The Ca(2+) channel inhibitor 2-APB reverses β-amyloid-induced LTP deficit in hippocampus by blocking BAX and caspase-3 hyperactivation

The Rise of Boron-Containing Compounds: Advancements in Synthesis, Medicinal Chemistry, and Emerging Pharmacology

Boron-containing compounds (BCC) have emerged as important pharmacophores. To date, five BCC drugs (including boronic acids and boroles) have been approved by the FDA for the treatment of cancer, infections, and atopic dermatitis, while some natural BCC are included in dietary supplements. Boron's Lewis acidity facilitates a mechanism of action via formation of reversible covalent bonds within the active site of target proteins. Boron has also been employed in the development of fluorophores, such as BODIPY for imaging, and in carboranes that are potential neutron capture therapy agents as well as novel agents in diagnostics and therapy. The utility of natural and synthetic BCC has become multifaceted, and the breadth of their applications continues to expand. This review covers the many uses and targets of boron in medicinal chemistry.

Aberrant mechanical loading induces annulus fibrosus cells apoptosis in intervertebral disc degeneration via mechanosensitive ion channel Piezo1

BACKGROUND

Intervertebral disc degeneration (IVDD) is closely associated with the structural damage in the annulus fibrosus (AF). Aberrant mechanical loading is an important inducement of annulus fibrosus cells (AFCs) apoptosis, which contributes to the AF structural damage and aggravates IVDD, but the underlying mechanism is still unclear. This study aims to investigate the mechanism of a mechanosensitive ion channel protein Piezo1 in aberrant mechanical loading-induced AFCs apoptosis and IVDD.

METHODS

Rats were subjected to lumbar instability surgery to induce the unbalanced dynamic and static forces to establish the lumbar instability model. MRI and histological staining were used to evaluate the IVDD degree. A cyclic mechanical stretch (CMS)-stimulated AFCs apoptosis model was established by a Flexcell system in vitro. Tunel staining, mitochondrial membrane potential (MMP) detection, and flow cytometry were used to evaluate the apoptosis level. The activation of Piezo1 was detected using western blot and calcium fluorescent probes. Chemical activator Yoda1, chemical inhibitor GSMTx4, and a lentiviral shRNA-Piezo1 system (Lv-Piezo1) were utilized to regulate the function of Piezo1. High-throughput RNA sequencing (RNA-seq) was used to explore the mechanism of Piezo1-induced AFCs apoptosis. The Calpain activity and the activation of Calpain2/Bax/Caspase3 axis were evaluated by the Calpain activity kit and western blot with the siRNA-mediated Calapin1 or Calpain2 knockdown. Intradiscal administration of Lv-Piezo1 was utilized to evaluate the therapeutic effect of Piezo1 silencing in IVDD rats.

RESULTS

Lumbar instability surgery promoted the expression of Piezo1 in AFCs and stimulated IVDD in rats 4 weeks after surgery. CMS elicited distinct apoptosis of AFCs, with enhanced Piezo1 activation. Yoda1 further promoted CMS-induced apoptosis of AFCs, while GSMTx4 and Lv-Piezo1 exhibited opposite effects. RNA-seq showed that knocking down Piezo1 inhibited the calcium signaling pathway. CMS enhanced Calpain activity and elevated the expression of BAX and cleaved-Caspase3. Calpain2, but not Calpain1 knockdown, inhibited the expression of BAX and cleaved-Caspase3 and alleviated AFCs apoptosis. Lv-Piezo1 significantly alleviated the progress of IVDD in rats after lumbar instability surgery.

CONCLUSIONS

Aberrant mechanical loading induces AFCs apoptosis to promote IVDD by activating Piezo1 and downstream Calpain2/BAX/Caspase3 pathway. Piezo1 is expected to be a potential therapeutic target in treating IVDD.

Boron-containing compounds on neurons: Actions and potential applications for treating neurodegenerative diseases

Boron-containing compounds (BCC) exert effects on neurons. After the expanding of both the identification and synthesis of new BCC, novel effects in living systems have been reported, many of these involving neuronal action. In this review, the actions of BCC on neurons are described; the effects have been inferred by boron deprivation or addition. Also, the effects can be related to those mediated by interaction on ionic channels, G-protein coupled receptors, or other receptors exerting modification on neuronal behavior. Additionally, BCC have exhibited effects by the modulation of inflammation or oxidative processes. BCC are expanding as drugs. Deprivation of boron sources from the diet shows the role of some natural BCC. However, the observations of several new synthesized compounds suggest their ability to act with attractive potency, efficacy, and long-term action on neuronal receptors or processes related with the origin and evolution of neurodegenerative processes. The details of BCC-target interactions are currently being elucidated in progress, as those observed from BCC-protein crystal complexes. Taking all of the above into account, the expansion is presumably near to having studies on the application of BCC as drugs on specific targets for treating neurodegenerative diseases.

Overexpression of Rhodopsin or Its Mutants Leads to Energy Metabolism Dysfunction in 661w Cells

Purpose

Retinitis pigmentosa (RP) is a heterogeneous group of inherited disorders characterized by photoreceptor degeneration. The rhodopsin gene (RHO) is the most frequent cause of autosomal dominant RP (ADRP), yet it remains unclear how RHO mutations cause heterogeneous phenotypes. Energy failure is a main cause of the secondary cone death during RP progression; however, its role in primary rod death induced by ADRP RHO mutants is unknown.

Methods

Three RHO missense mutations were chosen from different clinical classes. Wild-type (WT) RHO and its mutants, P23H (class B1), R135L (class A), and G188R (class B2), were overexpressed in 661w cells, a mouse photoreceptor cell line, and their effects on oxidative phosphorylation (OXPHOS) and aerobic glycolysis were compared separately.

Results

Here, we report that energy failure is an early event in the cell death caused by overexpression of WT RHO and its mutants. RHO overexpression leads to OXPHOS deficiency, which might be a result of mitochondrial loss. Nonetheless, only in WT RHO and P23H groups, energy stress triggers AMP-activated protein kinase activation and metabolic reprogramming to increase glycolysis. Metabolic reprogramming impairment in R135L and G188R groups might be the reason why energy failure and cell injury are much more severe in those groups.

Conclusions

Our results imply that overexpression of RHO missense mutants have distinct impacts on the two energy metabolic pathways, which might be related to their heterogeneous phenotypes.

The STIM1/2-Regulated Calcium Homeostasis Is Impaired in Hippocampal Neurons of the 5xFAD Mouse Model of Alzheimer's Disease

Alzheimer's disease (AD) is the most common cause of age-related dementia. Neuronal calcium homeostasis impairment may contribute to AD. Here we demonstrated that voltage-gated calcium (VGC) entry and store-operated calcium (SOC) entry regulated by calcium sensors of intracellular calcium stores STIM proteins are affected in hippocampal neurons of the 5xFAD transgenic mouse model. We observed excessive SOC entry in 5xFAD mouse neurons, mediated by STIM1 and STIM2 proteins with increased STIM1 contribution. There were no significant changes in cytoplasmic calcium level, endoplasmic reticulum (ER) bulk calcium levels, or expression levels of STIM1 or STIM2 proteins. The potent inhibitor BTP-2 and the FDA-approved drug leflunomide reduced SOC entry in 5xFAD neurons. In turn, excessive voltage-gated calcium entry was sensitive to the inhibitor of L-type calcium channels nifedipine but not to the T-type channels inhibitor ML218. Interestingly, the depolarization-induced calcium entry mediated by VGC channels in 5xFAD neurons was dependent on STIM2 but not STIM1 protein in cells with replete Ca²⁺ stores. The result gives new evidence on the VGC channel modulation by STIM2. Overall, the data demonstrate the changes in calcium signaling of hippocampal neurons of the AD mouse model, which precede amyloid plaque accumulation or other signs of pathology manifestation.

Cytotoxic terpenoids from Tripterygium hypoglaucum against human pancreatic cancer cells SW1990 by increasing the expression of Bax protein

ETHNOPHARMACOLOGICAL RELEVANCE

Tripterygium hypoglaucum (Kunmingshanhaitang in Chinese) is a plant of the genus Tripterygium which have been used as anti-tumor folk medicines in Yi and Bai ethnic groups in Yunnan province, China for hundreds of years. Terpenoids from T. hypoglaucum presented therapeutic effects on multiple tumors. But there were few studies about pancreatic cancer treatment of these terpenoids. Pancreatic cancer is an aggressive malignancy and lacked of specific drugs. Currently, anti-tumor drugs have poor therapeutic effect and prognosis for pancreatic cancer.

AIM OF THE STUDY

This study aimed to elucidate the terpenoids from T. hypoglaucum and illuminate their anti-pancreatic cancer bioactivities.

MATERIAL AND METHODS

Terpenoids were obtained through sequential chromatographic methods including silica gel, MCI gel, Sephadex LH-20, and preparative HPLC. Their structures were determined by HRESIMS, 1D and 2D NMR spectroscopic analysis. The absolute configurations of some new diterpenoids were assigned through comparison of experimental and calculated circular dichroism spectra. The cytotoxicity of isolates was measured using the MTT method on human pancreatic cancer cells SW1990. The effects on expressions of AKT, Erk1/2, p-AKT, p-Erk1/2, and Bax proteins in human pancreatic cancer cells SW1990 of these compounds were determined by western blotting assays.

RESULTS

Eleven new (compounds 1∼11) and fourteen known terpenoids (compounds 12∼25) were isolated from the underground parts of T. hypoglaucum. These compounds were belonged to abietane diterpenoids, isoprimara diterpenoids, ent-kaurane diterpenoids, oleanane triterpenoids, and friedelane triterpenoids. Compounds 5, 7, 8, 9, 16, 18, 22, 24, and 25 possessed significant cytotoxicity against SW1990 cells with IC₅₀ values of 19.28 ± 4.39, 9.91 ± 2.23, 27.32 ± 5.89, 56.43 ± 6.92, 0.16 ± 0.05, 0.58 ± 0.15, 0.81 ± 0.04, 0.48 ± 0.11, and 10.01 ± 1.39 μM respectively. After compounds 16, 22, and 24 been treated with the pancreatic cancer cells in medium and high doses, the protein expressions of AKT, p-AKT, Erk, and p-Erk were not remarkably reduced and the expressions of Bax protein were significantly increased.

CONCLUSION

This study indicated that terpenoids from T. hypoglaucum could inhibit human pancreatic cancer cells SW1990. Especially, compounds 16, 22, and 24 possessed significant cytotoxicity against SW1990 cells with low IC₅₀ values and could increase the expressions of Bax protein. These compounds shared a wide variety of structural characteristics which provided us more candidate molecules for the development of anti-pancreatic cancer drugs and further prompted us to investigate their anti-pancreatic mechanisms.

Elevating the Levels of Calcium Ions Exacerbate Alzheimer's Disease via Inducing the Production and Aggregation of β-Amyloid Protein and Phosphorylated Tau

Alzheimer’s disease (AD) is a neurodegenerative disease with a high incidence rate. The main pathological features of AD are β-amyloid plaques (APs), which are formed by β-amyloid protein (Aβ) deposition, and neurofibrillary tangles (NFTs), which are formed by the excessive phosphorylation of the tau protein. Although a series of studies have shown that the accumulation of metal ions, including calcium ions (Ca²⁺), can promote the formation of APs and NFTs, there is no systematic review of the mechanisms by which Ca²⁺ affects the development and progression of AD. In view of this, the current review summarizes the mechanisms by which Ca²⁺ is transported into and out of cells and organelles, such as the cell, endoplasmic reticulum, mitochondrial and lysosomal membranes to affect the balance of intracellular Ca²⁺ levels. In addition, dyshomeostasis of Ca²⁺ plays an important role in modulating the pathogenesis of AD by influencing the production and aggregation of Aβ peptides and tau protein phosphorylation and the ways that disrupting the metabolic balance of Ca²⁺ can affect the learning ability and memory of people with AD. In addition, the effects of these mechanisms on the synaptic plasticity are also discussed. Finally, the molecular network through which Ca²⁺ regulates the pathogenesis of AD is introduced, providing a theoretical basis for improving the clinical treatment of AD.

Wip1 phosphatase deficiency impairs spatial learning and memory

Spatial learning and memory are typically assessed to evaluate hippocampus-dependent cognitive and memory functions in vivo. Protein phosphorylation and dephosphorylation by kinases and phosphatases play critical roles in spatial learning and memory. Here we report that the Wip1 phosphatase is essential for spatial learning, with knockout mice lacking Wip1 phosphatase exhibiting dysfunctional spatial cognition. Aberrant phosphorylation of the Wip1 substrates p38, ATM, and p53 were observed in the hippocampi of Wip1^-/- mice, but only p38 inhibition reversed impairments in long-term potentiation in Wip1-knockout mice. p38 inhibition consistently ameliorated the spatial learning dysfunction caused by Wip1 deficiency. Our results demonstrate that deletion of Wip1 phosphatase impairs hippocampus-dependent spatial learning and memory, with aberrant downstream p38 phosphorylation involved in this process and providing a potential therapeutic target.

Rab11-mediated recycling endosome role in nervous system development and neurodegenerative diseases

STUDY

Membrane trafficking process is significant for the complex and precise regulatory of the nervous system. Rab11, as a small GTPase of the Rab superfamily, controls endocytic vesicular trafficking to the cell surface after sorting in recycling endosome (RE), coordinating with its receptors to maintain neurological function.

MATERIALS AND METHODS

This article reviewed the literature of Rab11 in nervous system.

RESULTS

Rab11-positive vesicles targeted transport growth-related molecules, such as integrins, protrudin, tropomyosin receptor kinase (Trk) A/B receptor and AMPA receptor (AMPAR) to membrane surface to promote the regeneration capacity of axon and dendrites and maintain synaptic plasticity. In addition, many studies have shown that the expression of Rab11 is decreased in multiple neurodegenerative diseases, which is highly correlated with the process of production, transport and clearance of disease-related pathological proteins. And overexpression or increased activity of Rab11 can greatly improve the defect of membrane trafficking and slow down the disease process.

CONCLUSION

With increasing research efforts on Rab11-dependent membrane trafficking mechanisms, a potential target for nerve regeneration and neurodegenerative diseases will be provided.

Protective effect of potassium 2-(l-hydroxypentyl)-benzoate on hippocampal neurons, synapses and dystrophic axons in APP/PS1 mice

RATIONALE

As the hub of memory and space, hippocampus is very sensitive to a wide variety of injuries and is one of the earliest brain structures to develop neurodegenerative changes in AD. Previous research has showed a protective effect of potassium 2-(l-hydroxypentyl)-benzoate (PHPB) on cognitive deficits in animal models of AD. However, it is unclear whether this protective effect is associated with hippocampal alterations.

OBJECTIVES

The present study was conducted to evaluate the protective effect of PHPB on hippocampal neurodegenerative changes in middle-aged APP/PS1 mice.

METHODS

Ten-month-old male APP/PS1 transgenic mice and age-matched wild-type mice were randomly divided into three groups. PHPB-treated APP/PS1 group received 30 mg/kg PHPB by oral gavage once daily for 12 weeks. Wild-type group and APP/PS1 group received the same volume of water alone. Twelve weeks later, mice (13-month-old) were tested for in vivo 1H-MRS examination and then sacrificed for subsequent biochemical and pathological examinations using transmission electron microscopy, Golgi staining, immunohistochemistry, and western blotting.

RESULTS

We found that PHPB treatment significantly improved the micromorphology of hippocampal neurons and subcellular organelles, ameliorated synapse loss and presynaptic axonal dystrophy, increased hippocampal dendritic spine density and dendritic complexity, enhanced the expression of hippocampal synapse-associated proteins, and improved hippocampal metabolism in middle-aged APP/PS1 mice.

CONCLUSIONS

Our study showed for the first time the protective effect of PHPB on hippocampal neurons, synapses, and dystrophic axons in APP/PS1 mice, which to some extent revealed the possible mechanism for its ability to improve cognition in animal models of AD.

Effects of 2-Aminoethyl Diphenylborinate, a Modulator of Transient Receptor Potential and Orai Channels in Subarachnoid Hemorrhage: An Experimental Study

BACKGROUND

Cerebral vasospasm remains a serious problem affecting morbidity and mortality in patients with subarachnoid hemorrhage (SAH) during neurosurgery. We aimed to demonstrate the role of the transient receptor potential channel and other channels for Ca²⁺ in the etiology of cerebral vasospasm using 2-aminoethyl diphenylborinate (2-APB) and the effective dose range of an unstudied pharmacological agent, which can limit vasospasm.

METHODS

We performed an experimental study using 32 Sprague-Dawley rats divided into 4 groups: sham group (n = 8), SAH group (n = 8), 2-APB group (SAH rats intraperitoneally administered with 0.5 mg/kg 2-APB; n = 8), and 2-APB-2 group (SAH rats intraperitoneally administered with 2 mg/kg 2-APB; n = 8). The rats were sacrificed after 24 hours, and superoxide dismutase, glutathione peroxidase, malondialdehyde, tumor necrosis factor-α, and interleukin-1β in the brain tissue and serum were measured. The histopathological investigation of brain tissue included measurement of the luminal diameter and wall thickness of the basilar artery (BA), and apoptotic cells in the hippocampus were counted after caspase staining.

RESULTS

Autologous arterial blood injection into the cisterna magna caused vasospasm in rats. 2-APB treatment increased the BA wall thickness and reduced the BA lumen diameter, inducing significant vascular changes. 2-APB also alleviated cell apoptosis at 24 hours after SAH.

CONCLUSION

In experimental SAH in rats, 2-APB treatment increased the BA wall thickness and reduced the BA lumen diameter, inducing significant vascular changes. 2-APB also alleviated cell apoptosis at 24 hours after SAH.

Gamma-H2AX upregulation caused by Wip1 deficiency increases depression-related cellular senescence in hippocampus

The PP2C family member Wild-type p53-induced phosphatase 1 (Wip1) critically regulates DNA damage response (DDR) under stressful situations. In the present study, we investigated whether Wip1 expression was involved in the regulation of DDR-induced and depression-related cellular senescence in mouse hippocampus. We found that Wip1 gene knockout (KO) mice showed aberrant elevation of hippocampal cellular senescence and of γ-H2AX activity, which is known as a biomarker of DDR and cellular senescence, indicating that the lack of Wip1-mediated γ-H2AX dephosphorylation facilitates cellular senescence in hippocampus. Administration of the antidepressant fluoxetine had no significant effects on the increased depression-like behaviors, enriched cellular senescence, and aberrantly upregulated hippocampal γ-H2AX activity in Wip1 KO mice. After wildtype C57BL/6 mice were exposed to the procedure of chronic unpredictable mild stress (CUMS), cellular senescence and γ-H2AX activity in hippocampus were also elevated, accompanied by the suppression of Wip1 expression in hippocampus when compared to the control group without CUMS experience. These CUMS-induced symptoms were effectively prevented following fluoxetine administration in wildtype C57BL/6 mice, with the normalization of depression-like behaviors. Our data demonstrate that Wip1-mediated γ-H2AX dephosphorylation may play an important role in the occurrence of depression-related cellular senescence.

Cassia obtusifolia seed ameliorates amyloid β-induced synaptic dysfunction through anti-inflammatory and Akt/GSK-3β pathways

ETHNOPHARMACOLOGICAL RELEVANCE

Tea infused with the seed of Cassia obtusifolia has been traditionally used as an herbal remedy for liver, eye, and acute inflammatory diseases. Recent pharmacological reports have indicated that Cassiae semen has neuroprotective effects, attributable to its anti-inflammatory actions, in ischemic stroke and Parkinson's disease models.

AIM OF THE STUDY

Previously, the ethanol extract of C. obtusifolia seeds (COE) was reported to have memory enhancing properties. However, the effects of COE in an Alzheimer's disease (AD) model are currently unknown. In this study, we investigated the effect(s) of COE on aberrant synaptic plasticity and memory impairment induced by amyloid β (Aβ), a key toxic component found in the AD brain.

MATERIALS AND METHODS

To determine the effect of COE on Aβ-induced aberrant synaptic plasticity, we used acute mouse hippocampal slices and delivered theta burst stimulation to induce long-term potentiation (LTP). Western blots were used to detect Aβ- and/or COE-induced changes in signaling proteins. The novel object location recognition test was conducted to determine the effect of COE on Aβ-induced recognition memory impairment.

RESULTS

COE was found to ameliorate Aβ-induced LTP impairment in the acute hippocampal slices. Glycogen synthase kinase-3β (GSK-3β), a key molecule in LTP impairment, was activated by Aβ. However, this process was inhibited by COE via Akt signaling. Moreover, COE was found to attenuate Aβ-induced microglia, inducible nitric oxide synthase (iNOS), and cyclooxygenase (COX) activation. In the in vivo studies performed, COE ameliorated the Aβ-induced object recognition memory impairment.

CONCLUSION

These results suggest that COE exhibits neuroprotective activities against Aβ-induced brain disorders.