Beclin 1 regulates neuronal transforming growth factor-β signaling by mediating recycling of the type I receptor ALK5

Enhanced LRP8 expression induced by Helicobacter pylori drives gastric cancer progression by facilitating β-Catenin nuclear translocation

INTRODUCTION

Helicobacter pylori (H. pylori) infection has been associated with gastric carcinogenesis. However, the precise involvement of LRP8, the low-density lipoprotein receptor-related protein 8, in H. pylori pathogenesis and gastric cancer (GC) remains poorly understood.

OBJECTIVES

To investigate the potential role of LRP8 in H. pylori infection and gastric carcinogenesis.

METHODS

Three-dimensional human-derived gastric organoids (hGO) and gastric cancer organoids (hGCO) were synthesized from the tissues obtained from human donors. In this work, multi-omics combined with in vivo and in vitro studies were conducted to investigate the potential involvement of LRP8 in H. pylori-induced GC.

RESULTS

We found that H. pylori infection significantly upregulated the expression of LRP8 in human GC tissues, cells, organoids, and mouse gastric mucous. In particular, LRP8 exhibited a distinct enrichment in cancer stem cells (CSC). Functionally, silencing of LRP8 affected the formation and proliferation of tumor spheroids, while increased expression of LRP8 was associated with increased proliferation and stemness of GC cells and organoids. Mechanistically, LRP8 promotes the binding of E-cadherin to β-catenin, thereby promoting nuclear translocation and transcriptional activity of β-catenin. Furthermore, LRP8 interacts with the cytotoxin-associated gene A (CagA) to form the CagA/LRP8/β-catenin complex. This complex further amplifies H. pylori-induced β-catenin nuclear translocation, leading to increased transcription of inflammatory factors and CSC markers. Clinical analysis demonstrated that abnormal overexpression of LRP8 is correlated with a poor prognosis and resistance to 5-Fluorouracil in patients with GC.

CONCLUSION

Our findings provide valuable information on the molecular intricacies of H. pylori-induced gastric carcinogenesis, offering potential therapeutic targets and prognostic markers for GC.

Ubiquitin E3 ligases assisted technologies in protein degradation: Sharing pathways in neurodegenerative disorders and cancer

E3 ligases, essential components of the ubiquitin-proteasome-mediated protein degradation system, play a critical role in cellular regulation. By covalently attaching ubiquitin (Ub) molecules to target proteins, these ligases mark them for degradation, influencing various bioprocesses. With over 600 E3 ligases identified, there is a growing realization of their potential as therapeutic candidates for addressing proteinopathies in cancer and neurodegenerative disorders (NDDs). Recent research has highlighted the need to delve deeper into the intricate roles of E3 ligases as nexus points in the pathogenesis of both cancer and NDDs. Their dysregulation is emerging as a common thread linking these seemingly disparate diseases, necessitating a comprehensive understanding of their molecular intricacies. Herein, we have discussed (i) the fundamental mechanisms through which different types of E3 ligases actively participate in selective protein degradation in cancer and NDDs, followed by an examination of common E3 ligases playing pivotal roles in both situations, emphasising common players. Moving to, (ii) the functional domains and motifs of E3 ligases involved in ubiquitination, we have explored their interactions with specific substrates in NDDs and cancer. Additionally, (iii) we have explored techniques like PROTAC, molecular glues, and other state-of-the-art methods for hijacking neurotoxic and oncoproteins. Lastly, (iv) we have provided insights into ongoing clinical trials, offering a glimpse into the evolving landscape of E3-based therapeutics for cancer and NDDs. Unravelling the intricate network of E3 ligase-mediated regulation holds the key to unlocking targeted therapies that address the specific molecular signatures of individual patients, heralding a new era in personalized medicines.

GDF1 ameliorates cognitive impairment induced by hearing loss

Hearing loss is associated with an increased risk of Alzheimer disease (AD). However, the mechanisms of hearing loss promoting the onset of AD are poorly understood. Here we show that hearing loss aggravates cognitive impairment in both wild-type mice and mouse models of AD. Embryonic growth/differentiation factor 1 (GDF1) is downregulated in the hippocampus of deaf mice. Knockdown of GDF1 mimics the detrimental effect of hearing loss on cognition, while overexpression of GDF1 in the hippocampus attenuates the cognitive impairment induced by deafness. Strikingly, overexpression of GDF1 also attenuates cognitive impairment in APP/PS1 transgenic mice. GDF1 activates Akt, which phosphorylates asparagine endopeptidase and inhibits asparagine endopeptidase-induced synaptic degeneration and amyloid-β production. The expression of GDF1 is downregulated by the transcription factor CCAAT-enhancer binding protein-β. These findings indicate that hearing loss could promote AD pathological changes by inhibiting the GDF1 signaling pathway; thus, GDF1 may represent a therapeutic target for AD.

Gasdermin E promotes translocation of p65 and c-jun into nucleus in keratinocytes for progression of psoriatic skin inflammation

Gasdermin E (GSDME) has recently been identified as a critical executioner to mediate pyroptosis. While epidermal keratinocytes can initiate GSDME-mediated pyroptosis, the role of keratinocyte GSDME in psoriatic dermatitis remains poorly characterized. Through analysis of GEO datasets, we found elevated GSDME levels in psoriatic lesional skin. Additionally, GSDME levels correlated with both psoriasis severity and response to biologics treatments. Single-cell RNA sequencing (scRNA-seq) from a GEO dataset revealed GSDME upregulation in keratinocytes of psoriasis patients. In the imiquimod (IMQ)-induced psoriasis-like dermatitis mouse model, both full-length and cleaved forms of caspase-3 and GSDME were elevated in the epidermis. Abnormal proliferation and differentiation of keratinocytes and dermatitis were attenuated in Gsdme-/- mice and keratinocyte-specific Gsdme conditional knockout mice after IMQ stimulation. Exposure of keratinocytes to mixed cytokines (M5), mimicking psoriatic conditions, led to GSDME cleavage. Moreover, the interaction between GSDME-FL and p65 or c-jun was significantly increased after M5 stimulation. GSDME knockdown inhibited nuclear translocation of p65 and c-jun and decreased upregulation of psoriatic inflammatory mediators such as IL1β, CCL20, CXCL1, CXCL8, S100A8, and S100A9 in M5-challenged keratinocytes. In conclusion, GSDME in keratinocytes contributes to the pathogenesis and progression of psoriasis, potentially in a pyroptosis-independent manner by interacting and promoting translocation of p65 and c-jun. These findings suggest that keratinocyte GSDME could serve as a potential therapeutic target for psoriasis treatment.

Interleukin-17 alleviates erastin-induced alveolar bone loss by suppressing ferroptosis via interaction between NRF2 and p-STAT3

AIM

To investigate the relationship between interleukin-17 (IL-17), ferroptosis and osteogenic differentiation.

MATERIALS AND METHODS

We first analysed the changes in ferroptosis-related molecules in experimental periodontitis models. The effects of erastin, a small-molecule ferroptosis inducer, and IL-17 on alveolar bone loss and repair in animal models were then investigated. Primary mouse mandibular osteoblasts were exposed to erastin and IL-17 in vitro. Ferroptosis- and osteogenesis-related genes and proteins were detected. Further, siRNA, immunofluorescence co-localization and immunoprecipitation were used to confirm the roles of the nuclear factor erythroid-2-related factor 2 (NRF2) and phosphorylated signal transducer and activator of transcription 3 (p-STAT3), as well as their interaction.

RESULTS

The levels of NRF2, glutathione peroxidase 4 and solute carrier family 7 member 11 were lower in the ligated tissues than in normal periodontal tissues. Alveolar bone loss in an in vivo experimental periodontitis model was aggravated by erastin and alleviated by IL-17. In vitro, IL-17 ameliorated erastin-inhibited osteogenic differentiation by reversing ferroptosis. Altered NRF2 expression correlated with changes in ferroptosis-related molecules and osteogenesis. Furthermore, the physical interaction between NRF2 and p-STAT3 was confirmed in the nucleus. In IL-17 + erastin-stimulated osteoblasts, the p-STAT3-NRF2 complex might actively participate in the downstream transcription of ferroptosis- and osteogenesis-related genes.

CONCLUSIONS

IL-17 administration conferred resistance to erastin-induced osteoblast ferroptosis and osteogenesis. The possible mechanism may involve p-STAT3 directly interacting with NRF2.

Dynamic interplay between IL-1 and WNT pathways in regulating dermal adipocyte lineage cells during skin development and wound regeneration

Dermal adipocyte lineage cells are highly plastic and can undergo reversible differentiation and dedifferentiation in response to various stimuli. Using single-cell RNA sequencing of developing or wounded mouse skin, we classify dermal fibroblasts (dFBs) into distinct non-adipogenic and adipogenic cell states. Cell differentiation trajectory analyses identify IL-1-NF-κB and WNT-β-catenin as top signaling pathways that positively and negatively associate with adipogenesis, respectively. Upon wounding, activation of adipocyte progenitors and wound-induced adipogenesis are mediated in part by neutrophils through the IL-1R-NF-κB-CREB signaling axis. In contrast, WNT activation, by WNT ligand and/or ablation of Gsk3, inhibits the adipogenic potential of dFBs but promotes lipolysis and dedifferentiation of mature adipocytes, contributing to myofibroblast formation. Finally, sustained WNT activation and inhibition of adipogenesis is seen in human keloids. These data reveal molecular mechanisms underlying the plasticity of dermal adipocyte lineage cells, defining potential therapeutic targets for defective wound healing and scar formation.

Rab11 and Its Role in Neurodegenerative Diseases

Vesicles mediate the trafficking of membranes/proteins in the endocytic and secretory pathways. These pathways are regulated by small GTPases of the Rab family. Rab proteins belong to the Ras superfamily of GTPases, which are significantly involved in various intracellular trafficking and signaling processes in the nervous system. Rab11 is known to play a key role especially in recycling many proteins, including receptors important for signal transduction and preservation of functional activities of nerve cells. Rab11 activity is controlled by GEFs (guanine exchange factors) and GAPs (GTPase activating proteins), which regulate its function through modulating GTP/GDP exchange and the intrinsic GTPase activity, respectively. Rab11 is involved in the transport of several growth factor molecules important for the development and repair of neurons. Overexpression of Rab11 has been shown to significantly enhance vesicle trafficking. On the other hand, a reduced expression of Rab11 was observed in several neurodegenerative diseases. Current evidence appears to support the notion that Rab11 and its cognate proteins may be potential targets for therapeutic intervention. In this review, we briefly discuss the function of Rab11 and its related interaction partners in intracellular pathways that may be involved in neurodegenerative processes.

Spinal CCK1 Receptors Contribute to Somatic Pain Hypersensitivity Induced by Malocclusion via a Reciprocal Neuron-Glial Signaling Cascade

Recent studies have shown that the incidence of chronic primary pain including temporomandibular disorders (TMD) and fibromyalgia syndrome (FMS) often exhibit comorbidities. We recently reported that central sensitization and descending facilitation system contributed to the development of somatic pain hypersensitivity induced by orofacial inflammation combined with stress. The purpose of this study was to explore whether TMD caused by unilateral anterior crossbite (UAC) can induce somatic pain hypersensitivity, and whether the cholecystokinin (CCK) receptor-mediated descending facilitation system promotes hypersensitivity through neuron-glia cell signaling cascade. UAC evoked thermal and mechanical pain hypersensitivity of the hind paws from day 5 to 70 that peaked at week 4 post UAC. The expression levels of CCK1 receptors, interleukin-18 (IL-18) and IL-18 receptors (IL-18R) were significantly up-regulated in the L4 to L5 spinal dorsal horn at 4 weeks post UAC. Intrathecal injection of CCK1 and IL-18 receptor antagonists blocked somatic pain hypersensitivity. IL-18 mainly co-localized with microglia, while IL-18R mainly co-localized with astrocytes and to a lesser extent with neurons. These findings indicate that the signaling transduction between neurons and glia at the spinal cord level contributes to the descending pain facilitation through CCK1 receptors during the development of the comorbidity of TMD and FMS. PERSPECTIVE: CCK1 receptor-dependent descending facilitation may mediate central mechanisms underlying the development of widespread somatic pain via a reciprocal neuron-glial signaling cascade, providing novel therapeutic targets for the clinical treatment of TMD and FMS comorbidities.

Açai Berry Mitigates Vascular Dementia-Induced Neuropathological Alterations Modulating Nrf-2/Beclin1 Pathways

The second-most common cause of dementia is vascular dementia (VaD). The majority of VaD patients experience cognitive impairment, which is brought on by oxidative stress and changes in autophagic function, which ultimately result in neuronal impairment and death. In this study, we examine a novel method for reversing VaD-induced changes brought on by açai berry supplementation in a VaD mouse model. The purpose of this study was to examine the impact of açai berries on the molecular mechanisms underlying VaD in a mouse model of the disease that was created by repeated ischemia-reperfusion (IR) of the whole bilateral carotid artery. Here, we found that açai berry was able to reduce VaD-induced behavioral alteration, as well as hippocampal death, in CA1 and CA3 regions. These effects are probably due to the modulation of nuclear factor erythroid 2-related factor 2 (Nrf-2) and Beclin-1, suggesting a possible crosstalk between these molecular pathways. In conclusion, the protective effects of açai berry could be a good supplementation in the future for the management of vascular dementia.

Small molecule C381 targets the lysosome to reduce inflammation and ameliorate disease in models of neurodegeneration

Neurodegenerative diseases are poorly understood and difficult to treat. One common hallmark is lysosomal dysfunction leading to the accumulation of aggregates and other undegradable materials, which cause damage to brain resident cells. Lysosomes are acidic organelles responsible for breaking down biomolecules and recycling their constitutive parts. In this work, we find that the antiinflammatory and neuroprotective compound, discovered via a phenotypic screen, imparts its beneficial effects by targeting the lysosome and restoring its function. This is established using a genome-wide CRISPRi target identification screen and then confirmed using a variety of lysosome-targeted studies. The resulting small molecule from this study represents a potential treatment for neurodegenerative diseases as well as a research tool for the study of lysosomes in disease.

Neurodegenerative diseases affect a rapidly growing number of the aging population globally. These conditions have proven extremely difficult to treat due to our limited understanding of their mechanisms, but they are characterized by protein aggregation, inflammation, lysosomal dysfunction, and neuronal death. Phenotypic drug screens promise to deliver “target agnostic” therapies without being hypothesis limited as with target-based screens. Here, we describe our work to develop and characterize small molecule C381. The compound is a benzyl urea derivative containing a piperidine ring. It is brain penetrant with a ClogP of 3.3 and an oral bioavailability of 48%. We tested the compound in Progranulin^−/− mice (a model of lysosomal storage disease and frontotemporal dementia) and the chronic 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) mouse model of Parkinson’s disease (PD) where it showed prominent antiinflammatory and neuroprotective effects. In the PD model, C381 restored cognitive function and rescued dopaminergic neuron loss. To identify the target, we performed a genome-wide CRISPR interference (CRISPRi) drug target identification screen, which implicated the lysosome. After validating the screen results with individual knockdown cell lines, follow-up functional studies revealed that C381 physically targets the lysosome, promotes lysosomal acidification, increases breakdown of lysosomal cargo, and improves lysosome resilience to damage. As a first-in-class compound capable of restoring lysosomal function, C381 has the potential both as a therapeutic and as a research compound to better understand lysosomal contributions to disease progression. Together, our work has produced a promising drug candidate for the treatment of neurodegenerative diseases marked by lysosomal dysfunction.

Equine lentivirus counteracts SAMHD1 restriction by Rev-mediated degradation of SAMHD1 via the BECN1-dependent lysosomal pathway

The innate immune restriction factor SAMHD1 can inhibit diverse viruses in myeloid cells. Mechanistically, SAMHD1 inhibits lentiviral replication including HIV-1 by depleting the nucleotide pool to interfere with their reverse transcription. Equine infectious anemia virus (EIAV) is an ancient lentivirus that preferentially attacks macrophages. However, the mechanism by which EIAV successfully establishes infection in macrophages with functional SAMHD1 remains unclear. Here, we demonstrate that while equine SAMDH1 can limit EIAV replication in equine macrophages at the reverse transcription stage, the antiviral effect is counteracted by the well-known transcriptional regulator Rev, which downregulates equine SAMHD1 through the lysosomal pathway. Remarkably, Rev hijacks BECN1 (beclin 1) and PIK3C3 to mediate SAMHD1 degradation in a canonical macroautophagy/autophagy-independent pathway. Our study illustrates that equine lentiviral Rev possesses important functions in evading cellular innate immunity in addition to its RNA regulatory function, and may provide new insights into the co-evolutionary arms race between SAMHD1 and lentiviruses.Abbreviations:3-MA: 3-methyladenine; AA: amino acid; ACTB: actin beta; AD: activation domain; ATG: autophagy related; Baf A1: bafilomycin A1; BD: binding domain; BECN1: beclin 1; BH3: BCL2-homology-3 domain; BiFC: bimolecular fluorescence complementation; CCD: coiled-coil domain; class III PtdIns3K: class III phosphatidylinositol 3-kinase; CQ: chloroquine; Co-IP: co-immunoprecipitation; dNTPase: dGTP-stimulated deoxynucleoside triphosphate triphosphohydrolase; ECD: evolutionarily conserved domain; EIAV: equine infectious anemia virus; eMDMs: equine monocyte-derived macrophages; GFP: green fluorescent protein; HD: histidine-aspartic; HIV-1: human immunodeficiency virus-1; hpi: hours post infection; hpt: hours post transfection; KO: knockout; LAMP2: lysosomal associated membrane protein 2; LMB: leptomycin B; PMA: phorbol 12-myristate 13-acetate; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; ND: unknown non-essential domain; NES: nuclear export signal; NLS: localization signal; NS: statistically non-significant; PIK3C3: phosphatidylinositol 3-kinase catalytic subunit type 3; RBD: RNA binding domain; RT: reverse transcriptase; siRNAs: small interfering RNAs; SAMHD1: SAM and HD domain containing deoxynucleoside triphosphate triphosphohydrolase 1; SIV: simian immunodeficiency virus; VN: C-terminal residues of Venus 174 to 238; VC: N-terminal residues 2 to 173 of Venus.

Molecular mechanisms of mammalian autophagy

The ubiquitin-proteasome pathway (UPP) and autophagy play integral roles in cellular homeostasis. As part of their normal life cycle, most proteins undergo ubiquitination for some form of redistribution, localization and/or functional modulation. However, ubiquitination is also important to the UPP and several autophagic processes. The UPP is initiated after specific lysine residues of short-lived, damaged or misfolded proteins are conjugated to ubiquitin, which targets these proteins to proteasomes. Autophagy is the endosomal/lysosomal-dependent degradation of organelles, invading microbes, zymogen granules and macromolecules such as protein, carbohydrates and lipids. Autophagy can be broadly separated into three distinct subtypes termed microautophagy, chaperone-mediated autophagy and macroautophagy. Although autophagy was once thought of as non-selective bulk degradation, advancements in the field have led to the discovery of several selective forms of autophagy. Here, we focus on the mechanisms of primary and selective mammalian autophagy pathways and highlight the current knowledge gaps in these molecular pathways.

Extracellular vesicles deposit PCNA to rejuvenate aged bone marrow-derived mesenchymal stem cells and slow age-related degeneration

Stem cell senescence increases alongside the progressive functional declines that characterize aging. The effects of extracellular vesicles (EVs) are now attracting intense interest in the context of aging and age-related diseases. Here, we demonstrate that neonatal umbilical cord (UC) is a source of EVs derived from mesenchymal stem cells (MSC-EVs). These UC-produced MSC-EVs (UC-EVs) contain abundant anti-aging signals and rejuvenate senescing adult bone marrow-derived MSCs (AB-MSCs). UC-EV-rejuvenated AB-MSCs exhibited alleviated aging phenotypes and increased self-renewal capacity and telomere length. Mechanistically, UC-EVs rejuvenate AB-MSCs at least partially by transferring proliferating cell nuclear antigen (PCNA) into recipient AB-MSCs. When tested in therapeutic context, UC-EV-triggered rejuvenation enhanced the regenerative capacities of AB-MSCs in bone formation, wound healing, and angiogenesis. Intravenously injected UC-EVs conferred anti-aging phenotypes including decreased bone and kidney degeneration in aged mice. Our findings reveal that UC-EVs are of high translational value in anti-aging intervention.

Mas receptor activation attenuates allergic airway inflammation via inhibiting JNK/CCL2-induced macrophage recruitment

BACKGROUND

Defective absorption of acute allergic airway inflammation is involved in the initiation and development of chronic asthma. After allergen exposure, there is a rapid recruitment of macrophages around the airways, which promote acute inflammatory responses. The Ang-(1-7)/Mas receptor axis reportedly plays protective roles in various tissue inflammation and remodeling processes in vivo. However, the exact role of Mas receptor and their underlying mechanisms during the pathology of acute allergic airway inflammation remains unclear.

OBJECTIVE

We investigated the role of Mas receptor in acute allergic asthma and explored its underlying mechanisms in vitro, aiming to find critical molecules and signal pathways.

METHODS

Mas receptor expression was assessed in ovalbumin (OVA)-induced acute asthmatic murine model. Then we estimated the anti-inflammatory role of Mas receptor in vivo and explored expressions of several known inflammatory cytokines as well as phosphorylation levels of MAPK pathways. Mas receptor functions and underlying mechanisms were studied further in the human bronchial epithelial cell line (16HBE).

RESULTS

Mas receptor expression decreased in acute allergic airway inflammation. Multiplex immunofluorescence co-localized Mas receptor and EpCAM, indicated that Mas receptor may function in the bronchial epithelium. Activating Mas receptor through AVE0991 significantly alleviated macrophage infiltration in airway inflammation, accompanied with down-regulation of CCL2 and phosphorylation levels of MAPK pathways. Further studies in 16HBE showed that AVE0991 pre-treatment inhibited LPS-induced or anisomycin-induced CCL2 increase and THP-1 macrophages migration via JNK pathways.

CONCLUSION

Our findings suggested that Mas receptor activation significantly attenuated CCL2 dependent macrophage recruitments in acute allergic airway inflammation through JNK pathways, which indicated that Mas receptor, CCL2 and phospho-JNK could be potential targets against allergic airway inflammation.

Identification of Methylated Gene Biomarkers in Patients with Alzheimer's Disease Based on Machine Learning

Background

Alzheimer's disease (AD) is a neurodegenerative disorder and characterized by the cognitive impairments. It is essential to identify potential gene biomarkers for AD pathology.

Methods

DNA methylation expression data of patients with AD were downloaded from the Gene Expression Omnibus (GEO) database. Differentially methylated sites were identified. The functional annotation analysis of corresponding genes in the differentially methylated sites was performed. The optimal diagnostic gene biomarkers for AD were identified by using random forest feature selection procedure. In addition, receiver operating characteristic (ROC) diagnostic analysis of differentially methylated genes was performed.

Results

A total of 10 differentially methylated sites including 5 hypermethylated sites and 5 hypomethylated sites were identified in AD. There were a total of 8 genes including thioredoxin interacting protein (TXNIP), noggin (NOG), regulator of microtubule dynamics 2 (FAM82A1), myoneurin (MYNN), ankyrin repeat domain 34B (ANKRD34B), STAM-binding protein like 1, ALMalpha (STAMBPL1), cyclin-dependent kinase inhibitor 1C (CDKN1C), and coronin 2B (CORO2B) that correspond to 10 differentially methylated sites. The cell cycle (FDR = 0.0284087) and TGF-beta signaling pathway (FDR = 0.0380372) were the only two significantly enriched pathways of these genes. MYNN was selected as optimal diagnostic biomarker with great diagnostic value. The random forests model could effectively predict AD.

Conclusion

Our study suggested that MYNN could be served as optimal diagnostic biomarker of AD. Cell cycle and TGF-beta signaling pathway may be associated with AD.

Promotion of cell autophagy and apoptosis in cervical cancer by inhibition of long noncoding RNA LINC00511 via transcription factor RXRA-regulated PLD1

An increasing number of studies have explored the relationship of long noncoding RNAs (lncRNAs) with cervical cancer, yet the role of LINC00511 in cervical cancer still remains elusive. The current dissertation was intended to explore the effect of LINC00511 on cervical cancer development by regulating phospholipase D1 (PLD1) expression through transcription factor retinoic X receptor alpha (RXRA). Differentially expressed lncRNA and messenger RNA related to cervical cancer were screened by microarray-based expression profiling. Cervical cancer and paracancerous tissues were harvested to determine the LINC00511 expression using reverse transcription-quantitative polymerase chain reaction and western blot analysis. The relationship among LINC00511, PLD1 promoter activity, and RXRA were determined via RNA immunoprecipitation, chromatin immunoprecipitation, and dual-luciferase reporter assays. Proliferation, autophagy, and apoptosis of cervical cancer cells were detected with a series of experiments. Tumor xenograft in nude mice was employed to determine the influence of LINC00511 and PLD1 on tumor formation and growth of cervical cancer in vivo. LINC00511 might influence the occurrence of cervical cancer by upregulating PLD1 expression via recruiting transcription factor RXRA. LINC00511 and PLD1 expressions were remarkably high in cervical cancer tissues and cells. LINC00511 combined with RXRA, and overexpression of LINC00511 in cervical cancer cells elevated PLD1 expression. Si-LINC00511, si-RXRA or si-PLD1 triggered repression of proliferation and promotion of autophagy and apoptosis of cervical cancer cells. In vivo experiment, si-LINC00511, or si-PLD1 inhibited the tumorigenic ability of nude mice. Collectively, this study suggests that LINC00511 acts as an oncogenic lncRNA in cervical cancer via the promotion of transcription factor RXRA-regulated PLD1.

Intestinal epithelial tight junction barrier regulation by autophagy-related protein ATG6/beclin 1

A defective tight junction (TJ) barrier is a key pathogenic factor for inflammatory bowel disease. Previously, we have shown that autophagy, a cell survival mechanism, enhances intestinal epithelial TJ barrier function. Autophagy-related protein-6 (ATG6/beclin 1), a key protein in the autophagy pathway, also plays a role in the endocytic pathway. The constitutive role of beclin 1 in the intestinal TJ barrier is not known. In Caco-2 cells, beclin 1 was found to be coimmunoprecipitated with the TJ protein occludin and colocalized with occludin on the membrane. Treatment of Caco-2 cells with beclin 1 peptide [transactivating regulatory protein (Tat)-beclin 1] reduced TJ barrier function. Activation of beclin 1 increased occludin endocytosis and reduced total occludin protein level. In contrast, beclin 1 siRNA transfection enhanced Caco-2 TJ barrier function. In pharmacologic and genetic autophagy inhibition studies, the constitutive function of beclin 1 in the TJ barrier was found to be autophagy independent. However, de novo induction of autophagy with starvation or rapamycin prevented Tat-beclin 1-induced increase in TJ permeability and reduction in occludin level. Induction of autophagy also resulted in reduced beclin 1-occludin association. In mouse colon, beclin 1 colocalized with occludin on the epithelial membrane. Perfusion of mouse colon with beclin 1 peptide caused an increase in colonic TJ permeability that was prevented by in vivo induction of autophagy. These findings show that beclin 1 plays a constitutive, autophagy-independent role in the regulation of intestinal TJ barrier function via endocytosis of occludin. Autophagy terminates constitutive beclin 1 function in the TJ barrier and enhances the TJ barrier.

Beclin 1 regulates recycling endosome and is required for skin development in mice

Beclin 1 is a key regulator of autophagy and endocytosis. However, its autophagy-independent functions remain poorly understood. Here, we report that Beclin 1 regulates recycling endosome and is required for skin development in vivo. We first established keratinocyte-specific Beclin 1-knockout mice and found that these mutant mice died owing to severe impairment of epidermal barrier. Beclin 1 plays a role in autophagy and the endocytic pathway in cooperation with Atg14 and UVRAG, respectively, and keratinocyte-specific Atg14-knockout mice do not show any abnormal phenotypes, suggesting that Beclin 1 has a role in skin development via the endocytic pathway. Furthermore, we found that Beclin 1 deficiency causes mislocalization of integrins via a defect of recycling endosome, abnormal cell detachment of basal cells and their immature differentiation, and abnormal skin development. These results provide the first genetic evidence showing the roles of Beclin 1 in recycling endosome and skin development.

Proteolytic cleavage of Beclin 1 exacerbates neurodegeneration

Background

Neuronal cell loss contributes to the pathology of acute and chronic neurodegenerative diseases, including Alzheimer’s disease (AD). It remains crucial to identify molecular mechanisms sensitizing neurons to various insults and cell death. To date, the multifunctional, autophagy-related protein Beclin 1 has been shown to be both necessary and sufficient for neuronal integrity in neurodegenerative models associated with protein aggregation. Interestingly, besides its role in cellular homeostasis, Beclin 1 has also been ascribed a role in apoptosis. This makes it critical to elucidate whether Beclin 1 regulates neuronal death and survival across neurodegenerative conditions independent of protein clearance. Here, we provide experimental evidence for a direct functional link between proteolytic cleavage of Beclin 1 and apoptotic neuronal cell loss in two independent models of neurodegeneration in vivo.

Methods

Proteolytic cleavage of Beclin 1 was characterized in lysates of human AD brain samples. We developed viral tools allowing for the selective neuronal expression of the various Beclin 1 forms, including Beclin 1 cleavage products as well as a cleavage-resistant form. The effect of these Beclin 1 forms on survival and integrity of neurons was examined in models of acute and chronic neurodegeneration in vitro and in vivo. Markers of neuronal integrity, neurodegeneration and inflammation were further assessed in a Kainic acid-based mouse model of acute excitotoxic neurodegeneration and in a hAPP-transgenic mouse model of AD following perturbation of Beclin 1 in the susceptible CA1 region of the hippocampus.

Results

We find a significant increase in caspase-mediated Beclin 1 cleavage fragments in brain lysates of human AD patients and mimic this phenotype in vivo using both an excitotoxic and hAPP-transgenic mouse model of neurodegeneration. Surprisingly, overexpression of the C-terminal cleavage-fragment exacerbated neurodegeneration in two distinct models of degeneration. Local inhibition of caspase activity ameliorated neurodegeneration after excitotoxic insult and prevented Beclin 1 cleavage. Furthermore, overexpression of a cleavage-resistant form of Beclin 1 in hippocampal neurons conferred neuroprotection against excitotoxic and Amyloid beta-associated insults in vivo.

Conclusions

Together, these findings indicate that the cleavage state of Beclin 1 determines its functional involvement in both neurodegeneration and neuroprotection. Hence, manipulating the cleavage state of Beclin 1 may represent a therapeutic strategy for preventing neuronal cell loss across multiple forms of neurodegeneration.

Electronic supplementary material

The online version of this article (10.1186/s13024-018-0302-4) contains supplementary material, which is available to authorized users.

Targeting the potent Beclin 1-UVRAG coiled-coil interaction with designed peptides enhances autophagy and endolysosomal trafficking

Beclin 1 is an essential autophagy protein. Through its coiled-coil domain, Beclin 1 recruits two modulators, Atg14L and UVRAG, to form Atg14L- or UVRAG-containing Beclin 1–Vps34 subcomplexes responsible for Vps34-dependent membrane trafficking processes including autophagy and endosomal trafficking. Our structural study of the Beclin 1–UVRAG coiled-coil complex reveals a strengthened interface to maintain potent Beclin 1–UVRAG interaction. This potency is essential for UVRAG to outcompete Atg14L and enhance Vps34-dependent endosomal trafficking. Our designed peptides can target the Beclin 1 coiled-coil domain, promote Atg14L– and UVRAG–Beclin 1 interaction, induce autophagy, and significantly enhance endolysosomal degradation of the EGF receptor. Our results testify to the feasibility of targeting Beclin 1 to regulate both autophagy and endosomal trafficking.

The Beclin 1–Vps34 complex, known as “mammalian class III PI3K,” plays essential roles in membrane-mediated transport processes including autophagy and endosomal trafficking. Beclin 1 acts as a scaffolding molecule for the complex and readily transits from its metastable homodimeric state to interact with key modulators such as Atg14L or UVRAG and form functionally distinct Atg14L/UVRAG-containing Beclin 1–Vps34 subcomplexes. The Beclin 1–Atg14L/UVRAG interaction relies critically on their coiled-coil domains, but the molecular mechanism remains poorly understood. We determined the crystal structure of Beclin 1–UVRAG coiled-coil complex and identified a strengthened interface with both hydrophobic pairings and electrostatically complementary interactions. This structure explains why the Beclin 1–UVRAG interaction is more potent than the metastable Beclin 1 homodimer. Potent Beclin 1–UVRAG interaction is functionally significant because it renders UVRAG more competitive than Atg14L in Beclin 1 binding and is critical for promoting endolysosomal trafficking. UVRAG coiled-coil mutants with weakened Beclin 1 binding do not outcompete Atg14L and fail to promote endolysosomal degradation of the EGF receptor (EGFR). We designed all-hydrocarbon stapled peptides that specifically targeted the C-terminal part of the Beclin 1 coiled-coil domain to interfere with its homodimerization. One such peptide reduced Beclin 1 self-association, promoted Beclin 1–Atg14L/UVRAG interaction, increased autophagic flux, and enhanced EGFR degradation. Our results demonstrate that the targeting Beclin 1 coiled-coil domain with designed peptides to induce the redistribution of Beclin 1 among its self-associated form or Atg14L/UVRAG-containing complexes enhances both autophagy and endolysosomal trafficking.

Intracellular trafficking of transforming growth factor β receptors

Transforming growth factor β (TGFβ) family members signal via heterotetrameric complexes of type I (TβRI) and type II (TβRII) dual specificity kinase receptors. The availability of the receptors on the cell surface is controlled by several mechanisms. Newly synthesized TβRI and TβRII are delivered from the Golgi apparatus to the cell surface via separate routes. On the cell surface, TGFβ receptors are distributed between different microdomains of the plasma membrane and can be internalized via clathrin- and caveolae-mediated endocytic mechanisms. Although receptor endocytosis is not essential for TGFβ signaling, localization of the activated receptor complexes on the early endosomes promotes TGFβ-induced Smad activation. Caveolae-mediated endocytosis, which is widely regarded as a mechanism that facilitates the degradation of TGFβ receptors, has been shown to be required for TGFβ signaling via non-Smad pathways. The importance of proper control of TGFβ receptor intracellular trafficking is emphasized by clinical data, as mislocalization of receptors has been described in connection with several human diseases. Thus, control of intracellular trafficking of the TGFβ receptors together with the regulation of their expression, posttranslational modifications and down-regulation, ensure proper regulation of TGFβ signaling.

Thrombospondin-1 modified bone marrow mesenchymal stem cells (BMSCs) promote neurite outgrowth and functional recovery in rats with spinal cord injury

Stem cell therapies are currently gaining momentum in the treatment of spinal cord injury (SCI). However, unsatisfied intrinsic neurite growth capacity constitutes significant obstacles for injured spinal cord repair and ultimately results in neurological dysfunction. The present study assessed the efficacy of thrombospondin-1 (TSP-1), a neurite outgrowth-promoting molecule, modified bone marrow mesenchymal stem cells (BMSCs) on promoting neurite outgrowth in vitro and in vivo of Oxygen–Glucose Deprivation (OGD) treated motor neurons and SCI rat models. The present results demonstrated that the treatment of BMSCs+TSP-1 could promote the neurite length, neuronal survival, and functional recovery after SCI. Additionally, TSP-1 could activate transforming growth factor-β1 (TGF-β1) then induced the smad2 phosphorylation, and expedited the expression of GAP-43 to promote neurite outgrowth. The present study for the first time demonstrated that BMSCs+TSP-1 could promote neurite outgrowth and functional recovery after SCI partly through the TGF-β1/p-Samd2 pathway. The study provided a novel encouraging evidence for the potential treatment of BMSCs modification with TSP-1 in patients with SCI.

C. elegans SMA-10 regulates BMP receptor trafficking

Signal transduction of the conserved transforming growth factor-β (TGFβ) family signaling pathway functions through two distinct serine/threonine transmembrane receptors, the type I and type II receptors. Endocytosis orchestrates the assembly of signaling complexes by coordinating the entry of receptors with their downstream signaling mediators. Recently, we showed that the C. elegans type I bone morphogenetic protein (BMP) receptor SMA-6, part of the TGFβ family, is recycled through the retromer complex while the type II receptor, DAF-4 is recycled in a retromer-independent, ARF-6 dependent manner. From genetic screens in C. elegans aimed at identifying new modifiers of BMP signaling, we reported on SMA-10, a conserved LRIG (leucine-rich and immunoglobulin-like domains) transmembrane protein. It is a positive regulator of BMP signaling that binds to the SMA-6 receptor. Here we show that the loss of sma-10 leads to aberrant endocytic trafficking of SMA-6, resulting in its accumulation in distinct intracellular endosomes including the early endosome, multivesicular bodies (MVB), and the late endosome with a reduction in signaling strength. Our studies show that trafficking defects caused by the loss of sma-10 are not universal, but affect only a limited set of receptors. Likewise, in Drosophila, we find that the fly homolog of sma-10, lambik (lbk), reduces signaling strength of the BMP pathway, consistent with its function in C. elegans and suggesting evolutionary conservation of function. Loss of sma-10 results in reduced ubiquitination of the type I receptor SMA-6, suggesting a possible mechanism for its regulation of BMP signaling.

Cell-free DNA-induced alteration of autophagy response and TLR9-signaling: Their relation to amelioration of DSS-colitis

BACKGROUND

The influence of cell-free DNA (fDNA) administration on the TLR9-autophagy regulatory crosstalk within inflammatory circumstances remains unclear.

AIMS

To examine the immunobiologic effects of iv. fDNA injection on the TLR9-mediated autophagy response in murine DSS-colitis.

METHODS

Different types of modified fDNAs were administered to DSS-colitic mice. Disease and histological activities, spleen index were measured. Changes of the TLR9-associated and autophagy-related gene expression profiles of lamina proprial cells and splenocytes were assayed by quantitative real-time PCR, and validated by immunohistochemistries. Ultrastructural changes of the colon were examined by transmission electron microscopy (TEM).

RESULTS

A single intravenous injection of colitic fDNA (C-DNA) exhibited beneficial clinical and histological effects on DSS-colitis, compared to normal (N-DNA). C-DNA administration displayed a more prominent impact on the outcome of the TLR9-autophagy response than N-DNA. C-DNA resulted in a decreased spleen index in DSS-colitic mice. C-DNA treatment of normal mice resulted in a downregulation of Beclin1 and ATG16L1 mRNA and protein expression in the colon. These as well as LC3B were downregulated in the spleen. In contrast, the Beclin1, ATG16L1 and LC3B gene and protein expressions were upregulated in both the colon and the spleen by C-DNA injection. Moreover, C-DNA administration to DSS-colitic mice resulted in a remarkable increase of epithelial autophagic vacuoles representing an intensified macroautophagy.

CONCLUSIONS

The effect of intravenously administered fDNA on the TLR9-mediated autophagy response is expressly dependent on the origin of fDNA (i.e. inflammatory or not) and on the characteristics of the local immunobiologic milieu (i.e. inflammatory or not, as well).

The TGF-β Family in Caenorhabditis elegans

Transforming growth factor β (TGF-β) and related ligands have potent effects on an enormous diversity of biological functions in all animals examined. Because of the strong conservation of TGF-β family ligand functions and signaling mechanisms, studies from multiple animal systems have yielded complementary and synergistic insights. In the nematode Caenorhabditis elegans, early studies were instrumental in the elucidation of TGF-β family signaling mechanisms. Current studies in C. elegans continue to identify new functions for the TGF-β family in this organism as well as new conserved mechanisms of regulation.