H2O2/Ca2+/Zn2+ Complex Can Be Considered a “Collaborative Sensor” of the Mitochondrial Capacity?

Exposome on skeletal muscle system: a mini-review

Exposomics is an ever-expanding field which captures the cumulative exposures to chemical, biological, physical, lifestyle, and social factors associated with biological responses. Since skeletal muscle is currently considered as the largest secretory organ and shows substantial plasticity over the life course, this reviews addresses the topic of exposome and skeletal muscle by reviewing the state-of-the-art evidence and the most intriguing perspectives. Muscle stem cells react to stressors via phosphorylated eukaryotic initiation factor 2α and tuberous sclerosis 1, and are sensible to hormetic factors via sirtuin 1. Microplastics can delay muscle regeneration via p38 mitogen-activated protein kinases and induce transdifferentiation to adipocytes via nuclear factor kappa B. Acrolein can inhibit myogenic differentiation and disrupt redox system. Heavy metals have been associated with reduced muscle strength in children. The deep study of pollutants and biological features can shed new light on neuromuscular pathophysiology. The analysis of a time-varying and dynamic exposome risk score from a panel of exposure and phenotypes of interest is promising. The systematization of hormetic factors and the role of the microbiota in modulating the effects of exposure on skeletal muscle responses are also promising. The comprehensive exposure assessment and its interactions with endogenous processes and the resulting biological effects deserve more efforts in the field of muscle health across the lifespan.

Exploration of individual colorectal cancer cell responses to H2O2 eustress using hopping probe scanning ion conductance microscopy

Colorectal cancer (CRC), a widespread malignancy, is closely associated with tumor microenvironmental hydrogen peroxide (H2O2) levels. Some clinical trials targeting H2O2 for cancer treatment have revealed its paradoxical role as a promoter of cancer progression. Investigating the dynamics of cancer cell H2O2 eustress at the single-cell level is crucial. In this study, non-contact hopping probe mode scanning ion conductance microscopy (HPICM) with high-sensitive Pt-functionalized nanoelectrodes was employed to measure dynamic extracellular to intracellular H2O2 gradients in individual colorectal cancer Caco-2 cells. We explored the relationship between cellular mechanical properties and H2O2 gradients. Exposure to 0.1 or 1 mmol/L H2O2 eustress increased the extracellular to intracellular H2O2 gradient from 0.3 to 1.91 or 3.04, respectively. Notably, cellular F-actin-dependent stiffness increased at 0.1 mmol/L but decreased at 1 mmol/L H2O2 eustress. This H2O2-induced stiffness modulated AKT activation positively and glutathione peroxidase 2 (GPX2) expression negatively. Our findings unveil the failure of some H2O2-targeted therapies due to their ineffectiveness in generating H2O2, which instead acts eustress to promote cancer cell survival. This research also reveals the complex interplay between physical properties and biochemical signaling in cancer cells' antioxidant defense, illuminating the exploitation of H2O2 eustress for survival at the single-cell level. Inhibiting GPX and/or catalase (CAT) enhances the cytotoxic activity of H2O2 eustress against CRC cells, which holds significant promise for developing innovative therapies targeting cancer and other H2O2-related inflammatory diseases.

Effect of physical activity on long COVID fatigue: an unsolved enigma

Covid-19 disease is well documented and often the most common symptoms include myalgia and muscle fatigue. Approximately 10% of those infected complain of persistent fatigue even many months after the end of the acute phase of the disease. This gives rise to a condition different from the previous one and commonly known as 'post-acute COVID-19 syndrome' or simply Long-COVID. Although the origin of muscle fatigue is multifactorial, the state of prolonged fatigue observed in the Long-COVID syndrome suggests the existence of a possible state of atrophy or rather acute sarcopenia. Under these conditions, the use of physical activity programs can effectively counteract the state of atrophy underlying the fatigue phenomena observed. If this is also the situation during the Long-COVID, the muscular symptom should be positively influenced by the administration of programmed physical activity cycles. In fact, in patients with Long-COVID, the few published papers seem to indicate that patients who are physically active and who make an effort to engage in physical activity even during the illness have decreased duration and intensity of the illness. However, analysis of the studies in the literature also suggests that a small percentage of people with Long-COVID do not appear to benefit from the application of physical activity programs, so further studies on homogeneous samples are needed to provide a firm answer to the question: can planned physical activity help patients during the pathological course of Long-COVID?

The Role of Mitochondrial Abnormalities in Diabetic Cardiomyopathy

Diabetic cardiomyopathy (DCM) is defined as the presence in diabetic patients of abnormal cardiac structure and performance (such as left ventricular hypertrophy, fibrosis, and arrhythmia) in the absence of other cardiac risk factors (such as hypertension or coronary artery disease). Although the pathogenesis of DCM remains unclear currently, mitochondrial structural and functional dysfunctions are recognised as a central player in the DCM development. In this review, we focus on the role of mitochondrial dynamics, biogenesis and mitophagy, Ca²⁺ metabolism and bioenergetics in the DCM development and progression. Based on the crucial role of mitochondria in DCM, application of mitochondria-targeting therapies could be effective strategies to slow down the progression of the disease.

Oxidative Stress in Skeletal Muscle

The accumulation of ROS, mainly due to increased mitochondrial production and/or decreased scavenger systems, is often associated with the term oxidative stress, used to define a condition judged to be problematic for muscle cells [...]

Interplay between Zn2+ Homeostasis and Mitochondrial Functions in Cardiovascular Diseases and Heart Ageing

Zinc plays an important role in cardiomyocytes, where it exists in bound and histochemically reactive labile Zn²⁺ forms. Although Zn²⁺ concentration is under tight control through several Zn²⁺-transporters, its concentration and intracellular distribution may vary during normal cardiac function and pathological conditions, when the protein levels and efficacy of Zn²⁺ transporters can lead to zinc re-distribution among organelles in cardiomyocytes. Such dysregulation of cellular Zn²⁺ homeostasis leads to mitochondrial and ER stresses, and interrupts normal ER/mitochondria cross-talk and mitophagy, which subsequently, result in increased ROS production and dysregulated metabolic function. Besides cardiac structural and functional defects, insufficient Zn²⁺ supply was associated with heart development abnormalities, induction and progression of cardiovascular diseases, resulting in accelerated cardiac ageing. In the present review, we summarize the recently identified connections between cellular and mitochondrial Zn²⁺ homeostasis, ER stress and mitophagy in heart development, excitation–contraction coupling, heart failure and ischemia/reperfusion injury. Additionally, we discuss the role of Zn²⁺ in accelerated heart ageing and ageing-associated rise of mitochondrial ROS and cardiomyocyte dysfunction.