BMAL1 regulates mitochondrial fission and mitophagy through mitochondrial protein BNIP3 and is critical in the development of dilated cardiomyopathy

The role of cardiomyocyte senescence in cardiovascular diseases: A molecular biology update

Cardiovascular diseases (CVD) are the leading cause of death worldwide, and advanced age is a main contributor to the prevalence of CVD. Cellular senescence is an irreversible state of cell cycle arrest that occurs in old age or after cells encounter various stresses. Senescent cells not only result in the reduction of cellular function, but also produce senescence-associated secretory phenotype (SASP) to affect surrounding cells and tissue microenvironment. There is increasing evidence that the gradual accumulation of senescent cardiomyocytes is causally involved in the decline of cardiovascular system function. To highlight the role of senescent cardiomyocytes in the pathophysiology of age-related CVD, we first introduced that senescent cardiomyoyctes can be identified by structural changes and several senescence-associated biomarkers. We subsequently provided a comprehensive summary of existing knowledge, outlining the compelling evidence on the relationship between senescent cardiomyocytes and age-related CVD phenotypes. In addition, we discussed that the significant therapeutic potential represented by the prevention of accelerated senescent cardiomyocytes, and the current status of some existing geroprotectors in the prevention and treatment of age-related CVD. Together, the review summarized the role of cardiomyocyte senescence in CVD, and explored the molecular knowledge of senescent cardiomyocytes and their potential clinical significance in developing senescent-based therapies, thereby providing important insights into their biology and potential therapeutic exploration.

Role of mitophagy in intervertebral disc degeneration: A narrative review

OBJECTIVE

The pivotal role of mitophagy in the initiation and progression of intervertebral disc (IVD) degeneration (IDD) has become increasingly apparent due to a growing body of research on its pathogenesis. This review summarizes the role of mitophagy in IDD and the therapeutic potential of targeting this process.

DESIGN

This narrative review is divided into three parts: the regulatory mechanisms of mitophagy, the role of mitophagy in IDD, and the applications and prospects of mitophagy for the treatment of IDD.

RESULTS

Mitophagy protects cells against harmful external stimuli and plays a crucial protective role by promoting extracellular matrix (ECM) production, inhibiting ECM degradation, and reducing apoptosis, senescence, and cartilage endplate calcification. However, excessive mitophagy is often detrimental to cells. Currently, the regulatory mechanisms governing appropriate and excessive mitophagy remain unclear.

CONCLUSIONS

Proper mitophagy effectively maintains IVD cell homeostasis and slows the progression of IDD. Conversely, excessive mitophagy may accelerate IDD development. Further research is needed to elucidate the regulatory mechanisms underlying appropriate and excessive mitophagy, which could provide new theoretical support for the application of mitophagy targeting to the treatment of IDD.

Causal Associations Between Sleep Traits and Low Grip Strength: A Bidirectional Mendelian Randomization Study

Background

Sleep disorders and low grip strength often co-occur clinically and are geriatric symptoms that cause significant socioeconomic burden. Previous observational studies have found an association between sleep behaviors and grip strength, but the causal relationship remains unclear.

Purpose

With the Mendelian randomization (MR) approach, the study aimed to determine the causal association between sleep traits (sleep duration, insomnia, daytime napping, sleep-wake disorders, chronotype) and low grip strength.

Methods

The study used genetic variants from the genome-wide association study (GWAS) archived in UK Biobank and FinnGen. We assessed the potential causal relationship between sleep behaviors and grip strength using inverse variance weighting (IVW), weighted median (WM), and MR-Egger. Additionally, we performed sensitivity analyses using Cochran's Q test, MR Egger Intercept test, funnel plots, and leave-one-out method.

Results

We found that sleep duration is causally negatively associated with low grip strength (OR = 0.618, 95% CI = 0.424-0.900, P = 0.012). Sleep-wake disorders have a positive association with low grip strength (OR = 1.018, 95% CI = 1.002-1.034, P = 0.029). Reversely, high low grip strength risk was causally associated with increased daytime napping (OR = 1.018, 95% CI = 1.004-1.032, P = 0.011).

Conclusion

The study revealed causal associations between sleep duration, sleep-wake disorders, and low grip strength. Understanding their relationship helps in early clinical intervention to improve the life quality of the elderly.

m6Am Methyltransferase PCIF1 Promotes LPP3 Mediated Phosphatidic Acid Metabolism and Renal Cell Carcinoma Progression

N6-methyl-2'-O-methyladenosine (m6Am), occurring adjacent to the 7-methylguanosine (m7G) cap structure and catalyzed by the newly identified writer PCIF1 (phosphorylated CTD interacting factor 1), has been implicated in the pathogenesis of various diseases. However, its involvement in renal cell carcinoma (RCC) remains unexplored. Here, significant upregulation of PCIF1 and m6Am levels in RCC tissues are identified, unveiling their oncogenic roles both in vitro and in vivo. Mechanically, employing m6Am-Exo-Seq, LPP3 (phospholipid phosphatase 3) mRNA is identified as a key downstream target whose translation is enhanced by m6Am modification. Furthermore, LPP3 is revealed as a key regulator of phosphatidic acid metabolism, critical for preventing its accumulation in mitochondria and facilitating mitochondrial fission. Consequently, Inhibition of the PCIF1/LPP3 axis significantly altered mitochondrial morphology and reduced RCC tumor progression. In addition, depletion of PCIF1 sensitizes RCC to sunitinib treatment. This study highlights the intricate interplay between m6Am modification, phosphatidic acid metabolism, and mitochondrial dynamics, offering a promising therapeutic avenue for RCC.

Cardiovascular adaptations and pathological changes induced by spaceflight: from cellular mechanisms to organ-level impacts

The advancement in extraterrestrial exploration has highlighted the crucial need for studying how the human cardiovascular system adapts to space conditions. Human development occurs under the influence of gravity, shielded from space radiation by Earth's magnetic field, and within an environment characterized by 24-hour day-night cycles resulting from Earth's rotation, thus deviating from these conditions necessitates adaptive responses for survival. With upcoming manned lunar and Martian missions approaching rapidly, it is essential to understand the impact of various stressors induced by outer-space environments on cardiovascular health. This comprehensive review integrates insights from both actual space missions and simulated experiments on Earth, to analyze how microgravity, space radiation, and disrupted circadian affect cardiovascular well-being. Prolonged exposure to microgravity induces myocardial atrophy and endothelial dysfunction, which may be exacerbated by space radiation. Mitochondrial dysfunction and oxidative stress emerge as key underlying mechanisms along with disturbances in ion channel perturbations, cytoskeletal damage, and myofibril changes. Disruptions in circadian rhythms caused by factors such as microgravity, light exposure, and irregular work schedules, could further exacerbate cardiovascular issues. However, current research tends to predominantly focus on disruptions in the core clock gene, overlooking the multifactorial nature of circadian rhythm disturbances in space. Future space missions should prioritize targeted prevention strategies and early detection methods for identifying cardiovascular risks, to preserve astronaut health and ensure mission success.

The Abl1 tyrosine kinase is a key player in doxorubicin-induced cardiomyopathy and its p53/p73 cell death mediated signaling differs in atrial and ventricular cardiomyocytes

BACKGROUND

Doxorubicin is an important anticancer drug, however, elicits dose-dependently cardiomyopathy. Given its mode of action, i.e. topoisomerase inhibition and DNA damage, we investigated genetic events associated with cardiomyopathy and searched for mechanism-based possibilities to alleviate cardiotoxicity. We treated rats at clinically relevant doses of doxorubicin. Histopathology and transmission electron microscopy (TEM) defined cardiac lesions, and transcriptomics unveiled cardiomyopathy-associated gene regulations. Genomic-footprints revealed critical components of Abl1-p53-signaling, and EMSA-assays evidenced Abl1 DNA-binding activity. Gene reporter assays confirmed Abl1 activity on p53-targets while immunohistochemistry/immunofluorescence microscopy demonstrated Abl1, p53&p73 signaling.

RESULTS

Doxorubicin treatment caused dose-dependently toxic cardiomyopathy, and TEM evidenced damaged mitochondria and myofibrillar disarray. Surviving cardiomyocytes repressed Parkin-1 and Bnip3-mediated mitophagy, stimulated dynamin-1-like dependent mitochondrial fission and induced anti-apoptotic Bag1 signaling. Thus, we observed induced mitochondrial biogenesis. Transcriptomics discovered heterogeneity in cellular responses with minimal overlap between treatments, and the data are highly suggestive for distinct cardiomyocyte (sub)populations which differed in their resilience and reparative capacity. Genome-wide footprints revealed Abl1 and p53 enriched binding sites in doxorubicin-regulated genes, and we confirmed Abl1 DNA-binding activity in EMSA-assays. Extraordinarily, Abl1 signaling differed in the heart with highly significant regulations of Abl1, p53 and p73 in atrial cardiomyocytes. Conversely, in ventricular cardiomyocytes, Abl1 solely-modulated p53-signaling that was BAX transcription-independent. Gene reporter assays established Abl1 cofactor activity for the p53-reporter PG13-luc, and ectopic Abl1 expression stimulated p53-mediated apoptosis.

CONCLUSIONS

The tyrosine kinase Abl1 is of critical importance in doxorubicin induced cardiomyopathy, and we propose its inhibition as means to diminish risk of cardiotoxicity.

E3 ubiquitin ligase UBR5 modulates circadian rhythm by facilitating the ubiquitination and degradation of the key clock transcription factor BMAL1

The circadian clock is the inner rhythm of life activities and is controlled by a self-sustained and endogenous molecular clock, which maintains a ~ 24 h internal oscillation. As the core element of the circadian clock, BMAL1 is susceptible to degradation through the ubiquitin-proteasome system (UPS). Nevertheless, scant information is available regarding the UPS enzymes that intricately modulate both the stability and transcriptional activity of BMAL1, affecting the cellular circadian rhythm. In this work, we identify and validate UBR5 as a new E3 ubiquitin ligase that interacts with BMAL1 by using affinity purification, mass spectrometry, and biochemical experiments. UBR5 overexpression induced BMAL1 ubiquitination, leading to diminished stability and reduced protein level of BMAL1, thereby attenuating its transcriptional activity. Consistent with this, UBR5 knockdown increases the BMAL1 protein. Domain mapping discloses that the C-terminus of BMAL1 interacts with the N-terminal domains of UBR5. Similarly, cell-line-based experiments discover that HYD, the UBR5 homolog in Drosophila, could interact with and downregulate CYCLE, the BMAL1 homolog in Drosophila. PER2-luciferase bioluminescence real-time reporting assay in a mammalian cell line and behavioral experiments in Drosophila reveal that UBR5 or hyd knockdown significantly reduces the period of the circadian clock. Therefore, our work discovers a new ubiquitin ligase UBR5 that regulates BMAL1 stability and circadian rhythm and elucidates the underlying molecular mechanism. This work provides an additional layer of complexity to the regulatory network of the circadian clock at the post-translational modification level, offering potential insights into the modulation of the dysregulated circadian rhythm.

Melatonin regulates mitochondrial dynamics and mitophagy: Cardiovascular protection

Despite extensive progress in the knowledge and understanding of cardiovascular diseases and significant advances in pharmacological treatments and procedural interventions, cardiovascular diseases (CVD) remain the leading cause of death globally. Mitochondrial dynamics refers to the repetitive cycle of fission and fusion of the mitochondrial network. Fission and fusion balance regulate mitochondrial shape and influence physiology, quality and homeostasis. Mitophagy is a process that eliminates aberrant mitochondria. Melatonin (Mel) is a pineal-synthesized hormone with a range of pharmacological properties. Numerous nonclinical trials have demonstrated that Mel provides cardioprotection against ischemia/reperfusion, cardiomyopathies, atherosclerosis and cardiotoxicity. Recently, interest has grown in how mitochondrial dynamics contribute to melatonin cardioprotective effects. This review assesses the literature on the protective effects of Mel against CVD via the regulation of mitochondrial dynamics and mitophagy in both in-vivo and in-vitro studies. The signalling pathways underlying its cardioprotective effects were reviewed. Mel modulated mitochondrial dynamics and mitophagy proteins by upregulation of mitofusin, inhibition of DRP1 and regulation of mitophagy-related proteins. The evidence supports a significant role of Mel in mitochondrial dynamics and mitophagy quality control in CVD.

Nicotine induces senescence in spermatogonia stem cells by disrupting homeostasis between circadian oscillation and rhythmic mitochondrial dynamics via the SIRT6/Bmal1 pathway

Infertility is intricately linked with alterations in circadian rhythms along with physiological decline and stem cell senescence. Yet, the direct involvement of circadian mechanisms in nicotine-induced injury to the testes, especially the senescence of spermatogonia stem cells (SSCs), is not well comprehended. This study revealed that nicotine exposure induced testis injury by triggering SSCs senescence along with the upregulation of senescence marker genes and senescence-associated secretory phenotype components. Moreover, nicotine treatment caused mitochondrial hyper-fusion, increased oxidative stress, and DNA damage. Exposure to nicotine was found to suppress the expression of sirtuin 6 (SIRT6), which accelerated the senescence of spermatogonia stem cells (SSCs). This acceleration led to increased acetylation of brain and muscle ARNT-like protein (Bmal1), consequently reducing the expression of Bmal1 protein. Conversely, the overexpression of Bmal1 alleviated mitochondrial hyper-fusion and senescence phenotypes induced by nicotine. Overall, this study unveiled a novel molecular mechanism behind nicotine-induced disorders in spermatogenesis and highlighted the SIRT6/Bmal1 regulatory pathway as a potential therapeutic target for combating nicotine-associated infertility.

Usp14 down-regulation corrects sleep and circadian dysfunction of a Drosophila model of Parkinson's disease

PD is a complex, multifactorial neurodegenerative disease, which occurs sporadically in aged population, with some genetically linked cases. Patients develop a very obvious locomotor phenotype, with symptoms such as bradykinesia, resting tremor, muscular rigidity, and postural instability. At the cellular level, PD pathology is characterized by the presence of intracytoplasmic neurotoxic aggregates of misfolded proteins and dysfunctional organelles, resulting from failure in mechanisms of proteostasis. Nonmotor symptoms, such as constipation and olfactory deficits, are also very common in PD. They include alteration in the circadian clock, and defects in the sleep-wake cycle, which is controlled by the clock. These non-motor symptoms precede the onset of the motor symptoms by many years, offering a window of therapeutic intervention that could delay-or even prevent-the progression of the disease. The mechanistic link between aberrant circadian rhythms and neurodegeneration in PD is not fully understood, although proposed underlying mechanisms include alterations in protein homeostasis (proteostasis), which can impact protein levels of core components of the clock. Loss of proteostasis depends on the progressive pathological decline in the proteolytic activity of two major degradative systems, the ubiquitin-proteasome and the lysosome-autophagy systems, which is exacerbated in age-dependent neurodegenerative conditions like PD. Accordingly, it is known that promoting proteasome or autophagy activity increases lifespan, and rescues the pathological phenotype of animal models of neurodegeneration, presumably by enhancing the degradation of misfolded proteins and dysfunctional organelles, which are known to accumulate in these models, and to induce intracellular damage. We can enhance proteostasis by pharmacologically inhibiting or down-regulating Usp14, a proteasome-associated deubiquitinating enzyme (DUB). In a previous work, we showed that inhibition of Usp14 enhances the activity of the ubiquitin-proteasome system (UPS), autophagy and mitophagy, and abolishes motor symptoms of two well-established fly models of PD that accumulate dysfunctional mitochondria. In this work we extended the evidence on the protective effect of Usp14 down-regulation, and investigated the beneficial effect of down-regulating Usp14 in a Pink1 Drosophila model of PD that develop circadian and sleep dysfunction. We show that down-regulation of Usp14 ameliorates sleep disturbances and circadian defects that are associated to Pink1 KO flies.

Chronic sleep fragmentation reduces left ventricular contractile function and alters gene expression related to innate immune response and circadian rhythm in the mouse heart

Sleep disorders have emerged as a widespread public health concern, primarily due to their association with an increased risk of developing cardiovascular diseases. Our previous research indicated a potential direct impact of insufficient sleep duration on cardiac remodeling in children and adolescents. Nevertheless, the underlying mechanisms behind the link between sleep fragmentation (SF) and cardiac abnormalities remain unclear. In this study, we aimed to investigate the effects of SF interventions at various life stages on cardiac structure and function, as well as to identify genes associated with SF-induced cardiac dysfunction. To achieve this, we established mouse models of chronic SF and two-week sleep recovery (SR). Our results revealed that chronic SF significantly compromised left ventricular contractile function across different life stages, leading to alterations in cardiac structure and ventricular remodeling, particularly during early life stages. Moreover, microarray analysis of mouse heart tissue identified two significant modules and nine hub genes (Ddx60, Irf9, Oasl2, Rnf213, Cmpk2, Stat2, Parp14, Gbp3, and Herc6) through protein-protein interaction analysis. Notably, the interactome predominantly involved innate immune responses. Importantly, all hub genes lost significance following SR. The second module primarily consisted of circadian clock genes, and real-time PCR validation demonstrated significant upregulation of Arntl, Dbp, and Cry1 after SF, while subsequent SR restored normal Arntl expression. Furthermore, the expression levels of four hub genes (Ddx60, Irf9, Oasl2, and Cmpk2) and three circadian clock genes (Arntl, Dbp, and Cry1) exhibited correlations with structural and functional echocardiographic parameters. Overall, our findings suggest that SF impairs left ventricular contractile function and ventricular remodeling during early life stages, and this may be mediated by modulation of the innate immune response and circadian rhythm. Importantly, our findings suggest that a short period of SR can alleviate the detrimental effects of SF on the cardiac immune response, while the influence of SF on circadian rhythm appears to be more persistent. These findings underscore the importance of good sleep for maintaining cardiac health, particularly during early life stages.

Sleep deprivation induces corneal endothelial dysfunction by downregulating Bmal1

BACKGROUND

Sleep deprivation (SD) is a common public health problem that contributes to various physiological disorders and increases the risk of ocular diseases. However, whether sleep loss can damage corneal endothelial function remains unclear. This study aimed to determine the effect and possible mechanism of SD on the corneal endothelium.

METHODS

Male C57BL/6J mice were subjected to establish SD models. After 10 days, quantitative RT-PCR (qRT-PCR) and western blot or immunostaining for the expression levels of zonula occludens-1 (ZO-1), ATPase Na+/K + transporting subunit alpha 1 (Atp1a1), and core clock genes in the corneal endothelium were evaluated. Reactive oxygen species staining and mitochondrial abundance characterized the mitochondrial function. The regulatory role of Bmal1 was confirmed by specifically knocking down or overexpressing basic helix-loop-helix ARNT like 1 protein (Bmal1) in vivo. In vitro, a mitochondrial stress test was conducted on cultured human corneal endothelial cells upon Bmal1 knockdown.

RESULTS

SD damaged the barrier and pump functions of mouse corneal endothelium, accompanied by mitochondrial dysfunction. Interestingly, SD dramatically downregulated the core clock gene Bmal1 expression level. Bmal1 knockdown disrupted corneal endothelial function, while overexpression of Bmal1 ameliorated the dysfunction induced by SD. Mitochondrial bioenergetic deficiency mediated by Bmal1 was an underlying mechanism for SD induced corneal endothelial dysfunction.

CONCLUSION

The downregulation of Bmal1 expression caused by SD led to corneal endothelial dysfunction via impairing mitochondrial bioenergetics. Our findings offered insight into how SD impairs the physiological function of the corneal endothelium and expanded the understanding of sleep loss leading to ocular diseases.

Mitophagy in relation to chronic inflammation/ROS in aging

Various assaults on mitochondria occur during the human aging process, contributing to mitochondrial dysfunction. This mitochondrial dysfunction is intricately connected with aging and diseases associated with it. In vivo, the accumulation of defective mitochondria can precipitate inflammatory and oxidative stress, thereby accelerating aging. Mitophagy, an essential selective autophagy process, plays a crucial role in managing mitochondrial quality control and homeostasis. It is a highly specialized mechanism that systematically removes damaged or impaired mitochondria from cells, ensuring their optimal functioning and survival. By engaging in mitophagy, cells are able to maintain a balanced and stable environment, free from the potentially harmful effects of dysfunctional mitochondria. An ever-growing body of research highlights the significance of mitophagy in both aging and age-related diseases. Nonetheless, the association between mitophagy and inflammation or oxidative stress induced by mitochondrial dysfunction remains ambiguous. We review the fundamental mechanisms of mitophagy in this paper, delve into its relationship with age-related stress, and propose suggestions for future research directions.

Time of exercise differentially impacts bone growth in mice

Although physical training has been shown to improve bone mass, the time of day to exercise for optimal bone growth remains uncertain. Here we show that engaging in physical activity during the early active phase, as opposed to the subsequent active or rest phase, results in a more substantial increase in bone length of male and female mice. Transcriptomic and metabolomic methodologies identify that exercise during the early active phase significantly upregulates genes associated with bone development and metabolism. Notably, oxidative phosphorylation-related genes show a rhythmic expression in the chondrification centre, with a peak at the early active phase, when more rhythmic genes in bone metabolism are expressed and bone growth is synergistically promoted by affecting oxidative phosphorylation, which is confirmed by subsequent pharmacological investigations. Finally, we construct a signalling network to predict the impact of exercise on bone growth. Collectively, our research sheds light on the intricacies of human exercise physiology, offering valuable implications for interventions.

The role of mitochondrial dynamics and mitophagy in skeletal muscle atrophy: from molecular mechanisms to therapeutic insights

Skeletal muscle is the largest metabolic organ of the human body. Maintaining the best quality control and functional integrity of mitochondria is essential for the health of skeletal muscle. However, mitochondrial dysfunction characterized by mitochondrial dynamic imbalance and mitophagy disruption can lead to varying degrees of muscle atrophy, but the underlying mechanism of action is still unclear. Although mitochondrial dynamics and mitophagy are two different mitochondrial quality control mechanisms, a large amount of evidence has indicated that they are interrelated and mutually regulated. The former maintains the balance of the mitochondrial network, eliminates damaged or aged mitochondria, and enables cells to survive normally. The latter degrades damaged or aged mitochondria through the lysosomal pathway, ensuring cellular functional health and metabolic homeostasis. Skeletal muscle atrophy is considered an urgent global health issue. Understanding and gaining knowledge about muscle atrophy caused by mitochondrial dysfunction, particularly focusing on mitochondrial dynamics and mitochondrial autophagy, can greatly contribute to the prevention and treatment of muscle atrophy. In this review, we critically summarize the recent research progress on mitochondrial dynamics and mitophagy in skeletal muscle atrophy, and expound on the intrinsic molecular mechanism of skeletal muscle atrophy caused by mitochondrial dynamics and mitophagy. Importantly, we emphasize the potential of targeting mitochondrial dynamics and mitophagy as therapeutic strategies for the prevention and treatment of muscle atrophy, including pharmacological treatment and exercise therapy, and summarize effective methods for the treatment of skeletal muscle atrophy.

The circadian rhythm: A new target of natural products that can protect against diseases of the metabolic system, cardiovascular system, and nervous system

BACKGROUND

The treatment of metabolic system, cardiovascular system, and nervous system diseases remains to be explored. In the internal environment of organisms, the metabolism of substances such as carbohydrates, lipids and proteins (including biohormones and enzymes) exhibit a certain circadian rhythm to maintain the energy supply and material cycle needed for the normal activities of organisms. As a key factor for the health of organisms, the circadian rhythm can be disrupted by pathological conditions, and this disruption accelerates the progression of diseases and results in a vicious cycle. The current treatments targeting the circadian rhythm for the treatment of metabolic system, cardiovascular system, and nervous system diseases have certain limitations, and the identification of safer and more effective circadian rhythm regulators is needed.

AIM OF THE REVIEW

To systematically assess the possibility of using the biological clock as a natural product target for disease intervention, this work reviews a range of evidence on the potential effectiveness of natural products targeting the circadian rhythm to protect against diseases of the metabolic system, cardiovascular system, and nervous system. This manuscript focuses on how natural products restore normal function by affecting the amplitude of the expression of circadian factors, sleep/wake cycles and the structure of the gut microbiota.

KEY SCIENTIFIC CONCEPTS OF THE REVIEW

This work proposes that the circadian rhythm, which is regulated by the amplitude of the expression of circadian rhythm-related factors and the sleep/wake cycle, is crucial for diseases of the metabolic system, cardiovascular system and nervous system and is a new target for slowing the progression of diseases through the use of natural products. This manuscript provides a reference for the molecular modeling of natural products that target the circadian rhythm and provides a new perspective for the time-targeted action of drugs.

Circadian Influences on Myocardial Ischemia-Reperfusion Injury and Heart Failure

The impact of circadian rhythms on cardiovascular function and disease development is well established, with numerous studies in genetically modified animals emphasizing the circadian molecular clock's significance in the pathogenesis and pathophysiology of myocardial ischemia and heart failure progression. However, translational preclinical studies targeting the heart's circadian biology are just now emerging and are leading to the development of a novel field of medicine termed circadian medicine. In this review, we explore circadian molecular mechanisms and novel therapies, including (1) intense light, (2) small molecules modulating the circadian mechanism, and (3) chronotherapies such as cardiovascular drugs and meal timings. These promise significant clinical translation in circadian medicine for cardiovascular disease. (4) Additionally, we address the differential functioning of the circadian mechanism in males versus females, emphasizing the consideration of biological sex, gender, and aging in circadian therapies for cardiovascular disease.

Circadian Effects on Vascular Immunopathologies

Circadian rhythms exert a profound impact on most aspects of mammalian physiology, including the immune and cardiovascular systems. Leukocytes engage in time-of-day-dependent interactions with the vasculature, facilitating the emigration to and the immune surveillance of tissues. This review provides an overview of circadian control of immune-vascular interactions in both the steady state and cardiovascular diseases such as atherosclerosis and infarction. Circadian rhythms impact both the immune and vascular facets of these interactions, primarily through the regulation of chemoattractant and adhesion molecules on immune and endothelial cells. Misaligned light conditions disrupt this rhythm, generally exacerbating atherosclerosis and infarction. In cardiovascular diseases, distinct circadian clock genes, while functioning as part of an integrated circadian system, can have proinflammatory or anti-inflammatory effects on these immune-vascular interactions. Here, we discuss the mechanisms and relevance of circadian rhythms in vascular immunopathologies.

Adaptive and maladaptive roles of different angiotensin receptors in the development of cardiac hypertrophy and heart failure

Angiotensin II (Ang II) is formed by the action of angiotensin-converting enzyme (ACE) in the renin-angiotensin system. This hormone is known to induce cardiac hypertrophy and heart failure and its actions are mediated by the interaction of both pro- and antihypertrophic Ang II receptors (AT1R and AT2R). Ang II is also metabolized by ACE 2 to Ang-(1-7), which elicits the activation of Mas receptors (MasR) for inducing antihypertrophic actions. Since heart failure under different pathophysiological situations is preceded by adaptive and maladaptive cardiac hypertrophy, we have reviewed the existing literature to gain some information regarding the roles of AT1R, AT2R, and MasR in both acute and chronic conditions of cardiac hypertrophy. It appears that the activation of AT1R may be involved in the development of adaptive and maladaptive cardiac hypertrophy as well as subsequent heart failure because both ACE inhibitors and AT1R antagonists exert beneficial effects. On the other hand, the activation of both AT2R and MasR may prevent the occurrence of maladaptive cardiac hypertrophy and delay the progression of heart failure, and thus therapy with different activators of these antihypertrophic receptors under chronic pathological stages may prove beneficial. Accordingly, it is suggested that a great deal of effort should be made to develop appropriate activators of both AT2R and MasR for the treatment of heart failure subjects.

Molecular mechanisms of artificial light at night affecting circadian rhythm disturbance

Artificial light at night (ALAN) pollution has been regarded as a global environmental concern. More than 80% of the global population is exposed to light pollution. Exacerbating this issue, artificially lit outdoor areas are growing by 2.2% per year, while continuously lit areas have brightened by 2.2% each year due to rapid population growth and expanding urbanization. Furthermore, the increasing prevalence of night shift work and smart device usage contributes to the inescapable influence of ALAN. Studies have shown that ALAN can disrupt endogenous biological clocks, resulting in a disturbance of the circadian rhythm, which ultimately affects various physiological functions. Up until now, scholars have studied various disease mechanisms caused by ALAN that may be related to the response of the circadian system to light. This review outlines the molecular mechanisms by which ALAN causes circadian rhythm abnormalities in sleep disorders, endocrine diseases, cardiovascular disease, cancer, immune impairment, depression, anxiety and cognitive impairments.

Selective autophagy in cancer: mechanisms, therapeutic implications, and future perspectives

Eukaryotic cells engage in autophagy, an internal process of self-degradation through lysosomes. Autophagy can be classified as selective or non-selective depending on the way it chooses to degrade substrates. During the process of selective autophagy, damaged and/or redundant organelles like mitochondria, peroxisomes, ribosomes, endoplasmic reticulum (ER), lysosomes, nuclei, proteasomes, and lipid droplets are selectively recycled. Specific cargo is delivered to autophagosomes by specific receptors, isolated and engulfed. Selective autophagy dysfunction is closely linked with cancers, neurodegenerative diseases, metabolic disorders, heart failure, etc. Through reviewing latest research, this review summarized molecular markers and important signaling pathways for selective autophagy, and its significant role in cancers. Moreover, we conducted a comprehensive analysis of small-molecule compounds targeting selective autophagy for their potential application in anti-tumor therapy, elucidating the underlying mechanisms involved. This review aims to supply important scientific references and development directions for the biological mechanisms and drug discovery of anti-tumor targeting selective autophagy in the future.

Transcriptome analysis of effects of Tecrl deficiency on cardiometabolic and calcium regulation in cardiac tissue

Catecholaminergic polymorphic ventricular tachycardia (CPVT) is a hereditary heart disease characterized by bidirectional or polymorphic ventricular tachycardia and an increased risk of sudden cardiac death. Although trans-2,3-enoyl-CoA reductase like (TECRL) is a newly reported pathogenic gene leading to CPVT that can influence intracellular calcium regulation, the unidentified mechanism underlying the pathogenesis of TECRL deficiency-mediated CPVT remains mainly elusive. In the present study, Tecrl knockout (KO) mice were established and the differentially expressed genes (DEGs) were investigated by RNA-sequencing from the heart tissues. In addition, 857 DEGs were identified in Tecrl KO mice. Subsequently, a weighted gene co-expression network analysis was conducted to discern the pivotal pathways implicated in the Tecrl-mediated regulatory network. Moreover, pathway mapping analyses demonstrated that essential metabolism-related pathways were significantly enriched, notably the fatty acid metabolic process and calcium regulation. Collectively, the data suggested a synergistic relationship between Tecrl deficiency and cardiometabolic and calcium regulation during the development of CPVT. Therefore, further studies on the potential function of TECRL in cardiac tissues would be beneficial to elucidate the pathogenesis of CPVT.

Endurance Exercise Training Mitigates Diastolic Dysfunction in Diabetic Mice Independent of Phosphorylation of Ulk1 at S555

Millions of diabetic patients suffer from cardiovascular complications. One of the earliest signs of diabetic complications in the heart is diastolic dysfunction. Regular exercise is a highly effective preventive/therapeutic intervention against diastolic dysfunction in diabetes, but the underlying mechanism(s) remain poorly understood. Studies have shown that the accumulation of damaged or dysfunctional mitochondria in the myocardium is at the center of this pathology. Here, we employed a mouse model of diabetes to test the hypothesis that endurance exercise training mitigates diastolic dysfunction by promoting cardiac mitophagy (the clearance of mitochondria via autophagy) via S555 phosphorylation of Ulk1. High-fat diet (HFD) feeding and streptozotocin (STZ) injection in mice led to reduced endurance capacity, impaired diastolic function, increased myocardial oxidative stress, and compromised mitochondrial structure and function, which were all ameliorated by 6 weeks of voluntary wheel running. Using CRISPR/Cas9-mediated gene editing, we generated non-phosphorylatable Ulk1 (S555A) mutant mice and showed the requirement of p-Ulk1at S555 for exercise-induced mitophagy in the myocardium. However, diabetic Ulk1 (S555A) mice retained the benefits of exercise intervention. We conclude that endurance exercise training mitigates diabetes-induced diastolic dysfunction independent of Ulk1 phosphorylation at S555.

Autophagy protects mitochondrial health in heart failure

The progression of heart failure is reported to be strongly associated with homeostatic imbalance, such as mitochondrial dysfunction and abnormal autophagy, in the cardiomyocytes. Mitochondrial dysfunction triggers autophagic and cardiac dysfunction. In turn, abnormal autophagy impairs mitochondrial function and leads to apoptosis or autophagic cell death under certain circumstances. These events often occur concomitantly, forming a vicious cycle that exacerbates heart failure. However, the role of the crosstalk between mitochondrial dysfunction and abnormal autophagy in the development of heart failure remains obscure and the underlying mechanisms are mainly elusive. The potential role of the link between mitochondrial dysfunction and abnormal autophagy in heart failure progression has recently garnered attention. This review summarized recent advances of the interactions between mitochondria and autophagy during the development of heart failure.

The ER membrane protein complex restricts mitophagy by controlling BNIP3 turnover

Lysosomal degradation of autophagy receptors is a common proxy for selective autophagy. However, we find that two established mitophagy receptors, BNIP3 and BNIP3L/NIX, are constitutively delivered to lysosomes in an autophagy-independent manner. This alternative lysosomal delivery of BNIP3 accounts for nearly all its lysosome-mediated degradation, even upon mitophagy induction. To identify how BNIP3, a tail-anchored protein in the outer mitochondrial membrane, is delivered to lysosomes, we performed a genome-wide CRISPR screen for factors influencing BNIP3 flux. This screen revealed both known modifiers of BNIP3 stability as well as a pronounced reliance on endolysosomal components, including the ER membrane protein complex (EMC). Importantly, the endolysosomal system and the ubiquitin-proteosome system regulated BNIP3 independently. Perturbation of either mechanism is sufficient to modulate BNIP3-associated mitophagy and affect underlying cellular physiology. More broadly, these findings extend recent models for tail-anchored protein quality control and install endosomal trafficking and lysosomal degradation in the canon of pathways that tightly regulate endogenous tail-anchored protein localization.

METTL3 boosts mitochondrial fission and induces cardiac fibrosis after ischemia/reperfusion injury

METTL3, an RNA methyltransferase enzyme, exerts therapeutic effects on various cardiovascular diseases. Myocardial ischemia-reperfusion injury (MIRI) and subsequently cardiac fibrosis is linked to acute cardiomyocyte death or dysfunction induced by mitochondrial damage, particularly mitochondrial fission. Our research aims to elucidate the potential mechanisms underlying the therapeutic actions of METTL3 in MIRI, with focus on mitochondrial fission. When compared with Mettl3flox mice subjected to MIRI, Mettl3 cardiomyocyte knockout (Mettl3Cko) mice have reduced infarct size, decreased serum levels of myocardial injury-related factors, limited cardiac fibrosis, and preserved myocardial ultrastructure and contractile/relaxation capacity. The cardioprotective actions of Mettl3 knockout were associated with reduced inflammatory responses, decreased myocardial neutrophil infiltration, and suppression of cardiomyocyte death. Through signaling pathway validation experiments and assays in cultured HL-1 cardiomyocytes exposed to hypoxia/reoxygenation, we confirmed that Mettl3 deficiency interfere with DNA-PKcs phosphorylation, thereby blocking the downstream activation of Fis1 and preventing pathological mitochondrial fission. In conclusion, this study confirms that inhibition of METTL3 can alleviate myocardial cardiac fibrosis inflammation and prevent cardiomyocyte death under reperfusion injury conditions by disrupting DNA-PKcs/Fis1-dependent mitochondrial fission, ultimately improving cardiac function. These findings suggest new approaches for clinical intervention in patients with MIRI.

The interplay between sex, time of day, fasting status, and their impact on cardiac mitochondrial structure, function, and dynamics

Mitochondria morphology and function, and their quality control by mitophagy, are essential for heart function. We investigated whether these are influenced by time of the day (TOD), sex, and fed or fasting status, using transmission electron microscopy (EM), mitochondrial electron transport chain (ETC) activity, and mito-QC reporter mice. We observed peak mitochondrial number at ZT8 in the fed state, which was dependent on the intrinsic cardiac circadian clock, as hearts from cardiomyocyte-specific BMAL1 knockout (CBK) mice exhibit different TOD responses. In contrast to mitochondrial number, mitochondrial ETC activities do not fluctuate across TOD, but decrease immediately and significantly in response to fasting. Concurrent with the loss of ETC activities, ETC proteins were decreased with fasting, simultaneous with significant increases of mitophagy, mitochondrial antioxidant protein SOD2, and the fission protein DRP1. Fasting-induced mitophagy was lost in CBK mice, indicating a direct role of BMAL1 in regulating mitophagy. This is the first of its kind report to demonstrate the interactions between sex, fasting, and TOD on cardiac mitochondrial structure, function and mitophagy. These studies provide a foundation for future investigations of mitochondrial functional perturbation in aging and heart diseases.

BMAL1 inhibits renal fibrosis and renal interstitial inflammation by targeting the ERK1/2/ELK-1/Egr-1 axis

RATIONALE

Renal fibrosis and renal interstitial inflammation due to hydronephrosis are associated with progressive chronic kidney disease (CKD). The clock gene BMAL1 is thought to be involved in various diseases, including hypertension, diabetes, etc. However, little is known about how BMAL1 regulates renal fibrosis and renal interstitial inflammation in obstructed kidneys.

METHODS

The expression level of BMAL1 in UUO was examined using the GEO database. Lentivirus, siRNA and adeno-associated virus were used to modulate BMAL1 levels in HK-2 cells and mouse kidney. qRT-PCR, immunofluorescence staining, histological analysis, ELISA and Western blot were used to determine the level of fibrin deposition and the release of inflammatory factors. Immunofluorescence staining and western blotting were used to examine the interaction between BMAL1 and the ERK1/2/ELK-1/Egr-1 axis.

RESULTS

Bioinformatics analysis and in vivo experiments in this study showed that the expression level of BMAL1 in UUO model kidneys was higher than that in normal kidneys. We then found that downregulation of BMAL1 promoted the production of extracellular matrix (ECM) proteins and proinflammatory factors in vivo and in vitro, whereas upregulation inhibited this process. In addition, we demonstrated that the ERK1/2/ELK-1/Egr-1 axis is an important pathway for BMAL1 to play a regulatory role, and the use of PD98059 abolished the promoting effect of down-regulation of BMAL1 on fibrosis and inflammation.

CONCLUSIONS

Our findings suggest that BAML1 can target the ERK1/2/ELK-1/Egr-1 axis to suppress fibrotic progression and inflammatory events in obstructed kidneys, thereby inhibiting the development of CKD.

Autophagy, Clock Genes, and Cardiovascular Disease

Circadian rhythms are 24-hour cycles that regulate physical, mental, and behavioural changes of most living organisms. In the heart, circadian rhythms regulate processes such as heart rate, blood pressure, blood coagulability, and vascular tone. However, in addition to regulating physiologic processes, circadian rhythms regulate pathophysiologic processes in the heart. In this regard, circadian rhythms regulate the onset, severity, and outcome of many cardiovascular diseases (CVDs), including myocardial infarction, diabetic cardiomyopathy, doxorubicin (Dox)-induced cardiotoxicity, and heart failure. Notably, the underlying mechanism of many of these diseases is linked to impaired cellular quality control processes, such as autophagy. Autophagy is a homeostatic cellular process that regulates the removal of damaged cellular components, allowing their degradation and recycling into their basic constituents for production of cellular energy. Many studies from recent years point to a regulatory link between autophagy and circadian machinery in the control of CVDs. In this review, we highlight the recent discoveries in the field of circadian-induced autophagy in the heart and provide the molecular mechanisms and signalling pathways that underlie the crosstalk between autophagy and clock gene control in response to cardiac injury. Understanding the mechanisms that underlie circadian-induced autophagy in response to cardiac stress may prove to be beneficial in developing novel therapeutic approaches to treat cardiac disease.

Targeting mitochondrial quality control for diabetic cardiomyopathy: Therapeutic potential of hypoglycemic drugs

Diabetic cardiomyopathy is a chronic cardiovascular complication caused by diabetes that is characterized by changes in myocardial structure and function, ultimately leading to heart failure and even death. Mitochondria serve as the provider of energy to cardiomyocytes, and mitochondrial dysfunction plays a central role in the development of diabetic cardiomyopathy. In response to a series of pathological changes caused by mitochondrial dysfunction, the mitochondrial quality control system is activated. The mitochondrial quality control system (including mitochondrial biogenesis, fusion and fission, and mitophagy) is core to maintaining the normal structure of mitochondria and performing their normal physiological functions. However, mitochondrial quality control is abnormal in diabetic cardiomyopathy, resulting in insufficient mitochondrial fusion and excessive fission within the cardiomyocyte, and fragmented mitochondria are not phagocytosed in a timely manner, accumulating within the cardiomyocyte resulting in cardiomyocyte injury. Currently, there is no specific therapy or prevention for diabetic cardiomyopathy, and glycemic control remains the mainstay. In this review, we first elucidate the pathogenesis of diabetic cardiomyopathy and explore the link between pathological mitochondrial quality control and the development of diabetic cardiomyopathy. Then, we summarize how clinically used hypoglycemic agents (including sodium-glucose cotransport protein 2 inhibitions, glucagon-like peptide-1 receptor agonists, dipeptidyl peptidase-4 inhibitors, thiazolidinediones, metformin, and α-glucosidase inhibitors) exert cardioprotective effects to treat and prevent diabetic cardiomyopathy by targeting the mitochondrial quality control system. In addition, the mechanisms of complementary alternative therapies, such as active ingredients of traditional Chinese medicine, exercise, and lifestyle, targeting mitochondrial quality control for the treatment of diabetic cardiomyopathy are also added, which lays the foundation for the excavation of new diabetic cardioprotective drugs.

Mitochondrial quality control in health and cardiovascular diseases

Cardiovascular diseases (CVDs) are one of the primary causes of mortality worldwide. An optimal mitochondrial function is central to supplying tissues with high energy demand, such as the cardiovascular system. In addition to producing ATP as a power source, mitochondria are also heavily involved in adaptation to environmental stress and fine-tuning tissue functions. Mitochondrial quality control (MQC) through fission, fusion, mitophagy, and biogenesis ensures the clearance of dysfunctional mitochondria and preserves mitochondrial homeostasis in cardiovascular tissues. Furthermore, mitochondria generate reactive oxygen species (ROS), which trigger the production of pro-inflammatory cytokines and regulate cell survival. Mitochondrial dysfunction has been implicated in multiple CVDs, including ischemia-reperfusion (I/R), atherosclerosis, heart failure, cardiac hypertrophy, hypertension, diabetic and genetic cardiomyopathies, and Kawasaki Disease (KD). Thus, MQC is pivotal in promoting cardiovascular health. Here, we outline the mechanisms of MQC and discuss the current literature on mitochondrial adaptation in CVDs.

Ruscogenin timing administration mitigates cerebral ischemia-reperfusion injury through regulating circadian genes and activating Nrf2 pathway

BACKGROUND

Ruscogenin (Rus), a steroidal sapogenin extracted from Ophiopogon japonicus (L. f.) Ker-Gawl., has the effect of alleviating cerebral ischemia-reperfusion injury (IRI), acute lung injury. At present, the chronopharmacological effects of Rus are still unknown.

PURPOSE

This study explored the alleviating effect and mechanism of Rus timing administration on mice cerebral IRI.

METHODS

The animals in different groups were administrated Rus (10 mg/kg) by gavage at four time points (23:00-01:00, 05:00-07:00, 11:00-13:00, 17:00-19:00) respectively for 3 days. On the 4th day, middle cerebral artery occlusion (MCAO) surgery was operated during 5:00-7:00. Behavioral tests were executed and the brain was collected for infarct volume, qPCR and immunoblot detection. The levels of tumor necrosis factor-α (TNF-α), interleukin 6 (IL-6), interleukin-1beta (IL-1β) and inducible nitric oxide synthase (iNOS) were detected by qPCR. Glutathione (GSH), superoxide dismutase (SOD) activity and malondialdehyde (MDA) content in serum and cerebral cortex were detected. The clock genes were tested by western blot. Based on these results, 17:00-19:00 was selected to administrate Rus for further mechanism study and Nrf2 blocker group was administrated all-trans-retinoic acid (ATRA) at 14:00 for 3 days.

RESULTS

Administration of Rus reduced cerebral infarcted volume, ameliorated the behavior score and upregulated the mRNA and protein expression of Per1, Bmal1, Clock, Rev-erbα, transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2), heme oxygenase-1 (HO-1), quinone oxidoreductase 1 (NQO1). Administration of Rus during 17:00-19:00 had better preventive effect than other three time points. Combined administration of ATRA blunted the preventive effect of Rus.

CONCLUSION

The preventive effect of Rus is affected by the time of administration, which was regulated by Nrf2 pathway. Taken together, we provide solid evidence to suggest that different administration time point affect the effectiveness of Rus in alleviating IRI.

Role of Bmal1 and Gut Microbiota in Alzheimer's Disease and Parkinson's Disease Pathophysiology: The Probable Effect of Melatonin on Their Association

In recent years, the role of new factors in the pathophysiology of neurodegenerative diseases has been investigated. Alzheimer's disease (AD) and Parkinson's disease (PD) are the most common neurodegenerative diseases worldwide. Although pathological changes such as the accumulation of aggregated proteins in the brain and inflammatory responses are known as the main factors involved in the development of these diseases, new studies show the role of gut microbiota and circadian rhythm in the occurrence of these changes. However, the association between circadian rhythm and gut microbiota in AD and PD has not yet been investigated. Recent results propose that alterations in circadian rhythm regulators, mainly Bmal1, may regulate the abundance of gut microbiota. This correlation has been linked to the regulation of the expression of immune-related genes and Bmal-1 mediated oscillation of IgA and hydrogen peroxide production. These data seem to provide new insight into the molecular mechanism of melatonin inhibiting the progression of AD and PD. Therefore, this manuscript aims to review the role of the gut microbiota and circadian rhythm in health and AD and PD and also presents a hypothesis on the effect of melatonin on their communication.

3-MCPD Induced Mitochondrial Damage of Renal Cells Via the Rhythmic Protein BMAL1 Targeting SIRT3/SOD2

Biorhythm regulates a variety of physiological functions and enables organisms to adapt to changing environments. 3-Monochloro-1,2-propanediol (3-MCPD) is a common food thermal processing contaminant, and the kidney is its toxic target organ. However, the nephrotoxicity mechanism of 3-MCPD has not been fully elucidated. In the study, we found that 3-MCPD caused mitochondrial damage in renal cells by inhibiting the SIRT3/SOD2 pathway. Further, we found that 3-MCPD could interfere with rhythm protein BMAL1 expression at protein and mRNA levels in mice kidney and NRK-52E cells. Simultaneously, the balance of the daily oscillation of SIRT3/SOD2 pathway proteins was impeded under 3-MCPD treatment. To determine the role of BAML1 in mitochondrial damage, we overexpressed the BMAL1 protein. The data showed that BMAL1 overexpression upregulated SIRT3 and SOD2 expression and attenuated mitochondrial damage caused by 3-MCPD. These results indicated that 3-MCPD inhibited the SIRT3/SOD2 pathway by affecting the expression of the rhythm protein BMAL1, thereby inducing mitochondrial damage in renal cells. Taken together, our work reveals that 3-MCPD may possess a toxic effect via circadian clock mechanisms.

Targeting mitochondrial circadian rhythms: The potential intervention strategies of Traditional Chinese medicine for myocardial ischaemia‒reperfusion injury

Coronary artery disease has one of the highest mortality rates in the country, and methods such as thrombolysis and percutaneous coronary intervention (PCI) can effectively improve symptoms and reduce mortality, but most patients still experience symptoms such as chest pain after PCI, which seriously affects their quality of life and increases the incidence of adverse cardiovascular events (myocardial ischaemiareperfusion injury, MIRI). MIRI has been shown to be closely associated with circadian rhythm disorders and mitochondrial dysfunction. Mitochondria are a key component in the maintenance of normal cardiac function, and new research shows that mitochondria have circadian properties. Traditional Chinese medicine (TCM), as a traditional therapeutic approach characterised by a holistic concept and evidence-based treatment, has significant advantages in the treatment of MIRI, and there is an interaction between the yin-yang theory of TCM and the circadian rhythm of Western medicine at various levels. This paper reviews the clinical evidence for the treatment of MIRI in TCM, basic experimental studies on the alleviation of MIRI by TCM through the regulation of mitochondria, the important role of circadian rhythms in the pathophysiology of MIRI, and the potential mechanisms by which TCM regulates mitochondrial circadian rhythms to alleviate MIRI through the regulation of the biological clock transcription factor. It is hoped that this review will provide new insights into the clinical management, basic research and development of drugs to treat MIRI.

Inflammation o'clock: interactions of circadian rhythms with inflammation-induced skeletal muscle atrophy

Circadian rhythms are ∼24 h cycles evident in behaviour, physiology and metabolism. The molecular mechanism directing circadian rhythms is the circadian clock, which is composed of an interactive network of transcription-translation feedback loops. The core clock genes include Bmal1, Clock, Rev-erbα/β, Per and Cry. In addition to keeping time, the core clock regulates a daily programme of gene expression that is important for overall cell homeostasis. The circadian clock mechanism is present in all cells, including skeletal muscle fibres, and disruption of the muscle clock is associated with changes in muscle phenotype and function. Skeletal muscle atrophy is largely associated with a lower quality of life, frailty and reduced lifespan. Physiological and genetic modification of the core clock mechanism yields immune dysfunction, alters inflammatory factor expression and secretion and is associated with skeletal muscle atrophy in multiple conditions, such as ageing and cancer cachexia. Here, we summarize the possible interplay between the circadian clock modulation of immune cells, systemic inflammatory status and skeletal muscle atrophy in chronic inflammatory conditions. Although there is a clear disruption of circadian clocks in various models of atrophy, the mechanism behind such alterations remains unknown. Understanding the modulatory potential of muscle and immune circadian clocks in inflammation and skeletal muscle health is essential for the development of therapeutic strategies to protect skeletal muscle mass and function of patients with chronic inflammation.

Defining diurnal fluctuations in mouse choroid plexus and CSF at high molecular, spatial, and temporal resolution

Transmission and secretion of signals via the choroid plexus (ChP) brain barrier can modulate brain states via regulation of cerebrospinal fluid (CSF) composition. Here, we developed a platform to analyze diurnal variations in male mouse ChP and CSF. Ribosome profiling of ChP epithelial cells revealed diurnal translatome differences in metabolic machinery, secreted proteins, and barrier components. Using ChP and CSF metabolomics and blood-CSF barrier analyses, we observed diurnal changes in metabolites and cellular junctions. We then focused on transthyretin (TTR), a diurnally regulated thyroid hormone chaperone secreted by the ChP. Diurnal variation in ChP TTR depended on Bmal1 clock gene expression. We achieved real-time tracking of CSF-TTR in awake TtrmNeonGreen mice via multi-day intracerebroventricular fiber photometry. Diurnal changes in ChP and CSF TTR levels correlated with CSF thyroid hormone levels. These datasets highlight an integrated platform for investigating diurnal control of brain states by the ChP and CSF.

The role of circadian clock-controlled mitochondrial dynamics in diabetic cardiomyopathy

Diabetes mellitus is a metabolic disease with a high prevalence worldwide, and cardiovascular complications are the leading cause of mortality in patients with diabetes. Diabetic cardiomyopathy (DCM), which is prone to heart failure with preserved ejection fraction, is defined as a cardiac dysfunction without conventional cardiac risk factors such as coronary heart disease and hypertension. Mitochondria are the centers of energy metabolism that are very important for maintaining the function of the heart. They are highly dynamic in response to environmental changes through mitochondrial dynamics. The disruption of mitochondrial dynamics is closely related to the occurrence and development of DCM. Mitochondrial dynamics are controlled by circadian clock and show oscillation rhythm. This rhythm enables mitochondria to respond to changing energy demands in different environments, but it is disordered in diabetes. In this review, we summarize the significant role of circadian clock-controlled mitochondrial dynamics in the etiology of DCM and hope to play a certain enlightening role in the treatment of DCM.

Pathological implications of cellular stress in cardiovascular diseases

Cellular stress has been a key factor in the development of cardiovascular diseases. Major types of cellular stress such as mitochondrial stress, endoplasmic reticulum stress, hypoxia, and replicative stress have been implicated in clinical complications of cardiac patients. The heart is the central regulator of the body by supplying oxygenated blood throughout the system. Impairment of cellular function could lead to heart failure, myocardial infarction, ischemia, and even stroke. Understanding the effect of these distinct types of cellular stress on cardiac function is crucial for the scientific community to understand and develop novel therapeutic approaches. This review will comprehensively explain the different mechanisms of cellular stress and the most recent findings related to stress-induced cardiac dysfunction.

The ER membrane protein complex governs lysosomal turnover of a mitochondrial tail-anchored protein, BNIP3, to restrict mitophagy

Lysosomal degradation of autophagy receptors is a common proxy for selective autophagy. However, we find that two established mitophagy receptors, BNIP3 and BNIP3L/NIX, violate this assumption. Rather, BNIP3 and NIX are constitutively delivered to lysosomes in an autophagy-independent manner. This alternative lysosomal delivery of BNIP3 accounts for nearly all of its lysosome-mediated degradation, even upon mitophagy induction. To identify how BNIP3, a tail-anchored protein in the outer mitochondrial membrane, is delivered to lysosomes, we performed a genome-wide CRISPR screen for factors influencing BNIP3 flux. By this approach, we revealed both known modifiers of BNIP3 stability as well as a pronounced reliance on endolysosomal components, including the ER membrane protein complex (EMC). Importantly, the endolysosomal system regulates BNIP3 alongside, but independent of, the ubiquitin-proteosome system (UPS). Perturbation of either mechanism is sufficient to modulate BNIP3-associated mitophagy and affect underlying cellular physiology. In short, while BNIP3 can be cleared by parallel and partially compensatory quality control pathways, non-autophagic lysosomal degradation of BNIP3 is a strong post-translational modifier of BNIP3 function. More broadly, these data reveal an unanticipated connection between mitophagy and TA protein quality control, wherein the endolysosomal system provides a critical axis for regulating cellular metabolism. Moreover, these findings extend recent models for tail-anchored protein quality control and install endosomal trafficking and lysosomal degradation in the canon of pathways that ensure tight regulation of endogenous TA protein localization.

Extracellular vesicles DJ-1 derived from hypoxia-conditioned hMSCs alleviate cardiac hypertrophy by suppressing mitochondria dysfunction and preventing ATRAP degradation

BACKGROUND

As a pathological myocardial remodeling process in a variety of cardiovascular diseases, cardiac hypertrophy still has no effective treatment. Human mesenchymal stem cells (hMSCs) derived extracellular vesicles (EVs) has been recognized as a promising treatment strategy for cardiac disease.

METHODS

In this study, the inhibitory effects on cardiac hypertrophy are compared between normoxia-conditioned hMSC-derived EVs (Nor-EVs) and hypoxia-conditioned hMSC-derived EVs (Hypo-EVs) in neonatal rat cardiomyocytes (NRCMs) after angiotensin II (Ang II) stimulation and in a mouse model of transverse aortic constriction (TAC).

RESULTS

We demonstrate that Hypo-EVs exert an increased inhibitory effect on cardiac hypertrophy compared with Nor-EVs. Parkinson disease protein 7 (PARK7/DJ-1) is identify as a differential protein between Nor-EVs and Hypo-EVs by quantitative proteomics analysis. Results show that DJ-1, which is rich in Hypo-EVs, alleviates mitochondrial dysfunction and excessive mitochondrial reactive oxygen species (mtROS) production as an antioxidant. Mechanistic studies demonstrate for the first time that DJ-1 may suppress cardiac hypertrophy by inhibiting the activity of proteasome subunit beta type 10 (PSMB10) through a direct physical interaction. This interaction can inhibit angiotensin II type 1 receptor (AT1R)-mediated signaling pathways resulting in cardiac hypertrophy through alleviating ubiquitination degradation of AT1R-associated protein (ATRAP).

CONCLUSIONS

When taken together, our study suggests that Hypo-EVs have significant potential as a novel therapeutic agent for the treatment of cardiac hypertrophy.

Mitochondrial Dysfunction and Therapeutic Perspectives in Cardiovascular Diseases

High mortality rates due to cardiovascular diseases (CVDs) have attracted worldwide attention. It has been reported that mitochondrial dysfunction is one of the most important mechanisms affecting the pathogenesis of CVDs. Mitochondrial DNA (mtDNA) mutations may result in impaired oxidative phosphorylation (OXPHOS), abnormal respiratory chains, and ATP production. In dysfunctional mitochondria, the electron transport chain (ETC) is uncoupled and the energy supply is reduced, while reactive oxygen species (ROS) production is increased. Here, we discussed and analyzed the relationship between mtDNA mutations, impaired mitophagy, decreased OXPHOS, elevated ROS, and CVDs from the perspective of mitochondrial dysfunction. Furthermore, we explored current potential therapeutic strategies for CVDs by eliminating mtDNA mutations (e.g., mtDNA editing and mitochondrial replacement), enhancing mitophagy, improving OXPHOS capacity (e.g., supplement with NAD+, nicotinamide riboside (NR), nicotinamide mononucleotide (NMN), and nano-drug delivery), and reducing ROS (e.g., supplement with Coenzyme Q10 and other antioxidants), and dissected their respective advantages and limitations. In fact, some therapeutic strategies are still a long way from achieving safe and effective clinical treatment. Although establishing effective and safe therapeutic strategies for CVDs remains challenging, starting from a mitochondrial perspective holds bright prospects.

7,8-Dihydroxyflavone alleviates cardiac fibrosis by restoring circadian signals via downregulating Bmal1/Akt pathway

Brain-derived neurotrophic factor (BDNF)/tyrosine kinase receptor B (TrkB) pathway is a therapeutic target in cardiac diseases. A BDNF mimetic, 7,8-dihydroxyflavone (7,8-DHF), is emerging as a protective agent in cardiomyocytes; however, its potential role in cardiac fibroblasts (CFs) and fibrosis remains unknown. Thus, we aimed to explore the effects of 7,8-DHF on cardiac fibrosis and the possible mechanisms. Myocardial ischemia (MI) and transforming growth factor-β1 (TGF-β1) were used to establish models of cardiac fibrosis. Hematoxylin & eosin and Masson's trichrome stains were used for histological analysis and determination of collagen content in mouse myocardium. Cell viability kit, EdU (5-ethynyl-2'-deoxyuridine) assay and immunofluorescent stain were employed to examine the effects of 7,8-DHF on the proliferation and collagen production of CFs. The levels of collagen I, α-smooth muscle actin (α-SMA), TGF-β1, Smad2/3, and Akt as well as circadian rhythm-related signals including brain and muscle Arnt-like protein 1 (Bmal1), period 2 (Per2), and cryptochrome 2 (Cry2) were analyzed. Treatment with 7,8-DHF markedly alleviated cardiac fibrosis in MI mice. It inhibited the activity of CFs accompanied by decreasing number of EdU-positive cells and downregulation of collagen I, α-SMA, TGF-β1, and phosphorylation of Smad2/3. 7,8-DHF significantly restored the dysregulation of Bmal1, Per2, and Cry2, but inhibited the overactive Akt. Further, inhibition of Bmal1 by SR9009 effectively attenuated CFs proliferation and collagen production of CFs. In summary, these findings indicate that 7,8-DHF attenuates cardiac fibrosis and regulates circadian rhythmic signals, at least partly, by inhibiting Bmal1/Akt pathway, which may provide new insights into therapeutic cardiac remodeling.

Integrative Bioinformatics Analysis Revealed Mitochondrial Dysfunction-Related Genes Underlying Intervertebral Disc Degeneration

Objective

Mitochondrial dysfunction plays an important role in intervertebral disc degeneration (IDD). We aim to explore the pathways and key genes that cause mitochondrial dysfunction during IDD and to further reveal the pathogenesis of IDD based on bioinformatic analyses.

Methods

Datasets GSE70362 and GSE124272 were downloaded from the Gene Expression Omnibus. Differentially expressed genes (DEGs) of mitochondrial dysfunction between IDD patients and healthy controls were screened by package limma package. Critical genes were identified by adopting gene ontology (GO), Kyoto encyclopedia of genes and genomes (KEGG) pathways, and protein-protein interaction (PPI) networks. We collected both degenerated and normal disc tissues obtained surgically, and we performed western blot and qPCR to verify the key DEGs identified in intervertebral disc tissues.

Results

In total, 40 cases of IDD and 24 healthy controls were included. We identified 152 DEGs, including 67 upregulated genes and 85 downregulated genes. Four genes related to mitochondrial dysfunction (SOX9, FLVCR1, NR5A1 and UCHL1) were screened out. Of them, SOX9, FLVCR1, and UCHL1 were down-regulated in peripheral blood and intervertebral disc tissues of IDD patients, while NR5A1 was up-regulated. The analysis of immune infiltration showed the concentrations of mast cells activated were significantly the highest in IDD patients. Compared with the control group, the level of T cells CD4 memory resting was the lowest in the patients. In addition, 24 cases of IDD tissues and 12 cases of normal disc tissues were obtained to verify the results of bioinformatics analysis. Both western blot and qPCR results were consistent with the results of bioinformatics analysis.

Conclusion

We identified four genes (SOX9, FLVCR1, NR5A1 and UCHL1) associated with mitochondrial dysfunction that play an important role in the progress of disc degeneration. The identification of these differential genes may provide new insights for the diagnosis and treatment of IDD.

Circadian Control of Mitochondria in Reactive Oxygen Species Homeostasis

Significance: Mitochondria produce most of the cellular ATP through the process of oxidative phosphorylation. Energy metabolism in the mitochondria is associated with the production of reactive oxygen species (ROS). Excessive ROS production leads to oxidative stress and compromises cellular physiology. Energy metabolism in the mitochondria depends on nutrient flux and cellular metabolic needs, which are in turn connected with the feeding/fasting cycle. In animals, the feeding/fasting cycle is controlled by the circadian clock that generates 24-h rhythms in behavior, metabolism, and signaling. Recent Advances: Here, we discuss the role of the circadian clock and rhythms in mitochondria on ROS homeostasis. The circadian clock is involved in mitochondrial ROS production and detoxification through the control of nutrient flux and oxidation, uncoupling, antioxidant defense, and mitochondrial dynamics. Critical Issues: Little is known on the molecular mechanisms of circadian control of mitochondrial functions. The circadian clock regulates the expression and activity of mitochondrial metabolic and antioxidant enzymes. The regulation involves a direct transcriptional control by Circadian Locomotor Output Cycles Kaput/brain and muscle ARNT-like 1(CLOCK/BMAL1), nuclear factor erythroid-2-related factor 2 (NRF2) transcriptional network, and sirtuin-dependent posttranslational protein modifications. Future Perspectives: We hypothesize that the circadian clock orchestrates mitochondrial physiology to synchronize it with the feeding/fasting cycle. Circadian coordination of mitochondrial function couples energy metabolism with diets and contributes to antioxidant defense to prevent metabolic diseases and delay aging. Antioxid. Redox Signal. 37, 647-663.

Fucoxanthin ameliorated myocardial fibrosis in STZ-induced diabetic rats and cell hypertrophy in HG-induced H9c2 cells by alleviating oxidative stress and restoring mitophagy

Diabetic cardiomyopathy (DCM) is one of the leading causes of death in diabetic patients, and is accompanied by increased oxidative stress and mitochondrial dysfunction. Fucoxanthin (FX), as a marine carotenoid, possesses strong antioxidant activity. The main purpose of our study was to explore whether FX could attenuate experimental cardiac hypertrophy by affecting mitophagy and oxidative stress. We found that FX improved lipid metabolism, myocardial damage, myocardial fibrosis and hypertrophy in the myocardial tissue of STZ-induced diabetic rats. Additionally, FX upregulated Nrf2 signaling to reduce the level of reactive oxygen species (ROS). FX also promoted Bnip3/Nix signaling to improve mitochondrial function and reduced the levels of mitochondrial and intracellular ROS, thereby reversing HG-induced H9c2 cell hypertrophy. However, treatment with the autophagy inhibitor CQ abolished the anti-hypertrophic effect of FX, accompanied by impaired mitochondrial function and increased ROS levels. In conclusion, we found that FX reduced the accumulation of TGF-β1, FN and α-SMA to relieve myocardial fibrosis in STZ-induced diabetic rats, and FX up-regulated Bnip3/Nix to promote mitophagy and enhanced Nrf2 signaling to alleviate oxidative stress, thereby inhibiting hypertrophy in HG-induced H9c2 cells. These results imply that FX may be developed as a functional food for DCM.

Mitochondrial autophagy in the sleeping brain

A significant percentage of the mitochondrial mass is replaced on a daily basis via mechanisms of mitochondrial quality control. Through mitophagy (a selective type of autophagy that promotes mitochondrial proteostasis) cells keep a healthy pool of mitochondria, and prevent oxidative stress and inflammation. Furthermore, mitophagy helps adapting to the metabolic demand of the cells, which changes on a daily basis.

Core components of the mitophagy process are PINK1 and Parkin, which mutations are linked to Parkinson’s Disease. The crucial role of PINK1/Parkin pathway during stress-induced mitophagy has been extensively studied in vitro in different cell types. However, recent advances in the field allowed discovering that mitophagy seems to be only slightly affected in PINK1 KO mice and flies, putting into question the physiological relevance of this pathway in vivo in the whole organism. Indeed, several cell-specific PINK1/Parkin-independent mitophagy pathways have been recently discovered, which appear to be activated under physiological conditions such as those that promote mitochondrial proteome remodeling during differentiation or in response to specific physiological stimuli.

In this Mini Review we want to summarize the recent advances in the field, and add another level of complexity by focusing attention on a potentially important aspect of mitophagy regulation: the implication of the circadian clock. Recent works showed that the circadian clock controls many aspects of mitochondrial physiology, including mitochondrial morphology and dynamic, respiratory activity, and ATP synthesis. Furthermore, one of the essential functions of sleep, which is controlled by the clock, is the clearance of toxic metabolic compounds from the brain, including ROS, via mechanisms of proteostasis. Very little is known about a potential role of the clock in the quality control mechanisms that maintain the mitochondrial repertoire healthy during sleep/wake cycles. More importantly, it remains completely unexplored whether (dys)function of mitochondrial proteostasis feedbacks to the circadian clockwork.

BMAL1 plays a critical role in the protection against cardiac hypertrophy through autophagy in vitro

Background

Heart disease could result from a malfunction in the core clock gene BMAL1, according to studies conducted on animals and humans in vitro and in vivo. However, in pathological conditions, the role of BMAL1 was not clear. In the present study, we identified a potential link between BMAL1 and cardiac hypertrophy.

Methods

Primary cultured neonatal rat cardiomyocytes were stimulated by Ang II. Cardiomyocytes immunofluorescence analysis was performed to observe the cell size. RT-PCR and Western blot were used to find out the gene and protein expression. Cell apoptosis was measured by TUNEL staining. The Elisa assay was performed which determine the release of cytokines led to the activation of cardiac fibro-blasts in cell-free supernatants. Furthermore, gain- and loss-of-function studies revealed that BMAL1 has an effect on Ang II-induced cardiac hypertrophy.

Results

We found that Ang II-induced cardiac hypertrophy as a result BMAL1 expression was reduced. However, overexpression of BMAL1 could prevent Ang II-induced hypertrophy. Additionally, although BMAL1 overexpression in hypertrophic cardiomyocytes could not prevent hypertrophy, it did reduce the apoptosis of hypertrophic cardiomyocytes after Ang II had induced it. In addition, BMAL1 knockdown did not aggravate Ang II-induced hypertrophy but accelerated its development. Finally, BMAL1 overexpression significantly resisted the effects of Ang II on oxidative stress, autophagy and, cardiac fibrosis in cardiomyocytes.

Conclusions

Our results showed that overexpression of BMAL1 effectively resisted cardiac hypertrophy induced by Ang II. Our findings provided a novel potential target for the treatment of cardiac hypertrophy.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12872-022-02822-3.

Mitochondrial quality control in cardiac ischemia/reperfusion injury: new insights into mechanisms and implications

The current effective method for the treatment of myocardial infarction is timely restoration of the blood supply to the ischemic area of the heart. Although reperfusion is essential for reestablishing oxygen and nutrient supplies, it often leads to additional myocardial damage, creating an important clinical dilemma. Reports from long-term studies have confirmed that mitochondrial damage is the critical mechanism in cardiac ischemia/reperfusion (I/R) injury. Mitochondria are dynamic and possess a quality control system that targets mitochondrial quantity and quality by modifying mitochondrial fusion, fission, mitophagy, and biogenesis and protein homeostasis to maintain a healthy mitochondrial network. The system of mitochondrial quality control involves complex molecular machinery that is highly interconnected and associated with pathological changes such as oxidative stress, calcium overload, and endoplasmic reticulum (ER) stress. Because of the critical role of the mitochondrial quality control systems, many reports have suggested that defects in this system are among the molecular mechanisms underlying myocardial reperfusion injury. In this review, we briefly summarize the important role of the mitochondrial quality control in cardiomyocyte function and focus on the current understanding of the regulatory mechanisms and molecular pathways involved in mitochondrial quality control in cardiac I/R damage.

K2P1 leak cation channels contribute to ventricular ectopic beats and sudden death under hypokalemia

Hypokalemia causes ectopic heartbeats, but the mechanisms underlying such cardiac arrhythmias are not understood. In reduced serum K⁺ concentrations that occur under hypokalemia, K2P1 two-pore domain K⁺ channels change ion selectivity and switch to conduct inward leak cation currents, which cause aberrant depolarization of resting potential and induce spontaneous action potential of human cardiomyocytes. K2P1 is expressed in the human heart but not in mouse hearts. We test the hypothesis that K2P1 leak cation channels contribute to ectopic heartbeats under hypokalemia, by analysis of transgenic mice, which conditionally express induced K2P1 specifically in hearts, mimicking K2P1 channels in the human heart. Conditional expression of induced K2P1 specifically in the heart of hypokalemic mice results in multiple types of ventricular ectopic beats including single and multiple ventricular premature beats as well as ventricular tachycardia and causes sudden death. In isolated mouse hearts that express induced K2P1, sustained ventricular fibrillation occurs rapidly after perfusion with low K⁺ concentration solutions that mimic hypokalemic conditions. These observed phenotypes occur rarely in control mice or in the hearts that lack K2P1 expression. K2P1-expressing mouse cardiomyocytes of transgenic mice much more frequently fire abnormal single and/or rhythmic spontaneous action potential in hypokalemic conditions, compared to wild type mouse cardiomyocytes without K2P1 expression. These findings confirm that K2P1 leak cation channels induce ventricular ectopic beats and sudden death of transgenic mice with hypokalemia and imply that K2P1 leak cation channels may play a critical role in human ectopic heartbeats under hypokalemia.