Benzothiazole aniline tetra(ethylene glycol) and 3-amino-1,2,4-triazole inhibit neuroprotection against amyloid peptides by catalase overexpression in vitro

Impose of KNDy/GnRH neural circuit in PCOS, ageing, cancer and Alzheimer's disease: StAR actions in prevention of neuroendocrine dysfunction

The Kisspeptin1 (KISS1)/neurokinin B (NKB)/Dynorphin (Dyn) [KNDy] neurons in the hypothalamus regulate the reproduction stage in human beings and rodents. KNDy neurons co-expressed all KISS1, NKB, and Dyn peptides, and hence commonly regarded as KISS1 neurons. KNDy neurons contribute to the "GnRH pulse generator" and are implicated in the regulation of pulsatile GnRH release. The estradiol (E2)-estrogen receptor (ER) interactions over GnRH neurons in the hypothalamus cause nitric oxide (NO) discharge, in addition to presynaptic GABA and glutamate discharge from respective neurons. The released GABA and glutamate facilitate the activity of GnRH neurons via GABAA-R and AMPA/kainate-R. The KISS1 stimulates MAPK/ERK1/2 signaling and cause the release of Ca2+ from intracellular store, which contribute to neuroendocrine function, increase apoptosis and decrease cell proliferation and metastasis. The ageing in women deteriorates KISS1/KISS1R interaction in the hypothalamus which causes lower levels of GnRH. Because examining the human brain is so challenging, decades of clinical research have failed to find the causes of KNDy/GnRH dysfunction. The KISS1/KISS1R interactions in the brain have a neuroprotective effect against Alzheimer's disease (AD). These findings modulate the pathophysiological role of the KNDy/GnRH neural network in polycystic ovarian syndrome (PCOS) associated with ageing and, its protective role in cancer and AD. This review concludes with protecting effect of the steroid-derived acute regulatory enzyme (StAR) against neurotoxicity in the hippocampus, and hypothalamus, and these measures are fundamental for delaying ageing with PCOS. StAR could serve as novel diagnostic marker and therapeutic target for the most prevalent hormone-sensitive breast cancers (BCs).

The SH-SY5Y human neuroblastoma cell line, a relevant in vitro cell model for investigating neurotoxicology in human: focus on organic pollutants

Investigation of the toxicity triggered by chemicals on the human brain has traditionally relied on approaches using rodent in vivo models and in vitro cell models including primary neuronal cultures and cell lines from rodents. The issues of species differences between humans and rodents, the animal ethical concerns and the time and cost required for neurotoxicity studies on in vivo animal models, do limit the use of animal-based models in neurotoxicology. In this context, human cell models appear relevant in elucidating cellular and molecular impacts of neurotoxicants and facilitating prioritization of in vivo testing. The SH-SY5Y human neuroblastoma cell line (ATCC® CRL-2266^TM) is one of the most used cell lines in neurosciences, either undifferentiated or differentiated into neuron-like cells. This review presents the characteristics of the SH-SY5Y cell line and proposes the results of a systematic review of literature on the use of this in vitro cell model for neurotoxicity research by focusing on organic environmental pollutants including pesticides, 2, 3, 7, 8-tetrachlorodibenzo-p-dioxin (TCDD), flame retardants, PFASs, parabens, bisphenols, phthalates, and PAHs. Organic environmental pollutants are widely present in the environment and increasingly known to cause clinical neurotoxic effects during fetal & child development and adulthood. Their effects on cultured SH-SY5Y cells include autophagy, cell death (apoptosis, pyroptosis, necroptosis, or necrosis), increased oxidative stress, mitochondrial dysfunction, disruption of neurotransmitter homeostasis, and alteration of neuritic length. Finally, the inherent advantages and limitations of the SH-SY5Y cell model are discussed in the context of chemical testing.

Fracture repair by IOX2: Regulation of the hypoxia inducible factor-1α signaling pathway and BMSCs

The treatment of fracture delayed union and nonunion has become a challenging problem. Hypoxia inducible factor-1α (HIF-1α) is reported to be a key factor in fracture healing, and is degraded by hydroxylation of prolyl hydroxylase (PHDs) under normal oxygen. Small molecules could inhibit the activity of PHDs, stabilize HIF-1α protein, regulate the expression of downstream target genes of HIF-1α, and make the body adapt to hypoxia. The migration and osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) is the most promising candidate for the treatment of fracture nonunion. Here we reported that IOX2, an HIF-1α PHD inhibitor, markedly improved the proliferation and migration of BMSCs by upregulating intracellular Ca²⁺ and concomitant decreasing reactive oxygen species (ROS) in vitro, and facilitated the repair of bone fracture by increasing the number of BMSCs and cartilage formation in vivo. No significant influence of IOX2 on the proliferation and migration of BMSCs after silencing of the HIF-1α. Together, our findings indicated that IOX2 promoted the proliferation and migration of BMSCs via the HIF-1α pathway and further accelerated fracture healing. These results provide a deeper understanding of the mechanism by which HIF promotes fracture healing.

Endocrine disruptors also function as nervous disruptors and can be renamed endocrine and nervous disruptors (ENDs)

Endocrine disruption (ED) and endocrine disruptors (EDs) emerged as scientific concepts in 1995, after numerous chemical pollutants were found to be responsible for reproductive dysfunction. The World Health Organization established in the United Nations Environment Programme a list of materials, plasticizers, pesticides, and various pollutants synthesized from petrochemistry that impact not only reproduction, but also hormonal functions, directly or indirectly. Cells communicate via either chemical or electrical signals transmitted within the endocrine or nervous systems. To investigate whether hormone disruptors may also interfere directly or indirectly with the development or functioning of the nervous system through either a neuroendocrine or a more general mechanism, we examined the scientific literature to ascertain the effects of EDs on the nervous system, specifically in the categories of neurotoxicity, cognition, and behaviour. To date, we demonstrated that all of the 177 EDs identified internationally by WHO are known to have an impact on the nervous system. Furthermore, the precise mechanisms underlying this neurodisruption have also been established. It was previously believed that EDs primarily function via the thyroid. However, this study presents substantial evidence that approximately 80 % of EDs operate via other mechanisms. It thus outlines a novel concept: EDs are also neurodisruptors (NDs) and can be collectively termed endocrine and nervous disruptors (ENDs). Most of ENDs are derived from petroleum residues, and their various mechanisms of action are similar to those of "spam" in electronic communications technologies. Therefore, ENDs can be considered as an instance of spam in a biological context.

Synthesis, in vitro and structural aspects of benzothiazole analogs as anti-oxidants and potential neuroprotective agents

Catalase, an important antioxidant enzyme, is known to have a neuroprotective role against neurodegenerative disorder. Earlier study has focussed on benzothiazole-triazole hybrid molecules that are larger in size and molecular weight and inhibit the amyloid β (Aβ)-catalase interaction thus aid in neuroprotection. Here we have synthesized the novel benzothiazole molecules with low molecular weight using One-pot methodology and assayed the neuroprotective effects of the synthesized compounds in the U87 MG cell line under H₂O₂ induced stressed condition and compared with other cell lines such as breast cancer (MCF-7) and macrophage (RAW-264.7) using cell viability assay. These analogs were found to enhance the neuronal cell viability and protect neuronal cells from the ROS mediated neuronal damage induced by H₂O₂. Furthermore, compounds 6a, 6b, 6c, 6d, and 7a modulate catalase and enhanced the catalase activity up to 90 % during the H₂O₂ exposure in the U87MG cell line. These analogs (6a, 6b, 6c and 6d) have exhibited strong binding energies of -7.39, -7.52, -6.5 and -7.1 as observed by molecular modeling studies using AutoDockTool-1.5.6. Lig Plot + program using potent analogs 6b and 6c and catalase enzyme indicated the presence of hydrophobic interactions in the catalytic site of catalase enzyme. Furthermore, a simulation study was conducted between ligand and catalase protein by DESMOND software that further strengthens these ligand and enzyme interactions. In silico ADMET study was conducted by the Swiss ADME program revealed the drug-likeliness of these analogs. The present study has identified benzothiazole analogs such as 6b, 6c and 6d have potential catalase modulating activity and is comparable with that of known drug Valproic acid, thus help in neuroprotection. This study can be further taken up for the in vivo animal model study for the possible therapy.

Peroxisomal Hydrogen Peroxide Metabolism and Signaling in Health and Disease

Hydrogen peroxide (H₂O₂), a non-radical reactive oxygen species generated during many (patho)physiological conditions, is currently universally recognized as an important mediator of redox-regulated processes. Depending on its spatiotemporal accumulation profile, this molecule may act as a signaling messenger or cause oxidative damage. The focus of this review is to comprehensively evaluate the evidence that peroxisomes, organelles best known for their role in cellular lipid metabolism, also serve as hubs in the H₂O₂ signaling network. We first briefly introduce the basic concepts of how H₂O₂ can drive cellular signaling events. Next, we outline the peroxisomal enzyme systems involved in H₂O₂ metabolism in mammals and reflect on how this oxidant can permeate across the organellar membrane. In addition, we provide an up-to-date overview of molecular targets and biological processes that can be affected by changes in peroxisomal H₂O₂ metabolism. Where possible, emphasis is placed on the molecular mechanisms and factors involved. From the data presented, it is clear that there are still numerous gaps in our knowledge. Therefore, gaining more insight into how peroxisomes are integrated in the cellular H₂O₂ signaling network is of key importance to unravel the precise role of peroxisomal H₂O₂ production and scavenging in normal and pathological conditions.

β- N-methylamino-L-alanine Inhibits Human Catalase Activity: Possible Implications for Neurodegenerative Disease Development

The naturally produced, nonprotein amino acid β- N-methylamino-l-alanine (BMAA) has been proposed as a significant contributor to sporadic neurodegenerative disease development worldwide. However, the existing hypothesized mechanisms of toxicity do not adequately explain the role of BMAA in neurodegenerative disease development. There is evidence for BMAA-induced enzyme inhibition, but the effect of BMAA on human stress response enzymes has received little attention, despite the well-described role of oxidative stress in neurodegenerative disease development. The aim of this study was therefore to investigate the effect of BMAA on human catalase activity and compare it to the known inhibitor 3-amino-1,2,4-triazole. BMAA inhibited human erythrocyte catalase in a cell-free exposure to the same extent as the known inhibitor. Based on enzyme kinetics, the inhibition appears to be noncompetitive, possibly as a result of BMAA binding in the nicotinamide adenine dinucleotide phosphate (NADPH) binding site. BMAA-induced catalase inhibition was also observed in a human cell line culture. We therefore propose that BMAA-induced enzyme inhibition, specifically catalase inhibition, is a mechanism of toxicity that may contribute to the neurotoxicity of BMAA, further supporting the role of BMAA in neurodegenerative disease development.

Synthesis and biological evaluation of triazole and isoxazole-tagged benzothiazole/benzoxazole derivatives as potent cytotoxic agents

Cancer is a major health problem and the most upsetting disease in humans, leading to death in both developed and developing countries.

Neuroprotection by Polynitrogen Manganese Complexes: Regulation of Reactive Oxygen Species-Related Pathways

Cell death in the central nervous system causes neurologic diseases, in which reactive oxygen species (ROS) play a critical role by either inducing cellular oxidative stress or by increasing the cell tolerance against insult. Neurologic diseases may potentially be treated by regulating ROS levels in a certain range with small molecules. We studied preconditioning with two polynitrogen manganese complexes (1 and 2) to regulate intracellular ROS levels in the protection of both the differentiated rat pheochromocytoma cell line (PC12 cells) and neurons against H₂O₂-induced apoptosis. Pre-treatment with the two complexes attenuated the cell apoptosis caused by H₂O₂. And the ROS-related neuroprotective mechanisms were explored. Both complexes activate the hypoxia inducible factor-related pathways and increase the cell adaptation to oxidative stress. Pre-treatment with complex 1 eliminated intracellular ROS, which also activated antioxidase system, while short-term incubation of complex 2, generated low levels of ROS leading to cell survival.

Oxidative stress and mitochondria-mediated cell death mechanisms triggered by the familial Danish dementia ADan amyloid

Familial Danish Dementia (FDD), an early-onset non-amyloid-β (Aβ) cerebral amyloidosis, is neuropathologically characterized by widespread cerebral amyloid angiopathy, parenchymal amyloid and preamyloid deposits, as well as neurofibrillary degeneration indistinguishable to that seen in Alzheimer's disease (AD). The main amyloid subunit composing FDD lesions, a 34-amino acid de-novo generated peptide ADan, is the direct result of a genetic defect at the 3'-end of the BRI2 gene and the physiologic action of furin-like proteolytic processing at the C-terminal region of the ADan precursor protein. We aimed to study the impact of the FDD mutation, the additional formation of the pyroglutamate (pE) posttranslational modification as well as the relevance of C-terminal truncations -all major components of the heterogeneous FDD deposits- on the structural and neurotoxic properties of the molecule. Our data indicates that whereas the mutation generated a β-sheet-rich hydrophobic ADan subunit of high oligomerization/fibrillization propensity and the pE modification further enhanced these properties, C-terminal truncations had the opposite effect mostly abolishing these features. The potentiation of pro-amyloidogenic properties correlated with the initiation of neuronal cell death mechanisms involving oxidative stress, perturbation of mitochondrial membrane potential, release of mitochondrial cytochrome c, and downstream activation of caspase-mediated apoptotic pathways. The amyloid-induced toxicity was inhibited by targeting specific components of these detrimental cellular pathways, using reactive oxygen scavengers and monoclonal antibodies recognizing the pathological amyloid subunit. Taken together, the data indicate that the FDD mutation and the pE posttranslational modification are both primary elements driving intact ADan into an amyloidogenic/neurotoxic pathway while truncations at the C-terminus eliminate the pro-amyloidogenic characteristics of the molecule, likely reflecting effect of physiologic clearance mechanisms.

Immunocytochemical staining of endogenous nuclear proteins with the HIS-1 anti-poly-histidine monoclonal antibody: a potential source of error in His-tagged protein detection

Histidine-tagged proteins are widely used in biochemical studies and frequently detected with antibodies specific for the histidine tag. Immunocytochemistry is widely used in studies with overexpressed proteins to determine cellular localization and in the case of histidine-tagged proteins can be carried out with anti-polyhistidine antibodies. Recent studies have suggested that polyhistidine sequences are present within a small number of human proteins and may direct expression to the nucleus and nuclear speckles compartments of the cell. In this study immunocytochemical staining of human SH-SY5Y neuroblastoma cell lines with the HIS-1 anti-polyhistidine monoclonal antibody were determined. Results showed that the HIS-1 anti-polyhistidine monoclonal antibody stained endogenous nuclear proteins in SH-SY5Y cells. The stained proteins were contained within the nuclear membrane, but were not directly linked to DNA. In a histidine-tagged catalase overexpressing cell line the HIS-1 anti-polyhistidine monoclonal antibody showed nuclear staining, whilst staining with the CAT-505 anti-catalase monoclonal antibody showed primarily cytoplasmic staining. These results suggest that anti-polyhistidine antibody staining shows significant cross-reactivity with endogenous nuclear proteins in SH-SY5Y neuroblastoma cells and may not be suitable for localization studies of histidine-tagged proteins. Immunocytochemical studies with anti-polyhistidine antibodies and localization of histidine-tagged proteins must be confirmed with protein specific antibodies or other methodology.

Effects of a disulfide bridge prior to amyloid formation of the ABRI peptide

Computational studies characterize remarkable differences between the most probable structures of the monomeric amyloidogenic peptide, ABRI, with and without a single disulfide bond; the peptide is compact and alpha-helical with the bond, otherwise it is partially extended with slight β-bridges and an exposed hydrophobic surface area.