugs may also elicit neurotoxic and neuroinflammatory effects. The neurotoxic potentials of MDMA and METH to dopaminergic and serotonergic neurons have been clearly demonstrated in both rodents and non-human primates. This review summarizes the species-specific cellular and molecular mechanisms involved in MDMA and METH-mediated neurotoxic and neuroinflammatory effects, along with the most important behavioral changes elicited by these substances in experimental animals and humans. Emphasis is placed on the neuropsychological and neurological consequences associated with the neuronal damage. Moreover, we point out the gap in our knowledge and the need for developing appropriate therapeutic strategies to manage the neurological problems associated with amphetamine-related drug abuse.

Caspase-11 plays an essential role in methamphetamine-induced dopaminergic neuron apoptosis

Methamphetamine (METH) is an extremely addictive stimulant drug that is widely used with high potential of abuse. Previous studies have shown that METH exposure damages the nervous system, especially dopaminergic neurons. However, the exact molecular mechanisms of METH-induced neurotoxicity remain unclear. We hypothesized that caspase-11 is involved in METH-induced neuronal apoptosis. We tested our hypothesis by examining the change of caspase-11 protein expression in dopaminergic neurons (PC12 and SH-SY5Y) and in the midbrain of rats exposed to METH with Western blotting. We also determined the effects of blocking caspase-11 expression with wedelolactone (a specific inhibitor of caspase-11) or siRNA on METH-induced apoptosis in PC12 cells and SH-SY5Y cells using Annexin V and TUNEL staining. Furthermore, we observed the protein expression changes of the apoptotic markers, cleaved caspase-3 and cleaved poly(ADP-ribose) polymerase 1 (PARP), after silencing the caspase-11 expression in rat midbrain by injecting LV-shcasp11 lentivirus using a stereotaxic positioning system. Results showed that METH exposure increased caspase-11 expression both in vitro and in vivo, with the effects in vitro being dose- and time-dependent. Inhibition of caspase-11 expression with either wedelolactone or siRNAs reduced the number of METH-induced apoptotic cells. In addition, blocking caspase-11 expression inhibited METH-induced activation of caspase-3 and PARP in vitro and in vivo, suggesting that caspase-11/caspase-3 signal pathway is involved in METH-induced neurotoxicity. These results indicate that caspase-11 plays an essential role in METH-induced neuronal apoptosis and may be a potential gene target for therapeutics in METH-caused neurotoxicity.

AST IV inhibits H₂O₂-induced human umbilical vein endothelial cell apoptosis by suppressing Nox4 expression through the TGF-β1/Smad2 pathway

Endothelial cell apoptosis plays an important role in the pathophysiological mechanisms of vascular complications in diabetes mellitus (DM). NADPH oxidase 4 (Nox4)-dependent reactive oxygen species (ROS) aggregation is the main cause of vascular endothelial cell apoptosis. The transforming growth factor-β1 (TGF-β1)/Smad2 signaling pathway is involved in the apoptosis of several types of cells. However, the association between vascular endothelial cell apoptosis and Nox4, and the involvement of the TGF-β1/Smad2 signaling pathway in vascular endothelial cell apoptosis remain unclear. In the present study, we aimed to investigate the role of Nox4-dependent ROS production and to determine the involvement of the TGF-β1/Smad2 signaling pathway in endothelial cell apoptosis induced by oxidative stress which causes vascular injury in DM. We demonstrated that hydrogen peroxide (H2O2) increased Nox4-dependent-ROS aggregation, as well as the expression of TGF-β1, Smad2, Bax and caspase-3, decreased Bcl-2 expression and increased the apoptosis of human umbilical vein endothelial cells (HUVECs). Treatment with diphenyliodonium (DPI), a specific inhibitor of Nox4 or astragaloside IV (AST IV), a monomer located in an extract of astragaloside, decreased Nox4 expression and the levels of ROS, decreased TGF-β1 and Smad2 expression, altered the expression of apoptosis-related genes and decreased the apoptosis of HUVECs. Treatment with LY2109761, a selective inhibitor of the TGF-β1/Smad2 pathway, produced results similar to those of DPI; however, LY2109761 had no effect on Nox4 expression and ROS levels. Taken together, the findings of the present study suggest that H2O2 contributes to HUVEC apoptosis by inducing Nox4-dependent ROS aggregation and activating the TGF-β1/Smad2 signaling pathway. Our data indicate that the protective effects of AST IV against vascular endothelial cell apoptosis in DM are mainly associated with the decrease in Nox4 expression through the TGF-β1/Smad2 signaling pathway. Furthermore, the inhibition of the activation of the TGF-β1/Smad2 signaling pathway may be another potential therapeutic strategy in the treatment of DM.