Growth Factor Signaling Research Articles

Left atrial single-cell transcriptomics reveals amphiregulin as a surrogate marker for atrial fibrillation

Atrial fibrillation (AF) is strongly associated with strokes, heart failure, and increased mortality. This study aims to identify the monocyte–macrophage heterogeneity and interactions of these cells with non-immune cells, and to identify functional biomarkers in patients with AF. Therefore, we assess the single cell landscape of left atria (LA), using a combination of single cell and nucleus RNA-seq. Myeloid cells in LA tissue are categorized into five macrophage clusters, three monocyte clusters, and others. Cell-Chat analysis revealed that monocytes and IL1B+ macrophages send epidermal growth factor (EGF) signals to fibroblasts. Amphiregulin (AREG) is the most upregulated gene in monocytes and IL1B+ macrophages in the AF group, compared with healthy controls from other groups. Serum AREG levels are higher in patients with persistent AF. These data suggested that EGF signaling pathway could be a therapeutic target for AF and serum AREG levels provide an effective biomarker for predicting persistent AF.

Prognostic and clinicopathological significance of survivin in gynecological cancer

Survivin belongs to the inhibitor of apoptosis protein (IAP) family and is encoded by the baculoviral inhibitor of apoptosis repeat-containing, or BIRC5, gene. It is preferentially expressed in cancers with functional complexity in cell signaling cascades such as extracellular signal-regulated kinases (ERK), mitogen-activated protein kinases (MAPK), heat shock protein-90 (HSP90), epidermal growth factor receptor (EGFR), phosphoinositide 3-kinase (PI3K), signal transducer and activator of transcription (STAT), hypoxia-inducible factor-1 alpha (HIF-1α), vascular endothelial growth factor (VEGF), and others. Survivin plays a role in cell division and cell death, properties that have attracted a large body of research to decipher its therapeutic and prognostic significance in cancer. Survivin has tumor-promoting effects in endometrial (EC) and ovarian (OC) cancers, and its upregulation in endometrial cancer has been associated with poor overall survival (OS). While survivin protein is abundantly expressed in OC, it is barely detectable in normal ovarian tissue or benign ovarian tumors. Survivin expression is also a marker for cervical intraepithelial neoplasia (CIN) and high-risk human papillomavirus, and a predictor of viral clearance and prognosis in uterine cervical cancer (UCC). Furthermore, nuclear survivin expression is very low in normal vulvar squamous epithelium and increases to become abundant in vulvar invasive squamous cell carcinoma (ISCC), conferring resistance to apoptosis in vulvar carcinogenesis. In this review, we discuss in detail the impact of survivin signaling on gynecological cancers and provide insight on its therapeutic and diagnostic potential, existing research gaps, and areas for future research.

Fibroblast growth factor 7 (FGF7) causes cartilage destruction, subchondral bone remodeling, and the premature growth plate closure in mice

ObjectiveFibroblast growth factor (FGF) signaling plays a significant role in osteoarthritis (OA) pathogenesis, though the OA-related functions of only a few FGFs have been fully elucidated. This study investigates the specific roles of FGF7 in OA development. MethodsFGF7 expression was analyzed in human (n=6) and mouse (n=10) cartilage. Experimental OA was induced by destabilization of the medial meniscus (DMM). The roles of FGF7 were explored using intra-articular (IA) injection of recombinant FGF7 (rFGF7) and whole-body Fgf7 knockout mice (Fgf7-/-). Subchondral bone remodeling and growth plate morphology were assessed microCT and histological analysis. ResultsFGF7 was upregulated in OA cartilage. IA injection of rFGF7 led to OA cartilage destruction (OARSI grade; 0.61 [95% CI 0.00–5.33]), while Fgf7-/- mice showed reduced DMM-induced cartilage erosion (OARSI grade; 1.89 [95% CI 1.08–3.00]) compared to WT mice (4.92 [95% CI 3.83–5.33]). These effects were associated with changes in matrix-degrading enzyme expression in chondrocytes. Mice receiving IA injection of rFGF7 (20 μg) exhibited increased subchondral bone thickness (68.01 μm [95% CI 61.55–74.46]) and decreased osteoclastogenesis (TRAP positivity; 1.94% [95% CI 1.41–2.47]) compared to controls (38.33 μm [95% CI 33.71–42.96]) and (4.23% [95% CI 3.28–5.19]), respectively. Additionally, rFGF7 treatment caused premature closure of growth plates, whereas Fgf7-/- mice exhibited significantly increased growth plate thickness. ConclusionsFGF7 exerts multiple functions in various joint tissues, including promoting cartilage destruction, inducing subchondral bone remodeling (SBP thickening), and triggering premature growth plate closure.

332 The role of fibroblast growth factor (FGF) signaling in skin inflammation

332 The role of fibroblast growth factor (FGF) signaling in skin inflammation

The Role of Insulin-Like Growth Factor (IGF-1) Signaling During Physical Exercise: A Systematic Review

Exercise is one of the non-pharmacological therapies that functions to improve public health. This study seeks to determine how increased IGF-1 levels during exercise as a hormone can trigger growth. For this study, a number of journal databases were searched, such as PubMed, Web of Science, Embase, and Science Direct. This study considers several aspects, such as research on exercise and IGF-1 published in reputable journals over the past five years. Our analysis only includes items published in reputable international journals. Using databases total of 159 publications were found. In this comprehensive analysis, about ten carefully selected and peer-reviewed papers were included. The standard operating procedure for this investigation was developed using Preferred Reporting Systematics and Meta-analysis (PRISMA). Based on the results of this systemic investigation, exercise has been shown to increase IGF-1 levels, a hormone that promotes growth. Physical exercise as a therapeutic effort and a means of improving public health.

Immune system regulation of physiological and pathological aspects of the ovarian follicle pool throughout the female reproductive lifespan.

The immune system plays a major role in ovarian physiology by regulating the ovarian follicle pool through complex signaling of different growth factors, cytokines, and chemokines. These may promote follicle activation and further growth but could also trigger follicle atresia and clearance of aging or damaged cells within the ovarian cortex. Moreover, extraglandular steroidogenesis potentially occurring in different immune cells like macrophages and natural killer cells might be another way of modulating follicle growth. Ovarian macrophages have recently been found to contain two different populations, namely resident macrophages and monocyte-derived cells, with potentially different roles. The immune system also plays a role in the development of pathological conditions, including premature ovarian insufficiency (POI). Indeed, autoimmune activation against various ovarian antigen targets results in lymphocytic oophoritis mainly targeting early growing follicles, but later leading to complete follicle pool depletion. Immune-mediated ovarian damage may also be caused by viral infection or be the consequence of iatrogenic damage. Certain novel cancer immunotherapies like checkpoint inhibitors have recently been shown to induce ovarian reserve damage in a murine model. Studies are needed to corroborate these findings and further investigate the potential of newly developed immunotherapies to treat POI. Technological advances such as single-cell analyses of less represented cell populations like immune cells inside the ovary are now contributing to valuable new information, which will hopefully lead to the development of new therapeutic strategies for women with fertility issues.

Tracing the Evolutionary Origin of Chordate Somites in the Hemichordate Ptychodera flava.

Metameric somites are a novel character of chordates with unclear evolutionary origins. In the early branching chordate amphioxus, anterior somites are derived from the paraxial mesodermal cells that bud off the archenteron (i.e., enterocoely) at the end of gastrulation. Development of the anterior somites requires fibroblast growth factor (FGF) signaling, and distinct somite compartments express orthologs of vertebrate nonaxial mesodermal markers. Thus, it has been proposed that the amphioxus anterior somites are homologous to the vertebrate head mesoderm, paraxial mesoderm, and lateral plate mesoderm. To trace the evolutionary origin of somites, it is essential to study the chordates' closest sister group, Ambulacraria, which includes hemichordates and echinoderms. The anterior coeloms of hemichordate and sea urchin embryos (respectively called protocoel and coelomic pouches) are also formed by enterocoely and require FGF signals for specification and/or differentiation. In this study, we applied RNA-seq to comprehensively screen for regulatory genes associated with the mesoderm-derived protocoel of the hemichordate Ptychodera flava. We also used a candidate gene approach to identify P. flava orthologs of chordate somite markers. In situ hybridization results showed that many of these candidate genes are expressed in distinct or overlapping regions of the protocoel, which indicates that molecular compartments exist in the hemichordate anterior coelom. Given that the hemichordate protocoel and amphioxus anterior somites share a similar ontogenic process (enterocoely), induction signal (FGF), and characteristic expression of orthologous genes, we propose that these two anterior coeloms are indeed homologous. In the lineage leading to the emergence of chordates, somites likely evolved from enterocoelic, FGF-dependent, and molecularly compartmentalized anterior coeloms of the deuterostome last common ancestor.

The PLCG2 Inhibits Tumor Progression and Mediates Angiogenesis by VEGF Signaling Pathway in Clear Cell Renal Cell Carcinoma.

Clear cell renal cell carcinoma (ccRCC) represents the most prevalent form of renal cell carcinoma. The management of early-stage ccRCC has a better prognosis, while patients with metastatic ccRCC have a lower five-year survival rate. Angiogenesis serves as the fundamental process underlying tumor metastasis. Therefore, it is crucial to discover new targets for angiogenesis to improve patient survival rates. The Cancer Genome Atlas database, International Cancer Genome Consortium database, Clinical Proteomic Tumor Analysis Consortium database, and a gene set of the vascular endothelial growth factor (VEGF) signaling pathway were utilized to identify differentially expressed genes. Western blot (WB), quantitative real-time polymerase chain reaction, and immunohistochemistry were employed to validate the downregulation of phospholipase C gamma 2 (PLCG2) in ccRCC tissues and cells. Cell Counting Kit-8 (CCK-8) assays, transwell assays, tube formation assays, and oil-red staining were performed to elucidate the biological functions of PLCG2 in tumor cells. Gene set enrichment analysis was applied to explore the downstream pathway. Subcutaneous tumor models and live small animal fluorescent imaging assay were utilized for in vivo investigation of the roles played by PLCG2. Our study has identified a novel biomarker, PLCG2, for ccRCC. PLCG2 is a central gene in regulating angiogenesis in ccRCC, as validated by bioinformatics analysis. The findings revealed a diminished expression of PLCG2 in both ccRCC tissues and cells. Further experiments in vivo and in vitro have demonstrated the significant roles of PLCG2 in tumor proliferation, invasion, migration, and lipid accumulation. Results of tube formation assays and WB support the role of PLCG2 in regulating VEGFA expression and angiogenesis. Our results show that PLCG2 functions as a potential biomarker and an independent prognostic indicator for ccRCC. PLCG2 may modulate angiogenesis by influencing the expression of VEGFA. Therefore, targeting PLCG2 could potentially lead to drug discovery and improved cancer treatment strategies.

Termites and other social insects as emerging model organisms of ageing research: how to achieve a long lifespan and a high fecundity.

Social insects (termites, ants and some bees and wasps) are emerging model organisms of ageing research. In this Commentary, I outline which advantages they offer compared with other organisms. These include the co-occurrence of extraordinarily long-lived, highly fecund queens together with short-lived workers within colonies that share the same genetic background. I then summarize which new insights have been gained so far from social insect studies. Research on social insects has led to the development of a universal mechanistic framework underlying the regulation of ageing and other life-history trade-offs in insects: the TI-J-LiFe network (short for TOR/IIS-juvenile hormone-lifespan/fecundity). Because of its conservative nature, this network can be extended to also incorporate vertebrates. Current data for social insect models suggest that molecular re-wirings along the I-J-Fe (IIS-juvenile hormone-fecundity) axis of the network can explain the concurrent long lifespans and high fecundity of queens. During social evolution, pathways that foster a high fecundity have apparently been uncoupled from mechanisms that shorten lifespan in solitary insects. Thus, fecundity-related vitellogenesis is uncoupled from life-shortening high juvenile hormone (JH)-titres in the honeybee and from insulin/insulin-like growth factor signalling (IIS) activity in ants. In termites, similarly, vitellogenesis seems tissue-specifically unlinked from JH signalling and IIS activity might have lost life-shortening consequences. However, as in solitary animals, the downstream processes (Li of the TI-J-LiFe network) that cause actual ageing (e.g. oxidative stress, transposable element activity, telomere attrition) seem to differ between species and environments. These results show how apparently hard-wired mechanisms underlying life-history trade-offs can be overcome during evolution.

PATH-53. DNA MUTATION SEQUENCING AND METHYLATION ANALYSIS OF SOMATICNF1 MUTANT IDH-WILDTYPE GLIOBLASTOMA IDENTIFIES THREE EPIGENETIC GROUPS ANDCDKN2A/B LOSS AS A NEGATIVE PROGNOSTIC BIOMARKER

Abstract The tumor suppressor NF1 is frequently mutated in IDH-wildtype glioblastoma. However, the molecular subgroups and clinically relevant biomarkers within somatic NF1 mutant, IDH-wildtype glioblastomas remain incompletely understood. Here, we combine methylation arrays and targeted DNA sequencing to identify epigenetic subgroups and clinical biomarkers within non-syndromic NF1 mutant IDH-wildtype glioblastoma. We identified 186 patients treated at the University of California San Francisco between 2016-2024 with newly diagnosed IDH-wildtype glioblastoma containing a somatic pathogenic NF1 mutation on a CLIA certified targeted DNA sequencing assay. Illumina EPIC DNA methylation arrays (n=129 patients) were processed using the minfi package and Heidelberg random forest classifier (v12.8). Downstream analyses including hierarchical clustering and survival analyses were performed in R. DNA sequencing identified 12 recurrently altered genes in greater than 10% of cases across cell cycle regulators (CDKN2A/B, TP53, RB1), PI3K signaling (PTEN, PIK3R1, PIK3CA), epigenetic modifiers (ATRX, SETD2), and growth factor signaling (EGFR, PDGFRA, PTPN11). DNA methylation analysis revealed three epigenetic subgroups. Group 1 showed lower median patient age and significantly increased TP53 co-mutation rate. Group 2 contained a significantly higher proportion of male patients and was significantly enriched for RB1 and TERT promoter alterations, with a majority of tumors classified as GBM-MES using the Heidelberg classifier. Group 3 showed a significantly higher proportion of female patients and was significantly enriched for homozygous CDKN2A/B deletion. Homozygous CDKN2A/B loss was associated with significantly worse overall survival across the entire non-syndromic NF1 mutant glioblastoma cohort but not in a propensity score matched NF1 wildtype glioblastoma cohort. DNA methylation profiling revealed three epigenetic subgroups characterized by distinct clinical features, co-mutation patterns, and reference DKFZ methylation classifier identities. CDKN2A/B loss may be a negative prognostic biomarker specifically in NF1 mutant glioblastomas; future multi-institutional studies are required to validate these findings and their therapeutic implications in a larger, representative cohort.

CNSC-44. TARGETING OF THE YAP/TAZ-TEAD AXIS DIMINISHES VIABILITY AND DIFFERENTIATION POTENTIAL IN PEDIATRIC HIGH-GRADE GLIOMA

Abstract Pediatric high-grade gliomas (pHGGs) are invasive and fast-growing brain malignancies. They account for up to 40% of all brain tumor-related deaths in childhood. Genetic alterations that characterize these gliomas include H3 onco-histone mutations and genetic alterations in receptor-tyrosine kinases (RTKs), including amplification, mutation, and gene fusions in RTKs. However, direct targeting with tyrosine kinase inhibitors (TKIs) has shown at best partial responses in patients due to the molecular heterogeneity within these tumors and the lack of pharmaceutical penetration into the central nervous system (CNS). Thus, alternative therapeutic approaches to treat pHGGs are urgently needed. The YAP/TAZ transcription factors, which cooperate with TEAD co-factors to promote target gene expression, orchestrate stem-cell fate decisions and proliferation downstream of growth factor signaling pathways, such as RTKs. We observed that YAP expression is upregulated in RTK mutant and H3 mutant pHGGs. Depletion of YAP via RNAi methods decreased proliferation, inhibited pHGG stem cell self-renewal, and induced apoptosis of pHGG cells. Use of Verteporfin (VP), a FDA-approved YAP/TAZ small molecule inhibitor, mimicked the effects seen by YAP genetic depletion. Using an in vitro human cortical organoid-tumor model in which tumor cells are engrafted to human brain cortical organoids, we screened for responses in tumor cells and in non-tumor cells in the neural microenvironment upon VP treatment, using single-cell RNA-sequencing and immunofluorescence to visualize responses. These organoid models offer improved models for modeling how the neural CNS microenvironment shapes responses of tumor cells to YAP/TAZ inhibition and VP treatments. Results from our work showing that YAP/TAZ-TEAD inhibition is a promising therapeutic avenue for management of pHGGs will be presented. Further pre-clinical work will follow to correlate observation and understand the therapeutic efficacy of YAP/TAZ-TEAD inhibition for pHGG treatment.

CSIG-26. TARGETING EPIGENETIC DYSREGULATION AND ADAPTIVE RESISTANCE MECHANISMS IN DIPG/DMG

Abstract Diffuse intrinsic pontine gliomas (DIPG/DMG) are devastating pediatric brain tumors with very limited treatment options and a uniformly fatal prognosis. The recurrent histone H3K27M mutation in DIPG disrupts epigenetic regulation, leading to the hypothesis that this mutation-induced dysregulation creates a vulnerability to epigenetic targeting. We conducted a screening of compounds targeting epigenetic enzymes to identify potential inhibitors of patient-derived DIPG cell growth. High-throughput screening identified chaetocin, a fungal metabolite, as a potent inhibitor of DIPG cell growth. Chaetocin treatment selectively decreased proliferation and increased apoptosis in DIPG cells, significantly extending survival in DIPG xenograft models while restoring H3K27me3 levels. The loss of the H3K9 methyltransferase SUV39H1 also inhibited DIPG cell growth. Transcriptomic and epigenomic profiling showed that SUV39H1 loss or inhibition downregulated stemness and oncogenic networks, including growth factor receptor signaling. However, D2 dopamine receptor (DRD2) signaling adaptively upregulated, conferring resistance. Combining chaetocin with the DRD2 antagonist ONC201 or radiotherapy synergistically enhanced antitumor efficacy. This study reveals a therapeutic vulnerability in DIPG cells by targeting the SUV39H1-H3K9me3 pathway and compensatory signaling loops. Combining SUV39H1-targeting chaetocin with other agents, such as ONC201, may offer a new strategy for effective DIPG treatment. The findings suggest that chaetocin, by targeting and suppressing the H3K9me3 methyltransferase SUV39H1, inhibits DIPG tumor growth by downregulating stemness-related genes and growth factor signaling pathways. Overall, the study highlights a new therapeutic vulnerability in DIPG through the SUV39H1-H3K9me3 epigenetic pathway and compensatory signaling loops, suggesting an effective treatment strategy for DIPG.

Application of extracorporeal shockwave to regulate subchondral bone homeostasis through tumor necrosis factor-α/hypoxia-inducible factor-1α/vascular endothelial growth factor signaling pathway in treatment of talus bone marrow edema.

To investigate the effect of extracorporeal shock wave on the treatment of talus bone marrow edema by regulating subchondral bone homeostasis through tumor necrosis factor-α (TNF-α)/hypoxia-inducible factor-1α (HIF-1α)/vascular endothelial growth factor (VEGF) signaling pathway. A total of 81 patients with talus bone marrow edema admitted to our hospital from May 2019 to May 2021 were studied and divided into control group (n = 40) and extracorporeal shock group (n = 41) according to random number table method. The control group was given conventional treatment, and the extracorporeal shock group was combined with extracorporeal shock wave therapy on the basis of the control group. The expression of TNF-α, HIF-1α, and VEGF in the 2 groups were compared, pain degree, and the area of talus bone marrow edema was evaluated by magnetic resonance imaging. The visual analogue scale scores of 1 month, 2 months and 5 months after treatment were decreased in both groups, and the extracorporeal shock group was lower than the control group (P < .05). After 5 months of treatment, the expressions of TNF-α and HIF-1α were decreased in both groups, and the extracorporeal shock group was lower than the control group, VEGF was increased, and the extracorporeal shock group was higher than the control group (P < .05), and the western blot expression levels of TNF-α, HIF-1α and VEGF in the extracorporeal shock group were higher than the control group (P < .05). The dorsiflexion motion and plantar flexion motion of both groups were increased, and the extracorporeal shock group was higher than the control group (P < .05). Extracorporeal shock wave therapy can regulate subchondral bone homeostasis through TNF-α/HIF-1α/VEGF signaling pathway to treat talus bone marrow edema, reduce the pain degree of talus bone marrow edema, and improve ankle joint function.

Cordycepin generally inhibits growth factor signal transduction in a systems pharmacology study.

Cordycepin (3' deoxyadenosine) has been widely researched as a potential cancer therapy, but many diverse mechanisms of action have been proposed. Here, we confirm that cordycepin triphosphate is likely to be the active metabolite of cordycepin and that it consistently represses growth factor-induced gene expression. Bioinformatic analysis, quantitative PCR and western blotting confirmed that cordycepin blocks the PI3K/AKT/mTOR and/or MEK/ERK pathways in six cell lines and that AMPK activation is not required. The effects of cordycepin on translation through mTOR pathway repression were detectable within 30 min, indicating a rapid process. These data therefore indicate that cordycepin has a universal mechanism of action, acting as cordycepin triphosphate on an as yet unknown target molecule involved in growth factor signalling.

Inhibition of cell growth and glycosaminoglycan biosynthesis by xylose analog 2-Az-Xyl

Sugar analogs are versatile chemical tools for probing or inhibiting glycan functions. However, chemical tools are insufficient for glycosaminoglycans (GAGs), which play crucial roles in various biological processes, such as extracellular matrix formation and growth factor signaling. To develop a new compound for detecting GAGs or manipulating GAG functions, we chemically synthesized 2-azide-xylose (2-Az-Xyl), an azide-type analog of Xyl that is a component of the common linkage tetrasaccharide in GAGs, and explored its application to biological experiments. Treatment of cultured cells with 2-Az-Xyl inhibited cell proliferation and reduced the levels of GAGs, particularly heparan sulfate (HS). Although this sugar analog did not perturb the biosynthesis of nucleotide sugars and expression of the key enzymes for HS biosynthesis, 2-Az-Xyl directly inhibited the activity of XYLT2, an initial enzyme for GAG biosynthesis, indicating that 2-Az-Xyl directly inhibits GAG biosynthesis. These findings suggest that 2-Az-Xyl inhibits cell proliferation by blocking GAG biosynthesis through inhibiting XYLT2 activity.

A non-catalytic role of IPMK is required for PLCγ1 activation in T cell receptor signaling by stabilizing the PLCγ1-Sam68 complex

BackgroundPhospholipase C gamma 1 (PLCγ1) is an important mediator of the T cell receptor (TCR) and growth factor signaling. PLCγ1 is activated by Src family kinases (SFKs) and produces inositol 1,4,5-triphosphate (InsP3) from phosphatidylinositol 4,5-bisphosphate (PIP2). Inositol polyphosphate multikinase (IPMK) is a pleiotropic enzyme with broad substrate specificity and non-catalytic activities that mediate various functional protein-protein interactions. Therefore, IPMK plays critical functions in key biological events such as cell growth. However, the contribution of IPMK to the activation of PLCγ1 in TCR signaling remains mostly unelucidated. The current study aimed to elucidate the functions of IPMK in TCR signaling and to uncover the mode of IPMK-mediated signaling action in PLCγ1 activation.MethodsConcanavalin A (ConA)-induced acute hepatitis model was established in CD4+ T cell-specific IPMK knockout mice (IPMKΔCD4). Histological analysis was performed to assess hepatic injury. Primary cultures of naïve CD4+ T cells were used to uncover the role of mechanisms of IPMK in vitro. Western blot analysis, quantitative real-time PCR, and flow cytometry were performed to analyze the TCR-stimulation-induced PLCγ1 activation and the downstream signaling pathway in naïve CD4+ T cells. Yeast two-hybrid screening and co-immunoprecipitation were conducted to identify the IPMK-binding proteins and protein complexes.ResultsIPMKΔCD4 mice showed alleviated ConA-induced acute hepatitis. CD4+ helper T cells in these mice showed reduced PLCγ1 Y783 phosphorylation, which subsequently dampens calcium signaling and IL-2 production. IPMK was found to contribute to PLCγ1 activation via the direct binding of IPMK to Src-associated substrate during mitosis of 68 kDa (Sam68). Mechanistically, IPMK stabilizes the interaction between Sam68 and to PLCγ1, thereby promoting PLCγ1 phosphorylation. Interfering this IPMK-Sam68 binding interaction with IPMK dominant-negative peptides impaired PLCγ1 phosphorylation.ConclusionsOur results demonstrate that IPMK non-catalytically promotes PLCγ1 phosphorylation by stabilizing the PLCγ1–Sam68 complex. Targeting IPMK in CD4+ T cells may be a promising strategy for managing immune diseases caused by excessive stimulation of TCR.

Stimulation of neutral lipid synthesis via viral growth factor signaling and ATP citrate lyase during vaccinia virus infection.

Fatty acid metabolism can provide various products essential for viral infections. How vaccinia virus (VACV), the prototype of poxviruses, modulates fatty acid metabolism is not well understood. Here, we show that VACV infection results in increased neutral lipid droplet synthesis, the organelles that play a crucial role in storing and mobilizing fatty acids for energy production via β-oxidation. Citrate is the first tricarboxylic acid (TCA) cycle intermediate that can be transported to the cytosol to be converted to acetyl-CoA for de novo fatty acid biosynthesis. We found that VACV infection stimulates the S455 phosphorylation of ATP citrate lyase (ACLY), a pivotal enzyme that links citrate metabolism with lipid metabolism. We demonstrate that the inhibition of neutral lipid droplet synthesis and ACLY severely suppresses VACV replication. Remarkably, we found that virus growth factor (VGF)-induced signaling is essential for the VACV-mediated upregulation of ACLY phosphorylation and neutral lipid droplets. Finally, we report that VGF-induced EGFR-Akt pathway and ACLY phosphorylation are important for VACV stimulation of neutral lipid synthesis. These findings identified a new way of rewiring cell metabolism by a virus and a novel function for VGF in the governance of virus-host interactions through the induction of a key enzyme at the crossroads of the TCA cycle and fatty acid metabolism. Our study also provides a mechanism for the role played by VGF and its downstream signaling cascades in the modulation of lipid metabolism in VACV-infected cells.IMPORTANCENeutral lipid droplets are vital players in cellular metabolism. Here, we showed that VACV induces neutral lipid droplet synthesis in infected primary human foreskin fibroblasts and identified the cellular and viral factors needed. We identified VACV encoded growth factor (VGF) as an essential viral factor that induces cellular EGFR-Akt signaling to increase lipid droplets. Interestingly, VACV increases the S455 phosphorylation of ACLY, a key metabolic enzyme that sits at the crossroads of carbohydrate and lipid metabolism in a VGF-EGFR-Akt-dependent manner. We also found that ACLY is vital for VACV-induced lipid droplet synthesis. Our findings identified the modulation of ACLY by a virus and identified it as a potential target for antiviral development against pathogenic poxviruses. Our study also expands the role of growth factor signaling in boosting VACV replication by targeting fatty acid metabolism.

Single-Cell RNA Sequencing Reveals Monocyte-Derived Interstitial Macrophages with a Pro-Fibrotic Phenotype in Bleomycin-Induced Pulmonary Fibrosis.

Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive lung disease with limited effective therapies. Interstitial macrophages (IMs), especially those derived from monocytes, play an unknown role in IPF pathogenesis. By using single-cell RNA sequencing (scRNA-seq), bleomycin (BLM)-induced pulmonary fibrosis mouse lungs were analyzed to characterize the cellular landscape and heterogeneity of macrophages in this model. scRNA-seq was used to identify distinct interstitial macrophage subpopulations in fibrotic lungs, with monocyte-derived macrophages exhibiting a pro-fibrotic gene expression profile enriched in wound healing, extracellular matrix (ECM) remodeling, and pro-fibrotic cytokine production functions. A pseudotime analysis revealed that IMs originated from monocytes and differentiated along a specific trajectory. A cell-cell communication analysis demonstrated strong interactions between monocyte-derived interstitial macrophages (Mo-IMs) and fibroblasts through the transforming growth factor beta (TGFβ), secreted phosphoprotein 1 (SPP1), and platelet-derived growth factor (PDGF) signaling pathways. Flow cytometry validated the presence and expansion of Mo-IMs subpopulations in BLM-treated mice. This study reveals the cellular heterogeneity and developmental trajectory of lung macrophages in early BLM-induced pulmonary fibrosis, highlighting the crucial role of Mo-IMs with a pro-fibrotic phenotype in IPF pathogenesis via interactions with fibroblasts. Targeting these specific macrophage subpopulations and associated signaling pathways may provide novel therapeutic strategies for IPF.

Common modes of ERK induction resolve into context-specific signalling via emergent networks and cell-type-specific transcriptional repression.

Fibroblast Growth Factor signalling via ERK exerts diverse roles in development and disease. In mammalian preimplantation embryos and naïve pluripotent stem cells ERK promotes differentiation, whereas in primed pluripotent states closer to somatic differentiation ERK sustains self-renewal. How can the same pathway produce different outcomes in two related cell types? To explore context-dependent ERK signalling we generated cell and mouse lines that allow for tissue- and time-specific ERK activation. Using these tools, we find that specificity in ERK response is mostly mediated by repression of transcriptional targets that occur in tandem with reductions in chromatin accessibility at regulatory regions. Furthermore, immediate early ERK responses are largely shared by different cell types but produce cell-specific programmes as these responses interface with emergent networks in the responding cells. Induction in naïve pluripotency is accompanied by chromatin changes, whereas in later stages it is not, suggesting that chromatin context does not shape signalling response. Altogether, our data suggest that cell-type-specific responses to ERK signalling exploit the same immediate early response, but then sculpt it to specific lineages via repression of distinct cellular programmes.

Long Non-coding RNA TPRG1-AS1 Interacts With CLTC in Liver Cancer Cells.

Certain long non-coding RNAs (lncRNAs), identified as potential tumor suppressors, have shown potential in inhibiting tumor growth. Here, we investigated a novel mechanism involving the direct interaction between lncRNA TPRG1-AS1 and Clathrin Heavy Chain (CLTC) in the Epidermal Growth Factor (EGF) signaling pathway for its tumor-suppressive effects. Our research revealed a direct physical interaction between TPRG1-AS1 and CLTC through RNA pulldown and RNA immunoprecipitation (RIP)-qPCR, which subsequently influenced the EGF signaling pathway. We confirmed phenotype changes by cell viability, sphere formation, and invasion. We confirmed the mechanism underlying these phenotypic changes through immunoblotting and immunocytochemistry. Firstly, we confirmed a reduction in the phenotype associated with the overexpression of TPRG1-AS1 (TPRG1-AS1oe) interacting with CLTC in the presence of EGF signaling. Next, it was observed that TPRG1-AS1oe suppressed EGF downstream signaling, specifically MAPK8 and MAPK14, in relation to CLTC. Moreover, we verified that overexpressed TPRG1-AS1 binds to CLTC and suppresses EGF downstream signaling using a custom HEX probe. Collectively our study uncovered a novel regulatory axis wherein TPRG1-AS1 interacts with CLTC, consequently attenuating EGF downstream signaling, particularly through the MAPK8 and MAPK14 pathways. These complex interactions ultimately lead to a reduction in the phenotype of liver cancer cells.