WIPI proteins: Biological functions and related syndromes

The pivotal role of dysregulated autophagy in the progression of non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) is a clinicopathologic syndrome characterized by excessive fat deposition in hepatocytes and a major cause of end-stage liver disease. Autophagy is a metabolic pathway responsible for degrading cytoplasmic products and damaged organelles, playing a pivotal role in maintaining the homeostasis and functionality of hepatocytes. Recent studies have shown that pharmacological intervention to activate or restore autophagy provides benefits for liver function recovery by promoting the clearance of lipid droplets (LDs) in hepatocytes, decreasing the production of pro-inflammatory factors, and inhibiting activated hepatic stellate cells (HSCs), thus improving liver fibrosis and slowing down the progression of NAFLD. This article summarizes the physiological process of autophagy, elucidates the close relationship between NAFLD and autophagy, and discusses the effects of drugs on autophagy and signaling pathways from the perspectives of hepatocytes, kupffer cells (KCs), and HSCs to provide assistance in the clinical management of NAFLD.

Bioinformatics analyses and experimental validation of ferroptosis-related genes in bronchopulmonary dysplasia pathogenesis

OBJECTIVE

We aimed to study the involvement of ferroptosis in the pathogenesis of bronchopulmonary dysplasia (BPD) by conducting bioinformatics analyses and identifying and validating the associated ferroptosis-related genes to explore new directions for treating BPD.

METHODS

The dataset GSE32472 on BPD was downloaded from the public genome database. Using R language, differentially expressed genes (DEGs) between the BPD and normal group were screened. In the present study, we adopted weighted gene correlation network analysis (WGCNA) for identifying BPD-related gene modules and ferroptosis-related genes were extracted from FerrDb. Their results were intersected to obtain the hub genes. After that, to explore the hub gene-related signaling pathways, the hub genes were exposed to gene ontology enrichment analysis. With the purpose of verifying the mRNA expression of the hub genes, a single-gene gene set enrichment analysis and quantitative reverse transcription polymerase chain reaction were conducted. Immune cell infiltration in BPD was analyzed using the CIBERSORT inverse fold product algorithm.

RESULTS

A total of 606 DEGs were screened. WGCNA provided the BPD-related gene module darkgreen4. The intersection of DEGs, intramodular genes, and ferroptosis-related genes revealed six ferroptosis-associated hub genes (ACSL1, GALNT14, WIPI1, MAPK14, PROK2, and CREB5). Receiver operating characteristic curve analysis demonstrated that the hub genes screened for BPD were of good diagnostic significance. According to the results of immune infiltration analysis, the proportions of CD8, CD4 naive, and memory resting T cells and M2 macrophage were elevated in the normal group, and the proportions of M0 macrophage, resting mast cell, and neutrophils were increased in the BPD group.

CONCLUSIONS

A total of six ferroptosis-associated hub genes in BPD were identified in this study, and they may be potential new therapeutic targets for BPD.

Bronchopulmonary dysplasia: analysis and validation of ferroptosis-related diagnostic biomarkers and immune cell infiltration features

BACKGROUND

Early and precise diagnosis of bronchopulmonary dysplasia (BPD) is essential to improve the prognosis of preterm infants with BPD. Studying ferroptosis-related genes for diagnostic markers of BPD was the objective of this study.

METHODS

Using the GEO database and the FerrDb database, we obtained the GSE32472 dataset and screened the ferroptosis-related differentially expressed mRNAs (FRDE-mRNAs). By using Gene Ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG), possible biological functions and pathways were identified for FRDE-mRNAs. Three machine learning algorithms (LASSO, SVM-RFE, Random Forest) were used to recognize hub genes, as well as CIBERSORT for exploring the immune landscape of BPD and controls. Functional predictions for hub genes were made using single-gene gene set enrichment analysis (GSEA).

RESULTS

Twenty three FRDE-mRNAs were obtained and were mainly involved in autophagy, fatty acid metabolism and ferroptosis. The four hub genes (LPIN1, ACADSB, WIPI1 and SLC7A11) screened were utilized to construct a diagnostic nomogram. The receiver operating characteristic (ROC) curves and calibration curves demonstrateld that the nomogram exhibited good predictive performance. Eight types of immune cell markers differed significantly between BPD and controls.

CONCLUSION

We developed a diagnostic model for BPD, which could facilitate the early diagnosis and timely intervention of BPD.

IMPACT

The role of ferroptosis in bronchopulmonary dysplasia is rarely reported. The ferroptosis-related genes (LPIN1, ACADSB, WIPI1 and SLC7A11) we identified could serve as early diagnostic biomarkers for BPD. Immune cell infiltration features in BPD and signaling pathways associated with marker genes give new insight into the disease process and provide a basis for further research.

LncRNAs as nodes for the cross-talk between autophagy and Wnt signaling in pancreatic cancer drug resistance

Pancreatic cancer is a malignancy with high mortality. In addition to the few symptoms until the disease reaches an advanced stage, the high fatality rate is attributed to its rapid development, drug resistance and lack of appropriate treatment. In the selection and research of therapeutic drugs, gemcitabine is the first-line drug for pancreatic cancer. Solving the problem of gemcitabine resistance in pancreatic cancer will contribute to the progress of pancreatic cancer treatment. Long non coding RNAs (lncRNAs), which are RNA transcripts longer than 200 nucleotides, play vital roles in cellular physiological metabolic activities. Currently, our group and others have found that some lncRNAs are aberrantly expressed in pancreatic cancer cells, which can regulate the process of cancer through autophagy and Wnt/β-catenin pathways simultaneously and affect the sensitivity of cancer cells to therapeutic drugs. This review presents an overview of the recent evidence concerning the node of lncRNA for the cross-talk between autophagy and Wnt/β-catenin signaling in pancreatic cancer, together with the practicability of lncRNAs and the core regulatory factors as targets in therapeutic resistance.

Autophagy in Its (Proper) Context: Molecular Basis, Biological Relevance, Pharmacological Modulation, and Lifestyle Medicine

Autophagy plays a critical role in maintaining cellular homeostasis and responding to various stress conditions by the degradation of intracellular components. In this narrative review, we provide a comprehensive overview of autophagy's cellular and molecular basis, biological significance, pharmacological modulation, and its relevance in lifestyle medicine. We delve into the intricate molecular mechanisms that govern autophagy, including macroautophagy, microautophagy and chaperone-mediated autophagy. Moreover, we highlight the biological significance of autophagy in aging, immunity, metabolism, apoptosis, tissue differentiation and systemic diseases, such as neurodegenerative or cardiovascular diseases and cancer. We also discuss the latest advancements in pharmacological modulation of autophagy and their potential implications in clinical settings. Finally, we explore the intimate connection between lifestyle factors and autophagy, emphasizing how nutrition, exercise, sleep patterns and environmental factors can significantly impact the autophagic process. The integration of lifestyle medicine into autophagy research opens new avenues for promoting health and longevity through personalized interventions.

Friends and Foes: The Ambivalent Role of Autophagy in HIV-1 Infection

Autophagy has emerged as an integral part of the antiviral innate immune defenses, targeting viruses or their components for lysosomal degradation. Thus, successful viruses, like pandemic human immunodeficiency virus 1 (HIV-1), evolved strategies to counteract or even exploit autophagy for efficient replication. Here, we provide an overview of the intricate interplay between autophagy and HIV-1. We discuss the impact of autophagy on HIV-1 replication and report in detail how HIV-1 manipulates autophagy in infected cells and beyond. We also highlight tissue and cell-type specifics in the interplay between autophagy and HIV-1. In addition, we weigh exogenous modulation of autophagy as a putative double-edged sword against HIV-1 and discuss potential implications for future antiretroviral therapy and curative approaches. Taken together, we consider both antiviral and proviral roles of autophagy to illustrate the ambivalent role of autophagy in HIV-1 pathogenesis and therapy.

Human WIPI β-propeller function in autophagy and neurodegeneration

The four human WIPI β-propellers, WIPI1 through WIPI4, belong to the ancient PROPPIN family and fulfill scaffold functions in the control of autophagy. In this context, WIPI β-propellers function as PI3P effectors during autophagosome formation and loss of WIPI function negatively impacts autophagy and contributes to neurodegeneration. Of particular interest are mutations in WDR45, the human gene that encodes WIPI4. Sporadic WDR45 mutations are the cause of a rare human neurodegenerative disease called BPAN, hallmarked by high brain iron accumulation. Here, we discuss the current understanding of the functions of human WIPI β-propellers and address unanswered questions with a particular focus on the role of WIPI4 in autophagy and BPAN.

A burning question from the first international BPAN symposium: is restoration of autophagy a promising therapeutic strategy for BPAN?

Beta-propeller protein-associated neurodegeneration (BPAN) is a rare neurodegenerative disease associated with severe cognitive and motor deficits. BPAN pathophysiology and phenotypic spectrum are still emerging due to the fact that mutations in the WDR45 (WD repeat domain 45) gene, a regulator of macroautophagy/autophagy, were only identified a decade ago. In the first international symposium dedicated to BPAN, which was held in Lyon, France, a panel of international speakers, including several researchers from the autophagy community, presented their work on human patients, cellular and animal models, carrying WDR45 mutations and their homologs. Autophagy researchers found an opportunity to explore the defective function of autophagy mechanisms associated with WDR45 mutations, which underlie neuronal dysfunction and early death. Importantly, BPAN is one of the few human monogenic neurological diseases targeting a regulator of autophagy, which raises the possibility that it is a relevant model to directly assess the roles of autophagy in neurodegeneration and to develop autophagy restorative therapeutic strategies for more common disorders.Abbreviations: ATG: autophagy related; BPAN: beta-propeller protein-associated neurodegeneration; ER: endoplasmic reticulum; KO: knockout; NBIA: neurodegeneration with brain iron accumulation; PtdIns3P: phosphatidylinositol-3-phosphate; ULK1: unc-51 like autophagy activating kinase 1; WDR45: WD repeat domain 45; WIPI: WD repeat domain, phosphoinositide interacting.

Coiled-coil-mediated dimerization of Atg16 is required for binding to the PROPPIN Atg21

PROPPINs/WIPIs are β-propeller proteins that bind phosphoinositides and contribute to the recruitment of protein complexes involved in membrane remodelling processes such as autophagosome formation and endosomal trafficking. Yeast Atg21 and mammalian WIPI2 interact with Atg16/ATG16L1 to mediate recruitment of the lipidation machinery to the autophagosomal membrane. Here, we used the reverse double two-hybrid method (RD2H) to identify residues in Atg21 and Atg16 critical for protein-protein binding. Although our results are generally consistent with the crystal structure of the Atg21-Atg16 complex reported previously, they also reveal that dimerization of the Atg16 coiled-coil domain is required for Atg21 binding. Furthermore, most of the residues identified in Atg21 are conserved in WIPI2 and we showed that these residues also mediate ATG16L1 binding. Strikingly, these residues occupy the same position in the β-propeller structure as residues in PROPPINs/WIPIs Hsv2 and WIPI4 that mediate Atg2/ATG2A binding, supporting the idea that these proteins use different amino acids at the same position to interact with different autophagic proteins. Finally, our findings demonstrate the effectiveness of the RD2H system to identify critical residues for protein-protein interactions and the utility of this method to generate combinatory mutants with a complete loss of binding capacity.

Extracellular transfer of a conserved polymerization factor for multi-flagellin filament assembly in Caulobacter

Unidirectional growth of filamentous protein assemblies including the bacterial flagellum relies on dedicated polymerization factors (PFs). The molecular determinants and structural transitions imposed by PFs on multi-subunit assembly are poorly understood. Here, we unveil FlaY from the polarized α-proteobacterium Caulobacter crescentus as a defining member of an alternative class of specialized flagellin PFs. Unlike the paradigmatic FliD capping protein, FlaY relies on a funnel-like β-propeller fold for flagellin polymerization. FlaY binds flagellin and is secreted by the flagellar secretion apparatus, yet it can also promote flagellin polymerization exogenously when donated from flagellin-deficient cells, serving as a transferable, extracellular public good. While the surge in FlaY abundance precedes bulk flagellin synthesis, FlaY-independent filament assembly is enhanced by mutation of a conserved region in multiple flagellin paralogs. We suggest that FlaYs are (multi-)flagellin PFs that evolved convergently to FliDs yet appropriated the versatile β-propeller fold implicated in human diseases for chaperone-assisted filament assembly.

Diagnostic and prognostic value of autophagy-related key genes in sepsis and potential correlation with immune cell signatures

Background: Autophagy is involved in the pathophysiological process of sepsis. This study was designed to identify autophagy-related key genes in sepsis, analyze their correlation with immune cell signatures, and search for new diagnostic and prognostic biomarkers. Methods: Whole blood RNA datasets GSE65682, GSE134347, and GSE134358 were downloaded and processed. Differential expression analysis and weighted gene co-expression network analysis (WGCNA) were used to identify autophagy-related key genes in sepsis. Then, key genes were analyzed by functional enrichment, protein-protein interaction (PPI), transcription factor (TF)-gene and competing endogenous RNA (ceRNA) network analysis. Subsequently, key genes with diagnostic efficiency and prognostic value were identified by receiver operating characteristic (ROC) curves and survival analysis respectively. The signatures of immune cells were estimated using CIBERSORT algorithm. The correlation between significantly different immune cell signatures and key genes was assessed by correlation analysis. Finally, key genes with both diagnostic and prognostic value were verified by RT-qPCR. Results: 14 autophagy-related key genes were identified and their TF-gene and ceRNA regulatory networks were constructed. Among the key genes, 11 genes (ATIC, BCL2, EEF2, EIF2AK3, HSPA8, IKBKB, NLRC4, PARP1, PRKCQ, SH3GLB1, and WIPI1) had diagnostic efficiency (AUC > 0.90) and 5 genes (CAPN2, IKBKB, PRKCQ, SH3GLB1 and WIPI1) were associated with survival prognosis (p-value < 0.05). IKBKB, PRKCQ, SH3GLB1 and WIPI1 had both diagnostic and prognostic value, and their expression were verified by RT-qPCR. Analysis of immune cell signatures showed that the abundance of neutrophil, monocyte, M0 macrophage, gamma delta T cell, activated mast cell and M1 macrophage subtypes increased in the sepsis group, while the abundance of resting NK cell, resting memory CD4+ T cell, CD8+ T cell, naive B cell and resting dendritic cell subtypes decreased. Most of the key genes correlated with the predicted frequencies of CD8+ T cells, resting memory CD4+ T cells, M1 macrophages and naive B cells. Conclusion: We identified autophagy-related key genes with diagnostic and prognostic value in sepsis and discovered associations between key genes and immune cell signatures. This work may provide new directions for the discovery of promising biomarkers for sepsis.