RAB21 controls autophagy and cellular energy homeostasis by regulating retromer-mediated recycling of SLC2A1/GLUT1

Golgi-associated retrograde protein (GARP) complex recruits retromer to trans-Golgi network for FgKex2 and FgSnc1 recycling, necessary for the development and pathogenicity of Fusarium graminearum

In eukaryotes, the retromer complex plays a crucial role in the sorting and retrograde transport of cargo proteins from endosomes to the trans-Golgi network (TGN). Despite its importance, the molecular details of this intracellular transport process remain unclear. Here, we have identified a Golgi-associated retrograde protein (GARP) complex as a mediator of vesicle transport that facilitates the recruitment of the retromer complex to the TGN to exert its functions. The GARP complex is mainly localized in the TGN where it interacts with the retromer complex. This interaction is evolutionarily conserved across species. Furthermore, we identified FgKex2 and FgSnc1 as cargo proteins in the GARP/retromer-mediated recycling pathway. Loss of GARP or retromer results in a complete missorting of FgKex2 and FgSnc1 into the vacuolar degradation pathway, which affects the growth, development, biogenesis of toxisomes and pathogenicity of Fusarium graminearum. In summary, we demonstrate for the first time that GARP promotes the recruitment of retromer from endosomes to the TGN, thereby establishing a GARP/retromer transport pathway that coordinates the recycling of cargo proteins FgKex2 and FgSnc1. This process is essential for maintaining sustained growth and development and significantly contributes to the pathogenicity of F. graminearum.

Metabolic landscape and rewiring in normal hematopoiesis, leukemia and aging

Recent advancements in metabolism research have demonstrated its critical roles in a lot of critical biological processes, including stemness maintenance, cell differentiation, proliferation, and function. Hematopoiesis is the fundamental cell differentiation process with the production of millions of red blood cells per second in carrying oxygen and white blood cells in fighting infection and cancers. The differentiation processes of hematopoietic stem and progenitor cells (HSPCs) are accompanied by significant metabolic reprogramming. In hematological malignancy, metabolic reprogramming is also essential to the malignant hematopoiesis processes. The metabolic rewiring is driven by distinct molecular mechanisms that meet the specific demands of different target cells. Leukemic cells, for instance, adopt unique metabolic profiles to support their heightened energy needs for survival and proliferation. Moreover, aging HSPCs exhibit altered energy consumption compared to their younger counterparts, often triggering protective mechanisms at the cellular level. In this review, we provide a comprehensive analysis of the metabolic processes involved in hematopoiesis and the metabolic rewiring that occurs under adverse conditions. In addition, we highlight current research directions and discuss the potential of targeting metabolic pathways for the management of hematological malignancies and aging.

Components of the Endosome-Lysosome Vesicular Machinery as Drivers of the Metastatic Cascade in Prostate Cancer

Prostate cancer remains a significant global health concern, with over 1.4 million new cases diagnosed and more than 330,000 deaths each year. The primary clinical challenge that contributes to poor patient outcomes involves the failure to accurately predict and treat at the onset of metastasis, which remains an incurable stage of the disease. This review discusses the emerging paradigm that prostate cancer metastasis is driven by a dysregulation of critical molecular machinery that regulates endosome-lysosome homeostasis. Endosome and lysosome compartments have crucial roles in maintaining normal cellular function but are also involved in many hallmarks of cancer pathogenesis, including inflammation, immune response, nutrient sensing, metabolism, proliferation, signalling, and migration. Here we discuss new insight into how alterations in the complex network of trafficking machinery, responsible for the microtubule-based transport of endosomes and lysosomes, may be involved in prostate cancer progression. A better understanding of endosome-lysosome dynamics may facilitate the discovery of novel strategies to detect and manage prostate cancer metastasis and improve patient outcomes.

S100A8 knockdown activates the PI3K/AKT signaling pathway to inhibit microglial autophagy and improve cognitive impairment mediated by chronic sleep deprivation

OBJECTIVE

Cognitive dysfunction is one of the major symptoms of chronic sleep deprivation (CSD). Abnormal autophagy and apoptosis are thought to be important mechanisms. S100 Calcium Binding Protein A8 (S100A8) plays a key role in autophagy and apoptosis of microglia. This study investigated whether S100A8 knockdown can effectively inhibit aberrant autophagy in microglia and improve cognitive function by activating the phosphatidylinositol 3-kinase (PI3K)/protein kinase B (AKT) signaling pathway under CSD conditions.

METHODS

CSD mouse models and BV2 cell autophagy models were established in vivo and in vitro. Transcriptome sequencing was used to determine the key regulator related to autophagy. The Morris water maze test was used to evaluate the cognitive behavior of the mice. RT-qPCR and western blot were conducted to examine S100A8 expression and autophagy signalling. HE, TUNEL, transmission electron microscopy, immunofluorescence, and histochemistry were performed to detect pathological changes, neuronal autophagy, apoptosis, or positive cells in hippocampal tissues, respectively.

RESULTS

Transcriptome sequencing showed that S100A8 was significantly elevated in CSD mice, and fluorescence colocalization results further suggested that S100A8 mainly colocalizes with microglia. In vivo studies revealed that knockdown of S100A8 alleviated CSD-induced cognitive impairment in mice. Through further mechanistic investigations employing both in vivo and in vitro models, we demonstrated that silencing S100A8 can activate the PI3K/AKT pathway, thereby reducing CSD-induced abnormal autophagy and apoptosis in microglia. Aberrant autophagy and apoptosis in microglia were reversed with the PI3K/AKT pathway inhibitor LY294002.

CONCLUSION

The S100A8/PI3K/AKT axis plays a crucial role in chronic sleep deprivation-mediated autophagy and apoptosis in microglia.

Endosomal traffic disorders: a driving force behind neurodegenerative diseases

Endosomes are crucial sites for intracellular material sorting and transportation. Endosomal transport is a critical process involved in the selective uptake, processing, and intracellular transport of substances. The equilibrium between endocytosis and circulation mediated by the endosome-centered transport pathway plays a significant role in cell homeostasis, signal transduction, and immune response. In recent years, there have been hints linking endosomal transport abnormalities to neurodegenerative diseases, including Alzheimer's disease. Nonetheless, the related mechanisms remain unclear. Here, we provide an overview of endosomal-centered transport pathways and highlight potential physiological processes regulated by these pathways, with a particular focus on the correlation of endosomal trafficking disorders with common pathological features of neurodegenerative diseases. Additionally, we summarize potential therapeutic agents targeting endosomal trafficking for the treatment of neurodegenerative diseases.

Atg5-deficient mesenchymal stem cells protect against non-alcoholic fatty liver by accelerating hepatocyte growth factor secretion

BACKGROUND/AIMS

Mesenchymal stem cells (MSCs) have shown promising therapeutic potential in treating liver diseases, such as non-alcoholic fatty liver disease (NAFLD). Genetic modification has been employed to enhance the characteristics of MSCs for more effective disease treatment. Here, we present findings on human adipose-derived MSCs with Atg5 deficiency, investigating their therapeutic impact and the associated mechanisms in NAFLD.

METHODS

In vitro, lentiviral transduction was employed to downregulate Atg5 or HGF in human adipose-derived MSCs using short hairpin RNA (shRNA). Subsequently, experiments were conducted to evaluate cell senescence, proliferation, cell cycle, apoptosis, and other pertinent aspects. In vivo, a non-alcoholic fatty liver mouse model was established by feeding them a high-fat diet (HFD), and the effects of MSCs transplantation were assessed through serological, biochemical, and pathological analyses.

RESULTS

Our research findings indicate that Atg5-deficient MSCs display heightened proliferative activity. Subsequent co-culturing of MSCs with hepatocytes and the transplantation of Atg5-deficient MSCs into NAFLD mouse models demonstrated their ability to effectively reduce lipid accumulation in the NAFLD disease model by modulating the AMPKα/mTOR/S6K/Srebp1 pathway. Furthermore, we observed that Atg5 deficiency enhances the secretion of hepatocyte growth factor (HGF) by promoting recycling endosome (RE) production. Lastly, our study revealed that 3-MA-primed MSCs can improve the characteristics of NAFLD by boosting the secretion of HGF.

CONCLUSIONS

Our research findings suggest that Atg5-deficient MSCs protect against NAFLD by accelerating HGF secretion. This indicates that Atg5 gene-modified MSCs may represent a promising strategy for treating NAFLD.

Vacuolar recruitment of retromer by a SNARE complex enables infection-related trafficking in rice blast

The retromer complex is a conserved sorting machinery that maintains cellular protein homeostasis by transporting vesicles containing cargo proteins to defined destinations. It is known to sort proteins at the vacuole membranes for retrograde trafficking, preventing their degradation in the vacuole. However, the detailed mechanism of retromer recruitment to the vacuole membrane has not yet been elucidated. Here, we show that the vacuolar SNARE complex MoPep12-MoVti1-MoVam7-MoYkt6 regulates retromer-mediated vesicle trafficking by recruiting the retromer to the vacuole membrane, which promotes host invasion in Magnaporthe oryzae. Such recruitment is also essential for the retrieval of the autophagy regulator MoAtg8 and enables appressorium-mediated host penetration. Furthermore, the vacuolar SNARE subunits are involved in suppressing the host defense response by regulating the deployment of retromer-MoSnc1-mediated effector secretion. Altogether, our results provide insights into the mechanism of vacuolar SNAREs-dependent retromer recruitment which is necessary for pathogenicity-related membrane trafficking events in the rice blast fungus.

Huanglian Jiedu Decoction enhances the stability of atherosclerotic plaques through SLC2A1-mediated efferocytosis

BACKGROUND

Atherosclerotic (AS) plaques require a dense necrotic core and a robust fibrous cap to maintain stability. While previous studies have indicated that the traditional Chinese medicine Huang Lian Jie Du Decoction (HLJDD) possesses the capability to stabilize AS plaques, the underlying mechanisms remain obscure. This study aims to delve deeper into the potential mechanisms by which HLJDD improves AS through an integrated research strategy.

METHODS

Leveraging an AS model in ApoE-/- mice exposed to a high-fat diet (HFD), we scrutinized the therapeutic effects of HLJDD using microscopic observations, oil red O staining, HE staining and Masson staining. Employing comprehensive techniques of network pharmacology, bioinformatics, and molecular docking, we elucidated the mechanism by which HLJDD stabilizes AS plaques. In vitro experiments, utilizing ox-LDL-induced macrophages and apoptotic vascular smooth muscle cells (VSMCs), assessed the impact of HLJDD on efferocytosis and the role of SLC2A1.

RESULTS

In vivo experiments showcased the efficacy of HLJDD in reducing the quantity of aortic plaques, diminishing lipid deposition, and enhancing plaque stability in AS mice. Employing network pharmacology and machine learning, we pinpointed SLC2A1 as a crucial regulatory target. Molecular docking further validated the binding of HLJDD components with SLC2A1. The experiments demonstrated a dose-dependent upregulation in SLC2A1 expression by HLJDD, amplifying efferocytosis. Importantly, this effect was reversed by the SLC2A1 inhibitor STF-31, highlighting the pivotal role of SLC2A1 as a target.

CONCLUSION

The HLJDD can modulate macrophage efferocytosis by enhancing the expression levels of SLC2A1, thereby improving the stability of atherosclerotic plaques.

Honokiol enhances the sensitivity of cetuximab in KRASG13D mutant colorectal cancer through destroying SNX3-retromer complex

Rationale : the proto-oncogene KRAS is frequently mutated in colorectal cancer (CRC), leading to inherent resistance against monoclonal antibodies targeting the epidermal growth factor receptor (EGFR), such as cetuximab. Therefore, addressing the primary resistance and expanding the indications for target therapy have become critical challenges. Methods : the screening of a natural product library against KRAS mutant CRC cells was conducted, leading to the discovery of a small molecule compound that sensitive to the KRASG13D mutation site. The anti-tumor activity of this small molecule compound in combination with cetuximab was evaluated using the KRASG13D mutant CRC models both in vivo and in vitro. This evaluation includes an examination of its effects on cell proliferation, viability, apoptosis, cell cycle progression, and tumor growth. Furthermore, RNA sequencing, western blot analysis, immunofluorescence, real-time quantitative PCR, and pull-down assays were employed to explore the molecular mechanisms underlying the synergistic anti-tumor effect of this small molecule compound in combination with cetuximab. Results : our study screened 882 compounds in KRAS mutant CRC cells and identified honokiol, a small molecule compound that exhibits specific sensitivity to KRASG13D mutant CRC cells. Furthermore, we revealed that the synergistic augmentation of cetuximab's sensitivity in vivo and in vitro models of KRASG13D mutant CRC in combination with honokiol. Mechanistically, honokiol suppresses SNX3-retromer mediated trafficking, thereby impeding lysosomal proteolytic capacity and inhibiting autophagy and macropinocytosis fluxes. Moreover, honokiol inhibits the conversion of RAS GDP to RAS GTP, heightening the susceptibility of KRASG13D CRC mutant cells to cetuximab. Conclusions : honokiol enhances the sensitivity of cetuximab by destroying SNX3 retromer in KRASG13D mutant CRC preclinical model. These findings present a promising strategy for expanding the indications of target therapy in KRAS mutant colorectal cancer patients.

PURA and GLUT1: Sweet partners for brain health

PURA, also known as Pur-alpha, is an evolutionarily conserved DNA/RNA-binding protein crucial for various cellular processes, including DNA replication, transcriptional regulation, and translational control. Comprising three PUR domains, it engages with nucleic acids and has a role in protein-protein interactions. The manifestation of PURA syndrome, arising from mutations in the PURA gene, presents neurologically with developmental delay, hypotonia, and seizures. In our prior work from 2018, we highlighted the unique case of a PURA patient displaying hypoglycorrhachia, suggesting a potential association with GLUT1 dysfunction in this syndrome. In this current study, we expand the patient cohort with PURA mutations exhibiting hypoglycorrhachia and aim to unravel the molecular basis of this phenomenon. We established an in vitro model in HeLa cells to modulate PURA expression and investigated GLUT1 function and expression. Our findings indicate that PURA levels directly impact glucose uptake through the functioning of GLUT1, without influencing significantly GLUT1 expression. Moreover, our study reveals evidence for a possible physical interaction between PURA and GLUT1, demonstrated by colocalization and co-immunoprecipitation of both proteins. Computational analyses, employing molecular dynamics, further corroborates these findings, demonstrating that PURA:GLUT1 interactions are plausible, and that the stability of the complex is altered when PURA is truncated and/or mutated. In conclusion, our results suggest that PURA plays a pivotal role in driving the function of GLUT1 for glucose uptake, potentially forming a regulatory complex. Additional investigations are warranted to elucidate the precise mechanisms governing this complex and its significance in ensuring proper GLUT1 function.

Hydrogen Sulfide Promotes Platelet Autophagy via PDGFR-α/PI3K/Akt Signaling in Cirrhotic Thrombocytopenia

Background and Aims

The role of platelet autophagy in cirrhotic thrombocytopenia (CTP) remains unclear. This study aimed to investigate the impact of platelet autophagy in CTP and elucidate the regulatory mechanism of hydrogen sulfide (H2S) on platelet autophagy.

Methods

Platelets from 56 cirrhotic patients and 56 healthy individuals were isolated for in vitro analyses. Autophagy markers (ATG7, BECN1, LC3, and SQSTM1) were quantified using enzyme-linked immunosorbent assay, while autophagosomes were visualized through electron microscopy. Western blotting was used to assess the autophagy-related proteins and the PDGFR/PI3K/Akt/mTOR pathway following treatment with NaHS (an H2S donor), hydroxocobalamin (an H2S scavenger), or AG 1295 (a selective PDGFR-α inhibitor). A carbon tetrachloride-induced cirrhotic BALB/c mouse model was established. Cirrhotic mice with thrombocytopenia were randomly treated with normal saline, NaHS, or hydroxocobalamin for 15 days. Changes in platelet count and aggregation rate were observed every three days.

Results

Cirrhotic patients with thrombocytopenia exhibited significantly decreased platelet autophagy markers and endogenous H2S levels, alongside increased platelet aggregation, compared to healthy controls. In vitro, NaHS treatment of platelets from severe CTP patients elevated LC3-II levels, reduced SQSTM1 levels, and decreased platelet aggregation in a dose-dependent manner. H2S treatment inhibited PDGFR, PI3K, Akt, and mTOR phosphorylation. In vivo, NaHS significantly increased LC3-II and decreased SQSTM1 expressions in platelets of cirrhotic mice, reducing platelet aggregation without affecting the platelet count.

Conclusions

Diminished platelet autophagy potentially contributes to thrombocytopenia in cirrhotic patients. H2S modulates platelet autophagy and functions possibly via the PDGFR-α/PI3K/Akt/mTOR signaling pathway.

Ras superfamily GTPases and signal transduction in Euglena gracilis

Biological complexity is challenging to define, but can be considered through one or more features, including overall genome size, number of genes, morphological features, multicellularity, number of life cycle stages and the ability to adapt to different environments. Euglena gracilis meets several of these criteria, with a large genome of ∼38,000 protein coding genes and a considerable ability to survive under many different conditions, some of which can be described as challenging or harsh. Potential molecular exemplars of complexity tying these aspects together are signalling pathways, including GTPases, kinases and ubiquitylation, which increase the functionality of the gene-encoded proteome manyfold. Each of these examples can modulate both protein activity and gene expression. To address the connection between genome size and complexity I have undertaken a brief, and somewhat qualitative, survey of the small ras-like GTPase superfamily of E. gracilis. Unexpectedly, apart from Rab-GTPases which control intracellular transport and organelle identify, the size of the GTPase cohort is modest, and, for example, has not scaled with gene number when compared to the close relatives, trypanosomatids. I suggest that understanding the functions of this protein family will be vital to uncovering the complexity of E. gracilis biology.

FAM91A1-TBC1D23 complex structure reveals human genetic variations susceptible for PCH

Pontocerebellar hypoplasia (PCH) is a group of rare neurodevelopmental disorders with limited diagnostic and therapeutic options. Mutations in WDR11, a subunit of the FAM91A1 complex, have been found in patients with PCH-like symptoms; however, definitive evidence that the mutations are causal is still lacking. Here, we show that depletion of FAM91A1 results in developmental defects in zebrafish similar to that of TBC1D23, an established PCH gene. FAM91A1 and TBC1D23 directly interact with each other and cooperate to regulate endosome-to-Golgi trafficking of KIAA0319L, a protein known to regulate axonal growth. Crystal structure of the FAM91A1-TBC1D23 complex reveals that TBC1D23 binds to a conserved surface on FAM91A1 by assuming a Z-shaped conformation. More importantly, the interaction between FAM91A1 and TBC1D23 can be used to predict the risk of certain TBC1D23-associated mutations to PCH. Collectively, our study provides a molecular basis for the interaction between TBC1D23 and FAM91A1 and suggests that disrupted endosomal trafficking underlies multiple PCH subtypes.

In what area of biology has a "new" type of cell death been discovered?

Cell death is a fundamental physiological process that occurs in all organisms and is crucial to each organism's evolution, ability to maintain a stable internal environment, and the development of multiple organ systems. Disulfidptosis is a new mode of cell death that is triggered when cells with high expression of solute carrier family 7 member 11 (SLC7A11) are exposed to glucose starvation to initiate the process of cell death. The disulfidptosis mechanism is a programmed cell death mode that triggers cell death through reduction-oxidation (REDOX) reactions and disulfur bond formation. In disulfidptosis, disulfur bonds play a crucial role and cause the protein in the cell to undergo conformational changes, eventually leading to cell death. This mode of cell death has unique characteristics and regulatory mechanisms in comparison with other modes of cell death. In recent years, an increasing number of studies have shown that the disulfidptosis mechanism plays a key role in the occurrence and development of a variety of diseases. For example, cancer, cardiovascular diseases, neurodegenerative diseases, and liver diseases are all closely related to cell disulfidptosis mechanisms. Therefore, it is of paramount clinical significance to conduct in-depth research regarding this mechanism. This review summarizes the research progress on the disulfidptosis mechanism, including its discovery history, regulatory mechanism, related proteins, and signaling pathways. Potential applications of the disulfidptosis mechanism in disease therapy and future research directions are also discussed. This mechanism represents another subversive discovery after ferroptosis, and provides both a fresh perspective and an innovative strategy for the treatment of cancer, as well as inspiration for the treatment of other diseases.

The role of adiponectin in cardiovascular disease

Cardiovascular disease (CVD) is a common disease that seriously threatens the health of human beings, especially middle-aged and elderly people over 50 years old. It has the characteristics of high prevalence, high disability rate and high mortality rate. Previous studies have shown that adiponectin has therapeutic effects on a variety of CVDs. As a key adipokine, adiponectin, is an abundant peptide-regulated hormone that is mainly released by adipocytes and cardiomyocytes, as well as endothelial and skeletal cells. Adiponectin can protect against CVD by improving lipid metabolism, protecting vascular endothelial cells and inhibiting foam cell formation and vascular smooth muscle cell proliferation. Further investigation of the molecular and cellular mechanisms underlying the adiponectin system may provide new ideas for the treatment of CVD. Herein, this review aims to describe the structure and function of adiponectin and adiponectin receptors, introduce the function of adiponectin in the protection of cardiovascular disease and analyze the potential use and clinical significance of this hormone in the protection and treatment of cardiovascular disease, which shows that adiponectin can be expected to become a new therapeutic target and biomarker for the diagnosis and treatment of CVD.

Cell death-related biomarker SLC2A1 has a significant role in prognosis prediction and immunotherapy efficacy evaluation in pan-cancer

Introduction: SLC2A1, a member of the SLC transporter family, is involved in a variety of cell death modalities and has been found to be associated with the prognosis and immune microenvironment of a variety of tumors. However, there is a lack of systematic and comprehensive studies on the role of SLC2A1 in pan-cancer. Methods: The mRNA, promoter methylation, and protein expression levels of SLC2A1 in pan-cancer were comprehensively evaluated using GEPIA2.0, TIMER2.0, and UALCAN databases. UCSCXenaShiny based on the cancer genomic atlas pan-cancer data and GEPIA2.0 database were used to assess the prognostic significance of SLC2A1 in pan-cancer. Genetic alterations in SLC2A1 were also evaluated using cBioPortal. The relevance of SLC2A1 to immune infiltrating cells in pan-cancer was evaluated using the XCELL algorithm in combination with the TIMER2.0 database. The correlation of SLC2A1 with the efficacy of immune checkpoint blocker (ICB) therapy was evaluated using the tumor immune dysfunction and exclusion (TIDE) score. The correlation of SLC2A1 with numerous immune-related markers was also evaluated using the TISIDB database. The correlation of SLC2A1 with tumor biological function was evaluated at the single-cell level using the CancerSEA database. Finally, the biological function of SLC2A1 was comprehensively evaluated using gene set enrichment analysis (GSEA) and protein interaction networks. Results: SLC2A1 expression is aberrant in a variety of tumors and is strongly associated with the prognosis of several cancers. SLC2A1 is significantly associated with a variety of immune infiltrating cells including CD8+ T cells, myeloid-derived suppressor cells and macrophages in a variety of tumors. Meanwhile, the expression of SLC2A1 significantly correlated with multiple immune-related markers. In addition, SLC2A1 can also predict the effect of immune checkpoint blocker therapy in some tumors. In a functional analysis, SLC2A1 was significantly associated with hypoxia, epithelial-mesenchymal transition, mTORC1 signaling, and multiple metabolic pathways in pan-cancer. Conclusion: Our study systematically and comprehensively summarizes the prognostic significance and immune-related role of SLC2A1 in pan-cancer and reveals the potential mechanism of SLC2A1 in regulating the tumor microenvironment and tumor behavior, providing a new effective pan-applicable biomarker for prognostic prediction and the evaluation of immunotherapeutic strategies for tumors.