John James Mackrill

Ca ²⁺ signaling mediates rapid cellular responses across eukaryotes, but its spatiotemporal dynamics remain largely inaccessible in many genetically less tractable microbial lineages. Oomycete plant pathogens, including Phytophthora species, undergo rapid transitions between motile, encysted, germinating, and invasive stages, yet the organization of Ca ²⁺ dynamics during these transitions is poorly understood. Here, we adapt the genetically encoded ratiometric biosensor MatryoshCaMP8s for in vivo calcium imaging in Phytophthora palmivora . The reporter is stably expressed without major detectable effects on sporulation or virulence and reports rapid ratiometric responses to cold shock and calcimycin/A23187. Using live-cell imaging, we uncover stage-specific Ca ²⁺ dynamics across the pre-infective and early infection cycle. Sporangia approaching zoospore release display spatially heterogeneous Ca ²⁺ transients, newly formed cysts occasionally exhibit Ca ²⁺ transients, and germinating cysts show recurrent Ca ²⁺ transients at the germ tube tip. Similar sharp ratiometric pulses occur during early plant infection, indicating that polarized Ca ²⁺ transients are not restricted to in vitro germination but recur at the host surface. Together, our work establishes live ratiometric calcium imaging in oomycetes, reveals polarized Ca ²⁺ transients as recurrent signatures of developmental transitions and early host colonization, and opens the way to mechanistic dissection of signaling, polarity, and infection in a major group of plant pathogens.

Breast cancer remains one of the leading causes of cancer-related mortality among women worldwide. Although cisplatin is widely used in chemotherapy, its clinical efficacy is often limited by adverse effects and resistance. Thus, natural bioactive compounds are gaining attention as complementary therapeutic agents. This study aimed to evaluate the anti-tumor effects of Annona muricata leaf extract on murine breast cancer 4T1 cells, used alone or in combination with cisplatin. Cisplatin induced intrinsic apoptosis through mitochondrial membrane disruption, up-regulation of the Bax gene and inhibition of the PI3K/AKT/mTOR signaling pathway. Cisplatin also promoted hypoxia by HIF1α gene expression, inflammation by TNFα and IL-6 gene expression, and induced cell cycle arrest at the sub-G1 phase by down-regulation of cyclin D1 and cyclin E1 genes. Annona muricata leaf extract triggered autophagy-mediated 4T1 cell death through mainly mTOR down-regulation and increased expression of Beclin1 and LC3 genes. It also induced cell cycle arrest at sub-G1 and S phases in a concentration- and time-dependent manner. When, combined with cisplatin, Annona muricata extract shifts the cell death pathway from intrinsic apoptosis toward autophagy by reduced caspase-3 gene expression and activity and enhanced LC3-I to LC3-II conversion. Moreover, Annona muricata extract attenuated cisplatin-induced inflammation by inhibiting TNFα and IL-6 gene expression and reinforced cell cycle arrest through suppression of the cyclin D1 gene. In conclusion, our results suggest that Annona muricata leaf extract exerts significant anti-tumor activity in breast cancer cells and may enhance cisplatin efficacy by shifting the signaling pathway from intrinsic apoptosis toward autophagy, and attenuating inflammation-related effects, supporting its potential use as a complementary therapeutic strategy.

Oxysterols can be derived from the diet, physiologically produced via specific enzymes, or are generated by autoxidation. These molecules have physiological properties and can also adversely affect vital organs. Indeed, some of them have pro-oxidant and pro-inflammatory activities and can lead to major pathologies. The present review focuses on oxysterols (7-ketocholesterol, 7β-hydroxycholesterol, 25-hydroxycholesterol, 27-hydroxycholesterol, 5,6α-epoxycholesterol, 5,6β-epoxycholesterol, and cholestane-3β, 5α, 6β-triol) involved either in cholesterol metabolism, age-related diseases (such as cardiovascular, neurodegenerative, and eye diseases, e.g., sarcopenia), and inflammatory diseases (especially Behcet’s disease and bowel and lung diseases (e.g., sarcoidosis, COVID-19)). Metabolic pathways associated with oxysterol-induced inflammation are discussed considering the cytokinic TLR4 pathway, non-cytokinic pathways, and the contribution of Ca²⁺ and K⁺ channels. Therapeutic approaches targeting oxysterol-induced inflammation either by natural or synthetic molecules are also presented.

Oxysterols can be derived from the dietary origin, physiologically produced via specific enzymes, or are generated by autoxidation. These molecules have physiological prop-erties and can also adversely affect vital organs. Indeed, some of them have pro-oxidant and pro-inflammatory activities and can lead to major pathologies. The present review focuses on oxysterols (7-ketocholesterol, 7β-hydroxycholesterol, 25-hydroxycholesterol, 27-hydroxycholesterol, 5,6α-epoxycholesterol, 5,6β-epoxycholesterol and cholestane-3β, 5α, 6β-triol) involved either in cholesterol metabolism, age-related diseases (such as cardiovascular, neurodegenerative, and eyes diseases, sarcopenia), and inflammatory diseases (especially Behcet’s disease, bowel and lung diseases (sarcoidosis, COVID-19)). Metabolic pathways associated with oxysterol-induced inflammation are discussed con-sidering the cytokinic TLR4 pathway, non-cytokinic pathways and the contribution of Ca2+ and K+ channels. Therapeutic approaches targeting oxysterol-induced inflammation ei-ther by natural or synthetic molecules are also presented.

Aim: Cardiac fibrosis contributes to systolic and diastolic dysfunction and can disrupt electrical pathways in the heart. There are currently no therapies that prevent or reverse fibrosis in human cardiac disease. However, animals like freshwater turtles undergo seasonal remodeling of their hearts, demonstrating the plasticity of fibrotic remodeling. In Trachemys scripta, cold temperature affects cardiac load, suppresses metabolism, and triggers a cardiac remodeling response that includes fibrosis.Methods: We investigated this remodeling using Fourier transform infrared (FTIR) imaging spectroscopy, together with functional assessment of muscle stiffness, and molecular, histological, and enzymatic analyses in control (25°C) T. scripta and after 8 weeks of cold (5°C) acclimation.Results: FTIR revealed an increase in absorption bands characteristic of protein, glycogen, and collagen following cold acclimation, with a corresponding decrease in bands characteristic of lipids and phosphates. Histology confirmed these responses. Functionally, micromechanical stiffness of the ventricle increased following cold exposure assessed via atomic force microscopy (AFM) and was associated with decreased activity of regulatory matrix metalloproteinases (MMPs) and increased expression of MMP inhibitors (TMPs) which regulate collagen deposition.Conclusions: By defining the structural and metabolic underpinnings of the cold‐induced remodeling response in the turtle heart, we show commonalities between metabolic and fibrotic triggers of pathological remodeling in human cardiac disease. We propose the turtle ventricle as a novel model for studying the mechanisms underlying fibrotic and metabolic cardiac remodeling.

During mammalian cardiomyocyte excitation–contraction coupling, Ca2+ influx through voltage-gated Ca2+ channels triggers Ca2+ release from the sarcoplasmic reticulum (SR) through ryanodine receptor channels. This Ca2+-induced Ca2+ release mechanism controls cardiomyocyte contraction and is exquisitely regulated by SR Ca2+ levels. The histidine-rich calcium-binding protein (HRC) and its aspartic acid-rich paralogue aspolin are high-capacity, low-affinity Ca2+-binding proteins. Aspolin also acts as a trimethylamine N-oxide demethylase. At low intraluminal Ca2+ concentrations, HRC binds to the SR Ca2+-ATPase 2, inhibiting its Ca2+-pumping activity. At high intraluminal Ca2+ levels, HRC interacts with triadin to reduce Ca2+ release through ryanodine receptor channels. This Review analyses the evolution of these Ca2+-regulatory proteins, to gain insights into their roles. It reveals that HRC homologues are present in chordates, annelid worms, molluscs, corals and sea anemones. In contrast, triadin appears to be a chordate innovation. Furthermore, HRC is evolving more rapidly than other cardiac excitation–contraction coupling proteins. This positive selection (or relaxed negative selection) occurs along most of the mammalian HRC protein sequence, with the exception being the C-terminal cysteine-rich region, which is undergoing negative selection. The histidine-rich region of HRC might be involved in pH sensing, as an adaptation to air-breathing, endothermic and terrestrial life. In addition, a cysteine-rich pattern within HRC and aspolin is also found in a wide range of iron–sulfur cluster proteins, suggesting roles in redox reactions and metal binding. The polyaspartic regions of aspolins are likely to underlie their trimethylamine N-oxide demethylase activity, which might be mimicked by the acidic regions of HRCs. These potential roles of HRCs and aspolins await experimental verification.

Obstructive sleep apnoea (OSA) involves impaired upper airway muscle function and is linked to several pathologies including systemic hypertension, daytime somnolence and cognitive decline. Selenium is an essential micronutrient that exerts many of its effects through selenoproteins. Evidence indicates that either deficient or excessive dietary selenium intake can result in impaired muscle function, termed nutritional myopathy. To investigate the effects of selenium on an upper airway muscle, the sternohyoid, rats were fed on diets containing deficient, normal (0.5 ppm sodium selenite) or excessive (5 ppm selenite) selenium for a period of two weeks. Sternohyoid contractile function was assessed ex vivo. Serum selenium levels and activity of the glutathione antioxidant system were determined by biochemical assays. The abundance of three key muscle selenoproteins (selenoproteins -N, -S and -W (SELENON, SELENOS and SELENOW)) in sternohyoid muscle were quantified by immunoblotting. Levels of these selenoproteins were also compared between rats exposed to chronic intermittent hypoxia, a model of OSA, and sham treated animals. Although having no detectable effect on selected organ masses and whole-body weight, either selenium-deficient or -excessive diets severely impaired sternohyoid contractile function. These changes did not involve altered fibre size distribution. These dietary interventions resulted in corresponding changes in serum selenium concentrations but did not alter the activity of glutathione-dependent antioxidant systems in sternohyoid muscle. Excess dietary selenium increased the abundance of SELENOW protein in sternohyoid muscles but had no effect on SELENON or SELENOS. In contrast, chronic intermittent hypoxia increased SELENON, decreased SELENOW and had no significant effect on SELENOS in sternohyoid muscle. These findings indicate that two-week exposure to selenium-deficient or -excessive diets drastically impaired upper airway muscle function. In the sternohyoid, SELENON, SELENOS and SELENOW proteins show distinct alterations in level following exposure to different dietary selenium intakes, or to chronic intermittent hypoxia. Understanding how alterations in Se and selenoproteins impact sternohyoid muscle function has the potential to be translated into new therapies for prevention or treatment of OSA.