Exosome-transmitted circular RNA circ-LMO7 facilitates the progression of osteosarcoma by regulating miR-21-5p/ARHGAP24 axis.

The potential function and mechanism of circRNAs in regulating malignant performances of Osteosarcoma (OS) cells have not been well investigated. The expression level of CircLMO7, miR-21-5p and ARHGAP24 were detected by RT-qPCR. The relationship between miR-21-5p and circ-LMO7, as well as between miR-21-5p and ARHGAP24, was predicted and examined through bioinformatics analysis and luciferase reporter gene experiments. Moreover, OS cell growth, invasion, migration, and apoptosis were detected using the cell counting kit-8 (CCK-8), transwell and flow cytometry assays, respectively. ARHGAP24 protein level was measured using western blotting. In present study, we choose to investigate the role and mechanism of circ-LOM7 on OS cell proliferation, migration and invasion. circ-LOM7 was found to be down-regulated in OS tissues and cell lines. Enforced expression of circ-LOM7 suppressed the growth, invasion, and migration of OS cells. In contrast, decreasing circ-LMO7 expression had opposite effects. Furthermore, miR-21-5p was predicted to be sponged by circ-LMO7, and had an opposite role of circ-LMO7 in OS. Moreover, ARHGAP24 served as miR-21-5p's downstream target. Mechanistically, circ-LMO7 was packed in exosomes and acted as a cancer-suppresser on OS by sponging miR-21-5p and upregulating the expression of ARHGAP24. The exosomal circ-LMO7 expression was significantly decreased in OS cell exosomes, and co-culture experiments showed that exosomal circ-LMO7 suppressed the proliferation ability of OS cells. Circ-LMO7 exerts as a tumor suppressor in OS, and the circ-LMO7/miR-21-5P/ARHGAP24 axis is involved in OS progression.

Functional synergy of a human-specific and an ape-specific metabolic regulator in human neocortex development.

Metabolism has recently emerged as a major target of genes implicated in the evolutionary expansion of human neocortex. One such gene is the human-specific gene ARHGAP11B. During human neocortex development, ARHGAP11B increases the abundance of basal radial glia, key progenitors for neocortex expansion, by stimulating glutaminolysis (glutamine-to-glutamate-to-alpha-ketoglutarate) in mitochondria. Here we show that the ape-specific protein GLUD2 (glutamate dehydrogenase 2), which also operates in mitochondria and converts glutamate-to-αKG, enhances ARHGAP11B's ability to increase basal radial glia abundance. ARHGAP11B + GLUD2 double-transgenic bRG show increased production of aspartate, a metabolite essential for cell proliferation, from glutamate via alpha-ketoglutarate and the TCA cycle. Hence, during human evolution, a human-specific gene exploited the existence of another gene that emerged during ape evolution, to increase, via concerted changes in metabolism, progenitor abundance and neocortex size.

DLC1 promotes mechanotransductive feedback for YAP via RhoGAP-mediated focal adhesion turnover.

Angiogenesis is a tightly controlled dynamic process demanding a delicate equilibrium between pro-angiogenic signals and factors that promote vascular stability. The spatiotemporal activation of the transcriptional co-factors YAP (herein referring to YAP1) and TAZ (also known WWTR1), collectively denoted YAP/TAZ, is crucial to allow for efficient collective endothelial migration in angiogenesis. The focal adhesion protein deleted-in-liver-cancer-1 (DLC1) was recently described as a transcriptional downstream target of YAP/TAZ in endothelial cells. In this study, we uncover a negative feedback loop between DLC1 expression and YAP activity during collective migration and sprouting angiogenesis. In particular, our study demonstrates that signaling via the RhoGAP domain of DLC1 reduces nuclear localization of YAP and its transcriptional activity. Moreover, the RhoGAP activity of DLC1 is essential for YAP-mediated cellular processes, including the regulation of focal adhesion turnover, traction forces, and sprouting angiogenesis. We show that DLC1 restricts intracellular cytoskeletal tension by inhibiting Rho signaling at the basal adhesion plane, consequently reducing nuclear YAP localization. Collectively, these findings underscore the significance of DLC1 expression levels and its function in mitigating intracellular tension as a pivotal mechanotransductive feedback mechanism that finely tunes YAP activity throughout the process of sprouting angiogenesis.

Case report of a novel mutation in the TNC gene in Chinese patients with nonsyndromic hearing loss.

RATIONALE: Hereditary hearing loss is known to exhibit a significant degree of genetic heterogeneity. Herein, we present a case report of a novel mutation in the tenascin-C (TNC) gene in Chinese patients with nonsyndromic hearing loss (NSHL). PATIENT CONCERNS: This includes a young deaf couple and their 2-year-old baby. DIAGNOSES: Based on the clinical information, hearing test, metagenomic next-generation sequencing (mNGS), Sanger sequencing, protein function and structure analysis, and model prediction, in our case, the study results revealed 2 heterozygous mutations in the TNC gene (c.2852C>T, p.Thr951Ile) and the TBC1 domain family member 24 (TBC1D24) gene (c.1570C>T, p.Arg524Trp). These mutations may be responsible for the hearing loss observed in this family. Notably, the heterozygous mutations in the TNC gene (c.2852C>T, p.Thr951Ile) have not been previously reported in the literature. INTERVENTIONS: Avoid taking drugs that can cause deafness, wearing hearing AIDS, and cochlear implants. OUTCOMES: Regular follow-up of family members is ongoing. LESSONS: The genetic diagnosis of NSHL holds significant importance as it helps in making informed treatment decisions, providing prognostic information, and offering genetic counseling for the patient's family.

Identification of m6A-related lncRNAs LINC02471 and DOCK9-DT as potential biomarkers for thyroid cancer.

Thyroid cancer (THCA) is the most common endocrine malignancy worldwide and has been rising at the fastest rate in recent years. Long-stranded non-coding RNAs (lncRNAs) and N6-methyladenosine (m6A) have been associated with immunotherapy efficacy and cancer prognosis. However, how m6A-associated lncRNAs (mrlncRNAs) affect the prognosis of patients with thyroid cancer is unclear. Therefore, this study utilized The Cancer Genome Atlas (TCGA) database to provide thyroid cancer-related transcriptomic data and related clinical data. The R program was used to identify m6A-related lncRNAs, and a risk model consisting of two lncRNAs (LINC02471 and DOCK9-DT) was obtained using least absolute shrinkage and selection operator (LASSO) Cox regression analysis. Kaplan-Meier survival analysis and transient subject operating characteristics (ROC) were used for analysis. The results showed a substantial association between immune cell infiltration and risk scores. Independent analyses confirmed that the expression of LINC02471 and DOCK9-DT was significantly higher in thyroid cancer tissues than in normal tissues, suggesting that they may be useful biomarkers for thyroid cancer.

Mechanism of GTPase activation of a prokaryotic small Ras-like GTPase MglA by an asymmetrically interacting MglB dimer.

Cell polarity oscillations in Myxococcus xanthus motility are driven by a prokaryotic small Ras-like GTPase, mutual gliding protein A (MglA), which switches from one cell pole to the other in response to extracellular signals. MglA dynamics is regulated by MglB, which functions both as a GTPase activating protein (GAP) and a guanine nucleotide exchange factor (GEF) for MglA. With an aim to dissect the asymmetric role of the two MglB protomers in the dual GAP and GEF activities, we generated a functional MglAB complex by coexpressing MglB with a linked construct of MglA and MglB. This strategy enabled us to generate mutations of individual MglB protomers (MglB1 or MglB2 linked to MglA) and delineate their role in GEF and GAP activities. We establish that the C-terminal helix of MglB1, but not MglB2, stimulates nucleotide exchange through a site away from the nucleotide-binding pocket, confirming an allosteric mechanism. Interaction between the N-terminal ß-strand of MglB1 and ß0 of MglA is essential for the optimal GEF activity of MglB. Specific residues of MglB2, which interact with Switch-I of MglA, partially contribute to its GAP activity. Thus, the role of the MglB2 protomer in the GAP activity of MglB is limited to restricting the conformation of MglA active site loops. The direct demonstration of the allosteric mechanism of GEF action provides us new insights into the regulation of small Ras-like GTPases, a feature potentially present in many uncharacterized GEFs.

The Ras GTPase-activating protein UvGap1 orchestrates conidiogenesis and pathogenesis in the rice false smut fungus Ustilaginoidea virens.

Ras GTPase-activating proteins (Ras GAPs) act as negative regulators for Ras proteins and are involved in various signalling processes that influence cellular functions. Here, the function of four Ras GAPs, UvGap1 to UvGap4, was identified and analysed in Ustilaginoidea virens, the causal agent of rice false smut disease. Disruption of UvGAP1 or UvGAP2 resulted in reduced mycelial growth and an increased percentage of larger or dumbbell-shaped conidia. Notably, the mutant ΔUvgap1 completely lost its pathogenicity. Compared to the wild-type strain, the mutants ΔUvgap1, ΔUvgap2 and ΔUvgap3 exhibited reduced tolerance to H2 O2 oxidative stress. In particular, the ΔUvgap1 mutant was barely able to grow on the H2 O2 plate, and UvGAP1 was found to influence the expression level of genes involved in reactive oxygen species synthesis and scavenging. The intracellular cAMP level in the ΔUvgap1 mutant was elevated, as UvGap1 plays an important role in maintaining the intracellular cAMP level by affecting the expression of phosphodiesterases, which are linked to cAMP degradation in U. virens. In a yeast two-hybrid assay, UvRas1 and UvRasGef (Ras guanyl nucleotide exchange factor) physically interacted with UvGap1. UvRas2 was identified as an interacting partner of UvGap1 through a bimolecular fluorescence complementation assay and affinity capture-mass spectrometry analysis. Taken together, these findings suggest that the UvGAP1-mediated Ras pathway is essential for the development and pathogenicity of U. virens.

SARS-CoV-2 virulence factor ORF3a blocks lysosome function by modulating TBC1D5-dependent Rab7 GTPase cycle.

SARS-CoV-2, the causative agent of COVID-19, uses the host endolysosomal system for entry, replication, and egress. Previous studies have shown that the SARS-CoV-2 virulence factor ORF3a interacts with the lysosomal tethering factor HOPS complex and blocks HOPS-mediated late endosome and autophagosome fusion with lysosomes. Here, we report that SARS-CoV-2 infection leads to hyperactivation of the late endosomal and lysosomal small GTP-binding protein Rab7, which is dependent on ORF3a expression. We also observed Rab7 hyperactivation in naturally occurring ORF3a variants encoded by distinct SARS-CoV-2 variants. We found that ORF3a, in complex with Vps39, sequesters the Rab7 GAP TBC1D5 and displaces Rab7 from this complex. Thus, ORF3a disrupts the GTP hydrolysis cycle of Rab7, which is beneficial for viral production, whereas the Rab7 GDP-locked mutant strongly reduces viral replication. Hyperactivation of Rab7 in ORF3a-expressing cells impaired CI-M6PR retrieval from late endosomes to the trans-Golgi network, disrupting the biosynthetic transport of newly synthesized hydrolases to lysosomes. Furthermore, the tethering of the Rab7- and Arl8b-positive compartments was strikingly reduced upon ORF3a expression. As SARS-CoV-2 egress requires Arl8b, these findings suggest that ORF3a-mediated hyperactivation of Rab7 serves a multitude of functions, including blocking endolysosome formation, interrupting the transport of lysosomal hydrolases, and promoting viral egress.

Novel prognostic biomarker TBC1D1 is associated with immunotherapy resistance in gliomas.

Background: Glioma, an aggressive brain tumor, poses a challenge in understanding the mechanisms of treatment resistance, despite promising results from immunotherapy. Methods: We identified genes associated with immunotherapy resistance through an analysis of The Cancer Genome Atlas (TCGA), Chinese Glioma Genome Atlas (CGGA), and Gene Expression Omnibus (GEO) databases. Subsequently, qRT-PCR and western blot analyses were conducted to measure the mRNA and protein levels of TBC1 Domain Family Member 1 (TBC1D1), respectively. Additionally, Gene Set Enrichment Analysis (GSEA) was employed to reveal relevant signaling pathways, and the expression of TBC1D1 in immune cells was analyzed using single-cell RNA sequencing (scRNA-seq) data from GEO database. Tumor Immune Dysfunction and Exclusion (TIDE) database was utilized to assess T-cell function, while Tumor Immunotherapy Gene Expression Resource (TIGER) database was employed to evaluate immunotherapy resistance in relation to TBC1D1. Furthermore, the predictive performance of molecules on prognosis was assessed using Kaplan-Meier plots, nomograms, and ROC curves. Results: The levels of TBC1D1 were significantly elevated in tumor tissue from glioma patients. Furthermore, high TBC1D1 expression was observed in macrophages compared to other cells, which negatively impacted T cell function, impaired immunotherapy response, promoted treatment tolerance, and led to poor prognosis. Inhibition of TBC1D1 was found to potentially synergistically enhance the efficacy of immunotherapy and prolong the survival of cancer patients with gliomas. Conclusion: Heightened expression of TBC1D1 may facilitate an immunosuppressive microenvironment and predict a poor prognosis. Blocking TBC1D1 could minimize immunotherapy resistance in cancer patients with gliomas.

RGS4 controls airway hyperresponsiveness through GAP-independent mechanisms.

Regulators of G protein signaling (RGS) proteins constrain G protein-coupled receptor (GPCR)-mediated and other responses throughout the body primarily, but not exclusively, through their GTPase-activating protein activity. Asthma is a highly prevalent condition characterized by airway hyper-responsiveness (AHR) to environmental stimuli resulting in part from amplified GPCR-mediated airway smooth muscle contraction. Rgs2 or Rgs5 gene deletion in mice enhances AHR and airway smooth muscle contraction, whereas RGS4 KO mice unexpectedly have decreased AHR because of increased production of the bronchodilator prostaglandin E2 (PGE2) by lung epithelial cells. Here, we found that knockin mice harboring Rgs4 alleles encoding a point mutation (N128A) that sharply curtails RGS4 GTPase-activating protein activity had increased AHR, reduced airway PGE2 levels, and augmented GPCR-induced bronchoconstriction compared with either RGS4 KO mice or WT controls. RGS4 interacted with the p85α subunit of PI3K and inhibited PI3K-dependent PGE2 secretion elicited by transforming growth factor beta in airway epithelial cells. Together, these findings suggest that RGS4 affects asthma severity in part by regulating the airway inflammatory milieu in a G protein-independent manner.

Heterozygous loss-of-function variants in DOCK4 cause neurodevelopmental delay and microcephaly.

Neurons form the basic anatomical and functional structure of the nervous system, and defects in neuronal differentiation or formation of neurites are associated with various psychiatric and neurodevelopmental disorders. Dynamic changes in the cytoskeleton are essential for this process, which is, inter alia, controlled by the dedicator of cytokinesis 4 (DOCK4) through the activation of RAC1. Here, we clinically describe 7 individuals (6 males and one female) with variants in DOCK4 and overlapping phenotype of mild to severe global developmental delay. Additional symptoms include coordination or gait abnormalities, microcephaly, nonspecific brain malformations, hypotonia and seizures. Four individuals carry missense variants (three of them detected de novo) and three individuals carry null variants (two of them maternally inherited). Molecular modeling of the heterozygous missense variants suggests that the majority of them affect the globular structure of DOCK4. In vitro functional expression studies in transfected Neuro-2A cells showed that all missense variants impaired neurite outgrowth. Furthermore, Dock4 knockout Neuro-2A cells also exhibited defects in promoting neurite outgrowth. Our results, including clinical, molecular and functional data, suggest that loss-of-function variants in DOCK4 probable cause a variable spectrum of a novel neurodevelopmental disorder with microcephaly.

C. elegans Afadin is required for epidermal morphogenesis and functionally interfaces with the cadherin-catenin complex and RhoGAP PAC-1/ARHGAP21.

During epithelial morphogenesis, the apical junctions connecting cells must remodel as cells change shape and make new connections with their neighbors. In the C. elegans embryo, new apical junctions form when epidermal cells migrate and seal with one another to encase the embryo in skin ('ventral enclosure'), and junctions remodel when epidermal cells change shape to squeeze the embryo into a worm shape ('elongation'). The junctional cadherin-catenin complex (CCC), which links epithelial cells to each other and to cortical actomyosin, is essential for C. elegans epidermal morphogenesis. RNAi genetic enhancement screens have identified several genes encoding proteins that interact with the CCC to promote epidermal morphogenesis, including the scaffolding protein Afadin (AFD-1), whose depletion alone results in only minor morphogenesis defects. Here, by creating a null mutation in afd-1, we show that afd-1 provides a significant contribution to ventral enclosure and elongation on its own. Unexpectedly, we find that afd-1 mutant phenotypes are strongly modified by diet, revealing a previously unappreciated parental nutritional input to morphogenesis. We identify functional interactions between AFD-1 and the CCC by demonstrating that E-cadherin is required for the polarized distribution of AFD-1 to cell contact sites in early embryos. Finally, we show that afd-1 promotes the enrichment of polarity regulator, and CCC-interacting protein, PAC-1/ARHGAP21 to cell contact sites, and we identify genetic interactions suggesting that afd-1 and pac-1 regulate epidermal morphogenesis at least in part through parallel mechanisms. Our findings reveal that C. elegans AFD-1 makes a significant contribution to epidermal morphogenesis and functionally interfaces with core and associated CCC proteins.

Investigation of a novel TBC1D24 variation causing autosomal dominant non-syndromic hearing loss.

Hearing loss is considered one of the most common sensory neurological defects, with approximately 60% of cases attributed to genetic factors. Human pathogenic variants in the TBC1D24 gene are associated with various clinical phenotypes, including dominant nonsyndromic hearing loss DFNA65, characterized by progressive hearing loss after the development of language. This study provides an in-depth analysis of the causative gene and mutations in a family with hereditary deafness. We recruited a three-generation family with autosomal dominant nonsyndromic hearing loss (ADNSHL) and conducted detailed medical histories and relevant examinations. Next-generation sequencing (NGS) was used to identify genetic variants in the proband, which were then validated using Sanger sequencing. Multiple computational software tools were employed to predict the impact of the variant on the function and structure of the TBC1D24 protein. A series of bioinformatics tools were applied to determine the conservation characteristics of the sequence, establish a three-dimensional structural model, and investigate changes in molecular dynamics. A detailed genotype and phenotype analysis were carried out. The family exhibited autosomal dominant, progressive, postlingual, and nonsyndromic sensorineural hearing loss. A novel heterozygous variant, c.1459C>T (p.His487Tyr), in the TBC1D24 gene was identified and confirmed to be associated with the hearing loss phenotype in this family. Conservation analysis revealed high conservation of the amino acid affected by this variant across different species. The mutant protein showed alterations in thermodynamic stability, elasticity, and conformational dynamics. Molecular dynamics simulations indicated changes in RMSD, RMSF, Rg, and SASA of the mutant structure. We computed the onset age of non-syndromic hearing loss associated with mutations in the TBC1D24 gene and identified variations in the hearing progression time and annual threshold deterioration across different frequencies. The identification of a new variant associated with rare autosomal dominant nonsyndromic hereditary hearing loss in this family broadens the range of mutations in the TBC1D24 gene. This variant has the potential to influence the interaction between the TLDc domain and TBC domain, thereby affecting the protein's biological function.

SynGAP regulates synaptic plasticity and cognition independently of its catalytic activity.

SynGAP is an abundant synaptic GTPase-activating protein (GAP) critical for synaptic plasticity, learning, memory, and cognition. Mutations in SYNGAP1 in humans result in intellectual disability, autistic-like behaviors, and epilepsy. Heterozygous Syngap1-knockout mice display deficits in synaptic plasticity, learning, and memory and exhibit seizures. It is unclear whether SynGAP imparts structural properties at synapses independently of its GAP activity. Here, we report that inactivating mutations within the GAP domain do not inhibit synaptic plasticity or cause behavioral deficits. Instead, SynGAP modulates synaptic strength by physically competing with the AMPA-receptor-TARP excitatory receptor complex in the formation of molecular condensates with synaptic scaffolding proteins. These results have major implications for developing therapeutic treatments for SYNGAP1-related neurodevelopmental disorders.

FilGAP controls cell-extracellular matrix adhesion and process formation of kidney podocytes.

The function of kidney podocytes is closely associated with actin cytoskeleton regulated by Rho small GTPases. Loss of actin-driven cell adhesions and processes is connected to podocyte dysfunction, proteinuria, and kidney diseases. FilGAP, a GTPase-activating protein for Rho small GTPase Rac1, is abundantly expressed in kidney podocytes, and its gene is linked to diseases in a family with focal segmental glomerulosclerosis. In this study, we have studied the role of FilGAP in podocytes in vitro. Depletion of FilGAP in cultured podocytes induced loss of actin stress fibers and increased Rac1 activity. Conversely, forced expression of FilGAP increased stress fiber formation whereas Rac1 activation significantly reduced its formation. FilGAP localizes at the focal adhesion (FA), an integrin-based protein complex closely associated with stress fibers, that mediates cell-extracellular matrix (ECM) adhesion, and FilGAP depletion decreased FA formation and impaired attachment to the ECM. Moreover, in unique podocyte cell cultures capable of inducing the formation of highly organized processes including major processes and foot process-like projections, FilGAP depletion or Rac1 activation decreased the formation of these processes. The reduction of FAs and process formations in FilGAP-depleted podocyte cells was rescued by inhibition of Rac1 or P21-activated kinase 1 (PAK1), a downstream effector of Rac1, and PAK1 activation inhibited their formations. Thus, FilGAP contributes to both cell-ECM adhesion and process formation of podocytes by suppressing Rac1/PAK1 signaling.

The high expression of TOP2A and MELK induces the occurrence of psoriasis.

BACKGROUND: Psoriasis is a chronic inflammatory skin disease. However, the influence of the TOP2A and MELK genes on psoriasis remains unclear. METHODS: Psoriasis datasets GSE166388 and GSE181318 were downloaded from the Gene Expression Omnibus (GEO) database generated from GPL570 and GPL22120. Differential gene expression (DEGs) was identified. Functional enrichment analysis, gene set enrichment analysis (GSEA), weighted gene co-expression network analysis (WGCNA), and immune infiltration analysis were conducted. The protein-protein interaction (PPI) network was constructed and analyzed. Gene expression heat map was generated. The most relevant diseases associated with core genes were determined through comparison with the Comparative Toxicogenomics Database (CTD) website. TargetScan was used to select miRNAs regulating central DEGs. RESULTS: A total of 773 DEGs were identified. According to Gene Ontology (GO) analysis, they were mainly enriched in mitochondrial gene expression, oxidative phosphorylation, mitochondrial envelope, mitochondria and ribosome. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed that target cells were mainly enriched in metabolic pathways, proteasome, and oxidative phosphorylation. Seven core genes (TOP2A, NUF2, MELK, ASPM, DLGAP5, CCNA2, DEPDC1B) were obtained. The gene expression heatmap showed high expression of core genes (TOP2A, MELK) in psoriasis samples, while DEPDC1B, CCNA2, DLGAP5, NUF2, ASPM were lowly expressed in psoriasis samples. CTD analysis found that TOP2A and MELK were related to skin neoplasms, skin diseases, psoriasis, erythema, dermatitis, and infections. CONCLUSION: TOP2A and MELK genes are highly expressed in psoriasis, and higher expression of TOP2A and MELK genes is associated with poorer prognosis.

Loss of TBC1D2B causes a progressive neurological disorder with gingival overgrowth.

Biallelic loss-of-function variants in TBC1D2B have been reported in five subjects with cognitive impairment and seizures with or without gingival overgrowth. TBC1D2B belongs to the family of Tre2-Bub2-Cdc16 (TBC)-domain containing RAB-specific GTPase activating proteins (TBC/RABGAPs). Here, we report five new subjects with biallelic TBC1D2B variants, including two siblings, and delineate the molecular and clinical features in the ten subjects known to date. One of the newly reported subjects was compound heterozygous for the TBC1D2B variants c.2584C>T; p.(Arg862Cys) and c.2758C>T; p.(Arg920*). In subject-derived fibroblasts, TBC1D2B mRNA level was similar to control cells, while the TBC1D2B protein amount was reduced by about half. In one of two siblings with a novel c.360+1G>T splice site variant, TBC1D2B transcript analysis revealed aberrantly spliced mRNAs and a drastically reduced TBC1D2B mRNA level in leukocytes. The molecular spectrum included 12 different TBC1D2B variants: seven nonsense, three frameshifts, one splice site, and one missense variant. Out of ten subjects, three had fibrous dysplasia of the mandible, two of which were diagnosed as cherubism. Most subjects developed gingival overgrowth. Half of the subjects had developmental delay. Seizures occurred in 80% of the subjects. Six subjects showed a progressive disease with mental deterioration. Brain imaging revealed cerebral and/or cerebellar atrophy with or without lateral ventricle dilatation. The TBC1D2B disorder is a progressive neurological disease with gingival overgrowth and abnormal mandible morphology. As TBC1D2B has been shown to positively regulate autophagy, defects in autophagy and the endolysosomal system could be associated with neuronal dysfunction and the neurodegenerative disease in the affected individuals.

Identification of new subtypes and potential genetic signatures in triple-negative breast cancer using weighted gene co-expression network analysis.

OBJECTIVE: Triple-negative breast cancer (TNBC) is a heterogeneous disease with aggressive behavior and poor prognosis. Here, we used gene expression profiling to define new subtypes of TNBC, which may improve prevention and treatment through personalized medicine. MATERIALS AND METHODS: Gene expression profiles from the public datasets GSE76250, GSE61724, GSE61723, and GES76275 were subjected to co-expression analysis to identify differentially expressed genes (DEGs) between TNBC and non-TNBC tissues. Consistency clustering was used to define TNBC subtypes, whose correlation with gene modules was analyzed. Enrichment analysis was used to identify module genes' biological functions and pathways. Single-sample gene set enrichment analysis was used to assess immune cell infiltration in the different TNBC subtypes, and the ChAMP package was used to examine methylation sites in TNBC. RESULTS: A total of 4,958 DEGs in TNBC were identified, which showed the same expression differences across all datasets as in the dataset GSE76250 and clustered into 9 co-expression modules. TNBC samples clustered into two subtypes based on nine hub genes from the modules. Class I showed the most significant correlation with module 1, whose genes were related mainly to interleukin-1 response, while class II showed the most significant correlation with module 6, whose genes were related mainly to the transforming growth factor-ß pathway. Class I was significantly enriched in cell cycle and DNA replication, and tumors of this subtype showed lower immune cell infiltration than class II tumors. Tumor infiltration by Th2 cells correlated positively with the expression of MCM10 and negatively with the expression of PREX2. A greater methylation of CIDEC, DLC1, EDNRB, EGR2 and SRPK1 correlated with better prognosis. CONCLUSIONS: Class I TNBC, for which a useful biomarker is MCM10, may be associated with a worse prognosis than class II TNBC, for which PREX2 may serve as a biomarker.

RACGAP1 drives proliferation, migration and invasion and suppresses autophagy of gastric cancer cells via inhibiting SIRT1/Mfn2.

Objective: Gastric cancer is the most frequent gastrointestinal malignancy with a poor prognosis. Rac GTPase activation protein 1 (RACGAP1) is a novel tumor promotor, whose detailed effect on gastric cancer remains to be further elucidated. Hence, this study identifies the action of RACGAP1 on gastric cancer and investigates the potential mechanism. Methods: RACGAP1 expression in gastric cancer was analyzed based on the data of The Cancer Genome Atlas (TCGA) database. Cell proliferation was measured by CCK-8 and colony formation assay. Cell migration and invasion were evaluated by transwell assay. Cell apoptosis was assessed by flow cytometry. Cell autophagy was evaluated via determining LC3. Results: RACGAP1 presented at high level in gastric cancer cells. Overexpressed RACGAP1 potentiated gastric cancer cell proliferation, migration, and invasion. Besides, silenced RACGAP1 induced cell apoptosis and autophagy. Furthermore, RACGAP1 suppressed the expression of SIRT1 and Mfn2. Conclusion: RACGAP1 was overexpressed in gastric cancer. RACGAP1 potentiated aggressive behaviors of gastric cancer, and suppressed cell apoptosis and autophagy via modulating SIRT1/Mfn2. RACGAP1 may be a valuable target in the treatment of gastric cancer.

ARHGAP6 Suppresses Breast Cancer Tumor Growth by Promoting Ferroptosis via RhoA-ROCK1-p38 MAPK Signaling.

BACKGROUND: Ferroptosis, a distinct iron-dependent form of regulated cell death, is induced by severe lipid peroxidation due to reactive oxygen species (ROS) generation. Breast cancer patient survival is correlated with the tumor-suppressing properties of Rho guanosine triphosphatase hydrolase enzyme (GTPase)-activating protein 6 (ARHGAP6). This study investigates the impact and mechanisms of ARHGAP6 on ferroptosis in breast cancer. METHODS: Using quantitative RT-PCR, Western blotting, and immunofluorescence staining, ARHGAP6 expression was detected in a gene expression dataset, cancer tissue samples, and cells. ARHGAP6 was overexpressed or silenced in breast cancer cell lines. Cell proliferation was measured using 5-ethynyl-2-deoxyuridine (EdU) assay, and cell death rate was determined using LDH cytotoxicity assay. As indicators of ferroptosis, Fe2+ ion content, lipid ROS, glutathione peroxidase 4 (GPX4), ChaC glutathione specific gamma-glutamylcyclotransferase 1 (CHAC1), prostaglandin-endoperoxide synthase 2 (PTGS2), solute carrier family 7 member 11 (SLC7A11), and acyl-CoA synthetase long chain family member 4 (ACSL4) levels were evaluated. RESULTS: ARHGAP6 was obviously downregulated in cancer tissues and cells. ARHGAP6 overexpression decreased cell proliferation, elevated cell death and lipid ROS, decreased GPX4 and SLC7A11, increased PTGS2, ACSL4, and CHAC1, and inhibited RhoA/ROCK1 and p38 MAPK signaling in cancer cells. ARHGAP6 knockdown exerted opposite effects to those of ARHGAP6 overexpression. p38 signaling suppression reversed the effect of ARHGAP6 knockdown on ferroptosis, while RhoA/ROCK1 signaling inhibition compromised the effect of ARHGAP6 on p38 MAPK signaling. In mice models, ARHGAP6 together with the ferroptosis inducer RSL3 cooperatively enhanced ferroptosis and inhibited tumor growth of cancer cells. ARHGAP6 mRNA level was positively correlated with that of ferroptosis indicators in tumor tissues. CONCLUSIONS: This study revealed that ARHGAP6 inhibited tumor growth of breast cancer by inducing ferroptosis via RhoA/ROCK1/p38 MAPK signaling. Integrating ARHGAP6 with ferroptosis-inducing agents may be a promising therapeutic strategy for breast cancer treatment.