PKC-β modulates Ca2+ mobilization through Stim1 phosphorylation

Ethanol extract of Moschus attenuates glutamate-induced cytotoxicity in HT22 cells by regulating the Nrf2 and MAPK pathways

ETHNOPHARMACOLOGICAL RELEVANCE

Moschus is a traditional Chinese materia medica for treating central nervous system disorders. Oxidative stress is a key pathogenic mechanism of Alzheimer's disease (AD) and serves as a critical bridge linking various pathological processes of AD. Previous studies have shown that Moschus can exert neuroprotective effects by inhibiting glutamate-induced neuronal cell damage. However, its underlying mechanisms remain unclear.

AIM OF THE STUDY

This study aimed to evaluate the effects and potential mechanisms of the ethanol extract of Moschus (EEM) on glutamate-induced oxidative damage in HT22 cells.

MATERIALS AND METHODS

The components of EEM were identified using GC-MS. An oxidative toxicity cell model was established by exposing HT22 cells to glutamate. Cell viability was assessed through CCK8 and LDH assays, and the modes of cell death were evaluated using FITC-Annexin V staining and TUNEL assays. Intracellular and mitochondrial ROS levels were measured with DCFH-DA and MitoSOX Red probes. Intracellular Ca2+ levels were measured with the Fluo-4 AM fluorescent probe. Mitochondrial function was analyzed using the JC-1 fluorescent probe. Protein expression levels of Bid, Calpain-1, Bax, Bcl-2, AIF, P-ERK, ERK, P-JNK, JNK, P-P38, P38, Nrf2, HO-1, Keap1, and NQO-1 were analyzed through western blotting. The distribution of AIF and Nrf2 in the cytoplasm and nucleus was examined through immunofluorescence staining.

RESULTS

Using GC-MS, 18 major components were identified in EEM. EEM significantly inhibited apoptosis, reduced ROS generation, and alleviated Ca2+ overload. EEM restored mitochondrial dysfunction by regulating the expression of mitochondria-related apoptotic proteins, including the downregulation of Calpain-1 and Bax, upregulation of Bid and Bcl-2, and inhibition of AIF nuclear translocation. EEM inhibited MAPK phosphorylation while activating the Nrf2/Keap1 signaling pathway.

CONCLUSIONS

Our study shows that EEM protects HT22 cells from glutamate-induced damage by regulating the MAPK and Nrf2 pathways, effectively reducing oxidative stress and apoptosis. In summary, this study first demonstrates at the cellular level that EEM exerts neuroprotective effects by modulating the MAPK and Nrf2 pathways. These findings provide new insights into the mechanism of Moschus against AD and establish a foundation for its potential application in AD.

Global insights into intermediate metabolites: Signaling, metabolic divergence and stress response modulation in plants

Climate change-induced environmental stresses pose significant challenges to plant survival and agricultural productivity. In response, many plants undergo genetic reprogramming, resulting in profound alterations in metabolic pathways and the production of diverse secondary metabolites. As a critical molecular junction, intermediate metabolites by targeted intensification or suppression of subpathways channel cell resources into a multifaceted array of functions such as cell signals, photosynthesis, energy metabolism, ROS homeostasis, producing defensive and protective molecules, epigenetic regulation and stress memory, phytohormones biosynthesis and cell wall architecture under stress conditions. Unlike the well-established functions of end products, intermediate metabolites are context-dependent and produce enigmatic alternatives during stress. As key components of signal transduction pathways, intermediate metabolites with relay and integration of stress signals ensure responses to stress combinations. Investigating efficient metabolic network pathways and their role in regulating unpredictable paths from upstream to downstream levels can unlock their full potential to shape the future of agriculture and ensure global food security. Here, we summarized the activity of some intermediate metabolites, from the perception step to tolerance responses to stress factors.

Molecular mechanisms of saliva secretion and hyposecretion

The exocrine salivary gland secretes saliva, a fundamental body component to maintain oral homeostasis. Saliva is composed of water, ions, and proteins such as amylase, mucins, and immunoglobulins that play essential roles in the digestion of food, lubrication, and prevention of dental caries and periodontitis. An increasing number of people experience saliva hyposecretion due to aging, medications, Sjögren's syndrome, and radiation therapy for head and neck cancer. However, current treatments are mostly limited to temporary symptomatic relief. This review explores the molecular mechanisms underlying saliva secretion and hyposecretion to provide insight into putative therapeutic targets for treatment. Proteins implicated in saliva secretion pathways, including Ca2+ -signaling proteins, aquaporins, soluble N-ethylmaleimide-sensitive factor attachment protein receptors, and tight junctions, are aberrantly expressed and localized in patients with saliva hyposecretion, such as Sjögren's syndrome. Analysis of studies on the mechanisms of saliva secretion and hyposecretion suggests that crosstalk between fluid and protein secretory pathways via Ca2+ /protein kinase C and cAMP/protein kinase A regulates saliva secretion. Impaired crosstalk between the two secretory pathways may contribute to saliva hyposecretion. Future research into the detailed regulatory mechanisms of saliva secretion and hyposecretion may provide information to define novel targets and generate therapeutic strategies for saliva hyposecretion.

Calcium signalling in hepatic metabolism: Health and diseases

The flexibility between the wide array of hepatic functions relies on calcium (Ca2+) signalling. Indeed, Ca2+ is implicated in the control of many intracellular functions as well as intercellular communication. Thus, hepatocytes adapt their Ca2+ signalling depending on their nutritional and hormonal environment, leading to opposite cellular functions, such as glucose storage or synthesis. Interestingly, hepatic metabolic diseases, such as obesity, type 2 diabetes and non-alcoholic fatty liver diseases, are associated with impaired Ca2+ signalling. Here, we present the hepatocytes' toolkit for Ca2+ signalling, complete with regulation systems and signalling pathways activated by nutrients and hormones. We further discuss the current knowledge on the molecular mechanisms leading to alterations of Ca2+ signalling in hepatic metabolic diseases, and review the literature on the clinical impact of Ca2+-targeting therapeutics.