Short AIP1 (ASK1-Interacting Protein-1) Isoform Localizes to the Mitochondria and Promotes Vascular Dysfunction

The SIRT1/GPS2/AIP1 axis regulates pulmonary vascular permeability in ventilator-induced lung injury

Mechanical ventilation (MV) is essential for patients who require life support, but undue mechanical stress leads to airway and alveolar injury, also known as ventilator-induced lung injury (VILI). MV induces changes in pulmonary endothelial barrier integrity by affecting cell junction proteins. The mechanisms of disruption of endothelial barrier integrity during VILI are still unclear. This study aimed to investigate the roles and mechanisms by which ASK1-interacting protein-1 (AIP1), G-protein pathway suppressor 2 (GPS2), and sirtuin 1 (SIRT1) affect VILI. Human lung microvascular endothelial cells (HLMVECs) were transfected with AIP1 small interfering RNA (siRNA), GPS2 siRNA, GPS2 cDNA, and SIRT1 siRNA and subjected to 20% cyclic stretch (CS). C57BL/6N mice were pretreated with the SIRT1 siRNA before MV. We found that CS of 20% activated oxidative stress, increased the reactive oxygen species (ROS) production, and disrupted the pulmonary endothelial cell barrier integrity. AIP1 depletion increased the ROS production and aggravated the disruption of endothelial barrier integrity. Loss of GPS2 decreased the level of AIP1, leading to low expression levels of cell junction proteins. These effects were alleviated by GPS2 overexpression. SIRT1 depletion induced a decrease in GPS2 and AIP1, and increased the ROS production, resulting in decreased expression levels of cell junction proteins. Furthermore, VILI was exacerbated by increased cytokine production (IL-6 and IL-1β), pulmonary oedema, and an elevated wet/dry weight ratio in SIRT1-depleted mice under MV. These results suggest that cyclic mechanical stretching activated oxidative stress and disrupted the expression of cell junction proteins. The SIRT1/GPS2/AIP1 axis influences the production of ROS to regulate the pulmonary endothelial cell barrier integrity during VILI.

Endothelial major vault protein alleviates vascular remodeling via promoting Parkin-mediated mitophagy

Many important vascular diseases including neointimal hyperplasia and atherosclerosis are characterized by the endothelial cell (EC) injury-initiated pathological vascular remodeling. However, the endogenous regulatory mechanisms underlying it are not fully understood. The present study investigates regulatory role of major vault protein (MVP) in the pathogenesis of vascular remodeling via controlling EC injury. By generating male murine vascular disease models, we find that ablation of endothelial MVP increases neointima formation and promotes atherosclerosis. Mechanistically, MVP directly binds with Parkin and inhibits the ubiquitination and proteasomal degradation of Parkin by dissociating the E3 ligase NEDD4L from Parkin, leading to activation of Parkin-mediated mitophagy pathway in the EC. Genetic modulation of endothelial MVP and Parkin influences the mitophagy, apoptosis, and neointima formation. These results demonstrate that MVP acts as an intracellular regulator promoting Parkin-mediated mitophagy. Our findings suggest that MVP/NEDD4L/Parkin axis may serve as the therapeutic target for treating intimal hyperplasia and atherosclerosis.

Beyond interacting with Rap1: Dissecting the roles of Rif1

Rap1 interacting factor 1 (Rif1), an evolutionarily conserved protein discovered in budding yeast, is crucial for controlling telomere length when it interacts with Rap1. Recent research, however, has shown that Rif1 not only controls telomere length and homeostasis, but also plays a role in transcriptional silencing, DNA replication timing, DNA replication fork protection, DNA damage repair and chromatin architecture. In this review, we summarize the current understanding of Rif1 in structure, function, and regulation, especially its relevance to cancer hallmarks. Also, we discuss its role as a regulator in the pathogenesis of disease.

Interspecies differences in mitochondria: Implications for cardiac and vascular translational research

Mitochondria are essential organelles that regulate cellular energy metabolism, redox balance, and signaling pathways related to proliferation, aging and survival. So far, significant interspecies differences exist in mitochondrial structure, function, and dynamics, which have critical implications for cardiovascular physiology and pharmacology. This review explores the main differences in mitochondrial properties across species of animals that are commonly used for translational research, emphasizing their cardiac and vascular relevance. By addressing key interspecies differences, including mitochondrial DNA (mtDNA) variation, bioenergetic profile, oxidative stress response, epigenetic regulation, mitochondrial biogenesis, and adaptive mechanisms, we aim to provide insights into the challenges and opportunities in translating preclinical findings to clinical applications. Understanding these interspecies differences is essential for optimizing the design and interpretation of preclinical studies and for developing effective mitochondrial-targeted therapies.

Epigenetic regulation in coronary artery disease: from mechanisms to emerging therapies

Atherosclerosis, the primary cause of coronary artery disease (CAD), remains a leading global cause of mortality. It is characterized by the accumulation of cholesterol-rich plaques and inflammation, which narrow the coronary arteries and increase the risk of rupture. To elucidate this complex biological process and improve therapeutic strategies, CAD has been extensively explored from an epigenetic perspective over the past two decades. Epigenetics is a field investigating heritable alterations in gene expression without DNA sequence changes, such as DNA methylation, histone modifications, and non-coding RNAs. Increasing evidence has indicated that the development of CAD is significantly influenced by epigenetic changes. Meanwhile, the impact of epigenetics in CAD is now transitioning from pathophysiology to therapeutics. Focusing on the key epigenetic enzymes and their target genes will help to facilitate the diagnosis and treatment of CAD. This review synthesizes novel epigenetic insights into CAD, addressing the pathological processes, key molecular mechanisms, and potential biomarkers. Furthermore, we discuss emerging therapeutic strategies targeting epigenetic pathways. By focusing on pivotal enzymes and their associated genes, this work aims to advance CAD diagnostics and interventions.

Immunoexpression Patterns of Megalin, Cubilin, Caveolin-1, Gipc1 and Dab2IP in the Embryonic and Postnatal Development of the Kidneys in Yotari (Dab1-/-) Mice

Our study examines the immunoexpression patterns of Megalin, Cubilin, Caveolin-1, Gipc1 and Dab2IP in the embryonic development (E) and postnatal (P) mouse kidney, with a focus on differentiating patterns between wild-type (wt) and yotari, Dab1-/- (yot) mice. Immunofluorescence revealed raised immunoexpression of receptors Megalin and Cubilin at the ampulla/collecting ducts and convoluted tubules across all developmental stages, with the most prominent immunoexpression observed in the convoluted tubules and the parietal epithelium of the Bowman's capsule. Quantitative analysis showed a higher percentage of Megalin and Cubilin in wt compared to yot mice at E13.5. Co-expression of Megalin and Cubilin was observed at the apical membrane of convoluted tubules and the parietal layer of the Bowman's capsule. The staining intensity of Megalin varied across developmental stages, with the strongest reactivity observed at the ampulla and collecting ducts at embryonic day (E) 13.5 in wt mice. In contrast, Caveolin-1 exhibited high immunoexpression in the metanephric mesenchyme, blood vessels, and the border area between the metanephric mesenchyme and renal vesicle, with a decrease in immunoexpression as development progressed. Gipc1 showed diffuse cytoplasmic staining in metanephric mesenchyme, convoluted tubules and collecting ducts, with significant differences in immunoexpression between wild-type and yot mice at both investigated embryonic time points. Dab2IP immunofluorescent staining was most prominent in renal vesicle/glomeruli and ampulla/collecting ducts at E13.5, with mild staining intensity observed in the distal convoluted tubules postnatally. Our findings elucidate distinct immunoexpression of patterns and potential parts of these proteins in the development and function of the kidney, highlighting the importance of further investigation into their regulatory mechanisms.

An update on the tumor-suppressive functions of the RasGAP protein DAB2IP with focus on therapeutic implications

The dynamic crosstalk between tumor and stromal cells is a major determinant of cancer aggressiveness. The tumor-suppressor DAB2IP (Disabled homolog 2 interacting protein) plays an important role in this context, since it modulates cell responses to multiple extracellular inputs, including inflammatory cytokines and growth factors. DAB2IP is a RasGAP and negatively controls Ras-dependent mitogenic signals. In addition, it modulates other major oncogenic pathways, including TNFα/NF-κB, WNT/β-catenin, PI3K/AKT, and androgen receptor signaling. In line with its tumor-suppressive role, DAB2IP is frequently inactivated in cancer by transcriptional and post-transcriptional mechanisms, including promoter methylation, microRNA-mediated downregulation, and protein-protein interactions. Intriguingly, some observations suggest that downregulation of DAB2IP in cells of the tumor stroma could foster establishment of a pro-metastatic microenvironment. This review summarizes recent insights into the tumor-suppressive functions of DAB2IP and the consequences of its inactivation in cancer. In particular, we explore potential approaches aimed at reactivating DAB2IP, or augmenting its expression levels, as a novel strategy in cancer treatment. We suggest that reactivation or upregulation of DAB2IP would concurrently attenuate multiple oncogenic pathways in both cancer cells and the tumor microenvironment, with implications for improved treatment of a broad spectrum of tumors.

Protective actions of vitamin D, anandamide and melatonin during vascular inflammation: Epigenetic mechanisms involved

Vascular inflammation is one of the main activating stimuli of cardiovascular disease and its uncontrolled development may worsen the progression and prognosis of these pathologies. Therefore, the search for new therapeutic options to treat this condition is undoubtedly needed. In this regard, it may be better to repurpose endogenous anti-inflammatory compounds already known, in addition to synthesizing new compounds for therapeutic purposes. It is well known that vitamin D, anandamide, and melatonin are promising endogenous substances with powerful and wide-spread anti-inflammatory properties. Currently, the epigenetic mechanisms underlying these effects are often unknown. This review summarizes the potential epigenetic mechanisms by which vitamin D, anandamide, and melatonin attenuate vascular inflammation. This information could contribute to the improvement in the therapeutic management of multiple pathologies associated with blood vessel inflammation, through the pharmacological manipulation of new target sites that until now have not been addressed.

SMURF1, a promoter of tumor cell progression?

Overexpression of HECT-type E3 ubiquitin ligase SMURF1 is correlated with poor prognosis in patients with various cancers, such as glioblastoma, colon cancer, and clear cell renal cell carcinoma. SMURF1 acts as a tumor promoter by ubiquitination modification and/or degradation of tumor-suppressing proteins. Combined treatment of Smurf1 knockdown with rapamycin showed collaborative antitumor effects in mice. This review described the role of HECT, WW, and C2 domains in regulating SMURF1 substrate selection. We summarized up to date SMURF1 substrates regulating different type cell signaling, thus, accelerating tumor progression, invasion, and metastasis. Furthermore, the downregulation of SMURF1 expression, inhibition of its E3 activity and regulation of its specificity to substrates prevent tumor progression. The potential application of SMURF1 regulators, specifically, wisely choose certain drugs by blocking SMURF1 selectivity in tumor suppressors, to develop novel anticancer treatments.

Vascular Endothelial Cells and Innate Immunity

In addition to the roles of endothelial cells (ECs) in physiological processes, ECs actively participate in both innate and adaptive immune responses. We previously reported that, in comparison to macrophages, a prototypic innate immune cell type, ECs have many innate immune functions that macrophages carry out, including cytokine secretion, phagocytic function, antigen presentation, pathogen-associated molecular patterns-, and danger-associated molecular patterns-sensing, proinflammatory, immune-enhancing, anti-inflammatory, immunosuppression, migration, heterogeneity, and plasticity. In this highlight, we introduce recent advances published in both ATVB and many other journals: (1) several significant characters classify ECs as novel immune cells not only in infections and allograft transplantation but also in metabolic diseases; (2) several new receptor systems including conditional danger-associated molecular pattern receptors, nonpattern receptors, and homeostasis associated molecular patterns receptors contribute to innate immune functions of ECs; (3) immunometabolism and innate immune memory determine the innate immune functions of ECs; (4) a great induction of the immune checkpoint receptors in ECs during inflammations suggests the immune tolerogenic functions of ECs; and (5) association of immune checkpoint inhibitors with cardiovascular adverse events and cardio-oncology indicates the potential contributions of ECs as innate immune cells.

Epigenetic Control of Mitochondrial Function in the Vasculature

The molecular signatures of epigenetic regulation and chromatin architecture are emerging as pivotal regulators of mitochondrial function. Recent studies unveiled a complex intersection among environmental factors, epigenetic signals, and mitochondrial metabolism, ultimately leading to alterations of vascular phenotype and increased cardiovascular risk. Changing environmental conditions over the lifetime induce covalent and post-translational chemical modification of the chromatin template which sensitize the genome to establish new transcriptional programs and, hence, diverse functional states. On the other hand, metabolic alterations occurring in mitochondria affect the availability of substrates for chromatin-modifying enzymes, thus leading to maladaptive epigenetic signatures altering chromatin accessibility and gene transcription. Indeed, several components of the epigenetic machinery require intermediates of cellular metabolism (ATP, AcCoA, NADH, α-ketoglutarate) for enzymatic function. In the present review, we describe the emerging role of epigenetic modifications as fine tuners of gene transcription in mitochondrial dysfunction and vascular disease. Specifically, the following aspects are described in detail: (i) mitochondria and vascular function, (ii) mitochondrial ROS, (iii) epigenetic regulation of mitochondrial function; (iv) the role of mitochondrial metabolites as key effectors for chromatin-modifying enzymes; (v) epigenetic therapies. Understanding epigenetic routes may pave the way for new approaches to develop personalized therapies to prevent mitochondrial insufficiency and its complications.