MICAL1 controls cell invasive phenotype via regulating oxidative stress in breast cancer cells

Post-translational targeting of Rab35 by the effector IcsB of Shigella determines intracellular bacterial niche formation

Escape from the bacterial-containing vacuole (BCV) is a key step of Shigella host cell invasion. Rab GTPases subverted to in situ-formed macropinosomes in the vicinity of the BCV have been shown to promote its rupture. The involvement of the BCV itself has remained unclear. We demonstrate that Rab35 is non-canonically entrapped at the BCV. Stimulated emission depletion imaging localizes Rab35 directly on the BCV membranes before vacuolar rupture. The bacterial effector IcsB, a lysine Nε-fatty acylase, is a key regulator of Rab35-BCV recruitment, and we show post-translational acylation of Rab35 by IcsB in its polybasic region. While Rab35 and IcsB are dispensable for the first step of BCV breakage, they are needed for the unwrapping of damaged BCV remnants from Shigella. This provides a framework for understanding Shigella invasion implicating re-localization of a Rab GTPase via its bacteria-dependent post-translational modification to support the mechanical unpeeling of the BCV.

PlexinA1 promotes gastric cancer migration through preventing MICAL1 protein ubiquitin/proteasome-mediated degradation in a Rac1-dependent manner

Metastasis promotes the development of tumors and is a significant cause of gastric cancer death. For metastasis to proceed, tumor cells must become mobile by modulating their cytoskeleton. MICAL1 (Molecule Interacting with CasL1) is known as an actin cytoskeleton regulator, but the mechanisms by which it drives gastric cancer cell migration are still unclear. Analysis of gastric cancer tissues revealed that MICAL1 expression is dramatically upregulated in stomach adenocarcinoma (STAD) samples as compared to noncancerous stomach tissues. Patients with high MICAL1 expression had shorter overall survival (OS), post-progression survival (PPS) and first-progression survival (FPS) compared with patients with low MICAL1 expression. RNAi-mediated silencing of MICAL1 inhibited the expression of Vimentin, a protein involved in epithelial-mesenchymal transition. This effect correlates with a significant reduction in gastric cancer cell migration. MICAL1 overexpression reversed these preventive effects. Immunoprecipitation experiments and immunofluorescence assays revealed that PlexinA1 forms a complex with MICAL1. Importantly, specific inhibition of PlexinA1 blocked the Rac1 activation and ROS production, which, in turn, impaired MICAL1 protein stability by accelerating MICAL1 ubiquitin/proteasome-dependent degradation. Overexpression of PlexinA1 enhanced Rac1 activation, ROS production, MICAL1 and Vimentin expressions, and favored cell migration. In conclusion, this study identified MICAL1 as an important facilitator of gastric cancer cell migration, at least in part, by affecting Vimentin expression and PlexinA1 promotes gastric cancer cell migration by binding to and suppressing MICAL1 degradation in a Rac1/ROS-dependent manner.

Membrane trafficking alterations in breast cancer progression

Breast cancer (BC) is the most common type of cancer in women, and remains one of the major causes of death in women worldwide. It is now well established that alterations in membrane trafficking are implicated in BC progression. Indeed, membrane trafficking pathways regulate BC cell proliferation, migration, invasion, and metastasis. The 22 members of the ADP-ribosylation factor (ARF) and the >60 members of the rat sarcoma (RAS)-related in brain (RAB) families of small GTP-binding proteins (GTPases), which belong to the RAS superfamily, are master regulators of membrane trafficking pathways. ARF-like (ARL) subfamily members are involved in various processes, including vesicle budding and cargo selection. Moreover, ARFs regulate cytoskeleton organization and signal transduction. RABs are key regulators of all steps of membrane trafficking. Interestingly, the activity and/or expression of some of these proteins is found dysregulated in BC. Here, we review how the processes regulated by ARFs and RABs are subverted in BC, including secretion/exocytosis, endocytosis/recycling, autophagy/lysosome trafficking, cytoskeleton dynamics, integrin-mediated signaling, among others. Thus, we provide a comprehensive overview of the roles played by ARF and RAB family members, as well as their regulators in BC progression, aiming to lay the foundation for future research in this field. This research should focus on further dissecting the molecular mechanisms regulated by ARFs and RABs that are subverted in BC, and exploring their use as therapeutic targets or prognostic markers.

Phosphorylated α-synuclein deposited in Schwann cells interacting with TLR2 mediates cell damage and induces Parkinson's disease autonomic dysfunction

Despite the significant frequency of autonomic dysfunction (AutD) in Parkinson's disease (PD) patients, its pathogenesis and diagnosis are challenging. Here, we aimed to further explore the mechanism of phosphorylated α-synuclein (p-α-syn) deposited in vagus nerve Schwann cells (SCs) causing SCs damage and PD AutD. 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP, 20 mg/kg) was administrated to C57BL/6 mice twice a week for 35 days. Following the final injection, locomotor functions, gastrointestinal symptoms, urine functions, and cardiovascular system functions were evaluated. Meanwhile, we examined p-α-syn deposited in vagus nerve SCs, Toll-like receptor 2 (TLR2) activation, and SCs loss using immunofluorescence, western blot, and Luxol fast blue staining. In vitro, the rat SCs line RSC96 cells were exposed to α-synuclein preformed fibril (α-syn PFF), and cell viability was detected by CCK8. Co-IP was used to identify the interaction between p-α-syn and TLR2. Furthermore, the role of TLR2 in p-α-syn-mediated SCs damage was confirmed by the administration of CU-CPT22, a specific blocker of TLR2. In vivo, apart from dyskinesia, MPTP mice exhibited constipation, urinary dysfunction, and cardiovascular failure, which were associated with the deposition of p-α-syn in vagus nerve SCs, TLR2 activation, and vagus nerve demyelination. In vitro, stimulation of α-syn PFF induced a time-dependent loss of viability, and p-α-syn deposited in RSC96 cells induced a cellular inflammatory response by interacting with TLR2, resulting in cell dysfunction and apoptosis. However, both SCs inflammatory response and cell viability were alleviated after inhibition of TLR2. Furthermore, 1 h fecal pellets and water content, the frequency of 1 h urine, blood pressure, heart rate, and heart rate variability of mice in the MPTP + CU-CPT22 group were also improved. Our results support the perspective that p-α-syn interacts with TLR2 induced SCs damage and is involved in PD AutD, which sheds fresh light on the mechanism of PD AutD and indicates a promising treatment for PD AutD targeting SCs p-α-syn/ TLR2 signaling pathway.

MICAL-mediated oxidation of actin and its effects on cytoskeletal and cellular dynamics

Actin and its dynamic structural remodelings are involved in multiple cellular functions, including maintaining cell shape and integrity, cytokinesis, motility, navigation, and muscle contraction. Many actin-binding proteins regulate the cytoskeleton to facilitate these functions. Recently, actin's post-translational modifications (PTMs) and their importance to actin functions have gained increasing recognition. The MICAL family of proteins has emerged as important actin regulatory oxidation-reduction (Redox) enzymes, influencing actin's properties both in vitro and in vivo. MICALs specifically bind to actin filaments and selectively oxidize actin's methionine residues 44 and 47, which perturbs filaments' structure and leads to their disassembly. This review provides an overview of the MICALs and the impact of MICAL-mediated oxidation on actin's properties, including its assembly and disassembly, effects on other actin-binding proteins, and on cells and tissue systems.

Adaptive and non-adaptive gene expression responses in prostate cancer during androgen deprivation

Androgen deprivation therapy is the cornerstone treatment of advanced prostate cancer. Eventually prostate cancer cells overcome androgen deprivation therapy, giving rise to castration resistant prostate cancer (CRPC) characterized by increased androgen receptor (AR) activity. Understanding the cellular mechanisms leading to CRPC is needed for development of novel treatments. We used long-term cell cultures to model CRPC; a testosterone-dependent cell line (VCaP-T) and cell line adapted to grow in low testosterone (VCaP-CT). These were used to uncover persistent and adaptive responses to testosterone level. RNA was sequenced to study AR-regulated genes. Expression level changed due to testosterone depletion in 418 genes in VCaP-T (AR-associated genes). To evaluate significance for CRPC growth, we compared which of them were adaptive i.e., restored expression level in VCaP-CT. Adaptive genes were enriched to steroid metabolism, immune response and lipid metabolism. The Cancer Genome Atlas Prostate Adenocarcinoma data were used to assess the association with cancer aggressiveness and progression-free survival. Expressions of 47 AR-associated or association gaining genes were statistically significant markers for progression-free survival. These included genes related to immune response, adhesion and transport. Taken together, we identified and clinically validated multiple genes being linked with progression of prostate cancer and propose several novel risk genes. Possible use as biomarkers or therapeutic targets should be studied further.

High MICAL1 expression correlates with cancer progression and immune infiltration in renal clear cell carcinoma

BACKGROUND

Molecule interacting with CasL 1 (MICAL1), a multidomain flavoprotein monooxygenase, is strongly involved in the biological processes related to cancer cell proliferation and metastasis. However, there were few reports on the clinical significance of MICAL1 in renal clear cell carcinoma.

METHODS

The expression and prognostic value of MICAL1 in renal clear cell carcinoma were explored using immunohistochemical assays, public TCGA-KIRC databases and multiple analysis methods, including survival analysis, univariate and multivariate analyses, KEGG and GSEA. Wound healing and Transwell assays were performed to check the 786-O cell and Caki-1 cell migration abilities after knockdown of MICAL1. Western blotting was used to assess the regulatory effect of MICAL1 on the Rac1 activation. Additionally, the function of MICAL1 and the correlations between MICAL1 and immune infiltration levels in KIRC were investigated using TIMER and TISIDB.

RESULTS

MICAL1 expression was significantly higher in carcinoma tissue compared with non-cancerous tissue. A survival analysis revealed that patients with high MICAL1 expression had shorter overall survival (OS) and disease-specific survival (DSS) compared with patients with low MICAL1 expression. ROC analysis also confirmed that MICAL1 has a high diagnostic value in KIRC. Importantly, the univariate and multivariate Cox analysis further confirmed that high MICAL1 expression was an independent risk factor for OS in patients with KIRC. In accordance with this, knockdown of MICAL1 expression decreased Rac1 activation and cell migration. KEGG and GSEA analysis revealed that the immune infiltration and Ras signaling pathways were significantly upregulated in the high MICAL1 expression group. In terms of immune infiltrating levels, MICAL1 expression was positively associated with CD8+/Treg cell infiltration levels. Specifically, bioinformatic analysis showed that MICAL1 expression had strong relationships with various T cell exhaustion markers.

CONCLUSIONS

MICAL1 expression may act as a prognostic biomarker for determining the prognosis in renal clear cell carcinoma and plays an important role in regulating tumor immune microenvironment and cell migratory capacity.

MICAL1 facilitates pancreatic cancer proliferation, migration, and invasion by activating WNT/β-catenin pathway

Background

MICAL1 is involved in the malignant processes of several types of cancer; however, the role of MICAL1 in pancreatic cancer (PC) has not been well-characterized. This study aimed to investigate the expression and function of MICAL1 in PC.

Methods

RT-qPCR and immunohistochemistry were used to detect MICAL1 expression in PC and adjacent nontumor tissues. Cell Counting Kit-8, EdU, clone formation, wound healing, and Transwell assays as well as animal models were used to investigate the effects of overexpression or inhibition of MICAL1 expression on the proliferation, invasion, and metastasis of PC cells. RNA-seq was used to explore the main pathway underlying the functions of MICAL1. Proteomics, mass spectrometry, and co-immunoprecipitation assays were used to investigate the interaction of proteins with MICAL1. Rescue experiments were conducted to validate these findings.

Results

Both MICAL1 mRNA and protein levels were upregulated in PC tissues compared with matched adjacent nontumor tissues. The expression level of MICAL1 was associated with the proliferative and metastatic status of PC. Repression of MICAL1 significantly inhibited PC cell growth, migration, and invasion in vitro and in vivo. RNA sequencing analysis indicated that MICAL1 was closely correlated with the WNT pathway. Overexpression of MICAL1 (1) promoted the phosphorylation of TBC1D1 at the Ser660 site, (2) facilitated the distribution of FZD7 on the cytomembrane, (3) inhibited the degradation of FZD7 in the lysosome, and (4) activated the WNT pathway.

Conclusions

MICAL1 was upregulated in PC and involved in stimulating the progression of PC cells by activating the WNT/β-catenin signaling pathway. Therefore, MICAL1 is a potential therapeutic target for PC.

Exosome-like nanovesicles derived from Phellinus linteus inhibit Mical2 expression through cross-kingdom regulation and inhibit ultraviolet-induced skin aging

Background

Phellinus linteus (PL), which is a typical medicinal fungus, has been shown to have antitumor and anti-inflammatory activities. However, studies on the effect of anti-photoaging are limited. Studies have shown that exosome-like nanovesicles are functional components of many medicinal plants, and miRNAs in exosome-like nanovesicles play a cross-kingdom regulatory role. At present, research on fungi exosome-like nanovesicles (FELNVs) is few.

Results

We systematically evaluated the anti-aging effects of PL. FELNVs of PL were isolated, and the functional molecular mechanisms were evaluated. The results of volunteer testing showed that PL had anti-aging activity. The results of component analysis showed that FELNVs were the important components of PL function. FELNVs are nanoparticles (100–260 nm) with a double shell structure. Molecular mechanism research results showed that miR-CM1 in FELNVs could inhibit Mical2 expression in HaCaT cells through cross-kingdom regulation, thereby promoting COL1A2 expression; inhibiting MMP1 expression in skin cells; decreasing the levels of ROS, MDA, and SA-β-Gal; and increasing SOD activity induced by ultraviolet (UV) rays. The above results indicated that miR-CM1 derived from PL inhibited the expression of Mical2 through cross-kingdom regulation and inhibited UV-induced skin aging.

Conclusion

miR-CM1 plays an anti-aging role by inhibiting the expression of Mical2 in human skin cells through cross-species regulation.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1186/s12951-022-01657-6.

Oxidation and reduction of actin: Origin, impact in vitro and functional consequences in vivo

Actin is among the most abundant proteins in eukaryotic cells and assembles into dynamic filamentous networks regulated by many actin binding proteins. The actin cytoskeleton must be finely tuned, both in space and time, to fulfill key cellular functions such as cell division, cell shape changes, phagocytosis and cell migration. While actin oxidation by reactive oxygen species (ROS) at non-physiological levels are known for long to impact on actin polymerization and on the cellular actin cytoskeleton, growing evidence shows that direct and reversible oxidation/reduction of specific actin amino acids plays an important and physiological role in regulating the actin cytoskeleton. In this review, we describe which actin amino acid residues can be selectively oxidized and reduced in many different ways (e.g. disulfide bond formation, glutathionylation, carbonylation, nitration, nitrosylation and other oxidations), the cellular enzymes at the origin of these post-translational modifications, and the impact of actin redox modifications both in vitro and in vivo. We show that the regulated balance of oxidation and reduction of key actin amino acid residues contributes to the control of actin filament polymerization and disassembly at the subcellular scale and highlight how improper redox modifications of actin can lead to pathological conditions.

MICAL1 Monooxygenase in Autosomal Dominant Lateral Temporal Epilepsy: Role in Cytoskeletal Regulation and Relation to Cancer

Autosomal dominant lateral temporal epilepsy (ADLTE) is a genetic focal epilepsy associated with mutations in the LGI1, RELN, and MICAL1 genes. A previous study linking ADLTE with two MICAL1 mutations that resulted in the substitution of a highly conserved glycine residue for serine (G150S) or a frameshift mutation that swapped the last three C-terminal amino acids for 59 extra residues (A1065fs) concluded that the mutations increased enzymatic activity and promoted cell contraction. The roles of the Molecule Interacting with CasL 1 (MICAL1) protein in tightly regulated semaphorin signaling pathways suggest that activating MICAL1 mutations could result in defects in axonal guidance during neuronal development. Further studies would help to illuminate the causal relationships of these point mutations with ADLTE. In this review, we discuss the proposed pathogenesis caused by mutations in these three genes, with a particular emphasis on the G150S point mutation discovered in MICAL1. We also consider whether these types of activating MICAL1 mutations could be linked to cancer.

Prmt1 upregulated by Hdc deficiency aggravates acute myocardial infarction via NETosis

Neutrophils are mobilized and recruited to the injured heart after myocardial infarction, and neutrophil count has been clinically implicated to be associated with coronary disease severity. Histidine decarboxylase (HDC) has been implicated in regulating reactive oxidative species (ROS) and the differentiation of myeloid cells. However, the effect of HDC on neutrophils after myocardial infarction remains unclear. Here, we found that neutrophils were disorderly recruited into the ischemic injured area of the myocardium of Hdc deficiency (Hdc^−/−) mice. Moreover, Hdc deficiency led to attenuated adhesion but enhanced migration and augmented ROS/neutrophil extracellular traps (NETs) production in neutrophils. Hdc^−/− mouse-derived NETs promoted cardiomyocyte death and cardiac fibroblast proliferation/migration. Furthermore, protein arginine methyltransferase 1 (PRMT1) was increased in Hdc^−/− mouse-derived neutrophils but decreased with exogenous histamine treatment. Its expression could be rescued by blocking histamine receptor 1 (H1R), inhibiting ATP synthesis or reducing SWItch/sucrose non fermentable (SWI/SNF) chromatin remodeling complex. Accordingly, histamine or MS023 treatment could decrease ROS and NETs ex vivo, and ameliorated cardiac function and fibrosis, along with the reduced NETs in plasma in vivo. Together, our findings unveil the role of HDC in NETosis by histamine–H1R–ATP–SWI/SNF–PRMT1–ROS signaling and provide new biomarkers and targets for identifying and tuning the detrimental immune state in cardiovascular disease.

Immune profiles and DNA methylation alterations related with non-muscle-invasive bladder cancer outcomes

BACKGROUND

Non-muscle-invasive bladder cancer (NMIBC) patients receive frequent monitoring because ≥ 70% will have recurrent disease. However, screening is invasive, expensive, and associated with significant morbidity making bladder cancer the most expensive cancer to treat per capita. There is an urgent need to expand the understanding of markers related to recurrence and survival outcomes of NMIBC.

METHODS AND RESULTS

We used the Illumina HumanMethylationEPIC array to measure peripheral blood DNA methylation profiles of NMIBC patients (N = 603) enrolled in a population-based cohort study in New Hampshire and applied cell type deconvolution to estimate immune cell-type proportions. Using Cox proportional hazard models, we identified that increasing CD4T and CD8T cell proportions were associated with a statistically significant decreased hazard of tumor recurrence or death (CD4T: HR = 0.98, 95% CI = 0.97-1.00; CD8T: HR = 0.97, 95% CI = 0.95-1.00), whereas increasing monocyte proportion and methylation-derived neutrophil-to-lymphocyte ratio (mdNLR) were associated with the increased hazard of tumor recurrence or death (monocyte: HR = 1.04, 95% CI = 1.00-1.07; mdNLR: HR = 1.12, 95% CI = 1.04-1.20). Then, using an epigenome-wide association study (EWAS) approach adjusting for age, sex, smoking status, BCG treatment status, and immune cell profiles, we identified 2528 CpGs associated with the hazard of tumor recurrence or death (P < 0.005). Among these CpGs, the 1572 were associated with an increased hazard and were significantly enriched in open sea regions; the 956 remaining CpGs were associated with a decreased hazard and were significantly enriched in enhancer regions and DNase hypersensitive sites.

CONCLUSIONS

Our results expand on the knowledge of immune profiles and methylation alteration associated with NMIBC outcomes and represent a first step toward the development of DNA methylation-based biomarkers of tumor recurrence.

MICAL1 inhibits colorectal cancer cell migration and proliferation by regulating the EGR1/β-catenin signaling pathway

MICAL1 has been reported to be involved in the malignant processes of several types of cancer cells, however, the roles of MICAL1 in colorectal cancer (CRC) have not been well-characterized. This study aims to investigate the cellular functions and molecular mechanisms of MICAL1 in CRC cells. Here, we found that both mRNA and protein levels of MICAL1 were down-regulated in colorectal cancer tissues compared with matched adjacent non-tumor tissues, and the expression level of MICAL1 was correlated with the metastatic status of colorectal cancer. Importantly, overexpression of MICAL1 significantly inhibited colorectal cancer cell migration and growth, and increased the level of E-cadherin and Occludin, and suppressed the expression level of Vimentin and N-cadherin; while silencing of MICAL1 promoted CRC cell migration and enhanced EMT. In addition, MICAL1 overexpression significantly inhibited the proliferation and growth of CRC in vitro and in vivo. Moreover, RNA sequencing and bioinformatics analysis identified that MICAL1 was closely correlated with "cell migration", "cell cycle" and "β-catenin signaling" genesets. Mechanistically, overexpression of MICAL1 downregulated the mRNA level of EGR1 and β-catenin, decreased the protein level and nuclear translocation of β-catenin, and inhibited the transcriptions of β-catenin downstream targets, c-myc and cyclin D1. The ectopic expression of EGR1 or β-catenin can significantly block the MICAL1-mediated inhibitory effects. Collectively, MICAL1 is down-regulated in CRC, and plays an inhibitory role in the migration and growth of CRC cells by suppressing the ERG1/β-catenin signaling pathway.

Early Pregnancy Exposure to Ambient Air Pollution among Late-Onset Preeclamptic Cases Is Associated with Placental DNA Hypomethylation of Specific Genes and Slower Placental Maturation

Exposure to ambient air pollution during pregnancy has been associated with an increased risk of preeclampsia (PE). Some suggested mechanisms behind this association are changes in placental DNA methylation and gene expression. The objective of this study was to identify how early pregnancy exposure to ambient nitrogen oxides (NO_x) among PE cases and normotensive controls influence DNA methylation (EPIC array) and gene expression (RNA-seq). The study included placentas from 111 women (29 PE cases/82 controls) in Scania, Sweden. First-trimester NO_x exposure was assessed at the participants’ residence using a dispersion model and categorized via median split into high or low NO_x. Placental gestational epigenetic age was derived from the DNA methylation data. We identified six differentially methylated positions (DMPs, q < 0.05) comparing controls with low NO_x vs. cases with high NO_x and 14 DMPs comparing cases and controls with high NO_x. Placentas with female fetuses showed more DMPs (N = 309) than male-derived placentas (N = 1). Placentas from PE cases with high NO_x demonstrated gestational age deceleration compared to controls with low NO_x (p = 0.034). No differentially expressed genes (DEGs, q < 0.05) were found. In conclusion, early pregnancy exposure to NO_x affected placental DNA methylation in PE, resulting in placental immaturity and showing sexual dimorphism.

MICAL1 regulates actin cytoskeleton organization, directional cell migration and the growth of human breast cancer cells as orthotopic xenograft tumours

The Molecule Interacting with CasL 1 (MICAL1) monooxygenase has emerged as an important regulator of cytoskeleton organization via actin oxidation. Although filamentous actin (F-actin) increases MICAL1 monooxygenase activity, hydrogen peroxide (H2O2) is also generated in the absence of F-actin, suggesting that diffusible H2O2 might have additional functions. MICAL1 gene disruption by CRISPR/Cas9 in MDA MB 231 human breast cancer cells knocked out (KO) protein expression, which affected F-actin organization, cell size and motility. Transcriptomic profiling revealed that MICAL1 deletion significantly affected the expression of over 700 genes, with the majority being reduced in their expression levels. In addition, the absolute magnitudes of reduced gene expression were significantly greater than the magnitudes of increased gene expression. Gene set enrichment analysis (GSEA) identified receptor regulator activity as the most significant negatively enriched molecular function gene set. The prominent influence exerted by MICAL1 on F-actin structures was also associated with changes in the expression of several serum-response factor (SRF) regulated genes in KO cells. Moreover, MICAL1 disruption attenuated breast cancer tumour growth in vivo. Elevated MICAL1 gene expression was observed in invasive breast cancer samples from human patients relative to normal tissue, while MICAL1 amplification or point mutations were associated with reduced progression free survival. Collectively, these results demonstrate that MICAL1 gene disruption altered cytoskeleton organization, cell morphology and migration, gene expression, and impaired tumour growth in an orthotopic in vivo breast cancer model, suggesting that pharmacological MICAL1 inhibition could have therapeutic benefits for cancer patients.

A novel bioavailable curcumin-galactomannan complex modulates the genes responsible for the development of chronic diseases in mice: A RNA sequence analysis

BACKGROUND

Chronic diseases or non-communicable diseases are a major burden worldwide due to the lack of highly efficacious treatment modalities and the serious side effects associated with the available therapies.

PURPOSE/STUDY DESIGN

A novel self-emulsifying formulation of curcumin with fenugreek galactomannan hydrogel scaffold as a water-dispersible non-covalent curcumin-galactomannan molecular complex (curcumagalactomannosides, CGM) has shown better bioavailability than curcumin and can be used for the prevention and treatment of chronic diseases. However, the exact potential of this formulation has not been studied, which would pave the way for its use for the prevention and treatment of multiple chronic diseases.

METHODS

The whole transcriptome analysis (RNAseq) was used to identify differentially expressed genes (DEGs) in the liver tissues of mice treated with LPS to investigate the potential of CGM on the prevention and treatment of chronic diseases. Expression analysis using DESeq2 package, GO, and pathway analysis of the differentially expressed transcripts was performed using UniProtKB and KEGG-KAAS server.

RESULTS

The results showed that 559 genes differentially expressed between the liver tissue of control mice and CGM treated mice (100 mg/kg b.wt. for 14 days), with adjusted p-value below 0.05, of which 318 genes were significantly upregulated and 241 were downregulated. Further analysis showed that 33 genes which were upregulated (log2FC > 8) in the disease conditions were significantly downregulated, and 32 genes which were downregulated (log2FC < -8) in the disease conditions were significantly upregulated after the treatment with CGM.

CONCLUSION

Overall, our study showed CGM has high potential in the prevention and treatment of multiple chronic diseases.

The dual functions of Rab11 and Rab35 GTPases-regulation of cell division and promotion of tumorigenicity

The broad studies of cancer have led researchers to the creditable understanding of biological and environmental factors that make benign cells to become malignant, as well as the developmental aspects of the tumour cells, known as the "hallmarks of cancer". However, additional research is needed to uncover the features of cancer biology, which would allow to design new and more effective treatment strategies for cancer patients. Since RabGTPases and their effectors are frequently altered in cancer, their role in a regulation of cell division leading to the acquisition of cancer cell-like phenotype has drawn a lot of attention from different research groups in recent years. Both, Rab11 and Rab35 belong to a superfamily of small monomeric GTPases that regulate a diverse array of cellular functions. Lately, Rab11 and Rab35 were declared as oncogenic, and because of their association with abundant cellular functions, a linkage to the induction of cancer, has been proposed. Although the clear connection between the improper regulation of Rab11 or Rab35 and the initiation of tumorigenicity has only beginning to emerge, in this review we will discuss the newest findings regarding the participation of RabGTPases in a control of cell division and promotion of tumorigenesis, trying to link the actual function to the cancer causality.

Proteomic analysis reveals brain Rab35 as a potential biomarker of mitragynine withdrawal in rats

Mitragyna speciosa, also known as kratom, has been used for mitigating the severity of opioid withdrawal in humans. Its main indole alkaloid, mitragynine, has been considered as a pharmacotherapy for pain conditions and opioid replacement therapy. However, at high doses, chronic mitragynine may also have an addiction potential. The effects of chronic action of mitragynine in the brain are still unknown. The present study developed a mitragynine withdrawal model in rats and used it for a proteomic analysis of mitragynine withdrawal effects. Mitragynine (30 mg/kg, i.p.) was administered daily over a period of 14 days and then withdrawn. A proteomic analysis revealed that from a total of 1524 proteins identified, 31 proteins were upregulated, and 3 proteins were downregulated in the mitragynine withdrawal model. The Rab35 protein expression increased most profoundly in the mitragynine withdrawal group as compared to vehicle group. Therefore, it is proposed that Rab35 in the brain might be considered as a potential biomarker during mitragynine withdrawal and might be valuable target protein in developing new pharmacotherapies in the future.

MICAL-L2 Is Essential for c-Myc Deubiquitination and Stability in Non-small Cell Lung Cancer Cells

Objectives: MICAL-L2, a member of the molecules interacting with the CasL (MICAL) family, was reported to be highly expressed in several types of cancers, however, the roles of MICAL-L2 in NSCLC pathogenesis remain to be explored. This study is designed to clarify the mechanisms by which MICAL-L2 participates in NSCLC cell proliferation.

Materials and Methods: The expression levels of MICAL-L2 in human lung cancer samples were assessed by immunohistochemical staining. Cells were transfected with siRNA or plasmids to regulate MICAL-L2 expression. Cell proliferation was measured by EdU staining and CCK-8 assays. MICAL-L2 and phosphorylated/total c-Myc expression were examined by Western blotting analysis. Interaction between MICAL-L2 and c-Myc was assessed by immunofluorescence staining, Western blotting and co-immunoprecipitation assays. Western blotting, polyubiquitylation detection and protein stability assays were used to assess whether MICAL-L2 exerts its oncogenic effect via c-Myc.

Results: We found that MICAL-L2 was highly expressed in human NSCLC. While overexpressing MICAL-L2 increased NSCLC cell proliferation, MICAL-L2 depletion decreased the proliferation of NSCLC cells, an effect that was linked to cell cycle arrest. MICAL-L2 physically interacted with the c-Myc protein and functioned to maintain nuclear c-Myc levels and prolonged its half-life. Knockdown of MICAL-L2 expression led to decreased c-Myc protein stability through accelerating polyubiquitylation of c-Myc and gave rise to c-Myc degradation. We further found that MICAL-L2 deubiquitinated c-Myc and blocked its degradation, presumably by inhibiting c-Myc phosphorylation at threonine residue 58.

Conclusions: These results indicate that MICAL-L2 is a key regulator of c-Myc deubiquitination and stability in the nucleus, and this activity may be involved in promoting NSCLC cell proliferation.

Investigating the Thioredoxin and Glutathione Systems' Response in Lymphoma Cells after Treatment with [Au(d2pype)2]CL

Lymphoma is a blood cancer comprising various subtypes. Although effective therapies are available, some patients fail to respond to treatment and can suffer from side effects. Antioxidant systems, especially the thioredoxin (Trx) and glutathione (GSH) systems, are known to enhance cancer cell survival, with thioredoxin reductase (TrxR) recently reported as a potential anticancer target. Since the GSH system can compensate for some Trx system functions, we investigated its response in three lymphoma cell lines after inhibiting TrxR activity with [Au(d2pype)2]Cl, a known TrxR inhibitor. [Au(d2pype)2]Cl increased intracellular reactive oxygen species (ROS) levels and induced caspase-3 activity leading to cell apoptosis through inhibiting both TrxR and glutathione peroxidase (Gpx) activity. Expression of the tumour suppresser gene TXNIP increased, while GPX1 and GPX4 expression, which are related to poor prognosis of lymphoma patients, decreased. Unlike SUDHL2 and SUDHL4 cells, which exhibited a decreased GSH/GSSG ratio after treatment, in KMH2 cells the ratio remained unchanged, while glutathione reductase and glutaredoxin expression increased. Since KMH2 cells were less sensitive to treatment with [Au(d2pype)2]Cl, the GSH system may play a role in protecting cells from apoptosis after TrxR inhibition. Overall, our study demonstrates that inhibition of TrxR represents a valid therapeutic approach for lymphoma.

Transcriptional regulation of alcohol induced liver fibrosis in a translational porcine hepatocellular carcinoma model

Hepatocellular carcinoma (HCC) is the 5th most common and 2nd deadliest cancer worldwide. HCC risk factors include alcohol induced liver cirrhosis, which prompts hepatic inflammation, cell necrosis, and fibrosis deposition. As 25% of HCC cases are associated with alcohol induced liver disease, understanding the effects of the cirrhotic liver microenvironment on HCC tumor biology and therapeutic responses are critical. This study utilized the Oncopig Cancer Model-a transgenic pig model that recapitulates human HCC through induced expression of KRAS^G12D and TP53^R167H driver mutations-to investigate the molecular mechanisms underlying alcohol induced liver disease. Oncopigs (n = 5) underwent fibrosis induction via infusion of ethanol and ethiodized oil (1:3 v/v dosed at 0.75 mL/kg) into the hepatic arterial circulation. Eight-weeks post induction, liver tissue samples from fibrotic and age-matched control (n = 5) Oncopigs were collected for histological evaluation and transcriptional profiling. Increased hepatic inflammation and fibrosis was observed in fibrotic Oncopigs via pathological assessment. Transcriptional profiling (RNA-seq) resulted in the identification of 4387 differentially expressed genes between Oncopig fibrotic and control livers. GO term enrichment analysis identified pathway alterations associated with cirrhosis progression in humans, including cell proliferation, angiogenesis, extracellular matrix deposition, and oxidation-reduction. Key alterations include activation of hepatic stellate cells, increased matrix metalloproteinase production, and altered expression of ABC and SLC transporter genes involved in transport of anticancer drugs.These results demonstrate Oncopig liver fibrosis recapitulates transcriptional hallmarks of human cirrhosis, making the Oncopig an ideal model for studying the effects of the cirrhotic liver microenvironment on HCC tumor biology and therapeutic response.

Development and clinical validation of a novel 9-gene prognostic model based on multi-omics in pancreatic adenocarcinoma

The prognoses of patients with pancreatic adenocarcinoma (PAAD) remain poor due to the lack of biomarkers for early diagnosis and effective prognosis prediction. RNA sequencing, single nucleotide polymorphism, and copy number variation data were downloaded from The Cancer Genome Atlas (TCGA). Univariate Cox regression was used to identify prognosis-related genes. GISTIC 2.0 was used to identify significantly amplified or deleted genes, and Mutsig 2.0 was used to analyze the mutation data. The Lasso method was used to construct a risk prediction model. The Rms package was used to evaluate the overall predictive performance of the signature. Finally, Western blot and polymerase chain reaction were performed to evaluate gene expression. A total of 54 candidate genes were obtained after integrating the genomic mutated genes and prognosis-related genes. The Lasso method was used to ascertain 9 characteristic genes, including UNC13B, TSPYL4, MICAL1, KLHDC7B, KLHL32, AIM1, ARHGAP18, DCBLD1, and CACNA2D4. The 9-gene signature model was able to help stratify samples at risk in the training and external validation cohorts. In addition, the overall predictive performance of our model was found to be superior to that of other models. KLHDC7B, AIM1, DCBLD1, TSPYL4, and MICAL1 were significantly highly expressed in tumor tissues compared to normal tissues. ARHGAP18 and CACNA2D4 had no difference in expression between tumor and normal tissues. UNC13B and KLHL32 expression in the normal group was higher than in the tumor group. The 9-gene signature constructed in this study can be used as a novel prognostic marker to predict the survival of patients with pancreatic adenocarcinoma.

Intramitochondrial Src kinase links mitochondrial dysfunctions and aggressiveness of breast cancer cells

High levels and activity of Src kinase are common among breast cancer subtypes, and several inhibitors of the kinase are currently tested in clinical trials. Alterations in mitochondrial activity is also observed among the different types of breast cancer. Src kinase is localized in several subcellular compartments, including mitochondria where it targets several proteins to modulate the activity of the organelle. Although the subcellular localization of other oncogenes modulates the potency of known treatments, nothing is known about the specific role of intra-mitochondrial Src (mtSrc) in breast cancer. The aim of this work was to determine whether mtSrc kinase has specific impact on breast cancer cells. We first observed that activity of mtSrc is higher in breast cancer cells of the triple negative subtype. Over-expression of Src specifically targeted to mitochondria reduced mtDNA levels, mitochondrial membrane potential and cellular respiration. These alterations of mitochondrial functions led to lower cellular viability, shorter cell cycle and increased invasive capacity. Proteomic analyses revealed that mtSrc targets the mitochondrial single-stranded DNA-binding protein, a regulator of mtDNA replication. Our findings suggest that mtSrc promotes aggressiveness of breast cancer cells via phosphorylation of mitochondrial single-stranded DNA-binding protein leading to reduced mtDNA levels and mitochondrial activity. This study highlights the importance of considering the subcellular localization of Src kinase in the development of potent therapy for breast cancer.

Identification of novel TGF-β regulated genes with pro-migratory roles

Transforming growth factor-β (TGF-β) signaling plays fundamental roles in the development and homeostasis of somatic cells. Dysregulated TGF-β signaling contributes to cancer progression and relapse to therapies by inducing epithelial-to-mesenchymal transition (EMT), enriching cancer stem cells, and promoting immunosuppression. Although many TGF-β-regulated genes have been identified, only a few datasets were obtained by next-generation sequencing. In this study, we performed RNA-sequencing analysis of MCF10A cells and identified 1166 genes that were upregulated and 861 genes that were downregulated by TGF-β. Gene set enrichment analysis revealed that focal adhesion and metabolic pathways were the top enriched pathways of the up- and downregulated genes, respectively. Genes in these pathways also possess significant predictive value for renal cancers. Moreover, we confirmed that TGF-β induced expression of MICAL1 and 2, and the histone demethylase, KDM7A, and revealed their regulatory roles on TGF-β-induced cell migration. We also show a critical effect of KDM7A in regulating the acetylation of H3K27 on TGF-β-induced genes. In sum, this study identified novel effectors that mediate the pro-migratory role of TGF-β signaling, paving the way for future studies that investigate the function of MICAL family members in cancer and the novel epigenetic mechanisms downstream TGF-β signaling.

Ampelopsin E Reduces the Invasiveness of the Triple Negative Breast Cancer Cell Line, MDA-MB-231

Breast cancer is the most common and the second leading cause of cancer-related deaths in women. It has two distinctive hallmarks: rapid abnormal growth and the ability to invade and metastasize. During metastasis, cancer cells are thought to form actin-rich protrusions, called invadopodia, which degrade the extracellular matrix. Current breast cancer treatments, particularly chemotherapy, comes with adverse effects like immunosuppression, resistance development and secondary tumour formation. Hence, naturally-occurring molecules claimed to be less toxic are being studied as new drug candidates. Ampelopsin E, a natural oligostilbene extracted from Dryobalanops species, has exhibited various pharmacological properties, including anticancer and anti-inflammatory activities. However, there is yet no scientific evidence of the effects of ampelopsin E towards metastasis. Scratch assay, transwell migration and invasion assays, invadopodia and gelatin degradation assays, and ELISA were used to determine the effects of ampelopsin E towards the invasiveness of MDA-MB-231 cells. Strikingly in this study, ampelopsin E was able to halt migration, transmigration and invasion in MDA-MB-231 cells by reducing formation of invadopodia and its degradation capability through significant reduction (p < 0.05) in expression levels of PDGF, MMP2, MMP9 and MMP14. In conclusion, ampelopsin E reduced the invasiveness of MDA-MB-231 cells and was proven to be a potential alternative in treating TNBC.

miR-205-5p suppresses pulmonary vascular smooth muscle cell proliferation by targeting MICAL2-mediated Erk1/2 signaling

Pulmonary arterial hypertension (PAH) is a devastating and fatal vascular disease for which currently there is no satisfying therapy available. Excessive cell proliferation of pulmonary arterial smooth muscle cells (PASMCs) contributes significantly to PAH pathogenesis. In this study, we found that miR-205-5p was lowly expressed in hypoxia-induced PAH mouse model and hypoxia-treated PASMCs. Restoration of miR-205-5p suppressed PASMCs proliferation. In contrast, molecule interacting with CasL 2 (MICAL2) was highly expressed in hypoxia-induced PAH mouse model and hypoxia-treated PASMCs. Overexpression of MICAL2 promoted cell proliferation. Furthermore, miR-205-5p inhibited MICAL2 expression levels by targeting the MICAL2 3' untranslated region. In addition, MICAL2 activated ERK1/2 signaling in PASMCs and ERK1/2 inhibitor blocked MICAL2-mediated-promotion effect on PASMCs proliferation. These results demonstrated that miR-205-5p suppressed PASMCs proliferation by targeting MICAL2, which activated ERK1/2 signaling. Therefore, miR-205-5p/MICAL2/Erk1/2 may serve as an ideal therapeutic target to PAH treatment.

MICAL-L2 potentiates Cdc42-dependent EGFR stability and promotes gastric cancer cell migration

Enhanced migration potential is a common characteristic of cancer cells induced by mechanisms that are incompletely defined. The present study was designed to investigate relationship of a new discovered cytoskeleton regulator MICAL‐L2 and the endogenous epidermal growth factor receptor (EGFR) signalling pathways in gastric cancer cell migration. Increased expression of MICAL‐L2 in gastric cancer cells up‐regulated EGFR protein level, accompanied by the increase of cell migration, whereas silencing MICAL‐L2 down‐regulated EGFR and inhibited cell migration. Expression of MICAL‐L2 was also shown positively correlated with the activation of HSP27/cytoskeleton and HSP27/β‐catenin signalling pathways that provide key mechanisms controlling cell migration. The up‐regulating effect of MICAL‐L2 on EGFR is mediated through a transcription‐independent mechanism that involves inhibiting EGFR protein degradation in lysosome. Further analysis indicated that Cdc42 activation contributed in maintaining the effect of MICAL‐L2 on EGFR stability. Furthermore analysis of clinic specimens revealed increased expression of MICAL‐L2 in carcinoma tissues and a positive correlation between MICAL‐L2 and EGFR expression levels. The above results indicate that MICAL‐L2 potentiates gastric cell migration via inhibiting EGFR degradation in lysosome via a Cdc42‐dependent manner that leads to the activation of EGFR/HSP27 signalling pathways.

Non-canonical Notch Signaling Regulates Actin Remodeling in Cell Migration by Activating PI3K/AKT/Cdc42 Pathway

Tumor cell migration is a critical step in cancer metastasis. Over-activated Notch pathway can promote the migration of cancer cells, especially in the breast cancer. However, the underlying mechanism of non-canonical Notch signaling in modulating the migration has not yet been clearly characterized. Here we demonstrated that DAPT, a gamma secretase inhibitor, inhibited protrusion formation and cell motility, and then reduced the migration of triple-negative breast cancer cells, through increasing the activity of Cdc42 by non-canonical Notch pathway. Phosphorylation of AKT on S473 was surprisingly increased when Notch signaling was inhibited by DAPT. Inhibition of PI3K and AKT by LY294002 and MK2206, respectively, or knockdown of AKT expression by siRNA blocked DAPT-induced activation of Cdc42. Moreover, immunofluorescence staining further showed that DAPT treatment reduced the formation of lamellipodia and induced actin cytoskeleton remodeling. Taken together, these results indicated that DAPT inhibited Notch signaling and consequently activated PI3K/AKT/Cdc42 signaling by non-canonical pathway, facilitated the formation of filopodia and inhibited the assembly of lamellipodia, and finally resulted in the decrease of migration activity of breast cancer cells.

NEDD9 Facilitates Hypoxia-Induced Gastric Cancer Cell Migration via MICAL1 Related Rac1 Activation

Aims and Hypothesis: NEDD9 is highly expressed in gastric cancer and has a significant involvement in its pathogenesis. However, the mechanism behind hypoxia-promoted cancer cell migration and its regulation because of NEDD9 is still unknown. The aim of this study is to investigate the involvement of NEDD9 in gastric cancer cell migration under hypoxia and explore the underlying potential molecular mechanisms.

Actin Post-translational Modifications: The Cinderella of Cytoskeletal Control

Actin is one of the most abundant proteins in eukaryotic cells and the main component of the microfilament system. It plays essential roles in numerous cellular activities, including muscle contraction, maintenance of cell integrity, and motility, as well as transcriptional regulation. Besides interacting with various actin-binding proteins (ABPs), proper actin function is regulated by post-translational modifications (PTMs), such as acetylation, arginylation, oxidation, and others. Here, we explain how actin PTMs can contribute to filament formation and stability, and may have additional actin regulatory functions, which potentially contribute to disease development.

EGF Stimulates Rab35 Activation and Gastric Cancer Cell Migration by Regulating DENND1A-Grb2 Complex Formation

Aims: The aim of this study was to reveal the specific molecular mechanisms by which DENND1A accepts EGF signaling and activates Rab35 in gastric cancer.

Methods: The expression of proteins related to DENND1A was examined by western blot analysis. Activation of Rab35 was assessed by GST-pulldown. The interaction of DENND1A and Grb2 was assessed by GST-pulldown and co-immunoprecipitation assays. The relationship between DENND1A and cell migration and invasion was detected using wound healing and transwell by gene overexpression and RNA interference.

Results: EGF stimulation significantly promoted cell migration, whereas transfection with siRab35 partially inhibited EGF-promoted cell migration. DENND1A is also involved in these processes and active Rab35. Moreover, DENND1A binds to the N-terminal and C-terminal SH3 domains of Grb2 through PRD. Of special interest is the observation that EGFR can recruit Grb2-DENND1A complex under EGF stimulation. Further results reveal that the higher the expression of DENND1A, the shorter progression-free survival of gastric cancer patients.

Conclusion: In summary, we confirmed that EGF-Grb2-DENND1A-Rab35 signaling pathway with the interaction of DENND1A and Grb2 as a regulatory center could regulate gastric cancer cell migration and invasion. Ultimately, the expression level of DENND1A predicts the survival status of gastric cancer patients and may become one of the important targets for the treatment of gastric cancer.

Human MICAL1: Activation by the small GTPase Rab8 and small-angle X-ray scattering studies on the oligomerization state of MICAL1 and its complex with Rab8

Human MICAL1 is a member of a recently discovered family of multidomain proteins that couple a FAD-containing monooxygenase-like domain to typical protein interaction domains. Growing evidence implicates the NADPH oxidase reaction catalyzed by the flavoprotein domain in generation of hydrogen peroxide as a second messenger in an increasing number of cell types and as a specific modulator of actin filaments stability. Several proteins of the Rab families of small GTPases are emerging as regulators of MICAL activity by binding to its C-terminal helical domain presumably shifting the equilibrium from the free - auto-inhibited - conformation to the active one. We here extend the characterization of the MICAL1-Rab8 interaction and show that indeed Rab8, in the active GTP-bound state, stabilizes the active MICAL1 conformation causing a specific four-fold increase of k_cat of the NADPH oxidase reaction. Kinetic data and small-angle X-ray scattering (SAXS) measurements support the formation of a 1:1 complex between full-length MICAL1 and Rab8 with an apparent dissociation constant of approximately 8 μM. This finding supports the hypothesis that Rab8 is a physiological regulator of MICAL1 activity and shows how the protein region preceding the C-terminal Rab-binding domain may mask one of the Rab-binding sites detected with the isolated C-terminal fragment. SAXS-based modeling allowed us to propose the first model of the free full-length MICAL1, which is consistent with an auto-inhibited conformation in which the C-terminal region prevents catalysis by interfering with the conformational changes that are predicted to occur during the catalytic cycle.

Rab11a-Rab8a cascade regulates the formation of tunneling nanotubes through vesicle recycling

Tunneling nanotubes (TNTs) are actin-enriched membranous channels enabling cells to communicate over long distances. TNT-like structures form between various cell types and mediate the exchange of different cargos, such as ions, vesicles, organelles and pathogens; thus, they may play a role in physiological conditions and diseases (e.g. cancer and infection). TNTs also allow the intercellular passage of protein aggregates related to neurodegenerative diseases, thus propagating protein misfolding. Understanding the mechanism of TNT formation is mandatory in order to reveal the mechanism of disease propagation and to uncover their physiological function. Vesicular transport controlled by the small GTPases Rab11a and Rab8a can promote the formation of different plasma membrane protrusions (filopodia, cilia and neurites). Here, we report that inhibiting membrane recycling reduces the number of TNT-connected cells and that overexpression of Rab11a and Rab8a increases the number of TNT-connected cells and the propagation of vesicles between cells in co-culture. We demonstrate that these two Rab GTPases act in a cascade in which Rab11a activation of Rab8a is independent of Rabin8. We also show that VAMP3 acts downstream of Rab8a to regulate TNT formation.

The role of the oncogenic Rab35 in cancer invasion, metastasis, and immune evasion, especially in leukemia

The study of cancer has allowed researchers to describe some biological characteristics that tumor cells acquire during their development, known as the “hallmarks of cancer” but more research is needed to expand our knowledge about cancer biology and to generate new strategies of treatment. The role that RabGTPases might play in some hallmarks of cancer represents interesting areas of study since these proteins are frequently altered in cancer. However, their participation is not well known. Recently, Rab35was recognized as an oncogenic RabGTPase and and because of its association with different cellular functions, distinctly important in immune cells, a possible role of Rab35 in leukemia can be suggested. Nevertheless, the involvement of Rab35 in cancer remains poorly understood and its possible specific role in leukemia remains unknown. In this review, we analyze general aspects of the participation of RabGTPases in cancer, and especially, the plausible role of Rab35 in leukemia.

NEDD9 stimulated MMP9 secretion is required for invadopodia formation in oral squamous cell carcinoma

Neural precursor cell expressed developmentally downregulated 9 (NEDD9) is a component of the metastatic signatures of melanoma, breast cancer, glioblastoma, lung cancer and head and neck squamous cell carcinoma (HNSCC). Here we tested the efficacy of NEDD9's domains in stimulating matrix metalloproteinase (MMP) secretion and invadopodia formation in cells stably expressing various NEDD9 mutants. Replacement of the 13 YxxP motif substrate domain (SD) tyrosines and the C-terminal Y629 with phenylalanines (F14NEDD9) eliminated tyrosine phosphorylation, MMP9 secretion and loss of invadopodia formation. Mutation of the N-terminal SH3 domain Y12 to glutamic acid (Y12ENEDD9) or phenylalanine (Y12FNEDD9) reduced MMP9 secretion and inhibited invadopodia formation. SH3 domain deletion (∆SH3NEDD9) resulted in the loss of MMP9 secretion and a lack of invadopodia formation. The SH3–SD domain (SSNEDD9) construct exhibited tyrosine phosphorylation and stimulated MMP9 secretion, as did ∆CTNEDD9 which lacked the C-terminus (∆C-terminal; ∆CT). E13NEDD9 expression blocked MMP9 secretion and invadopodia formation. MICAL1 (molecule interacting with Cas-L1) silencing with a short hairpin RNA reduced MMP9 secretion, vimentin and E-cadherin levels while increasing N-cadherin and Rab6 levels, consistent with reduced invasive behavior. These findings indicate that NEDD9 SD phosphorylation and SH3 domain interactions are necessary for increasing MMP9 secretion and invadopodia formation.

MICAL1 facilitates breast cancer cell proliferation via ROS-sensitive ERK/cyclin D pathway

Molecule interacting with CasL 1 (MICAL1) is a multidomain flavoprotein mono-oxygenase that strongly involves in cytoskeleton dynamics and cell oxidoreduction metabolism. Recently, results from our laboratory have shown that MICAL1 modulates reactive oxygen species (ROS) production, and the latter then activates phosphatidyl inositol 3-kinase (PI3K)/protein kinase B (Akt) signalling pathway which regulates breast cancer cell invasion. Herein, we performed this study to assess the involvement of MICAL1 in breast cancer cell proliferation and to explore the potential molecular mechanism. We noticed that depletion of MICAL1 markedly reduced cell proliferation in breast cancer cell line MCF-7 and T47D. This effect of MICAL1 on proliferation was independent of wnt/β-catenin and NF-κB pathways. Interestingly, depletion of MICAL1 significantly inhibited ROS production, decreased p-ERK expression and unfavourable for proliferative phenotype of breast cancer cells. Likewise, MICAL1 overexpression increased p-ERK level as well as p-ERK nucleus translocation. Moreover, we investigated the effect of MICAL1 on cell cycle-related proteins. MICAL1 positively regulated CDK4 and cyclin D expression, but not CDK2, CDK6, cyclin A and cyclin E. In addition, more expression of CDK4 and cyclin D by MICAL1 overexpression was blocked by PI3K/Akt inhibitor LY294002. LY294002 treatment also attenuated the increase in the p-ERK level in MICAL1-overexpressed breast cancer cells. Together, our results suggest that MICAL1 exhibits its effect on proliferation via maintaining cyclin D expression through ROS-sensitive PI3K/Akt/ERK signalling in breast cancer cells.

Rab35 GTPase and cancer: Linking membrane trafficking to tumorigenesis

Rab35 is a small GTPase that is involved in many cellular processes, including membrane trafficking, cell polarity, lipid homeostasis, immunity, phagocytosis and cytokinesis. Recent studies showed that activating mutations confer Rab35 with oncogenic properties. Conversely, downregulation of Rab35 inverts apico-basal cell polarity and promotes cell migration. Here we review Rab35's known functions in membrane trafficking and signaling, cell division and cell migration in cancer cells and discuss the importance of Rab35-dependent membrane trafficking in cancer progression.

MICAL2 promotes breast cancer cell migration by maintaining epidermal growth factor receptor (EGFR) stability and EGFR/P38 signalling activation

AIM

MICAL2, a cytoskeleton dynamics regulator, is identified associated with survival and metastasis of several types of cancers recently. This study was designed to investigate the role of MICAL2 in breast cancer cell migration as well as its underlying mechanisms.

METHODS

The relationship between MICAL2 and EGF/EGFR signalling was analysed by gene overexpression and knock-down techniques. Cell migration was measured by wound-healing assays. Activation of EGF/EGFR signalling pathways were evaluated by immunofluorescence, qPCR, Western blotting and zymography techniques. Rac1 activity was assessed by pull-down assay. Correlation of MICAL2 and EGFR in breast cancer specimens was examined by immunohistochemical analysis.

RESULTS

Ectopic expression of MICAL2 in MCF-7 cells augmented EGFR protein level, accompanied by the promotion of cell migration. Silencing MICAL2 in MDA-MB-231 cells destabilized EGFR and inhibited cell migration. In mechanism, the maintaining effect of MICAL2 on EGFR protein content was due to a delay in EGFR degradation. Expression of MICAL2 was also shown positively correlated with the activation of P38/HSP27 and P38/MMP9 signallings, which are the main downstream signalling cascades of EGF/EGFR involved in cell migration. Further analysis indicated that Rac1 activation contributed to the maintaining effect of MICAL2 on EGFR stability. In addition, analysis of breast cancer specimens revealed a positive correlation between MICAL2 and EGFR levels and an association between MICAL2 expression and worse prognosis.

CONCLUSION

MICAL2 is a major regulator of breast cancer cell migration, maintaining EGFR stability and subsequent EGFR/P38 signalling activation through inhibiting EGFR degradation in a Rac1-dependent manner.

Mesenchymal stem cells promote cell invasion and migration and autophagy-induced epithelial-mesenchymal transition in A549 lung adenocarcinoma cells

Mesenchymal stem cells (MSCs) are recruited into the tumour microenvironment and promote tumour growth and metastasis. Tumour microenvironment-induced autophagy is considered to suppress primary tumour formation by impairing migration and invasion. Whether these recruited MSCs regulate tumour autophagy and whether autophagy affects tumour growth are controversial. Our data showed that MSCs promote autophagy activation, reactive oxygen species production, and epithelial-mesenchymal transition (EMT) as well as increased migration and invasion in A549 cells. Decreased expression of E-cadherin and increased expression of vimentin and Snail were observed in A549 cells cocultured with MSCs. Conversely, MSC coculture-mediated autophagy positively promoted tumour EMT. Autophagy inhibition suppressed MSC coculture-mediated EMT and reduced A549 cell migration and invasion slightly. Furthermore, the migratory and invasive abilities of A549 cells were additional increased when autophagy was further enhanced by rapamycin treatment. Taken together, this work suggests that microenvironments containing MSCs can promote autophagy activation for enhancing EMT; MSCs also increase the migratory and invasive abilities of A549 lung adenocarcinoma cells. Mesenchymal stem cell-containing microenvironments and MSC-induced autophagy signalling may be potential targets for blocking lung cancer cell migration and invasion.

The MICALs are a Family of F-actin Dismantling Oxidoreductases Conserved from Drosophila to Humans

Cellular form and function – and thus normal development and physiology – are specified via proteins that control the organization and dynamic properties of the actin cytoskeleton. Using the Drosophila model, we have recently identified an unusual actin regulatory enzyme, Mical, which is directly activated by F-actin to selectively post-translationally oxidize and destabilize filaments – regulating numerous cellular behaviors. Mical proteins are also present in mammals, but their actin regulatory properties, including comparisons among different family members, remain poorly defined. We now find that each human MICAL family member, MICAL-1, MICAL-2, and MICAL-3, directly induces F-actin dismantling and controls F-actin-mediated cellular remodeling. Specifically, each human MICAL selectively associates with F-actin, which directly induces MICALs catalytic activity. We also find that each human MICAL uses an NADPH-dependent Redox activity to post-translationally oxidize actin’s methionine (M) M44/M47 residues, directly dismantling filaments and limiting new polymerization. Genetic experiments also demonstrate that each human MICAL drives F-actin disassembly in vivo, reshaping cells and their membranous extensions. Our results go on to reveal that MsrB/SelR reductase enzymes counteract each MICAL’s effect on F-actin in vitro and in vivo. Collectively, our results therefore define the MICALs as an important phylogenetically-conserved family of catalytically-acting F-actin disassembly factors.

Overexpression of MICAL2, a novel tumor-promoting factor, accelerates tumor progression through regulating cell proliferation and EMT

Molecule interacting with CasL 2 (MICAL2), a microtubule associated monooxygenase, is involved in cell growth, axon guidance, vesicle trafficking and apoptosis. Recent studies have demonstrated that MICAL2 is highly expressed in tumor and accelerates tumor progression and it is deemed to be a novel tumor-promoting factor. MICAL2 overexpression increases cell proliferation to accelerate tumor growth, and MICAL2 also promotes epithelial-mesenchymal transition (EMT)-related proteins to increase cancer cell metastasis. On mechanism, MICAL2 induces EMT by regulating SRF (serum response factor)/MRTF-A (myocardin related transcription factor A) signaling, Semaphorin/Plexin pathway and inducing ROS (Reactive oxygen species) production. In the present review, we introduced MICAL family, expatiated the structure and functions of MICALs, and summarized the mechanisms of MICAL2 involving tumor progression. The challenges and perspectives for MICAL2 in tumor are also discussed.

Folliculin Interacts with Rab35 to Regulate EGF-Induced EGFR Degradation

Aims and Hypothesis: This study aims to investigate the mechanism involved in intracellular regulation of EGFR degradation induced by EGF.

Methods: Phosphorylation of proteins related to EGFR signaling was examined by western blot analysis. Activation, connection between Rab35 and folliculin (FLCN) were assessed by pulldown, coimmunoprecipitation assays separately. The relationship between FLCN and cell growth was detected using gene overexpression and knock-down techniques.

Results: Here, we demonstrate that interfering with FLCN, a tumor suppressor, reduces the rate of EGF-induced EGFR degradation, resulting in prolonged activation of downstream signaling. Rab35 is also involved in these processes. Moreover, C-terminal of FLCN binds to and activates Rab35. Of special interest is the observation that erlotinib, a selective EGFR inhibitor, not only obstructs the EGFR-mediated cellular signaling, but also abolishes EGF-stimulated EGFR degradation. Further results reveal that EGF facilitates the activation of Rab35, and FLCN modulates EGF-dependent Rab35 activation and cell growth.

Conclusions: Taken together, our study proposes a negative-feedback regulation model in which FLCN mediates EGF-induced Rab35 activation, thereby increasing EGFR degradation and attenuating EGFR signaling.

Regulated methionine oxidation by monooxygenases

Protein function can be regulated via post-translational modifications by numerous enzymatic and non-enzymatic mechanisms, including oxidation of cysteine and methionine residues. Redox-dependent regulatory mechanisms have been identified for nearly every cellular process, but the major paradigm has been that cellular components are oxidized (damaged) by reactive oxygen species (ROS) in a relatively unspecific way, and then reduced (repaired) by designated reductases. While this scheme may work with cysteine, it cannot be ascribed to other residues, such as methionine, whose reaction with ROS is too slow to be biologically relevant. However, methionine is clearly oxidized in vivo and enzymes for its stereoselective reduction are present in all three domains of life. Here, we revisit the chemistry and biology of methionine oxidation, with emphasis on its generation by enzymes from the monooxygenase family. Particular attention is placed on MICALs, a recently discovered family of proteins that harbor an unusual flavin-monooxygenase domain with an NADPH-dependent methionine sulfoxidase activity. Based on structural and kinetic information we provide a rational framework to explain MICAL mechanism, inhibition, and regulation. Methionine residues that are targeted by MICALs are reduced back by methionine sulfoxide reductases, suggesting that reversible methionine oxidation may be a general mechanism analogous to the regulation by phosphorylation by kinases/phosphatases. The identification of new enzymes that catalyze the oxidation of methionine will open a new area of research at the forefront of redox signaling.

Amplification of F-Actin Disassembly and Cellular Repulsion by Growth Factor Signaling

Extracellular cues that regulate cellular shape, motility, and navigation are generally classified as growth promoting (i.e., growth factors/chemoattractants and attractive guidance cues) or growth preventing (i.e., repellents and inhibitors). Yet, these designations are often based on complex assays and undefined signaling pathways and thus may misrepresent direct roles of specific cues. Here, we find that a recognized growth-promoting signaling pathway amplifies the F-actin disassembly and repulsive effects of a growth-preventing pathway. Focusing on Semaphorin/Plexin repulsion, we identified an interaction between the F-actin-disassembly enzyme Mical and the Abl tyrosine kinase. Biochemical assays revealed Abl phosphorylates Mical to directly amplify Mical Redox-mediated F-actin disassembly. Genetic assays revealed that Abl allows growth factors and Semaphorin/Plexin repellents to combinatorially increase Mical-mediated F-actin disassembly, cellular remodeling, and repulsive axon guidance. Similar roles for Mical in growth factor/Abl-related cancer cell behaviors further revealed contexts in which characterized positive effectors of growth/guidance stimulate such negative cellular effects as F-actin disassembly/repulsion.

Structure-function studies of MICAL, the unusual multidomain flavoenzyme involved in actin cytoskeleton dynamics

MICAL (from the Molecule Interacting with CasL) indicates a family of multidomain proteins conserved from insects to humans, which are increasingly attracting attention for their participation in the control of actin cytoskeleton dynamics, and, therefore, in the several related key processes in health and disease. MICAL is unique among actin binding proteins because it catalyzes a NADPH-dependent F-actin depolymerizing reaction. This unprecedented reaction is associated with its N-terminal FAD-containing domain that is structurally related to p-hydroxybenzoate hydroxylase, the prototype of aromatic monooxygenases, but catalyzes a strong NADPH oxidase activity in the free state. This review will focus on the known structural and functional properties of MICAL forms in order to provide an overview of the arguments supporting the current hypotheses on the possible mechanism of action of MICAL in the free and F-actin bound state, on the modulating effect of the CH, LIM, and C-terminal domains that follow the catalytic flavoprotein domain on the MICAL activities, as well as that of small molecules and proteins interacting with MICAL.

Emerging roles of MICAL family proteins - from actin oxidation to membrane trafficking during cytokinesis

Cytokinetic abscission is the terminal step of cell division, leading to the physical separation of the two daughter cells. The exact mechanism mediating the final scission of the intercellular bridge connecting the dividing cells is not fully understood, but requires the local constriction of endosomal sorting complex required for transport (ESCRT)-III-dependent helices, as well as remodelling of lipids and the cytoskeleton at the site of abscission. In particular, microtubules and actin filaments must be locally disassembled for successful abscission. However, the mechanism that actively removes actin during abscission is poorly understood. In this Commentary, we will focus on the latest findings regarding the emerging role of the MICAL family of oxidoreductases in F-actin disassembly and describe how Rab GTPases regulate their enzymatic activity. We will also discuss the recently reported role of MICAL1 in controlling F-actin clearance in the ESCRT-III-mediated step of cytokinetic abscission. In addition, we will highlight how two other members of the MICAL family (MICAL3 and MICAL-L1) contribute to cytokinesis by regulating membrane trafficking. Taken together, these findings establish the MICAL family as a key regulator of actin cytoskeleton dynamics and membrane trafficking during cell division.

Oxidation of F-actin controls the terminal steps of cytokinesis

Cytokinetic abscission, the terminal step of cell division, crucially depends on the local constriction of ESCRT-III helices after cytoskeleton disassembly. While the microtubules of the intercellular bridge are cut by the ESCRT-associated enzyme Spastin, the mechanism that clears F-actin at the abscission site is unknown. Here we show that oxidation-mediated depolymerization of actin by the redox enzyme MICAL1 is key for ESCRT-III recruitment and successful abscission. MICAL1 is recruited to the abscission site by the Rab35 GTPase through a direct interaction with a flat three-helix domain found in MICAL1 C terminus. Mechanistically, in vitro assays on single actin filaments demonstrate that MICAL1 is activated by Rab35. Moreover, in our experimental conditions, MICAL1 does not act as a severing enzyme, as initially thought, but instead induces F-actin depolymerization from both ends. Our work reveals an unexpected role for oxidoreduction in triggering local actin depolymerization to control a fundamental step of cell division.

Cytokinetic abscission relies on the local constriction after cytoskeleton disassembly, but it is not known how the actin filaments are disassembled. Here, the authors show that the redox enzyme MICAL1 is recruited by Rab35 and induces oxidation-mediated depolymerization of actin, which is required to recruit ESCRT-III and complete abscission.