Apoptosis-inducing factor: A matter of neuron life and death

Segmental testicular infarction in adolescent:experience of new treatment and testicular function monitoring

Segmental testicular infarction is a relatively rare acute or subacute condition that is often overlooked in the differential diagnosis of testicular pain. Ultrasound is highly sensitive in detecting testicular damage. Combining testicular tumour markers with MRI can effectively identify tumours and infarctions. Conservative treatment programs for adolescents suggest that testicular function should be monitored. We report the case of a 12-year-old boy with testicular infarction who was treated with antibiotics, dexamethasone, and vitamin C. We monitored reproductive hormones, inhibin B, anti-Müllerian hormone, and testicular volume to assess the patient's testicular function. LH increased 3.02 fold on day 14 and 3.8 fold on day 42; T increased 6.92 times on day 14 and 7.95 fold on day 42; inhibin B increased 2.72 fold on day 14 and 4.06 fold on day 42; the left testicular volume increased 1.14 fold on day 42; the right testicular volume decreased by 8 %; and the infarct area decreased by 71 %. This case study demonstrated the effectiveness of conservative treatment with antibiotics, dexamethasone, and vitamin C for segmental testicular infarction. Close monitoring of testicular function is essential for optimal management of this rare condition in adolescent patients.

The Multifaceted Role of miR-21 in Pancreatic Cancers

With the lack of specific signs and symptoms, pancreatic ductal adenocarcinoma (PDAC) is often diagnosed at late metastatic stages, resulting in poor survival outcomes. Among various biomarkers, microRNA-21 (miR-21), a small non-coding RNA, is highly expressed in PDAC. By inhibiting regulatory proteins at the 3' untranslated regions (UTR), miR-21 holds significant roles in PDAC cell proliferation, epithelial-mesenchymal transition, angiogenesis, as well as cancer invasion, metastasis, and resistance therapy. We conducted a systematic search across major databases for articles on miR-21 and pancreatic cancer mainly published within the last decade, focusing on their diagnostic, prognostic, therapeutic, and biological roles. This rigorous approach ensured a comprehensive review of miR-21's multifaceted role in pancreatic cancers. In this review, we explore the current understandings and future directions regarding the regulation, diagnostic, prognostic, and therapeutic potential of targeting miR-21 in PDAC. This exhaustive review discusses the involvement of miR-21 in proliferation, epithelial-mesenchymal transition (EMT), apoptosis modulation, angiogenesis, and its role in therapy resistance. Also discussed in the review is the interplay between various molecular pathways that contribute to tumor progression, with specific reference to pancreatic ductal adenocarcinoma.

A genetically encoded fluorescent protein sensor for mitochondrial membrane damage detection

Mitochondria are essential cellular organelles; detecting mitochondrial damage is crucial in cellular biology and toxicology. Compared with existing chemical probe detection methods, genetically encoded fluorescent protein sensors can directly indicate cellular and molecular events without involving exogenous reagents. In this study, we introduced a molecular sensor system, MMD-Sensor, for monitoring mitochondrial membrane damage. The sensor consists of two molecular modules. Module I is a fusion structure of the mitochondrial localization sequence (MLS), AIF cleavage site sequence (CSS), nuclear localization sequence (NLS), N-terminus of mNeonGreen and mCherry. Module II is a fusion structure of the C-terminus of mNeonGreen, NLS sequence, and mtagBFP2. Under normal condition, Module I is constrained in the inner mitochondrial membrane anchored by MLS, while Module II is restricted to the nucleus by its NLS fusion component. If the mitochondrial membrane is damaged, CSS is cut from the inner membrane, causing Module I to shift into the nucleus guided by the NLS fusion component. After Module I enters the nucleus, the N- and C-terminus of mNeonGreen meet each other and rebuild its intact 3D structure through fragment complementation and thus generates green fluorescence in the nucleus. Dynamic migration of red fluorescence from mitochondria to the nucleus and generation of green fluorescence in the nucleus indicate mitochondrial membrane damage. Using the MMD-Sensor, mitochondrial membrane damage induced by various reagents, such as uncoupling agents, ATP synthase inhibitors, monovalent cationic carriers, and ROS, in HeLa and 293T cells are directly observed and evaluated.

Selective vulnerability of hippocampal CA1 and CA3 pyramidal cells: What are possible pathomechanisms and should more attention be paid to the CA3 region in future studies?

Transient ischemia and reperfusion selectively damage neurons in brain, with hippocampal pyramidal cells being particularly vulnerable. Even within hippocampus, heterogeneous susceptibility is evident, with higher vulnerability of CA1 versus CA3 neurons described for several decades. Therefore, numerous studies have focused exclusively on CA1. Pediatric cardiac surgery is increasingly focusing on studies of hippocampal structures, and a negative impact of cardiopulmonary bypass on the hippocampus cannot be denied. Recent studies show a shift in selective vulnerability from neurons of CA1 to CA3. This review shows that cell damage is increased in CA3, sometimes stronger than in CA1, depending on several factors (method, species, age, observation period). Despite a highly variable pattern, several markers illustrate greater damage to CA3 neurons than previously assumed. Nevertheless, the underlying cellular mechanisms have not been fully deciphered to date. The complexity is reflected in possible pathomechanisms discussed here, with numerous factors (NMDA, kainate and AMPA receptors, intrinsic oxidative stress potential and various radicals, AKT isoforms, differences in vascular architecture, ratio of pro- and anti-apoptotic Bcl-2 factors, vulnerability of interneurons, mitochondrial dysregulation) contributing to either enhanced CA1 or CA3 vulnerability. Furthermore, differences in expressed genome, proteome, metabolome, and transcriptome in CA1 and CA3 appear to influence differential behavior after damaging stimuli, thus metabolomics-, transcriptomics-, and proteomics-based analyses represent a viable option to identify pathways of selective vulnerability in hippocampal neurons. These results emphasize that future studies should focus on the CA3 field in addition to CA1, especially with regard to improving therapeutic strategies after ischemic/hypoxic brain injury.

Nose-to-brain translocation and nervous system injury in response to indium tin oxide nanoparticles of long-term low-dose exposures

Indium tin oxide (ITO) is a semiconductor nanomaterial with broad application in liquid crystal displays, solar cells, and electrochemical immune sensors. It is worth noting that, with the gradual increase in worker exposure opportunities, the exposure risk in occupational production cannot be ignored. At present, the toxicity of ITO mainly focuses on respiratory toxicity. ITO inhaled through the upper respiratory tract can cause pathological changes such as interstitial pneumonia and pulmonary fibrosis. Still, extrapulmonary toxicity after nanoscale ITO nanoparticle (ITO NPs) exposure, such as long-term effects on the central nervous system, should also be of concern. Therefore, we set up exposure dose experiments (0 mg·kg-1, 3.6 mg·kg-1, and 36 mg·kg-1) based on occupational exposure limits to treat C57BL/6 mice via nasal drops for 15 weeks. Moreover, we conducted a preliminary assessment of the neurotoxicity of ITO NPs (20-30 nm) in vivo. The results indicated that ITO NPs can cause diffuse inflammatory infiltrates in brain tissue, increased glial cell responsiveness, abnormal neuronal cell lineage transition, neuronal migration disorders, and neuronal apoptosis related to the oxidative stress induced by ITO NPs exposure. Hence, our findings provide useful information for the fuller risk assessment of ITO NPs after occupational exposure.

Cholesterol dependent cytolysins and the brain: Revealing a potential therapeutic avenue for bacterial meningitis

Bacterial meningitis is a catastrophic nervous system disorder with high mortality and wide range of morbidities. Some of the meningitis-causing bacteria occupy cholesterol dependent cytolysins (CDCs) to increase their pathogenicity and arrange immune-evasion strategy. Studies have observed that the relationship between CDCs and pathogenicity in these meningitides is complex and involves interactions between CDC, blood-brain barrier (BBB), glial cells and neurons. In BBB, these CDCs acts on capillary endothelium, tight junction (TJ) proteins and neurovascular unit (NVU). CDCs also observed to elicit intriguing effects on brain inflammation which involves microglia and astrocyte activations, along with neuronal damage as the end-point of pathological pathways in bacterial meningitis. As some studies mentioned potential advantage of CDC-targeted therapeutic mechanisms to combat CNS infections, it might be a fruitful avenue to deepen our understanding of CDC as a candidate for adjuvant therapy to combat bacterial meningitis.

Analysis of differentially expressed proteins after EHP-infection and characterization of caspase 3 protein in the whiteleg shrimp (Litopenaeus vannamei)

Whiteleg shrimp (Litopenaeus vannamei) is the most important species of shrimp farmed worldwide in terms of its economic value. Enterocytozoon hepatopenaei (EHP) infects the hepatopancreas, resulting in the hepatopancreatic microsporidiosis (HPM) of the host, which causes slow growth of the shrimp and poses a threat to the farming industry. In this study, differentially expressed proteins (DEPs) between EHP-infected and uninfected shrimp were investigated through proteomics sequencing. A total of 9908 peptides and 2092 proteins were identified. A total of 69 DEPs were identified in the hepatopancreas (HP), of which, 28 were upregulated and 41 were downregulated. Our results showed that the differences among the level of multiple proteins involved in the apoptosis were significant after the EHP infection, which indicated that the apoptosis pathway was activated in whiteleg shrimp. In addition, expression leve of caspase 3 gene were identified related to the EHP infection. Furthermore, predictions of spatial structure, analysis of phylogeny and chromosome-level linearity of the caspase 3 protein were performed as well. In conclusion, a relatively complete proteomic data set of hepatopancreas tissues in whiteleg shrimp were established in this study. Findings about genes involved in the apoptosis here will provide a further understanding of the molecular mechanism of EHP infection in the internal immunity of whiteleg shrimp.

Interaction between Porcine Alveolar Macrophage-Tang Cells and Streptococcus suis Strains of Different Virulence: Phagocytosis and Apoptosis

Streptococcus suis is an important swine bacterial pathogen that activates macrophages to secrete inflammatory cytokines. Primary porcine alveolar macrophages (PAMs) are inconvenient to obtain, but it is unknown whether immortalized PAM-Tang cells can replace them as a better cell model for the study of the interaction between S. suis and macrophages. In this study, the phagocytic integrity, polarization, and pro-inflammatory cytokine secretion of PAM-Tang cells were confirmed by live-cell imaging, electron microscopy, confocal microscopy, and ELISA. Interestingly, the S. suis serotype 9 avirulent strain W7119 induced higher levels of adhesion and pro-inflammatory cytokines in PAM-Tang cells than the S. suis serotype 2 virulent strain 700794. Prolonged incubation with S. suis caused more cytotoxic cell damage, and the virulent strain induced higher levels of cytotoxicity to PAM-Tang cells. The virulent strain also induced higher levels of apoptosis in PAM-Tang cells, as shown by terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-biotin nick end labeling (TUNEL) assay. In addition, it is the first report of virulent and avirulent S. suis inducing PAM-Tang polarization towards pro-inflammatory M1 macrophages and p53- and caspase-dependent apoptosis in PAMs. Taken together, this study contributes to a better understand of interactions between macrophages and S. suis isolates of different virulence, and confirms that PAM-Tang cells provide a long-term, renewable resource for investigating macrophage infections with bacteria.

Streptococcus suis Serotype 2 Infection Induces Splenomegaly with Splenocyte Apoptosis

Little is known about the damage to the important peripheral immune organ spleen caused by Streptococcus suis infection. In this study, we found that S. suis induced splenomegaly and lymphocyte disruption in spleens of mice. To explore the mechanism of splenic lesions induced by S. suis, we conducted further studies. The results showed that S. suis induced apoptosis in B cells, which is related to the cleavage of caspase-3 and caspase-8, but not the release of apoptosis-inducing factor (AIF). Thus, S. suis induced apoptosis in the spleen through caspase-dependent and AIF-independent pathways. Inflammation lesions induced in the spleen of infected mice were also investigated; we found macrophages increased in histopathological lesions of infected spleens from 12 h postinoculation to 7 days postinoculation (dpi), and the type of increased macrophages was M1 type by confocal microscopy, which can secrete proinflammatory cytokines. Meanwhile, inflammasome NLRP3 and caspase-1 were activated, and gasdermin D (GSDMD) was cleaved, which causes pyroptosis that may result in the release of numerous proinflammatory cytokines. What's more, the increase of p-JNK and p-p38 indicated that the MAPK pathway was also involved in the proinflammatory responses during S. suis infection, whereas anti-inflammatory responses in spleen were suppressed, with regulatory T cells (Tregs) upregulating at 1 dpi. Taken together, proinflammatory immune responses dominate in early infection, which induce splenomegaly and splenocyte apoptosis. This is the first report of mechanisms associated with S. suis-induced splenic lesions. IMPORTANCE Streptococcus suis serotype 2 is considered an emerging pathogen and represents a threat to humans and animals. The spleen is an important peripheral immune organ, and splenomegaly is a consequence of lesions and an important clinical indicator of S. suis infection. However, knowledge of the mechanisms underlying spleen lesions is still very limited. In the present work, we made the investigation to explain the phenomenon and the related immunomodulation in a mouse infection model. The obtained results show that inflammation contributes to splenomegaly, while apoptosis contributes to lymphocyte disruption in spleens. Related signaling pathways were discovered which have never been associated with S. suis-induced splenic injury. The new knowledge generated will help us better understand the mechanism of S. suis pathogenesis.

Oxidative stress and mitochondrial dysfunction following traumatic brain injury: From mechanistic view to targeted therapeutic opportunities

Traumatic brain injury (TBI) is one of the most prevalent causes of permanent physical and cognitive disabilities. TBI pathology results from primary insults and a multi-mechanistic biochemical process, termed as secondary brain injury. Currently, there are no pharmacological agents for definitive treatment of patients with TBI. This article is presented with the purpose of reviewing molecular mechanisms of TBI pathology, as well as potential strategies and agents against pathological pathways. In this review article, materials were obtained by searching PubMed, Scopus, Elsevier, Web of Science, and Google Scholar. This search was considered without time limitation. Evidence indicates that oxidative stress and mitochondrial dysfunction are two key mediators of the secondary injury cascade in TBI pathology. TBI-induced oxidative damage results in the structural and functional impairments of cellular and subcellular components, such as mitochondria. Impairments of mitochondrial electron transfer chain and mitochondrial membrane potential result in a vicious cycle of free radical formation and cell apoptosis. The results of some preclinical and clinical studies, evaluating mitochondria-targeted therapies, such as mitochondria-targeted antioxidants and compounds with pleiotropic effects after TBI, are promising. As a proposed strategy in recent years, mitochondria-targeted multipotential therapy is a new hope, waiting to be confirmed. Moreover, based on the available findings, biologics, such as stem cell-based therapy and transplantation of mitochondria are novel potential strategies for the treatment of TBI; however, more studies are needed to clearly confirm the safety and efficacy of these strategies.

Erythropoietin regulates signaling pathways associated with neuroprotective events

Erythropoietin is a cytokine that binds to the Erythropoietin receptor and regulates the formation of erythroid cells during erythropoiesis in the bone marrow. However, many other organs and tissues express Erythropoietin and its receptor, such as the Nervous System, which principally regulates tissue protection. In the Central Nervous System, Erythropoietin is principally expressed by astrocytes, while neurons mainly express Erythropoietin receptors. Moreover, Erythropoietin acts as a pleiotropic molecule with neuroprotective effects, and its mechanisms of signal transduction pathways are defined, and there is a growing interest in its therapeutic potential. This review focuses on the role of Erythropoietin and its relationship with HIF1, PI3/Akt, GSK3B, JAK/STAT, and MAPKs signaling pathways that leads to cell survival after injury in the Central Nervous System. Knowledge of these signaling systems comprehensively could better guide EPO treatment to restoring different SNC alterations mediated by different insults.

Anti-apoptotic and pro-survival effect of exercise training on early aged hypertensive rat cerebral cortex

The anti-apoptotic and pro-survival effects of exercise training were evaluated on the early aged hypertensive rat cerebral cortex. The brain tissues were analysed from ten sedentary male Wistar Kyoto normotensive rats (WKY), ten sedentary spontaneously 12 month early aged hypertensive rats (SHR), and ten hypertensive rats undergoing treadmill exercise training (60 min/day, 5 days/week) for 12 weeks (SHR-EX). TUNEL-positive apoptotic cells, the expression levels of endonuclease G (EndoG) and apoptosis-inducing factor (AIF) (caspase-independent apoptotic pathway), Fas ligand, Fas death receptor, tumor necrosis factor (TNF)-α, TNF receptor 1, Fas-associated death domain, active caspase-8 and active caspase-3 (Fas-mediated apoptotic pathways) as well as t-Bid, Bax, Bak, Bad, cytochrome c, active caspase 9 and active caspase-3 (mitochondria-mediated apoptotic pathways) were reduced in SHR-EX compared with SHR. Pro-survival Bcl2, Bcl-xL, p-Bad, 14-3-3, insulin-like growth factor (IGF)-1, pPI3K/PI3K, and pAKT/AKT were significantly increased in SHR-EX compared to those in SHR. Exercise training suppressed neural EndoG/AIF-related caspase-independent, Fas/FasL-mediated caspase-dependent, mitochondria-mediated caspase-dependent apoptotic pathways as well as enhanced Bcl-2 family-related and IGF-1-related pro-survival pathways in the early aged hypertensive cerebral cortex. These findings indicated new therapeutic effects of exercise training on preventing early aged hypertension-induced neural apoptosis in cerebral cortex.

Neurotoxicity associated with chronic exposure to dichlorophenoxyacetic acid (2,4-D) - a simulation of environmental exposure in adult rats

The herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) is the second most widely used herbicide in the world. The objective of this study was to evaluate the neurotoxic effects and the possible role of the dysregulation of apoptosis in the genesis of brain damage in chronic exposure to 2,4-D in rats. Eighty adult male rats were distributed into eight groups (n = 10) and exposed orally (contaminated feed) and via inhalation, with two groups exposed to distilled water (control) and six to 2,4-D in three distinct concentrations. They were exposed for 6 months. A neurobehavioral assessment was performed, and the brain was collected for histopathology and immunohistochemistry. The animals in the control groups showed greater motility in the open-field test and a greater number of entries in the elevated-plus-maze test than those exposed to 2,4-D (p < 0.05). Neuronal necrosis was more incident in animals exposed to 2,4-D (p < 0.05). There was a negative correlation between the expression of BAX and the measurement of the cerebral cortex thickness (r = -0.713; p = 0.047). Regardless of the route of exposure, 2,4-D led to a deficit in neurobehavioral tests and decreased thickness of the cerebral cortex associated with increased expression of the pro-apoptotic protein BAX.

The mitochondrial-targeted peptide SBT-20 ameliorates inflammation and oxidative stress in chronic renal failure

Chronic renal failure (CRF) is the final outcome of the development of chronic kidney disease with different causes. Although CRF is a common clinical disease, its pathogenesis remains to be improved. SBT-20 belongs to a class of cell-permeable peptides that target the inner mitochondrial membrane, reduce reactive oxygen species (ROS), normalize electron transport chain function, and ATP generation. Our experiment was to evaluate whether SBT-20 affected the oxidative stress and inflammatory process of CRF. The levels of ROS production, mitochondrial membrane potential, NF- κB-p65, TNF-α, Drp1, and mfn2 were measured before and after SBT-20 treatment. We observed that SBT-20 treatment inhibited H2O2-induced mitochondrial ROS production. SBT-20 could also restore the mitochondrial membrane potential and reduce the elevated levels of NF-κB-p65 and TNF-α in HK-2 cells. In vivo, the renal function of CRF mice recovered after treating with SBT-20, the levels of necrotic cells and inflammation decreased, and the morphology of mitochondria recovered. The results showed that SBT-20 had a protective effect on CRF by reducing oxidative stress, inflammation progression via down-regulating of NF-κB-p65, TNF-α, and Drp1 and upregulating of Mfn2. These data support SBT-20 could be used as a potential preparation for CRF.

Mitochondria as a target for neuroprotection: role of methylene blue and photobiomodulation

Mitochondrial dysfunction plays a central role in the formation of neuroinflammation and oxidative stress, which are important factors contributing to the development of brain disease. Ample evidence suggests mitochondria are a promising target for neuroprotection. Recently, methods targeting mitochondria have been considered as potential approaches for treatment of brain disease through the inhibition of inflammation and oxidative injury. This review will discuss two widely studied approaches for the improvement of brain mitochondrial respiration, methylene blue (MB) and photobiomodulation (PBM). MB is a widely studied drug with potential beneficial effects in animal models of brain disease, as well as limited human studies. Similarly, PBM is a non-invasive treatment that promotes energy production and reduces both oxidative stress and inflammation, and has garnered increasing attention in recent years. MB and PBM have similar beneficial effects on mitochondrial function, oxidative damage, inflammation, and subsequent behavioral symptoms. However, the mechanisms underlying the energy enhancing, antioxidant, and anti-inflammatory effects of MB and PBM differ. This review will focus on mitochondrial dysfunction in several different brain diseases and the pathological improvements following MB and PBM treatment.

Oligomannuronate prevents mitochondrial dysfunction induced by IAPP in RINm5F islet cells by inhibition of JNK activation and cell apoptosis

Background

Oligomannuronates (OM) are natural products from alginate that is frequently used as food supplement. The aim of this study was to investigate the in vitro protective effects of OM on RINm5F cells against human Islet amyloid polypeptide (IAPP) induced mitochondrial dysfunction, as well as the underlying mechanisms.

Methods

In the present study, we obtained several kinds of OM with different molecular masses, and then we used RINm5F cells as a model to elucidate the involvement of JNK signal pathway in hIAPP-induced mitochondrial dysfunction in pancreatic beta cells, and the protective effects of OM are associated with its ability to attenuate the mitochondrial dysfunction.

Results

Our results demonstrated that human IAPP induced mitochondrial dysfunction, as evidence by loss of ΔΨm and ATP content, and decrease in oxygen consumption and complex activities, was accompanied by JNK activation, changes in the expressions of Bcl-2 and Bax proteins, release of cytochrome c (Cyto-c) and apoptosis inducing factor (AIF) from mitochondria into cytosol. Interestingly, the human IAPP induced damage in RINm5F cells were effectively restored by co-treatment of OM. Moreover, JNK activation was required for the OM mediated changes in RINm5F cells.

Conclusions

OM prevented mitochondrial dysfunction induced by human IAPP in RINm5F islet cells through JNK dependent signaling pathways.

Streptococcus suis Serotype 2 Infection Causes Host Immunomodulation through Induction of Thymic Atrophy

Streptococcus suis serotype 2 is an important bacterial pathogen of swine and is also an emerging zoonotic agent that may be harmful to human health. Although the virulence genes of S. suis have been extensively studied, the mechanisms by which they damage the central immune organs have rarely been studied. In the current work, we wanted to uncover more details about the impact and mechanisms of S. suis on specific populations of thymic and immune cells in infected mice. Terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-biotin nick end labeling (TUNEL) assays revealed that S. suis infection induced apoptosis in CD3⁺, CD14⁺, and epithelial cells from the thymus. S. suis infection resulted in a rapid depletion of mitochondrial permeability and release of cytochrome c (CytC) and apoptosis-inducing factor (AIF) through upregulation of Bax expression and downregulation of Bcl-xl and Bcl2 expression in thymocytes. Moreover, S. suis infection increased cleavage of caspase-3, caspase-8, and caspase-9. Thus, S. suis induced thymocyte apoptosis through a p53- and caspase-dependent pathway, which led to a decrease of CD3⁺ cells in the thymus, subsequently decreasing the numbers of CD4⁺ and CD8⁺ cells in the peripheral blood. Finally, expression dysregulation of proinflammatory cytokines in the serum, including interleukin 2 (IL-2), IL-6, IL-12 (p70), tumor necrosis factor (TNF), and IL-10, was observed in mice after S. suis type 2 infection. Taken together, these results suggest that S. suis infection can cause atrophy of the thymus and induce apoptosis of thymocytes in mice, thus likely suppressing host immunity.

Autophagy is Activated In Vivo during Trimethyltin-Induced Apoptotic Neurodegeneration: A Study in the Rat Hippocampus

Trimethyltin (TMT) is an organotin compound known to produce significant and selective neuronal degeneration and reactive astrogliosis in the rodent central nervous system. Autophagy is the main cellular mechanism for degrading and recycling protein aggregates and damaged organelles, which in different stress conditions, such as starvation, generally improves cell survival. Autophagy is documented in several pathologic conditions, including neurodegenerative diseases. This study aimed to investigate the autophagy and apoptosis signaling pathways in hippocampal neurons of TMT-treated (Wistar) rats to explore molecular mechanisms involved in toxicant-induced neuronal injury. The microtubule-associated protein light chain (LC3, autophagosome marker) and sequestosome1 (SQSTM1/p62) (substrate of autophagy-mediated degradation) expressions were examined by Western blotting at different time points after intoxication. The results demonstrate that the LC3 II/I ratio significantly increased at 3 and 5 days, and that p62 levels significantly decreased at 7 and 14 days. Immunofluorescence images of LC3/neuronal nuclear antigen (NeuN) showed numerous strongly positive LC3 neurons throughout the hippocampus at 3 and 5 days. The terminal deoxynucleotidyltransferase dUTP nick end labeling (TUNEL) assay indicated an increase in apoptotic cells starting from 5 days after treatment. In order to clarify apoptotic pathway, immunofluorescence images of apoptosis-inducing factor (AIF)/NeuN did not show nuclear translocation of AIF in neurons. Increased expression of cleaved Caspase-3 was revealed at 5-14 days in all hippocampal regions by Western blotting and immunohistochemistry analyses. These data clearly demonstrate that TMT intoxication induces a marked increase in both autophagy and caspase-dependent apoptosis, and that autophagy occurring just before apoptosis could have a potential role in neuronal loss in this experimental model of neurodegeneration.

Rapamycin Inhibited Photoreceptor Necroptosis and Protected the Retina by Activation of Autophagy in Experimental Retinal Detachment

Purpose: After experimental retinal detachment (RD), the applications of caspase inhibitor z-vad-fmk (a pan-caspase inhibitor) could inhibit apoptosis, but increased receptor interacting protein (RIP)-mediated necroptosis. In this study, we investigated whether rapamycin could inhibit necroptosis and cooperate with z-vad-fmk to protect the retina after RD. Methods: RD animal models were established in Sprague-Dawley rats by subretinal injection of sodium hyaluronate and treated with subretinal injections of z-vad-fmk or z-vad-fmk combined with rapamycin. On day 3 after RD, retinas were collected and analyzed by transmission electron microscopy (TEM), ROS assay, and western blot (for beclin-1, LC-3, RIP-1, AIF). On day 7 after RD, retinas were observed by H&E staining. Vision-dependent behavior of rats was tested by the modified Morris water maze. Results: TEM and H&E staining indicated that rapamycin combined with z-vad-fmk could reduce photoreceptor necrosis and preserve the ONL thickness after RD. The modified Morris water maze test showed that vision-dependent behavior was also significantly improved in the rapamycin + z-vad-fmk group.Western Blotting results demonstrated that rapamycin promoted the activation of autophagy by promoting beclin-1 and LC-3 induction and inhibited z-vad-fmk-induced necroptosis by inhibiting RIP-1 expression. In addition, rapamycin could also inhibit ROS production and AIF release. Conclusions: These findings indicated that rapamycin is a promising therapeutic agent that inhibits z-VAD-induced necroptosis, and protects photoreceptors and improves functional outcome in combination with z-vad-fmk.

Photoreceptor degeneration in microphthalmia (Mitf) mice: partial rescue by pigment epithelium-derived factor

Dysfunction and loss of the retinal pigment epithelium (RPE) are hallmarks of retinal degeneration, but the underlying pathogenetic processes are only partially understood. Using mice with a null mutation in the transcription factor gene Mitf, in which RPE deficiencies are associated with retinal degeneration, we evaluated the role of trophic factors secreted by the RPE in retinal homeostasis. In such mice, the thickness of the outer nuclear layer (ONL) is as in wild type up to postnatal day 10, but then is progressively reduced, associated with a marked increase in the number of apoptotic cells and a decline in staining for rhodopsin. We show that retinal degeneration and decrease in rhodopsin staining can be prevented partially in three different ways: first, by recombining mutant-derived postnatal retina with postnatal wild-type RPE in tissue explant cultures; second, by adding to cultured mutant retina the trophic factor pigment epithelium-derived factor (PEDF; also known as SERPINF1), which is normally produced in RPE under the control of Mitf; and third, by treating the eyes of Mitf mutant mice in vivo with drops containing a bioactive PEDF 17-mer peptide. This latter treatment also led to marked increases in a number of rod and cone genes. The results indicate that RPE-derived trophic factors, in particular PEDF, are instrumental in retinal homeostasis, and suggest that PEDF or its bioactive fragments may have therapeutic potential in RPE deficiency-associated retinal degeneration.

Different influences on mitochondrial function, oxidative stress and cytotoxicity of antibiotics on primary human neuron and cell lines

Although antibiotics are generally well tolerated, their toxic effects on the central nervous system have been gained attention. In this study, we systematically investigated the neuron toxicity of antibiotics from six different classes. We show that clinically relevant concentrations of metronidazole, tigecycline, azithromycin and clindamycin but not ampicillin or sulfamethoxazole induce apoptosis of human primary neuron cells and lines. Notably, tigecycline, azithromycin and clindamycin cause neuron cell oxidative damage whereas metronidazole has no effect on reactive oxygen species (ROS) production, suggesting that metronidazole induces neuron death via ROS-independent mechanism. Tigecycline, azithromycin and clindamycin induce mitochondrial dysfunctions via targeting different mitochondrial respiratory complexes, leading to mitochondrial membrane potential disruption and energy crisis. The deleterious effects of antibiotics are reversed by pretreatment of neuron cells with antioxidant. Our work highlights the different influences of antibiotics on mitochondrial dysfunction, oxidative damage and cytotoxicity in neuron cells. We also provide a strategy to prevent the neurotoxicity.

Protective effects of hawthorn (Crataegus pinnatifida) polyphenol extract against UVB-induced skin damage by modulating the p53 mitochondrial pathway in vitro and in vivo

This study investigated the effect of a hawthorn polyphenol extract (HPE) on ultraviolet B (UVB)-induced damage in HaCaT cells and mice. High-performance liquid chromatography/electrospray ionization tandem mass spectrometry was used to analyze the phenolic composition of HPE. The protective effects of HPE and its main components were compared in HaCaT cells. An enzyme-linked immunosorbent assay was used to detect DNA damage (8-hydroxydeoxyguanosine levels). Flow cytometry and western blotting were used to measure the extent of apoptosis and the levels of apoptosis-related proteins, respectively. Treatment with HPE or its polyphenol components inhibited the UVB-induced damage by removing an excess of reactive oxygen species (ROS), reducing DNA damage and p53 activation, regulating the protein expression of B-cell lymphoma 2 family members toward antiapoptotic ratios, and reducing caspase activation. Similar effects were observed in a UVB-irradiated mouse skin, as detected using terminal deoxynucleotidyl transferase dUTP nick-end labeling, immunohistochemistry, and western blotting assays. These results suggest that HPE can be used as a natural dietary supplement for the prevention and treatment of UVB radiation-induced skin damage. PRACTICAL APPLICATIONS: Hawthorn (Crataegus pinnatifida) shows antioxidant, anti-inflammatory, and lipid-lowering effects. As natural, healthy, and effective additives, HPEs have been widely used in food and health products. The results of this study reveal the molecular mechanisms underlying HPE effects, showing that HPE reverses the effects of UVB irradiation via removal of an excess of ROS and reduction of DNA damage and p53 expression in vitro and in vivo. Consequently, HPE upregulates the expression of antiapoptotic BCL-2 and downregulates that of proapoptotic BAX, thereby reducing the activation of caspase-3/9 and inhibiting apoptosis. These findings suggest that HPE can be used as the base ingredient for antiphotoaging food products. This study provides both theoretical and experimental background for hawthorn deep processing and utilization.

Cell Death Mechanisms of Neurodegeneration

There are common mechanisms shared by genetically or pathologically distinct neurodegenerative diseases, such as excitotoxicity, mitochondrial deficits and oxidative stress, protein misfolding and translational dysfunction, autophagy and microglia activation. This indicates that although the original cause may differ in individual diseases or even subtypes of certain disorders, these disrupted common cell functions and signaling, together with aging, may lead to final execution of cell death through similar pathways. The variable neurodegenerative disease symptoms are probably caused by the type, location, and connection of the cell populations that suffer from dysfunction and loss. Besides apoptosis, necroptosis, and autophagy, an important form of death termed parthanatos plays a prominent role in stroke and several neurodegenerative diseases, which is due to PARP-1 overactivation, PAR accumulation, nuclear translocation of the mitochondria protein AIF, and large-scale DNA cleavage. Understanding the mechanisms and interactions of cell death signaling will not only help to develop neuroprotective strategies to halt neurodegeneration, but also provide biomarkers for monitoring disease progression and recovery.

Hydrogen-rich saline protects rat from oxygen glucose deprivation and reperusion-induced apoptosis through VDAC1 via Bcl-2

BACKGROUND

Hydrogen is received as an inert gas that thought to be non-functional in vivo previously. Recently, emerging evidences showed that in ischemia/reperfusion (IR) condition, hydrogen reduced cellular reactive oxygen species (ROS) production and ameliorated cell apoptosis. However, the underlying mechanism of hydrogen on IR-induced apoptosis remains elusive. Here we tried to unravel the mode of action of hydrogen with rat adrenal medulla cell line PC-12 in vitro.

METHODS

The mitochondrial functions before and after oxygen glucose deprivation and reperfusion (OGD/RP) were determined with corresponding dyes. The expression of Bcl-2, Bax, VDAC1, cytochrome c and caspase 9 was detected using qRT-PCR and Western Blotting method. Then Bcl-2 inhibitor, AB-199, was applied to investigate the role of Bcl-2 in OGD/RP-induced cell apoptosis. Finally, we manipulated the expression of VDAC1 with plasmids transfection to understand the effects of VDAC1 on Bcl-2-mediated anti-apoptosis in OGD/RP.

RESULTS

In this study, we demonstrated that hydrogen-rich saline (HRS) reduced OGD/RP-mediated neuronal loss by stimulating the expression of Bcl-2, which suppressed the activity of VDAC1. Consequently, HRS maintained the mitochondrial functions, restrained the release of cytochrome c and caspase 9 activation, resulting in ameliorated cell viability.

CONCLUSIONS

HRS ameliorated OGD/RP-induced PC-12 cell apoptosis and provided a novel treatment option for ischemia.

Natural borneol is a novel chemosensitizer that enhances temozolomide-induced anticancer efficiency against human glioma by triggering mitochondrial dysfunction and reactive oxide species-mediated oxidative damage

Background

Temozolomide (TMZ)-based chemotherapy represents an effective way for treating human glioma. However, its clinical application is limited because of its side effects and resistance to standard chemotherapy. Hence, the search for novel chemosensitizers to augment their anticancer efficiency has attracted much attention. Natural borneol (NB) has been identified as a potential chemosensitizer in treating human cancers. However, the synergistic effect and mechanism of NB and TMZ in human glioma have not been investigated yet.

Materials and methods

U251 human glioma cells were cultured, and the cytotoxicity and apoptosis of NB and/or TMZ were examined by MTT assay, flow cytometric analysis and Western blot. Nude mice tumor model was also employed to evaluate the in vivo anticancer effect and mechanism.

Results

The results showed that the combined treatment of NB and TMZ more effectively inhibited human glioma growth via triggering mitochondria-mediated apoptosis in vitro, accompanied by the caspase activation. Combined treatment of NB and TMZ also caused mitochondrial dysfunction through disturbing Bcl-2 family expression. Further investigation revealed that NB enhanced TMZ-induced DNA damage through inducing reactive oxide species (ROS) overproduction. Moreover, glioma tumor xenograft growth in vivo was more effectively inhibited by the combined treatment with NB and TMZ through triggering apoptosis and anti-angiogenesis.

Conclusion

Taken together, our findings validated that the strategy of using NB and TMZ could be a highly efficient way to achieve anticancer synergism.

Antibiotic drug piperacillin induces neuron cell death through mitochondrial dysfunction and oxidative damage

Although nerve damage/toxicity has been shown to be one of the side effects in patients given prolonged antibiotic treatment, the mechanisms of the action of antibiotics on neuron cells are not clear. In this work, we investigated the toxicity of piperacillin (an antibiotic that can penetrate the blood–brain barrier) on neuron cells and its underlying mechanisms. We show that clinically relevant doses of piperacillin induce apoptosis in SH-SY5Y and human primary neuron cells through activating caspase-3 activity and decreasing Mcl-1 and Bcl-2 levels. In addition, piperacillin causes mitochondrial dysfunction in neuron cells as shown by the reduction of mitochondrial respiration, membrane potential, and ATP production. We further demonstrate that piperacillin increases accumulation of mitochondrial superoxide and reactive oxygen species, suggesting the oxidative stress in neuron cells. Consistently, oxidative damage to DNA, proteins, and membrane lipids are observed in neuron cells exposed to piperacillin. The deleterious effects of piperacillin are abolished in neuron cells by antioxidant N-acetyl-l-cysteine, further confirming that piperacillin causes neuron cell death through inducing mitochondrial dysfunction and oxidative damage. Our work demonstrates the role of piperacillin in inducing oxidative damage in neuron cells and also provides a therapeutic strategy to prevent the side effects of antibiotic treatment.

Targeting Sentinel Proteins and Extrasynaptic Glutamate Receptors: a Therapeutic Strategy for Preventing the Effects Elicited by Perinatal Asphyxia?

Perinatal asphyxia (PA) is a relevant cause of death at the time of labour, and when survival is stabilised, associated with short- and long-term developmental disabilities, requiring inordinate care by health systems and families. Its prevalence is high (1 to 10/1000 live births) worldwide. At present, there are few therapeutic options, apart from hypothermia, that regrettably provides only limited protection if applied shortly after the insult.PA implies a primary and a secondary insult. The primary insult relates to the lack of oxygen, and the secondary one to the oxidative stress triggered by re-oxygenation, formation of reactive oxygen (ROS) and reactive nitrogen (RNS) species, and overactivation of glutamate receptors and mitochondrial deficiencies. PA induces overactivation of a number of sentinel proteins, including hypoxia-induced factor-1α (HIF-1α) and the genome-protecting poly(ADP-ribose) polymerase-1 (PARP-1). Upon activation, PARP-1 consumes high amounts of ATP at a time when this metabolite is scarce, worsening in turn the energy crisis elicited by asphyxia. The energy crisis also impairs ATP-dependent transport, including glutamate re-uptake by astroglia. Nicotinamide, a PARP-1 inhibitor, protects against the metabolic cascade elicited by the primary stage, avoiding NAD+ exhaustion and the energetic crisis. Upon re-oxygenation, however, oxidative stress leads to nuclear translocation of the NF-κB subunit p65, overexpression of the pro-inflammatory cytokines IL-1β and TNF-α, and glutamate-excitotoxicity, due to impairment of glial-glutamate transport, extracellular glutamate overflow, and overactivation of NMDA receptors, mainly of the extrasynaptic type. This leads to calcium influx, mitochondrial impairment, and inactivation of antioxidant enzymes, increasing further the activity of pro-oxidant enzymes, thereby making the surviving neonate vulnerable to recurrent metabolic insults whenever oxidative stress is involved. Here, we discuss evidence showing that (i) inhibition of PARP-1 overactivation by nicotinamide and (ii) inhibition of extrasynaptic NMDA receptor overactivation by memantine can prevent the short- and long-term consequences of PA. These hypotheses have been evaluated in a rat preclinical model of PA, aiming to identify the metabolic cascades responsible for the long-term consequences induced by the insult, also assessing postnatal vulnerability to recurrent oxidative insults. Thus, we present and discuss evidence demonstrating that PA induces long-term changes in metabolic pathways related to energy and oxidative stress, priming vulnerability of cells with both the neuronal and the glial phenotype. The effects induced by PA are region dependent, the substantia nigra being particularly prone to cell death. The issue of short- and long-term consequences of PA provides a framework for addressing a fundamental issue referred to plasticity of the CNS, since the perinatal insult triggers a domino-like sequence of events making the developing individual vulnerable to recurrent adverse conditions, decreasing his/her coping repertoire because of a relevant insult occurring at birth.

Changes in PPARδ expression in a rat model of stress-induced depression

Depression is a common mental disorder that has been linked to a decrease in the expression of serotonin and/or the serotonin transporter in the brain. Antidepressants that target the monoaminergic system are widely used in the clinical setting. Peroxisome proliferator-activated receptor δ (PPAR δ) overexpression or activation is thought to improve depression-like behaviours in rodents. The present study was designed to characterize the changes in PPARδ expression in the hippocampus in rats with stress-induced depression. We used an unpredictable chronic mild stress (CMS) model in rats to study the role of PPARδ in the hippocampus. Behaviour was evaluated via a forced swim test (FST), a tail suspension test (TST), and a sucrose preference test (SPT). Then, the changes in PPARδ expression and other signals were determined using Western blots. We found that PPARδ expression in the hippocampus was markedly reduced in rats with depression. Moreover, the expression of the serotonin transporter was also significantly decreased. Treatment with a PPARδ agonist enhanced the expression of PPARδ and the serotonin transporter in the hippocampus of rats with stress-induced depression. Additionally, treatment with a PPARδ agonist increased the expression of the serotonin transporter in cultured hippocampal (H19-7) cells, and this action was ablated in the absence of PPARδ, which was attenuated with shRNA. Taken together, we found that PPARδ plays an important role in the regulation of serotonin transporter expression and that chronic stress may lower PPARδ expression in the brain via apoptosis and may attenuate serotonin transporter expression, thus inducing depression in rats.

Cell Death in the Developing Brain after Hypoxia-Ischemia

Perinatal insults such as hypoxia–ischemia induces secondary brain injury. In order to develop the next generation of neuroprotective therapies, we urgently need to understand the underlying molecular mechanisms leading to cell death. The cell death mechanisms have been shown to be quite different in the developing brain compared to that in the adult. The aim of this review is update on what cell death mechanisms that are operating particularly in the setting of the developing CNS. In response to mild stress stimuli a number of compensatory mechanisms will be activated, most often leading to cell survival. Moderate-to-severe insults trigger regulated cell death. Depending on several factors such as the metabolic situation, cell type, nature of the stress stimulus, and which intracellular organelle(s) are affected, the cell undergoes apoptosis (caspase activation) triggered by BAX dependent mitochondrial permeabilzation, necroptosis (mixed lineage kinase domain-like activation), necrosis (via opening of the mitochondrial permeability transition pore), autophagic cell death (autophagy/Na⁺, K⁺-ATPase), or parthanatos (poly(ADP-ribose) polymerase 1, apoptosis-inducing factor). Severe insults cause accidental cell death that cannot be modulated genetically or by pharmacologic means. However, accidental cell death leads to the release of factors (damage-associated molecular patterns) that initiate systemic effects, as well as inflammation and (regulated) secondary brain injury in neighboring tissue. Furthermore, if one mode of cell death is inhibited, another route may step in at least in a scenario when upstream damaging factors predominate over protective responses. The provision of alternative routes through which the cell undergoes death has to be taken into account in the hunt for novel brain protective strategies.

Critical role of EphA4 in early brain injury after subarachnoid hemorrhage in rat

Early brain injury (EBI) is reported as a primary cause of mortality in subarachnoid hemorrhage (SAH) patients. Eph receptor A4 (EphA4) has been associated with blood-brain barrier integrity and pro-apoptosis. We aimed to investigate a role of EphA4 in EBI after SAH. One hundred and seventy-nine male adult Sprague-Dawley rats were randomly divided into sham versus endovascular perforation model of SAH groups. SAH grade, neurological score, Evans blue dye extravasation, brain water content, mortality, Fluoro-Jade staining, immunofluorescence staining, and western blot experiments were performed after SAH. Small interfering RNA (siRNA) for EphA4, recombinant Ephexin-1 (rEphx-1), and Fasudil, a potent ROCK2 inhibitor, were used for intervention to study a role of EphA4 on EBI after SAH. The expression of EphA4, Ephexin-1, RhoA, and ROCK2 significantly increased after SAH. Knockdown of EphA4 using EphA4 siRNA injection intracerebroventricularly (i.c.v) reduced Evans blue extravasation, decreased brain water content, and alleviated neurobehavioral dysfunction after SAH. Additionally, the expression of Ephexin-1, RhoA, ROCK2 and cleaved caspase-3 were decreased. Tight junction proteins increased, and apoptotic neuron death decreased. The effects of EphA4 siRNA were abolished by rEphx-1. In contrast, Fasudil abolished the effects of rEphx-1. These results suggest that EphA4, a novel and promising target for treatment, exacerbates EBI through an Ephexin-1/ROCK2 pathway after SAH.

Potential Therapeutic Benefits of Maintaining Mitochondrial Health in Peripheral Neuropathies

Background: Peripheral neuropathies are a group of diseases characterized by malfunctioning of peripheral nervous system. Neuropathic pain, one of the core manifestations of peripheral neuropathy remains as the most severe disabling condition affecting the social and daily routine life of patients suffering from peripheral neuropathy.

Method: The current review is aimed at unfolding the possible role of mitochondrial dysfunction in peripheral nerve damage and to discuss on the probable therapeutic strategies against neuronal mitotoxicity. The article also highlights the therapeutic significance of maintaining a healthy mitochondrial environment in neuronal cells via pharmacological management in context of peripheral neuropathies.

Results: Aberrant cellular signaling coupled with changes in neurotransmission, peripheral and central sensitization are found to be responsible for the pathogenesis of variant toxic neuropathies. Current research reports have indicated the possible involvement of mitochondria mediated redox imbalance as one of the principal causes of neuropathy aetiologies. In addition to imbalance in redox homeostasis, mitochondrial dysfunction is also responsible for alterations in physiological bioenergetic metabolism, apoptosis and autophagy pathways.

Conclusions: In spite of various etiological factors, mitochondrial dysfunction has been found to be a major pathomechanism underlying the neuronal dysfunction associated with peripheral neuropathies. Pharmacological modulation of mitochondria either directly or indirectly is expected to yield therapeutic relief from various primary and secondary mitochondrial diseases.

Potential role of Apoptosis Inducing Factor in evolutionarily significant eukaryote, Dictyostelium discoideum survival

Apoptosis Inducing Factor (AIF), a phylogenetically conserved mitochondrial inter-membrane space flavoprotein has an important role in caspase independent cell death. Nevertheless, AIF is also essential for cell survival. It is required for mitochondrial organization and energy metabolism. Upon apoptotic stimulation, AIF induces DNA fragmentation after its mitochondrio-nuclear translocation. Although it executes critical cellular functions in a coordinated manner, the exact mechanism still remains obscure. The present study aims to understand AIF's role in cell survival, growth and development by its down-regulation in an interesting unicellular eukaryote, D. discoideum which exhibits multicellularity upon starvation. Constitutive AIF down-regulated (dR) cells exhibited slower growth and delayed developmental morphogenesis. Also, constitutive AIF dR cells manifested high intracellular ROS, oxidative DNA damage and calcium levels with lower ATP content. Interestingly, constitutive AIF dR cells showed amelioration in cell growth upon antioxidant treatment, strengthening its role as ROS regulator. Under oxidative stress, AIF dR cells showed early mitochondrial membrane depolarization followed by AIF translocation from mitochondria to nucleus and exhibited necrotic cell death as compared to paraptoptic cell death of control cells. Thus, the results of this study provide an exemplar where AIF is involved in growth and development by regulating ROS levels and maintaining mitochondrial function in D. discoideum, an evolutionarily significant model organism exhibiting caspase independent apoptosis.

Lycium barbarum polysaccharides attenuates N-methy-N-nitrosourea-induced photoreceptor cell apoptosis in rats through regulation of poly (ADP-ribose) polymerase and caspase expression

ETHNOPHARMACOLOGICAL RELEVANCE

Lycium barbarum L., popularly known as "Goji berry", a classic of Traditional Chinese Medicine has long been used to treat ocular diseases and cardiovascular diseases. Recently, the photoreceptor cell protection of Lycium barbarum polysaccharides (LBP), a water extract from Lycium barbarum L. has received more attention. The present study was designed to investigate the effect of LBP on N-methyl-N-nitrosourea (MNU)-induced photoreceptor cell apoptosis, and the involvement of the poly (ADP-ribose) polymerase (PARP) and caspase.

MATERIALS AND METHODS

Photoreceptor cell injury was induced in male Sprague-Dawley rats by an intraperitoneal injection of MNU 60mg/kg. Seven days prior to MNU injection, LBP were intragastrical administered daily, rats were sacrificed at 24h and 7 days after MNU injection. Retinal morphologies, photoreceptor cells apoptosis, and protein expression were evaluated at 24h and 7 days after MNU injection.

RESULTS

Morphologically, the outer nuclear layer was well preserved in the LBP-treated rat retinas throughout the experimental period. Terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-digoxigenin nick-end labeling (TUNEL) assays showed that LBP could significantly suppress the loss of photoreceptor cells, as determined by the photoreceptor cell ratio at the central retina 24h and 7 days after MNU administration. Western-blot analysis demonstrated the expression levels of procaspase-9, -7, -3 and cleaved caspase-9, -7, -3 were upregulated, and PARP were downregulated both 24h and 7 days after MNU injection. LBP treatment significantly decreased protein levels of procaspase and cleaved caspase, increased the level of PARP and cleaved PARP on 24h and 7 days.

CONCLUSIONS

LBP inhibits MNU-induced rat photoreceptor cell apoptosis and protects retinal structure via the regulation of the expressions of PARP and caspase.

PKD signaling and pancreatitis

BACKGROUND

Acute pancreatitis is a serious medical disorder with no current therapies directed to the molecular pathogenesis of the disorder. Inflammation, inappropriate intracellular activation of digestive enzymes, and parenchymal acinar cell death by necrosis are the critical pathophysiologic processes of acute pancreatitis. Thus, it is necessary to elucidate the key molecular signals that mediate these pathobiologic processes and develop new therapeutic strategies to attenuate the appropriate signaling pathways in order to improve outcomes for this disease. A novel serine/threonine protein kinase D (PKD) family has emerged as key participants in signal transduction, and this family is increasingly being implicated in the regulation of multiple cellular functions and diseases.

METHODS

This review summarizes recent findings of our group and others regarding the signaling pathway and the biological roles of the PKD family in pancreatic acinar cells. In particular, we highlight our studies of the functions of PKD in several key pathobiologic processes associated with acute pancreatitis in experimental models.

RESULTS

Our findings reveal that PKD signaling is required for NF-κB activation/inflammation, intracellular zymogen activation, and acinar cell necrosis in rodent experimental pancreatitis. Novel small-molecule PKD inhibitors attenuate the severity of pancreatitis in both in vitro and in vivo experimental models. Further, this review emphasizes our latest advances in the therapeutic application of PKD inhibitors to experimental pancreatitis after the initiation of pancreatitis.

CONCLUSIONS

These novel findings suggest that PKD signaling is a necessary modulator in key initiating pathobiologic processes of pancreatitis, and that it constitutes a novel therapeutic target for treatments of this disorder.

Tozasertib attenuates neuronal apoptosis via DLK/JIP3/MA2K7/JNK pathway in early brain injury after SAH in rats

BACKGROUND AND PURPOSE

Since tozasertib is neuroprotective for injured optic nerve, this study is intended to test whether tozasertib reduces early brain injury after subarachnoid hemorrhage (SAH) in a rat model.

METHODS

Two hundred sixteen (216) male Sprague-Dawley rats were randomly subjected to endovascular perforation model of SAH and sham group. SAH grade, neurological score, and brain water content were measured at 24 and 72 h after SAH. Dual leucine zipper kinase (DLK) and its downstream factors, JNK-interacting protein 3 (JIP3), MA2K7, p-JNK/JNK (c-Jun N-terminal kinase), and apoptosis related proteins cleaved caspase-3 (CC-3), Bim, Bcl-2, and cleaved caspase-9 (CC-9) were analyzed by western blot at 24 h after SAH. Apoptotic cells were detected by terminal deoxynucleotid transferase-deoxyuridine triphosphate (dUTP) nick end labeling (TUNEL). DLK small interfering RNA (siRNA), JIP3 siRNA and MA2K7 siRNA, the JNK, p38MAPK, and MEK inhibitors SP600125, SB203580, and PD98059 were used for intervention.

RESULTS

Tozasertib reduced neuronal apoptosis, attenuated brain edema and improved neurobehavioral deficits 24 and 72 h after SAH. At 24 h After SAH, DLK/JIP3/MA2K7/p-JNK/CC-3 expressions were elevated markedly and tozasertib reduced DLK, MA2K7/p-JNK/CC-3 expressions but enhanced JIP3 expression. In the presence of tozasertib, DLK/JIP3/MA2K7 siRNA and SP600125, SB203580 and PD98059 deteriorated the neurobehavioral deficits, brain edema and increased the expression of CC-3. SAH potentiated the expression of Bim, CC-9, and CC-3 but reduced Bcl-2, while tozasertib reduced expression of Bim, CC-9, and CC-3 but enhanced Bcl-2.

CONCLUSIONS

Tozasertib reduced neuronal apoptosis and improved outcome possibly via DLK/JIP3/MA2K7/JNK pathways after SAH.

Trim69 regulates zebrafish brain development by ap-1 pathway

Proteins belonging to the TRIM family have been implicated in a variety of cellular processes such as apoptosis, differentiation, neurogenesis, muscular physiology and innate immune responses. Trim69, previously identified as a novel gene cloned from a human testis cDNA library, has a homologous gene in zebrafish and this study focused on investigating the function of trim69 in zebrafish neurogenesis. Trim69 was found to be expressed in zebrafish embryo brain at the early stages. Knockdown of trim69 led to deformed brain development, obvious signs of apoptosis present in the head, and decreased expression of neuronal differentiation and stem cell markers. This phenotype was rescued upon co-injection of human mRNA together along with the trim69 knockdown. Results of this study also showed an interaction between TRIM69 and c-Jun in human cells, and upon TRIM69 knock down c-Jun expression subsequently increased, whereas the over-expression of TRIM69 led to the down-regulation of c-Jun. Additionally, knockdown both c-Jun and trim69 can rescue the deformed brain, evident cellular apoptosis in the head and decreased expression of neuronal differentiation and stem cell markers. Overall, our results support a role for trim69 in the development of the zebrafish brain through ap-1 pathway.

Maternal Omega-3 Supplement Improves Dopaminergic System in Pre- and Postnatal Inflammation-Induced Neurotoxicity in Parkinson's Disease Model

Evidence suggests that idiopathic Parkinson's disease (PD) is the consequence of a neurodevelopmental disruption, rather than strictly a consequence of aging. Thus, we hypothesized that maternal supplement of omega-3 polyunsaturated fatty acids (ω-3 PUFA) may be associated with neuroprotection mechanisms in a self-sustaining cycle of neuroinflammation and neurodegeneration in lipopolysaccharide (LPS)-model of PD. To test this hypothesis, behavioral and neurochemical assay were performed in prenatally LPS-exposed offspring at postnatal day 21. To further determine whether prenatal LPS exposure and maternal ω-3 PUFAs supplementation had persisting effects, brain injury was induced on PN 90 rats, following bilateral intranigral LPS injection. Pre- and postnatal inflammation damage not only affected dopaminergic neurons directly, but it also modified critical features, such as activated microglia and astrocyte cells, disrupting the support provided by the microenvironment. Unexpectedly, our results failed to show any involvement of caspase-dependent and independent apoptosis pathway in neuronal death mechanisms. On the other hand, learning and memory deficits detected with a second toxic exposure were significantly attenuated in maternal ω-3 PUFAs supplementation group. In addition, ω-3 PUFAs promote beneficial effect on synaptic function, maintaining the neurochemical integrity in remaining neurons, without necessarily protect them from neuronal death. Thus, our results suggest that ω-3 PUFAs affect the functional ability of the central nervous system in a complex way in a multiple inflammation-induced neurotoxicity animal model of PD and they disclose new ways of understanding how these fatty acids control responses of the brain to different challenges.

Key Role of the Adenylate Moiety and Integrity of the Adenylate-Binding Site for the NAD(+)/H Binding to Mitochondrial Apoptosis-Inducing Factor

Apoptosis-inducing factor (AIF) is a mitochondrial flavoprotein with pro-life and pro-death activities, which plays critical roles in mitochondrial energy metabolism and caspase-independent apoptosis. Defects in AIF structure or expression can cause mitochondrial abnormalities leading to mitochondrial defects and neurodegeneration. The mechanism of AIF-induced apoptosis was extensively investigated, whereas the mitochondrial function of AIF is poorly understood. A unique feature of AIF is the ability to form a tight, air-stable charge-transfer (CT) complex upon reaction with NADH and to undergo a conformational switch leading to dimerization, proposed to be important for its vital and lethal functions. Although some aspects of interaction of AIF with NAD(+)/H have been analyzed, its precise mechanism is not fully understood. We investigated how the oxidized and photoreduced wild-type and G307A and -E variants of murine AIF associate with NAD(+)/H and nicotinamide mononucleotide (NMN(+)/H) to determine the role of the adenylate moiety in the binding process. Our results indicate that (i) the adenylate moiety of NAD(+)/H is crucial for the association with AIF and for the subsequent structural reorganization of the complex, but not for protein dimerization, (ii) FAD reduction rather than binding of NAD(+)/H to AIF initiates conformational rearrangement, and (iii) alteration of the adenylate-binding site by the G307E (equivalent to a pathological G308E mutation in human AIF) or G307A replacements decrease the affinity and association rate of NAD(+)/H, which, in turn, perturbs CT complex formation and protein dimerization but has no influence on the conformational switch in the regulatory peptide.

Ovarian steroids regulate gene expression related to DNA repair and neurodegenerative diseases in serotonin neurons of macaques

Depression often accompanies the perimenopausal transition and it often precedes overt symptomology in common neurodegenerative diseases (NDDs, such as Alzheimer's, Parkinson's, Huntington, amyotrophic lateral sclerosis). Serotonin dysfunction is frequently found in the different etiologies of depression. We have shown that ovariectomized (Ovx) monkeys treated with estradiol (E) for 28 days supplemented with placebo or progesterone (P) on days 14-28 had reduced DNA fragmentation in serotonin neurons of the dorsal raphe nucleus, and long-term Ovx monkeys had fewer serotonin neurons than intact controls. We questioned the effect of E alone or E+P (estradiol supplemented with progesterone) on gene expression related to DNA repair, protein folding (chaperones), the ubiquitin-proteosome, axon transport and NDD-specific genes in serotonin neurons. Ovx macaques were treated with placebo, E or E+P (n=3 per group) for 1 month. Serotonin neurons were laser captured and subjected to microarray analysis and quantitative real-time PCR (qRT-PCR). Increases were confirmed with qRT-PCR in five genes that code for proteins involved in repair of strand breaks and nucleotide excision. NBN1, PCNA (proliferating nuclear antigen), GADD45A (DNA damage-inducible), RAD23A (DNA damage recognition) and GTF2H5 (gene transcription factor 2H5) significantly increased with E or E+P treatment (all analysis of variance (ANOVA), P<0.01). Chaperone genes HSP70 (heat-shock protein 70), HSP60 and HSP27 significantly increased with E or E+P treatment (all ANOVA, P<0.05). HSP90 showed a similar trend. Ubiquinase coding genes UBEA5, UBE2D3 and UBE3A (Parkin) increased with E or E+P (all ANOVA, P<0.003). Transport-related genes coding kinesin, dynein and dynactin increased with E or E+P treatment (all ANOVA, P<0.03). SCNA (α-synuclein) and ADAM10 (α-secretase) increased (both ANOVA, P<0.02) but PSEN1 (presenilin1) decreased (ANOVA, P<0.02) with treatment. APP decreased 10-fold with E or E+P administration. Newman-Keuls post hoc comparisons indicated variation in the response to E alone versus E+P across the different genes. In summary, E or E+P increased gene expression for DNA repair mechanisms in serotonin neurons, thereby rendering them less vulnerable to stress-induced DNA fragmentation. In addition, E or E+P regulated four genes encoding proteins that are often misfolded or malfunctioning in neuronal populations subserving overt NDD symptomology. The expression and regulation of these genes in serotonergic neurons invites speculation that they may mediate an underlying disease process in NDDs, which in turn may be ameliorated or delayed with timely hormone therapy in women.

Mitochondria: key players in the neurotoxic effects of amphetamines

Amphetamines are a class of psychotropic drugs with high abuse potential, as a result of their stimulant, euphoric, emphathogenic, entactogenic, and hallucinogenic properties. Although most amphetamines are synthetic drugs, of which methamphetamine, amphetamine, and 3,4-methylenedioxymethamphetamine ("ecstasy") represent well-recognized examples, the use of natural related compounds, namely cathinone and ephedrine, has been part of the history of humankind for thousands of years. Resulting from their amphiphilic nature, these drugs can easily cross the blood-brain barrier and elicit their well-known psychotropic effects. In the field of amphetamines' research, there is a general consensus that mitochondrial-dependent pathways can provide a major understanding concerning pathological processes underlying the neurotoxicity of these drugs. These events include alterations on tricarboxylic acid cycle's enzymes functioning, inhibition of mitochondrial electron transport chain's complexes, perturbations of mitochondrial clearance mechanisms, interference with mitochondrial dynamics, as well as oxidative modifications in mitochondrial macromolecules. Additionally, other studies indicate that amphetamines-induced neuronal toxicity is closely regulated by B cell lymphoma 2 superfamily of proteins with consequent activation of caspase-mediated downstream cell death pathway. Understanding the molecular mechanisms at mitochondrial level involved in amphetamines' neurotoxicity can help in defining target pathways or molecules mediating these effects, as well as in developing putative therapeutic approaches to prevent or treat the acute- or long-lasting neuropsychiatric complications seen in human abusers.

Celastrol induces apoptosis and autophagy via the ROS/JNK signaling pathway in human osteosarcoma cells: an in vitro and in vivo study

Osteosarcoma is the most common primary malignant tumor of bone, the long-term survival of which has stagnated in the past several decades. Celastrol, a triterpene from traditional Chinese medicine, has been proved to possess potent anti-tumor effect on various cancers. However, the effect of celastrol on human osteosarcoma and the underlying mechanisms remains to be elucidated. We reported here that celastrol could inhibit cell proliferation by causing G2/M phase arrest. Exposure to celastrol resulted in the activation of caspase-3, -8, and -9, indicating that celastrol induced apoptosis through both extrinsic and intrinsic pathways. Autophagy occurred in celastrol-treated cells as evidenced by formation of autophagosome and accumulation of LC3B-II. The celastrol-induced cell death was remarkably restored by the combination of autophagy and apoptosis inhibitors. Furthermore, inhibition of apoptosis enhanced autophagy while suppression of autophagy diminished apoptosis. Celastrol also induced JNK activation and ROS generation. The JNK inhibitor significantly attenuated celastrol-triggered apoptosis and autophagy while ROS scavenger could completely reverse them. The ROS scavenger also prevented G2/M phase arrest and phosphorylation of JNK. Importantly, we found that celastrol had the similar effects on primary osteosarcoma cells. Finally, in vivo, celastrol suppressed tumor growth in the mouse xenograft model. Taken together, our results revealed that celastrol caused G2/M phase arrest, induced apoptosis and autophagy via the ROS/JNK signaling pathway in human osteosarcoma cells. Celastrol is therefore a promising candidate for development of antitumor drugs targeting osteosarcoma.

Oxidative stress associated with neuronal apoptosis in experimental models of epilepsy

Epilepsy is considered one of the most common neurological disorders worldwide. Oxidative stress produced by free radicals may play a role in the initiation and progression of epilepsy; the changes in the mitochondrial and the oxidative stress state can lead mechanism associated with neuronal death pathway. Bioenergetics state failure and impaired mitochondrial function include excessive free radical production with impaired synthesis of antioxidants. This review summarizes evidence that suggest what is the role of oxidative stress on induction of apoptosis in experimental models of epilepsy.

Strategy to Suppress Oxidative Damage-Induced Neurotoxicity in PC12 Cells by Curcumin: the Role of ROS-Mediated DNA Damage and the MAPK and AKT Pathways

Oxidative damage plays a key role in causation and progression of neurodegenerative diseases. Inhibition of oxidative stress represents one of the most effective ways in treating human neurologic diseases. Herein, we evaluated the protective effect of curcumin on PC12 cells against H2O2-induced neurotoxicity and investigated its underlying mechanism. The results indicated that curcumin pre-treatment significantly suppressed H2O2-induced cytotoxicity, inhibited the loss of mitochondrial membrane potential (Δψm) through regulation of Bcl-2 family expression, and ultimately reversed H2O2-induced apoptotic cell death in PC12 cells. Attenuation of caspase activation, poly(ADP-ribose) polymerase (PARP) cleavage, DNA damage, and accumulation of reactive oxygen species (ROS) all confirmed its protective effects. Moreover, curcumin markedly alleviated the dysregulation of the MAPK and AKT pathways induced by H2O2. Taken together, our findings suggest that the strategy of using curcumin could be a highly effective way in combating oxidative damage-mediated human neurodegenerative diseases.

Genetic inhibition of protein kinase Cε attenuates necrosis in experimental pancreatitis

Understanding the regulation of death pathways, necrosis and apoptosis, in pancreatitis is important for developing therapies directed to the molecular pathogenesis of the disease. Protein kinase Cε (PKCε) has been previously shown to regulate inflammatory responses and zymogen activation in pancreatitis. Furthermore, we demonstrated that ethanol specifically activated PKCε in pancreatic acinar cells and that PKCε mediated the sensitizing effects of ethanol on inflammatory response in pancreatitis. Here we investigated the role of PKCε in the regulation of death pathways in pancreatitis. We found that genetic deletion of PKCε resulted in decreased necrosis and severity in the in vivo cerulein-induced pancreatitis and that inhibition of PKCε protected the acinar cells from CCK-8 hyperstimulation-induced necrosis and ATP reduction. These findings were associated with upregulation of mitochondrial Bak and Bcl-2/Bcl-xL, proapoptotic and prosurvival members in the Bcl-2 family, respectively, as well as increased mitochondrial cytochrome c release, caspase activation, and apoptosis in pancreatitis in PKCε knockout mice. We further confirmed that cerulein pancreatitis induced a dramatic mitochondrial translocation of PKCε, suggesting that PKCε regulated necrosis in pancreatitis via mechanisms involving mitochondria. Finally, we showed that PKCε deletion downregulated inhibitors of apoptosis proteins, c-IAP2, survivin, and c-FLIPs while promoting cleavage/inactivation of receptor-interacting protein kinase (RIP). Taken together, our findings provide evidence that PKCε activation during pancreatitis promotes necrosis through mechanisms involving mitochondrial proapoptotic and prosurvival Bcl-2 family proteins and upregulation of nonmitochondrial pathways that inhibit caspase activation and RIP cleavage/inactivation. Thus PKCε is a potential target for prevention and/or treatment of acute pancreatitis.