Gαi1 and Gαi3mediate VEGF-induced VEGFR2 endocytosis, signaling and angiogenesis

Requirement of Gαi1 and Gαi3 in interleukin-4-induced signaling, macrophage M2 polarization and allergic asthma response

IL-4 induces Akt activation in macrophages, required for full M2 (alternative) polarization. We examined the roles of Gαi1 and Gαi3 in M2 polarization using multiple genetic methods.

Methods and Results: In MEFs and primary murine BMDMs, Gαi1/3 shRNA, knockout or dominant negative mutations attenuated IL-4-induced IL4Rα endocytosis, Gab1 recruitment as well as Akt activation, leaving STAT6 signaling unaffected. Following IL-4 stimulation, Gαi1/3 proteins associated with the intracellular domain of IL-4Rα and the APPL1 adaptor, to mediate IL-4Rα endosomal traffic and Gab1-Akt activation in BMDMs. In contrast, gene silencing of Gαi1/3 with shRNA or knockout resulted in BMDMs that were refractory to IL-4-induced M2 polarization. Conversely, Gαi1/3-overexpressed BMDMs displayed preferred M2 response with IL-4 stimulation. In primary human macrophages IL-4-induced Akt activation and Th2 genes expression were inhibited with Gαi1/3 silencing, but augmented with Gαi1/3 overexpression. In Gαi1/3 double knockout (DKO) mice, M2 polarization, by injection of IL-4 complex or chitin, was potently inhibited. Moreover, in a murine model of asthma, ovalbumin-induced airway inflammation and hyperresponsiveness were largely impaired in Gαi1/3 DKO mice.

Conclusion: These findings highlight novel and essential roles for Gαi1/3 in regulating IL-4-induced signaling, macrophage M2 polarization and allergic asthma response.

Transactivation of G protein-coupled receptors (GPCRs) and receptor tyrosine kinases (RTKs): Recent insights using luminescence and fluorescence technologies

Alterations in signalling due to bidirectional transactivation of G protein-coupled receptor (GPCRs) and receptor tyrosine kinases (RTKs) are well established. Transactivation significantly diversifies signalling networks within a cell and has been implicated in promoting both advantageous and disadvantageous physiological and pathophysiological outcomes, making the GPCR/RTK interactions attractive new targets for drug discovery programmes. Transactivation has been observed for a plethora of receptor pairings in multiple cell types; however, the precise molecular mechanisms and signalling effectors involved can vary with receptor pairings and cell type. This short review will discuss the recent applications of proximity-based assays, such as resonance energy transfer and fluorescence-based imaging in investigating the dynamics of GPCR/RTK complex formation, subsequent effector protein recruitment and the cellular locations of complexes in living cells.

SphK1-targeted miR-6784 inhibits functions of skin squamous cell carcinoma cells

Sphingosine kinase 1 (SphK1) is overexpressed in skin squamous cell carcinoma (SCC). It has emerged as a novel therapeutic oncotarget. The current study identified a novel SphK1-targeting microRNA, microRNA-6784 (miR-6784). Here, we show that miR-6784 is located at the cytoplasm of A431 skin SCC cells. It directly binds to SphK1 mRNA. Ectopic overexpression of miR-6784 inhibited SphK1 3’-untranslated region (UTR) luciferase activity and downregulated its expression. Moreover, miR-6784 overexpression caused ceramide accumulation in skin SCC cells. Functional studies in established (A431 and SCC9) and primary skin SCC cells revealed that miR-6784 overexpression inhibited cell viability, proliferation, migration, and invasion. It also simultaneously provoked apoptosis activation. Conversely, miR-6784 silencing by antagomiR-6784 induced SphK1 elevation and augmented A431 cell proliferation, migration, and invasion. miR-6784 overexpression-induced anti-A431 cell activity was inhibited by the expression of an UTR-null SphK1 construct. CRISPR/Cas9-induced SphK1 knockout inhibited A431 cell growth. Importantly, miR-6784 was completely ineffective when treating SphK1-knockout A431 cells. Collectively, miR-6784 silences SphK1 and inhibits skin SCC cell progression.

Ulinastatin alleviates traumatic brain injury by reducing endothelin-1

Background

Brain edema is one of the major causes of fatality and disability associated with injury and neurosurgical procedures. The goal of this study was to evaluate the effect of ulinastatin (UTI), a protease inhibitor, on astrocytes in a rat model of traumatic brain injury (TBI).

Methodology

A rat model of TBI was established. Animals were randomly divided into 2 groups – one group was treated with normal saline and the second group was treated with UTI (50,000 U/kg). The brain water content and permeability of the blood–brain barrier were assessed in the two groups along with a sham group (no TBI). Expression of the glial fibrillary acidic protein, endthelin-1 (ET-1), vascular endothelial growth factor (VEGF), and matrix metalloproteinase 9 (MMP-9) were measured by immunohistochemistry and western blot. Effect of UTI on ERK and PI3K/AKT signaling pathways was measured by western blot.

Results

UTI significantly decreased the brain water content and extravasation of the Evans blue dye. This attenuation was associated with decreased activation of the astrocytes and ET-1. UTI treatment decreased ERK and Akt activation and inhibited the expression of pro-inflammatory VEGF and MMP-9.

Conclusion

UTI can alleviate brain edema resulting from TBI by inhibiting astrocyte activation and ET-1 production.

Three-dimensional Imaging Coupled with Topological Quantification Uncovers Retinal Vascular Plexuses Undergoing Obliteration

Introduction: Murine models provide microvascular insights into the 3-D network disarray seen in retinopathy and cardiovascular diseases. Light-sheet fluorescence microscopy (LSFM) has emerged to capture retinal vasculature in 3-D, allowing for assessment of the progression of retinopathy and the potential to screen new therapeutic targets in mice. We hereby coupled LSFM, also known as selective plane illumination microscopy, with topological quantification, to characterize the retinal vascular plexuses undergoing preferential obliteration. Method and Result: In postnatal mice, we revealed the 3-D retinal microvascular network in which the vertical sprouts bridge the primary (inner) and secondary (outer) plexuses, whereas, in an oxygen-induced retinopathy (OIR) mouse model, we demonstrated preferential obliteration of the secondary plexus and bridging vessels with a relatively unscathed primary plexus. Using clustering coefficients and Euler numbers, we computed the local versus global vascular connectivity. While local connectivity was preserved (p > 0.05, n = 5 vs. normoxia), the global vascular connectivity in hyperoxia-exposed retinas was significantly reduced (p < 0.05, n = 5 vs. normoxia). Applying principal component analysis (PCA) for auto-segmentation of the vertical sprouts, we corroborated the obliteration of the vertical sprouts bridging the secondary plexuses, as evidenced by impaired vascular branching and connectivity, and reduction in vessel volumes and lengths (p < 0.05, n = 5 vs. normoxia). Conclusion: Coupling 3-D LSFM with topological quantification uncovered the retinal vasculature undergoing hyperoxia-induced obliteration from the secondary (outer) plexus to the vertical sprouts. The use of clustering coefficients, Euler's number, and PCA provided new network insights into OIR-associated vascular obliteration, with translational significance for investigating therapeutic interventions to prevent visual impairment.

Apatinib induces apoptosis and autophagy via the PI3K/AKT/mTOR and MAPK/ERK signaling pathways in neuroblastoma

The clinical outcome of neuroblastoma (NB) has significantly improved in the last 30 years for patients with localized disease; however, the overall survival (OS) for patients with metastasis remains poor. Apatinib, a selective inhibitor of the vascular endothelial growth factor receptor-2 (VEGFR-2) tyrosine kinase, which was discovered to be highly associated with metastasis, has been reported to exert antitumor effects in numerous types of cancer. However, the effect of apatinib in NB remains relatively unknown. The present study aimed to investigate the antitumor effects of apatinib in NB cells in vitro. The results revealed that apatinib inhibited cell viability and colony formation, whilst inducing cell cycle arrest and the apoptosis of NB cells. Additionally, apatinib inhibited the migration and invasion of NB cells, in addition to promoting the autophagy of NB cells. Western blotting demonstrated that the protein expression levels of phosphorylated (p)-AKT, p-mTOR and p-P70S6K, and downstream molecules associated with the cell cycle and apoptosis, such as cyclin D1 and the Bcl-2/Bax ratio of NB cells, were significantly decreased following treatment with apatinib. In addition, western blotting and immunofluorescence assays identified that the expression level of microtubule-associated protein 1A/1B-light chain 3-II, which is expressed in autophagosomes, was upregulated following apatinib treatment. In conclusion, the findings of the present study suggested that apatinib may induce apoptosis and autophagy via the PI3K/AKT/mTOR and mitogen-activated protein kinase/ERK signaling pathways in NB cells. Thus, apatinib may be a potential antitumor agent for the clinical treatment of NB.

Protective effect of Soluble Epoxide Hydrolase Inhibition in Retinal Vasculopathy associated with Polycystic Kidney Disease

Rationale: Vasoregression secondary to glial activation develops in various retinal diseases, including retinal degeneration and diabetic retinopathy. Photoreceptor degeneration and subsequent retinal vasoregression, characterized by pericyte loss and acellular capillary formation in the absence diabetes, are also seen in transgenic rats expressing the polycystic kidney disease (PKD) gene. Activated Müller glia contributes to retinal vasodegeneration, at least in part via the expression of the soluble epoxide hydrolase (sEH). Given that an increase in sEH expression triggered vascular destabilization in diabetes, and that vasoregression is similar in diabetic mice and PKD rats, the aim of the present study was to determine whether sEH inhibition could prevent retinal vasoregression in the PKD rat.

Methods: One-month old male homozygous transgenic PKD rats were randomly allocated to receive vehicle or a sEH inhibitor (sEH-I; Sar5399, 30 mg/kg) for four weeks. Wild-type Sprague-Dawley (SD) littermates received vehicle as controls. Retinal sEH expression and activity were measured by Western blotting and LC-MS, and vasoregression was quantified in retinal digestion preparations. Microglial activation and immune response cytokines were assessed by immunofluorescence and quantitative PCR, respectively. 19,20-dihydroxydocosapentaenoic acid (19,20-DHDP) mediated Notch signaling, microglial activation and migration were assessed in vivo and in vitro.

Results: This study demonstrates that sEH expression and activity were increased in PKD retinae, which led to elevated production of 19,20-DHDP and the depression of Notch signaling. The latter changes elicited pericyte loss and the recruitment of CD11b⁺/CD74⁺ microglia to the perivascular region. Microglial activation increased the expression of immune-response cytokines, and reduced levels of Notch3 and delta-like ligand 4 (Dll4). Treatment with Sar5399 decreased 19,20-DHDP generation and increased Notch3 expression. Sar5399 also prevented vasoregression by reducing pericyte loss and suppressed microglial activation as well as the expression of immune-response cytokines. Mechanistically, the activation of Notch signaling by Dll4 maintained a quiescent microglial cell phenotype, i.e. reduced both the surface presentation of CD74 and microglial migration. In contrast, in retinal explants, 19,20-DHDP and Notch inhibition both promoted CD74 expression and reversed the Dll4-induced decrease in migration.

Conclusions: Our data indicate that 19,20-DHDP-induced alterations in Notch-signaling result in microglia activation and pericyte loss and contribute to retinal vasoregression in polycystic kidney disease. Moreover, sEH inhibition can ameliorate vasoregression through reduced activity of inflammatory microglia. sEH inhibition is thus an attractive new therapeutic approach to prevent retinal vasoregression.

Oxidative Stress Induces a VEGF Autocrine Loop in the Retina: Relevance for Diabetic Retinopathy

BACKGROUND

Oxidative stress (OS) plays a central role in diabetic retinopathy (DR), triggering expression and release of vascular endothelial growth factor (VEGF), the increase of which leads to deleterious vascular changes. We tested the hypothesis that OS-stimulated VEGF induces its own expression with an autocrine mechanism.

METHODS

MIO-M1 cells and ex vivo mouse retinal explants were treated with OS, with exogenous VEGF or with conditioned media (CM) from OS-stressed cultures.

RESULTS

Both in MIO-M1 cells and in retinal explants, OS or exogenous VEGF induced a significant increase of VEGF mRNA, which was abolished by VEGF receptor 2 (VEGFR-2) inhibition. OS also caused VEGF release. In MIO-M1 cells, CM induced VEGF expression, which was abolished by a VEGFR-2 inhibitor. Moreover, the OS-induced increase of VEGF mRNA was abolished by a nuclear factor erythroid 2-related factor 2 (Nrf2) blocker, while the effect of exo-VEGF resulted Nrf2-independent. Finally, both the exo-VEGF- and the OS-induced increase of VEGF expression were blocked by a hypoxia-inducible factor-1 inhibitor.

CONCLUSIONS

These results are consistent with the existence of a retinal VEGF autocrine loop triggered by OS. This mechanism may significantly contribute to the maintenance of elevated VEGF levels and therefore it may be of central importance for the onset and development of DR.

PI3K-Akt-mTOR inhibition by GNE-477 inhibits renal cell carcinoma cell growth in vitro and in vivo

Sustained activation of PI3K-Akt-mTOR cascade is important for renal cell carcinoma (RCC) cell progression. GNE-477 is a novel and efficacious PI3K-mTOR dual inhibitor. The current study tested its anti-RCC cell activity. In the primary cultured human RCC cells, GNE-477 potently inhibited cell growth, viability and proliferation, as well as cell cycle progression, migration and invasion. Furthermore, it induced robust apoptosis activation in primary RCC cells, but being non-cytotoxic to HK-2 epithelial cells and primary human renal epithelial cells. In the primary RCC cells GNE-477 inactivated PI3K-Akt-mTOR cascade by blocking phosphorylation of p85, Akt1, p70S6K1 and S6. Restoring Akt-mTOR activation by a constitutively-active Akt1 reversed GNE-477-induced anti-RCC cell activity. In nude mice intraperitoneal injection of GNE-477 potently suppressed RCC xenograft tumor growth. Collectively, targeting PI3K-Akt-mTOR cascade by GNE-477 inhibits RCC cell growth in vitro and in vivo.

I-BET726 suppresses human skin squamous cell carcinoma cell growth in vitro and in vivo

Bromodomain-containing protein 4 (BRD4) is a potential therapeutic target of skin squamous cell carcinoma (SCC). I-BET726 is a novel BRD4 inhibitor. Its potential effect in skin SCC cells was tested in the present study. We show that I-BET726 potently inhibited survival, proliferation, cell cycle progression, and migration in established (A431/SCC-9/SCC-12/SCC-13 lines) and primary human skin SCC cells. I-BET726 induced significant apoptosis activation in skin SCC cells. It was more efficient in inhibiting skin SCC cells than known BRD4 inhibitors (JQ1, CPI203, and AZD5153). I-BET726 not only downregulated BRD4-regulated proteins (c-Myc, Bcl-2, and cyclin D1), but also inhibited sphingosine kinase 1 (SphK1) and Akt signalings in SCC cells. Restoring Akt activation, by a constitutively active S473D mutant Akt1 (“caAkt1”), partially inhibited I-BET726-induced cytotoxicity in A431 cells. In vivo, I-BET726 oral administration potently inhibited A431 xenograft growth in severe combined immunodeficient mice. Downregulation of BRD4-regulated proteins and inhibition of the SphK1-Akt signaling were detected in I-BET726-treated A431 xenograft tumor tissues. Together, I-BET726 inhibits skin SCC cell growth in vitro and in vivo.

ARV-825-induced BRD4 protein degradation as a therapy for thyroid carcinoma

Bromodomain-containing protein 4 (BRD4) is overexpressed in thyroid carcinoma, represents as an important therapeutic target. ARV-825 is a novel cereblon-based PROTAC (Proteolysis Targeting Chsimera) compound. It can induce fast and sustained BRD4 protein degradation. Its potential effect in human thyroid carcinoma cells was studied here. In TPC-1 cells and primary human thyroid carcinoma cells, ARV-825 potently inhibited cell viability, proliferation and migration. Furthermore, ARV-825 induced robust apoptosis activation in the thyroid carcinoma cells. ARV-825 induced BRD4 protein degradation and downregulation of its targets, including c-Myc, Bcl-xL and cyclin D1 in thyroid carcinoma cells. It was significantly more potent in inhibiting thyroid carcinoma cells than the known small molecule BRD4 inhibitors. In vivo studies demonstrated that ARV-825 oral administration potently suppressed TPC-1 xenograft tumor growth in severe combined immunodeficient mice. BRD4 protein degradation as well as c-Myc, Bcl-xL and cyclin D1 downregulation were detected in ARV-825-treated TPC-1 tumor tissues. Taken together, ARV-825 induces BRD4 protein degradation and inhibits thyroid carcinoma cell growth in vitro and in vivo.

Bcl-6-directed follicular helper T cells promote vascular inflammatory injury in diabetic retinopathy

Diabetic retinopathy (DR) is a vision-threatening complication of diabetes mellitus characterized by chronic retinal microvascular inflammation. The involvement of CD4+ T cells in retinal vascular inflammation has been considered, but the specific subset and mechanism of T cell-mediated response during the process remains unclear. Here, we aim to investigate the potential role of follicular helper T (Tfh) cells, a newly identified subset of CD4+ T cells in retinal vascular inflammation in DR.

Methods: Patients with DR were enrolled and the PD-1⁺CXCR5⁺CD4⁺ Tfh cells were detected in the peripheral blood by flow cytometry. The streptozotocin (STZ)-induced DR model and oxygen-induced retinopathy (OIR) model were established, and 79-6, an inhibitor of Bcl-6, was injected intraperitoneally to suppress Tfh cells. The Tfh cells-related genes were investigated in the spleen, lymph nodes, and retina of mice by flow cytometry, immunofluorescence, and qPCR.

Results: The Tfh cells expanded in the circulation of patients with DR and also increased in circulation, lymph nodes and retinal tissues from the STZ-induced DR mice and OIR mice. Notably, inhibition of Bcl-6, a critical transcription factor for Tfh cells development, prevented upregulation of Tfh cells and its typical IL-21 cytokine, and ameliorated vascular leakage in DR mice or retinal angiogenesis in OIR mice, indicating that Bcl-6-directed Tfh cells could promote vascular inflammation and angiogenesis.

Conclusions: Our results suggested that excessive Bcl-6-directed Tfh cells represent an unrecognized feature of DR and be responsible for the retinal vascular inflammation and angiogenesis, providing opportunities for new therapeutic approaches to DR.

MicroRNA-4651 targets bromodomain-containing protein 4 to inhibit non-small cell lung cancer cell progression

Bromodomain-containing protein 4 (BRD4) overexpression in non-small cell lung cancer (NSCLC) promotes cancer progression. Here, we show that miR-4651 selectively targets and negatively regulates BRD4 in A549 and primary human NSCLC cells. RNA pull-down experiments confirmed that miR-4651 directly binds to BRD4 mRNA. Further, ectopic overexpression of miR-4651 in A549 cells and primary NSCLC cells decreased BRD4 3'-UTR luciferase reporter activity and its expression, whereas miR-4651 inhibition elevated both. Functional studies demonstrated that NSCLC cell growth, proliferation, and migration were suppressed with ectopic miR-4651 overexpression but enhanced with miR-4651 inhibition. BRD4 re-expression using a 3'-UTR mutant BRD4 reversed A549 cell inhibition induced by miR-4651 overexpression. Further, miR-4651 overexpression or inhibition failed to alter the functions of BRD4-KO A549 cells. In vivo, miR-4651-overexpressing A549 xenografts grew slowly than control A549 xenografts in severe combined immunodeficient mice. Finally, miR-4651 was downregulated in human NSCLC tissues, correlating with BRD4 elevation. Together, miR-4651 targets BRD4 to inhibit NSCLC cell growth in vitro and in vivo.

microRNA-1203 targets and silences cyclophilin D to protect human endometrial cells from oxygen and glucose deprivation-re-oxygenation

Oxygen and glucose deprivation (OGD)-re-oxygenation (OGDR) stimulation to the human endometrial cells mimics ischemia-reperfusion injury. Cyclophilin D (CypD)-dependent programmed necrosis pathway mediates OGDR-induced cytotoxicity to human endometrial cells. We here identified a novel CypD-targeting miRNA, microRNA-1203 (miR-1203). In T-HESC and primary human endometrial cells, ectopic overexpression of miR-1203, using a lentiviral construct, potently downregulated the CypD 3’-untranslated region (3’-UTR) activity and its expression. Both were however upregulated in endometrial cells with forced miR-1203 inhibition by its anti-sense sequence. Functional studies demonstrated that ectopic miR-1203 overexpression in endometrial cells alleviated OGDR-induced programmed necrosis, inhibiting mitochondrial CypD-p53-adenine nucleotide translocator 1 association, mitochondrial depolarization, reactive oxygen species production, and medium lactate dehydrogenase release. Contrarily OGDR-induced programmed necrosis and cytotoxicity were intensified with forced miR-1203 inhibition in endometrial cells. Significantly, ectopic miR-1203 overexpression or inhibition failed to change OGDR-induced cytotoxicity in CypD-knockout T-HESC cells. Furthermore, ectopic miR-1203 overexpression was unable to protect T-HESC endometrial cells from OGDR when CypD was restored by an UTR-depleted CypD construct. Collectively, these results show that miR-1203 targets and silences CypD to protect human endometrial cells from OGDR

Osthole: A Traditional Chinese Medicine for Ocular Anti-Angiogenic Therapy

PURPOSE

Osthole is an agent isolated from Cnidium monnieri (L.) Cusson and has been used to treat several disorders. Corneal neovascularization is a sight-threatening condition associated with several inflammatory or infectious ocular disorders. In this study, we investigated the anti-angiogenic effects of osthole on corneal neovascularization and the underlying mechanism.

METHODS

MTT assay, HE staining, and calcein-AM/propidium iodide staining was conducted to detect the toxicity of osthole in vitro and in vivo. Corneal neovascularization of ICR mice was induced by alkali burn and observed by a slit lamp microscopy on day 7 after alkali injury. EdU assay, Ki67 immunofluorescence assay, Transwell migration assay, and Matrigel assay were conducted to investigate the role of osthole in endothelial angiogenic effects in vitro. Western blots were conducted to investigate the anti-angiogenic mechanism of osthole in corneal neovascularization.

RESULTS

Administration of osthole ranging from 0.05 to 25 µM had no detectable cytotoxicity or tissue toxicity in vivo and in vitro. Topical administration of osthole inhibited corneal neovascularization induced by alkali burn. Osthole decreased the proliferation, migration, and tube-formation of endothelial cells induced by VEGF. Osthole inhibited endothelial angiogenic functions through blocking the phosphorylation of ERK1/2, JNK, and p38.

CONCLUSION

Our study provides evidence that osthole is a promising drug for the treatment of corneal neovascularization.

Targeting cyclophilin-D by miR-1281 protects human macrophages from Mycobacterium tuberculosis-induced programmed necrosis and apoptosis

Mycobacterium tuberculosis (MTB) infection induces cytotoxicity to host human macrophages. The underlying signaling mechanisms are largely unknown. Here we discovered that MTB infection induced programmed necrosis in human macrophages, causing mitochondrial cyclophilin-D (CypD)-p53-adenine nucleotide translocator type 1 association, mitochondrial depolarization and lactate dehydrogenase medium release. In human macrophages MTB infection-induced programmed necrosis and apoptosis were largely attenuated by CypD inhibition (by cyclosporin A), silencing and knockout, but intensified with ectopic CypD overexpression. Further studies identified microRNA-1281 as a CypD-targeting miRNA. Ectopic overexpression of microRNA-1281 decreased CypD 3'-untranslated region activity and its expression, protecting human macrophages from MTB-induced programmed necrosis and apoptosis. Conversely, microRNA-1281 inhibition in human macrophages, by the anti-sense sequence, increased CypD expression and potentiated MTB-induced cytotoxicity. Importantly, in CypD-KO macrophages miR-1281 overexpression or inhibition was ineffective against MTB infection. Restoring CypD expression, by an untranslated region-depleted CypD construct, reversed miR-1281-induced cytoprotection against MTB in human macrophages. Collectively, these results show that targeting CypD by miR-1281 protects human macrophages from MTB-induced programmed necrosis and apoptosis.

microRNA-579 upregulation mediates death of human macrophages with mycobacterium tuberculosis infection

Mycobacterium tuberculosis (MTB) infection could induce death of host human macrophages, promoting bacterial spread. In the current study we tested the potential role of microRNA-579 (miR-579) in the death of macrophages infected with MTB. In the primary human macrophages MTB infection induced upregulation of miR-579 but downregulation of its mRNA targets, SIRT1 and PDK1, which were accompanied by significant macrophage death and apoptosis. miR-579 inhibition, by its anti-sense sequence, restored SIRT1-PDK1 expression and significantly attenuated MTB-induced cytotoxicity and apoptosis in human macrophages. Conversely, ectopic overexpression of miR-579 further downregulated SIRT1-PDK1 expression and exacerbated MTB-induced cytotoxicity in human macrophages. Further studies showed that cPWWP2A, the miR-579's endogenous sponge circRNA, was downregulated in MTB-infected macrophages. Conversely, forced overexpression of cPWWP2A, by a recombinant adeno-associated virus construct, reversed MTB-induced miR-579 upregulation and macrophage cytotoxicity. Taken together, our results show that miR-579 upregulation mediates MTB-induced macrophage cytotoxicity. Targeting cPWWP2A-miR-579 axis could be a novel strategy to protect human macrophages from MTB infection.

p38gamma overexpression promotes renal cell carcinoma cell growth, proliferation and migration

Recent studies have proposed that p38gamma (p38γ) might be critically involved in tumorigenesis and cancer progression. Its expression and potential functions in human renal cell carcinoma (RCC) are studied here. We show that p38γ mRNA and protein levels are upregulated in human RCC tissues, as compared to its levels in the surrounding normal renal tissues. p38γ upregulation was also detected in established (786-O line) and primary human RCC cells. Functional studies in 786-O cells and primary human RCC cells demonstrated that p38γ silencing (by targeted shRNAs) or CRISPR/Cas9-mediated p38γ knockout (KO) potently inhibited cell growth, viability, proliferation and migration. Furthermore, p38γ shRNA or KO in RCC cells decreased retinoblastoma (Rb) phosphorylation and downregulated cyclin E1/A expression. Additionally, significant apoptosis activation was detected in p38γ-silenced and p38γ-KO RCC cells. Contrarily, ectopic overexpression of p38γ facilitated cell growth, viability, proliferation and migration in RCC cells. Taken together, we show that p38γ overexpression promotes RCC cell growth, proliferation and migration. p38γ could be a novel therapeutic target for human RCC.

Mechanistic insight into activation of MAPK signaling by pro-angiogenic factors

Background

Angiogenesis is important in physiological and pathological conditions, as blood vessels provide nutrients and oxygen needed for tissue growth and survival. Therefore, targeting angiogenesis is a prominent strategy in both tissue engineering and cancer treatment. However, not all of the approaches to promote or inhibit angiogenesis lead to successful outcomes. Angiogenesis-based therapies primarily target pro-angiogenic factors such as vascular endothelial growth factor-A (VEGF) or fibroblast growth factor (FGF) in isolation. However, pre-clinical and clinical evidence shows these therapies often have limited effects. To improve therapeutic strategies, including targeting FGF and VEGF in combination, we need a quantitative understanding of the how the promoters combine to stimulate angiogenesis.

Results

In this study, we trained and validated a detailed mathematical model to quantitatively characterize the crosstalk of FGF and VEGF intracellular signaling. This signaling is initiated by FGF binding to the FGF receptor 1 (FGFR1) and heparan sulfate glycosaminoglycans (HSGAGs) or VEGF binding to VEGF receptor 2 (VEGFR2) to promote downstream signaling. The model focuses on FGF- and VEGF-induced mitogen-activated protein kinase (MAPK) signaling and phosphorylation of extracellular regulated kinase (ERK), which promotes cell proliferation. We apply the model to predict the dynamics of phosphorylated ERK (pERK) in response to the stimulation by FGF and VEGF individually and in combination. The model predicts that FGF and VEGF have differential effects on pERK. Additionally, since VEGFR2 upregulation has been observed in pathological conditions, we apply the model to investigate the effects of VEGFR2 density and trafficking parameters. The model predictions show that these parameters significantly influence the response to VEGF stimulation.

Conclusions

The model agrees with experimental data and is a framework to synthesize and quantitatively explain experimental studies. Ultimately, the model provides mechanistic insight into FGF and VEGF interactions needed to identify potential targets for pro- or anti-angiogenic therapies.

Electronic supplementary material

The online version of this article (10.1186/s12918-018-0668-5) contains supplementary material, which is available to authorized users.