FUNDC1: A Promising Mitophagy Regulator at the Mitochondria-Associated Membrane for Cardiovascular Diseases

Mitochondrial autophagy (or mitophagy) regulates the mitochondrial network and function to contribute to multiple cellular processes. The protective effect of homeostatic mitophagy in cardiovascular diseases (CVDs) has attracted increasing attention. FUN14 domain containing 1 (FUNDC1), an identified mitophagy receptor, plays an essential role in CVDs. Different expression levels of FUNDC1 and its phosphorylated state at different sites alleviate or exacerbate hypoxia and ischemia/reperfusion injury, cardiac hypertrophy, or metabolic damage through promotion or inhibition of mitophagy. In addition, FUNDC1 can be enriched at contact sites between mitochondria and the endoplasmic reticulum (ER), determining the formation of mitochondria-associated membranes (MAMs) that regulate cellular calcium (Ca2+) homeostasis and mitochondrial dynamics to prevent heart dysfunction. Moreover, FUNDC1 has also been involved in inflammatory cardiac diseases such as septic cardiomyopathy. In this review, we collect and summarize the evidence on the roles of FUNDC1 exclusively in various CVDs, describing its interactions with different cellular organelles, its involvement in multiple cellular processes, and its associated signaling pathways. FUNDC1 may become a promising therapeutic target for the prevention and management of various CVDs.

Fission of megamitochondria into multiple smaller well-defined mitochondria in the ageing zebrafish retina

Mitochondria are essential adenosine triphosphate (ATP)-generating cellular organelles. In the retina, they are highly numerous in the photoreceptors and retinal pigment epithelium (RPE) due to their high energetic requirements. Fission and fusion of the mitochondria within these cells allow them to adapt to changing demands over the lifespan of the organism. Using transmission electron microscopy, we examined the mitochondrial ultrastructure of zebrafish photoreceptors and RPE from 5 days post fertilisation (dpf) through to late adulthood (3 years). Notably, mitochondria in the youngest animals were large and irregular shaped with a loose cristae architecture, but by 8 dpf they had reduced in size and expanded in number with more defined cristae. When investigating temporal gene expression of several mitochondrial-related markers, they indicated fission as the dominant mechanism contributing to these changes observed over time. This is likely to be due to continued mitochondrial stress resulting from the oxidative environment of the retina and prolonged light exposure. We have characterised retinal mitochondrial ageing in a key vertebrate model organism, that provides a basis for future studies of retinal diseases that are linked to mitochondrial dysfunction.

Molecular Effectors of Photodynamic Therapy-Mediated Resistance to Cancer Cells

Photodynamic therapy (PDT) is currently enjoying considerable attention as the subject of experimental research to treat resistant cancers. The preferential accumulation of a non-toxic photosensitizer (PS) in different cellular organelles that causes oxidative damage by combining light and molecular oxygen leads to selective cell killing. However, one major setback, common among other treatment approaches, is tumor relapse and the development of resistance causing treatment failure. PDT-mediated resistance could result from increased drug efflux and decreased localization of PS, reduced light exposure, increased DNA damage repair, and altered expression of survival genes. This review highlights the essential insights of PDT reports in which PDT resistance was observed and which identified some of the molecular effectors that facilitate the development of PDT resistance. We also discuss different perceptions of PDT and how its current limitations can be overturned to design improved cancer resistant treatments.

Mitochondrial TFAM as a Signaling Regulator between Cellular Organelles: A Perspective on Metabolic Diseases

Tissues actively involved in energy metabolism are more likely to face metabolic challenges from bioenergetic substrates and are susceptible to mitochondrial dysfunction, leading to metabolic diseases. The mitochondria receive signals regarding the metabolic states in cells and transmit them to the nucleus or endoplasmic reticulum (ER) using calcium (Ca2+) for appropriate responses. Overflux of Ca2+ in the mitochondria or dysregulation of the signaling to the nucleus and ER could increase the incidence of metabolic diseases including insulin resistance and type 2 diabetes mellitus. Mitochondrial transcription factor A (Tfam) may regulate Ca2+ flux via changing the mitochondrial membrane potential and signals to other organelles such as the nucleus and ER. Since Tfam is involved in metabolic function in the mitochondria, here, we discuss the contribution of Tfam in coordinating mitochondria-ER activities for Ca2+ flux and describe the mechanisms by which Tfam affects mitochondrial Ca2+ flux in response to metabolic challenges.

Autophagy in Cisplatin Nephrotoxicity during Cancer Therapy

Cisplatin is a widely used chemotherapeutic agent but its clinical use is often limited by nephrotoxicity. Autophagy is a lysosomal degradation pathway that removes protein aggregates and damaged or dysfunctional cellular organelles for maintaining cell homeostasis. Upon cisplatin exposure, autophagy is rapidly activated in renal tubule cells to protect against acute cisplatin nephrotoxicity. Mechanistically, the protective effect is mainly related to the clearance of damaged mitochondria via mitophagy. The role and regulation of autophagy in chronic kidney problems after cisplatin treatment are currently unclear, despite the significance of research in this area. In cancers, autophagy may prevent tumorigenesis, but autophagy may reduce the efficacy of chemotherapy by protecting cancer cells. Future research should focus on developing drugs that enhance the anti-tumor effects of cisplatin while protecting kidneys during cisplatin chemotherapy.

A review of mitochondrial disease in dogs

Mitochondria are maternally inherited cellular organelles located in the cytoplasm of most eukaryotic cells. Mitochondrial diseases are a type of metabolic disorder, involving the respiratory chain under the control of both the mitochondrial DNA and nuclear DNA. In dogs, mitochondriopathies are considered rare, with few clinical syndromes having had their structural, biochemical and genetic basis identified. In this review, the basis for suspecting a mitochondrial disease clinically is summarised, with particular focus on mitochondrial encephalopathies, encephalomyelopathies and neuropathies. Recognisable confirmed mitochondriopathies including spongiform leukoencephalomyelopathy, Alaskan Husky encephalopathy, Leigh-like subacute necrotising encephalopathy and sensory ataxic neuropathy in the Golden Retriever are described in detail, alongside previously reported individual cases of presumptive mitochondriopathies of unknown origin. Genetic mutations reported in the literature are reviewed. A clear classification for mitochondrial diseases in veterinary medicine is lacking, and this review is the first to address this class of diseases specifically in dogs.

Diagnostic Approaches to Various Muscle Diseases Based on Muscle Pathology

Muscle pathology can give much information to reach the diagnosis of neuromuscular disorders. Major pathological changes occurred in skeletal muscles include muscle fiber atrophy/hypertrophy, necrosis/regeneration, inflammation, myofibrillar disorganization, abnormal inclusions, and disruptions in cellular organelles. Physicians should be able to understand what each of these findings indicates. However, these are not always specific to a certain disease, and instead most of them are commonly found in many of muscle diseases. Thus, muscle pathological findings should be carefully interpreted under the given clinical settings.

Texture feature extraction from microscope images enables a robust estimation of ER body phenotype in Arabidopsis

Background Cellular components are controlled by genetic and physiological factors that define their shape and size. However, quantitively capturing the morphological characteristics and movement of cellular organelles from micrograph images is challenging, because the analysis deals with complexities of images that frequently lead to inaccuracy in the estimation of the features. Here we show a unique quantitative method to overcome biases and inaccuracy of biological samples from confocal micrographs. Results We generated 2D images of cell walls and spindle-shaped cellular organelles, namely ER bodies, with a maximum contrast projection of 3D confocal fluorescent microscope images. The projected images were further processed and segmented by adaptive thresholding of the fluorescent levels in the cell walls. Micrographs are composed of pixels, which have information on position and intensity. From the pixel information we calculated three types of features (spatial, intensity and Haralick) in ER bodies corresponding to segmented cells. The spatial features include basic information on shape, e.g., surface area and perimeter. The intensity features include information on mean, standard deviation and quantile of fluorescence intensities within an ER body. Haralick features describe the texture features, which can be calculated mathematically from the interrelationship between the pixel information. Together these parameters were subjected to multivariate analysis to estimate the morphological diversity. Additionally, we calculated the displacement of the ER bodies using the positional information in time-lapse images. We captured similar morphological diversity and movement within ER body phenotypes in several microscopy experiments performed in different settings and scanned under different objectives. We then described differences in morphology and movement of ER bodies between A. thaliana wild type and mutants deficient in ER body-related genes. Conclusions The findings unexpectedly revealed multiple genetic factors that are involved in the shape and size of ER bodies in A. thaliana. This is the first report showing morphological characteristics in addition to the movement of cellular components and it quantitatively summarises plant phenotypic differences even in plants that show similar cellular components. The estimation of morphological diversity was independent of the cell staining method and the objective lens used in the microscopy. Hence, our study enables a robust estimation of plant phenotypes by recognizing small differences in complex cell organelle shapes and their movement, which is beneficial in a comprehensive analysis of the molecular mechanism for cell organelle formation that is independent of technical variations.

Vitamins E and C attenuates liver injury induced by copper nanoparticle in Rats (Rattus norvegicus)

Nanoparticles are widely used in many different fields, and production. However, the ingestion of nanoparticles from environmental pollution may have significant health impacts, which are currently poorly understood. In this study we aimed to investigate the cellular toxicity of copper nanoparticles on liver tissue of Rat, and also investigate the role of vitamin E and C, separately or together, in reducing the cellular damage that may be caused by copper nanoparticles. In this study 56 (5–6) weeks old rats with a weight of 120 ± 10 grams were divided into seven groups, treated with copper nanoparticles for four weeks, then treated with vitamins, either alone or together, for another four weeks where is control. Rats were treated with copper nanoparticles showed changes in the ultrastructure of the liver tissue, in which there was a clear decrease in the number of cellular organelles in hepatocytes. Which show small in their size, and had irregular nuclear envelopes, swelling of the mitochondria, shortening of their cristae and effects on their matrix, an increase in the size of lysosomes, an increase in the number of lipid droplets, and an expansion of the Disse spaces. The treatment with vitamins C or E or both, marked improvement was found in the size and number of organelles. The cells returned to almost their normal state. We concluded that vitamins C and E have a positive role in reducing the toxic effects of copper nanoparticles. We recommended their use in doses of 250 mg/kg/day.