Dissecting the association of autophagy-related genes with cardiovascular diseases and intermediate vascular traits: A population-based approach

Puerarin Reversing Autophagy-Lysosomal Dysfunction via Acid Sphingomyelinase Inhibition in Cardiomyocytes

Heart failure (HF) is a major cardiovascular disorder characterised by high prevalence and mortality rate. Recent studies have emphasised the role of autophagy in development and progression of HF. Dysfunctions in lysosomes and autophagic processes are closely associated with the aetiology of HF. Puerarin (PUE), a traditional Chinese medicine known for its antioxidant, anti-inflammatory and antiapoptotic properties, is widely used for the treatment of HF. However, the effectiveness of PUE in HF management via the modulation of autophagy requires further investigation. We used a mouse model of transverse aortic constriction to investigate protective effects of PUE on the autophagy-lysosomal pathway (ALP). We assessed heart function using echocardiography and performed histological staining for fibrosis and hypertrophy. RT-qPCR for atrial natriuretic peptide (ANP)/brain natriuretic peptide (BNP) and Western blotting for p62/LC3/LAMP1/Beclin1 were performed. Immunofluorescence was used to identify the autophagosomes, autolysosomes and lysosomes. In addition, immunohistochemistry was performed to detect acid sphingomyelinase (ASM) and ceramides. ASM siRNA was transfected into cardiomyocytes to evaluate autophagy. PUE treatment significantly reduced myocardial fibrosis and hypertrophy in HF-induced mice. PUE also effectively ameliorated ALP impairment in HF-induced mice and H9c2 cells. Mechanistically, PUE restored lysosomal homeostasis by inhibiting ASM expression and lysosomal transport, thereby enhancing lysosomal activity. These results underscore the therapeutic potential of PUE in correcting the ASM-mediated disruption of the HF-linked autophagy-lysosomal pathway.

ATG4B as a novel biomarker for abdominal aortic aneurysm: integrated evaluation through experimental and bioinformatics analyses

Autophagy related gene 4B (ATG4B) plays a central role in autophagy machinery, but its clinical relevance to AAA remains unknown. In this study, 205 AAA patients and 205 age- and sex-matched controls were included to detect the serum ATG4B levels. Meanwhile, abdominal aortic specimens from 24 AAA patients and 6 human organ donors were collected to evaluate the mRNA and in situ protein expression of ATG4B. We observed significantly higher ATG4B mRNA and protein expression levels in AAA group compared to those in control group, with a positive correlation between mRNA levels and serum/in situ protein levels (serum, r = 0.518, P = 0.010; in situ, r = 0.453, P = 0.026). Serum ATG4B exhibited the diagnostic potential for AAA (AUC = 0.702, sensitivity = 75.6%) and intraluminal thrombus recognition (AUC = 0.602, sensitivity = 67.9%). Logistic regression revealed a significant association between elevated serum ATG4B and an increased risk of AAA and intraluminal thrombus formation. Deceased patients displayed higher baseline serum ATG4B levels, which could predict postoperative mortality (HR = 1.028, 95%CI = 1.007-1.049, P = 0.009, AUC = 0.612, sensitivity = 84.6%). The bioinformatics analysis suggested that ATG4B may modulate cellular autophagy and influence pathways associated with inflammation, lipid metabolism, or apoptosis, thereby contributing to the occurrence and development of AAA. The drug-gene interaction network identified 13 potential therapeutic drugs targeting ATG4B. In conclusion, ATG4B may serve as a promising biomarker for the diagnosis and prognostic assessment of AAA patients and play a key role in the pathogenesis of AAA.

Autophagy and lysosomal dysfunction in diabetes and its complications

Autophagy is critical for energy homeostasis and the function of organelles such as endoplasmic reticulum (ER) and mitochondria. Dysregulated autophagy due to aging, environmental factors, or genetic predisposition can be an underlying cause of not only diabetes through β-cell dysfunction and metabolic inflammation, but also diabetic complications such as diabetic kidney diseases (DKDs). Dysfunction of lysosomes, effector organelles of autophagic degradation, due to metabolic stress or nutrients/metabolites accumulating in metabolic diseases is also emerging as a cause or aggravating element in diabetes and its complications. Here, we discuss the etiological role of dysregulated autophagy and lysosomal dysfunction in diabetes and a potential role of autophagy or lysosomal modulation as a new avenue for treatment of diabetes and its complications.

Insights on E1-like enzyme ATG7: functional regulation and relationships with aging-related diseases

Autophagy is a dynamic self-renovation biological process that maintains cell homeostasis and is responsible for the quality control of proteins, organelles, and energy metabolism. The E1-like ubiquitin-activating enzyme autophagy-related gene 7 (ATG7) is a critical factor that initiates classic autophagy reactions by promoting the formation and extension of autophagosome membranes. Recent studies have identified the key functions of ATG7 in regulating the cell cycle, apoptosis, and metabolism associated with the occurrence and development of multiple diseases. This review summarizes how ATG7 is precisely programmed by genetic, transcriptional, and epigenetic modifications in cells and the relationship between ATG7 and aging-related diseases.

Cross-trait analyses identify shared genetics between migraine, headache, and glycemic traits, and a causal relationship with fasting proinsulin

The co-occurrence of migraine and glycemic traits has long been reported in observational epidemiological studies, but it has remained unknown how they are linked genetically. We used large-scale GWAS summary statistics on migraine, headache, and nine glycemic traits in European populations to perform cross-trait analyses to estimate genetic correlation, identify shared genomic regions, loci, genes, and pathways, and test for causal relationships. Out of the nine glycemic traits, significant genetic correlation was observed for fasting insulin (FI) and glycated haemoglobin (HbA1c) with both migraine and headache, while 2-h glucose was genetically correlated only with migraine. Among 1703 linkage disequilibrium (LD) independent regions of the genome, we found pleiotropic regions between migraine and FI, fasting glucose (FG), and HbA1c, and pleiotropic regions between headache and glucose, FI, HbA1c, and fasting proinsulin. Cross-trait GWAS meta-analysis with glycemic traits, identified six novel genome-wide significant lead SNPs with migraine, and six novel lead SNPs with headache (Pmeta < 5.0 × 10-8 and Psingle-trait < 1 × 10-4), all of which were LD-independent. Genes with a nominal gene-based association (Pgene ≤ 0.05) were significantly enriched (overlapping) across the migraine, headache, and glycemic traits. Mendelian randomisation analyses produced intriguing, but inconsistent, evidence for a causal relationship between migraine and headache with multiple glycemic traits; and consistent evidence suggesting increased fasting proinsulin levels may causally decrease the risk of headache. Our findings indicate that migraine, headache, and glycemic traits share a common genetic etiology and provide genetic insights into the molecular mechanisms contributing to their comorbid relationship.

β Cell and Autophagy: What Do We Know?

Pancreatic β cells are central to glycemic regulation through insulin production. Studies show autophagy as an essential process in β cell function and fate. Autophagy is a catabolic cellular process that regulates cell homeostasis by recycling surplus or damaged cell components. Impaired autophagy results in β cell loss of function and apoptosis and, as a result, diabetes initiation and progress. It has been shown that in response to endoplasmic reticulum stress, inflammation, and high metabolic demands, autophagy affects β cell function, insulin synthesis, and secretion. This review highlights recent evidence regarding how autophagy can affect β cells' fate in the pathogenesis of diabetes. Furthermore, we discuss the role of important intrinsic and extrinsic autophagy modulators, which can lead to β cell failure.

Autophagy in Hematological Malignancies

Simple Summary

Autophagy is a dynamic and tightly regulated process that seems to have dual effects in cancer. In some contexts, it can induce carcinogenesis and promote cancer cell survival, whereas in others, it acts preventing tumor cell growth and tumor progression. Thus, autophagy functions seem to strictly depend on cancer ontogenesis, progression, and type. Here, we will dive into the current knowledge of autophagy in hematological malignancies and will highlight the main genetic components involved in each cancer type.

Abstract

Autophagy is a highly conserved metabolic pathway via which unwanted intracellular materials, such as unfolded proteins or damaged organelles, are digested. It is activated in response to conditions of oxidative stress or starvation, and is essential for the maintenance of cellular homeostasis and other vital functions, such as differentiation, cell death, and the cell cycle. Therefore, autophagy plays an important role in the initiation and progression of tumors, including hematological malignancies, where damaged autophagy during hematopoiesis can cause malignant transformation and increase cell proliferation. Over the last decade, the importance of autophagy in response to standard pharmacological treatment of hematological tumors has been observed, revealing completely opposite roles depending on the tumor type and stage. Thus, autophagy can promote tumor survival by attenuating the cellular damage caused by drugs and/or stabilizing oncogenic proteins, but can also have an antitumoral effect due to autophagic cell death. Therefore, autophagy-based strategies must depend on the context to create specific and safe combination therapies that could contribute to improved clinical outcomes. In this review, we describe the process of autophagy and its role on hematopoiesis, and we highlight recent research investigating its role as a potential therapeutic target in hematological malignancies. The findings suggest that genetic variants within autophagy-related genes modulate the risk of developing hemopathies, as well as patient survival.

Association of ATG7 gene polymorphisms with microscopic polyangiitis in Chinese individuals

Microscopic polyangiitis (MPA) is a type of antineutrophil cytoplasmic antibody (ANCA)-related vasculitis. Autophagy-related gene 7 (ATG7) protects against complicated disorder states in model organisms, but the way ATG7 dysfunction contributes to MPA remains elusive. This investigation assessed the impacts of ATG7 single-nucleotide polymorphisms (SNPs) on microscopic polyangiitis (MPA) in China. A total of 211 controls and 214 MPA patients were recruited and analyzed. Polymerase chain reaction (PCR) and high-throughput sequencing were adopted to detect the ATG7 SNPs (rs75492008, rs2594966, rs6442260 and rs8154), and stratification analysis, different genetic models and differences in allele and genotype frequencies were evaluated. Haplotype evaluation was performed after linkage disequilibrium (LD) analyses, and interactions between alleles were assessed. Generalized multifactor dimensionality reduction (GMDR) was adopted to analyze SNP-SNP interactions among the four ATG7 SNPs and phosphatidylinositol-4, 5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA) and unc-nc-like autophagy activating kinase 1 (ULK1) SNPs previously studied by our team. Relationships between ATG7 polymorphisms, disease activity biomarkers and therapeutic effects in MPA were analyzed. Sex stratification analysis of the rs2594966 GG genotype with codominant and recessive models showed OR=3.42, 95% CI [1.19-9.80], P=0.041 and OR=3.31, 95% CI [1.23-8.90], P=0.012, respectively. Haplotype G-G-C-T was related to an increased MPA risk (OR=1.5, 95% CI [0.999-2.266], P=0.029). Permutation testing of GMDR suggested that ATG7 rs6442260 and rs8154, PIK3CA rs1607237, and ULK1 rs4964879 might interact with each other in MPA development (P<0.05). Among 214 MPA patients, 79 available complete follow-up clinical datasets were gathered from September 2009 to October 2020, showing that rs75492008 and rs4964879 affect the correlation between C-reactive protein (CRP) and the erythrocyte sedimentation rate (ESR) in MPA activity. Patients with rs8154 TT and rs1607237 CC genotypes had better clinical treatment effects (P<0.05). Gene polymorphisms may be related to MPA in China, exhibiting correlation with MPA activity indicators, treatment and prognosis.

Moments in autophagy and disease: Past and present

Over the past several decades, research on autophagy, a highly conserved lysosomal degradation pathway, has been advanced by studies in different model organisms, especially in the field of its molecular mechanism and regulation. The malfunction of autophagy is linked to various diseases, among which cancer and neurodegenerative diseases are the major focus. In this review, we cover some other important diseases, including cardiovascular diseases, infectious and inflammatory diseases, and metabolic disorders, as well as rare diseases, with a hope of providing a more complete understanding of the spectrum of autophagy's role in human health.

The regulatory factors and pathological roles of autophagy-related protein 4 in diverse diseases: Recent research advances

Macroautophagy (autophagy) is an evolutionarily conserved and dynamic degradation/recycling pathway in which portions of the cytoplasm, such as dysfunctional proteins and surplus organelles, are engulfed by double-membrane bound vesicles through a lysosome-dependent process. As the only proteolytic enzyme of the core mammalian autophagy proteins, autophagy-related protein 4 (ATG4) primes newly synthesized pro-light chain 3 (LC3) to form LC3-I that attaches to phosphatidylethanolamine and delipidates LC3-PE to LC3-I for recycling. Besides autophagy, ATG4 has been shown to be involved in regulating various biological and pathological processes. The roles of ATG4 in cancer therapy, a methodology for ATG4 activity detection, and the discovery of chemical modulators have been well-reviewed. However, a comprehensive summary on how ATG4 is regulated by multiple factors and, thereby, how ATG4 influences autophagy or other pathways remains lacking. In this paper, we summarize multiple processes and molecules that regulate the activity of ATG4, such as micro-RNAs, posttranslational modifications, and small molecules. Additionally, we focus on the relationship between ATG4 and diverse diseases, including cancer, neurodegeneration, microbial infection, and other diseases. It provides insight regarding potential ATG4-targeted therapeutic opportunities, which could be beneficial for future studies and human health.

Pathogenic Single Nucleotide Polymorphisms on Autophagy-Related Genes

In recent years, the study of single nucleotide polymorphisms (SNPs) has gained increasing importance in biomedical research, as they can either be at the molecular origin of a determined disorder or directly affect the efficiency of a given treatment. In this regard, sequence variations in genes involved in pro-survival cellular pathways are commonly associated with pathologies, as the alteration of these routes compromises cellular homeostasis. This is the case of autophagy, an evolutionarily conserved pathway that counteracts extracellular and intracellular stressors by mediating the turnover of cytosolic components through lysosomal degradation. Accordingly, autophagy dysregulation has been extensively described in a wide range of human pathologies, including cancer, neurodegeneration, or inflammatory alterations. Thus, it is not surprising that pathogenic gene variants in genes encoding crucial effectors of the autophagosome/lysosome axis are increasingly being identified. In this review, we present a comprehensive list of clinically relevant SNPs in autophagy-related genes, highlighting the scope and relevance of autophagy alterations in human disease.

Comprehensive autophagy evaluation in cardiac disease models

Autophagy is a highly conserved recycling mechanism essential for maintaining cellular homeostasis. The pathophysiological role of autophagy has been explored since its discovery 50 years ago, but interest in autophagy has grown exponentially over the last years. Many researchers around the globe have found that autophagy is a critical pathway involved in the pathogenesis of cardiac diseases. Several groups have created novel and powerful tools for gaining deeper insights into the role of autophagy in the aetiology and development of pathologies affecting the heart. Here, we discuss how established and emerging methods to study autophagy can be used to unravel the precise function of this central recycling mechanism in the cardiac system.

Autophagy in the control and pathogenesis of parasitic infections

Background

Autophagy has a crucial role in the defense against parasites. The interplay existing between host autophagy and parasites has varied outcomes due to the kind of host cell and microorganism. The presence of autophagic compartments disrupt a significant number of pathogens and are further cleared by xenophagy in an autolysosome. Another section of pathogens have the capacity to outwit the autophagic pathway to their own advantage.

Result

To comprehend the interaction between pathogens and the host cells, it is significant to distinguish between starvation-induced autophagy and other autophagic pathways. Subversion of host autophagy by parasites is likely due to differences in cellular pathways from those of ‘classical’ autophagy and that they are controlled by parasites in a peculiar way. In xenophagy clearance at the intracellular level, the pathogens are first ubiquitinated before autophagy receptors acknowledgement, followed by labeling with light chain 3 (LC3) protein. The LC3 in LC3-associated phagocytosis (LAP) is added directly into vacuole membrane and functions regardless of the ULK, an initiation complex. The activation of the ULK complex composed of ATG13, FIP200 and ATG101causes the initiation of host autophagic response. Again, the recognition of PAMPs by conserved PRRs marks the first line of defense against pathogens, involving Toll-like receptors (TLRs). These all important immune-related receptors have been reported recently to regulate autophagy.

Conclusion

In this review, we sum up recent advances in autophagy to acknowledge and understand the interplay between host and parasites, focusing on target proteins for the design of therapeutic drugs. The target host proteins on the initiation of the ULK complex and PRRs-mediated recognition of PAMPs may provide strong potential for the design of therapeutic drugs against parasitic infections.

GAA compound heterozygous mutations associated with autophagic impairment cause cerebral infarction in Pompe disease

Clinical manifestations of the late-onset adult Pompe disease (glycogen storage disease type II) are heterogeneous. To identify genetic defects of a special patient population with cerebrovascular involvement as the main symptom, we performed whole-genome sequencing (WGS) analysis on a consanguineous Chinese family of total eight members including two Pompe siblings both had cerebral infarction. Two novel compound heterozygous variants were found in GAA gene: c.2238G>C in exon 16 and c.1388_1406del19 in exon 9 in the two patients. We verified the function of the two mutations in leading to defects in GAA protein expression and enzyme activity that are associated with autophagic impairment. We further performed a gut microbiome metagenomics analysis, found that the child’s gut microbiome metagenome is very similar to his mother. Our finding enriches the gene mutation spectrum of Pompe disease, and identified the association of the two new mutations with autophagy impairment. Our data also indicates that gut microbiome could be shared within Pompe patient and cohabiting family members, and the abnormal microbiome may affect the blood biochemical index. Our study also highlights the importance of deep DNA sequencing in potential clinical applications.

Autophagy as an emerging therapeutic target for age-related vascular pathologies

Introduction: The incidence of age-related vascular diseases such as arterial stiffness, hypertension and atherosclerosis, is rising dramatically and is substantially impacting healthcare systems. Mounting evidence suggests that there is an important role for autophagy in maintaining (cardio)vascular health. Impaired vascular autophagy has been linked to arterial aging and the initiation of vascular disease.Areas covered: The function and implications of autophagy in vascular smooth muscle cells and endothelial cells are discussed in healthy blood vessels and arterial disease. Furthermore, we discuss current treatment options for vascular disease and their links with autophagy. A literature search was conducted in PubMed up to October 2019.Expert opinion: Although the therapeutic potential of inducing autophagy in age-related vascular pathologies is considerable, several issues should be addressed before autophagy induction can be clinically used to treat vascular disease. These issues include uncertainty regarding the most effective drug target as well as the lack of potency and selectivity of autophagy inducing drugs. Moreover, drug tolerance or autophagy mediated cell death have been reported as possible adverse effects. Special attention is required for determining the cause of autophagy deficiency to optimize the treatment strategy.