Pharmacological intervention of MKL/SRF signaling by CCG-1423 impedes endothelial cell migration and angiogenesis

Inhibition of RhoA Prevents Cryptococcus neoformans Capsule Glucuronoxylomannan-Stimulated Brain Endothelial Barrier Disruption

Cryptococcus neoformans (Cn) is an opportunistic fungus that causes severe central nervous system (CNS) disease in immunocompromised individuals. Brain parenchyma invasion requires fungal traversal of the blood-brain barrier. In this study, we describe that Cn alters the brain endothelium by activating small GTPase RhoA, causing reorganization of the actin cytoskeleton and tight junction modulation to regulate endothelial barrier permeability. We confirm that the main fungal capsule polysaccharide glucuronoxylomannan is responsible for these alterations. We reveal a therapeutic benefit of RhoA inhibition by CCG-1423 in vivo. RhoA inhibition prolonged survival and reduced fungal burden in a murine model of disseminated cryptococcosis, supporting the therapeutic potential of targeting RhoA in the context of cryptococcal infection. We examine the complex virulence of Cn in establishing CNS disease, describing cellular components of the brain endothelium that may serve as molecular targets for future antifungal therapies to alleviate the burden of life-threatening cryptococcal CNS infection.

mDia2 is an important mediator of MRTF-A-dependent regulation of breast cancer cell migration

Dysregulated actin cytoskeleton gives rise to aberrant cell motility and metastatic spread of tumor cells. This study evaluates the effect of overexpression of wild-type versus functional mutants of MRTF-A on migration and invasion of breast cancer (BC) cells. Our studies indicate that SRF's interaction is critical for MRTF-A-induced promotion of both two-dimensional and three-dimensional cell migration, while the SAP-domain function is important selectively for three-dimensional cell migration. Increased MRTF-A activity is associated with more effective membrane protrusion, a phenotype that is attributed predominantly to SRF's interaction with MRTF. We demonstrate formin-family protein mDia2 as an important mediator of MRTF-stimulated actin polymerization at the leading edge and cell migration. Multiplexed quantitative immunohistochemistry and transcriptome analyses of clinical BC specimens further demonstrate a positive correlation between nuclear localization of MRTF with malignant traits of cancer cells and enrichment of MRTF-SRF gene signature in pair-matched distant metastases versus primary tumors. In conclusion, this study establishes a novel mechanism of MRTF-dependent regulation of cell migration and provides evidence for the association between MRTF activity and increased malignancy in human BC, justifying future development of specific small molecule inhibitors of the MRTF-SRF transcriptional complex as potential therapeutic agents in BC.

mDia2 is an important mediator of MRTF-A-dependent regulation of breast cancer cell migration

Dysregulated actin cytoskeleton gives rise to aberrant cell motility and metastatic spread of tumor cells. This study evaluates the effect of overexpression of wild-type vs functional mutants of MRTF-A on migration and invasion of breast cancer (BC) cells. Our studies indicate that SRF's interaction is critical for MRTF-A-induced promotion of both 2D and 3D cell migration, while the SAP-domain function is important selectively for 3D cell migration. Increased MRTF-A activity is associated with more effective membrane protrusion, a phenotype that is attributed predominantly to SRF's interaction of MRTF. We demonstrate formin-family protein mDia2 as an important mediator of MRTF-stimulated actin polymerization at the leading edge and cell migration. Multiplexed quantitative immunohistochemistry and transcriptome analyses of clinical BC specimens further demonstrate a positive correlation between nuclear localization of MRTF with malignant traits of cancer cells and enrichment of MRTF-SRF gene signature in pair-matched distant metastases vs primary tumors. In conclusion, this study establishes a novel mechanism of MRTF-dependent regulation of cell migration and provides evidence for the association between MRTF activity and increased malignancy in human breast cancer, justifying future development of a specific small molecule inhibitor of the MRTF-SRF transcriptional complex as a potential therapeutic agent in breast cancer.

SIGNIFICANCE

Actin cytoskeletal dysregulation gives rise to metastatic dissemination of cancer cells. This study mechanistically investigates the impact of specific functional disruption of MRTF (a transcriptional co-factor of SRF) on breast cancer cell migration.This study establishes a novel mechanism linking mDia2 to MRTF-dependent regulation of cell migration and provides clinical evidence for the association between MRTF activity and increased malignancy in human breast cancer.Findings from these studies justify future exploration of specific small molecule inhibitor of the MRTF-SRF transcriptional complex as a potential therapeutic agent in breast cancer.

Haplo-insufficiency of Profilin1 in vascular endothelial cells is beneficial but not sufficient to confer protection against experimentally induced atherosclerosis

Actin cytoskeleton plays an important role in various aspects of atherosclerosis, a key driver of ischemic heart disease. Actin-binding protein Profilin1 (Pfn1) is overexpressed in atherosclerotic plaques in human disease, and Pfn1, when partially depleted globally in all cell types, confers atheroprotection in vivo. This study investigates the impact of endothelial cell (EC)-specific partial loss of Pfn1 expression in atherosclerosis development. We utilized mice engineered for conditional heterozygous knockout of the Pfn1 gene in ECs, with atherosclerosis induced by depletion of hepatic LDL receptor by gene delivery of PCSK9 combined with high-cholesterol diet. Our studies show that partial depletion of EC Pfn1 has certain beneficial effects marked by dampening of select pro-atherogenic cytokines (CXCL10 and IL7) with concomitant reduction in cytotoxic T cell abundance but is not sufficient to reduce hyperlipidemia and confer atheroprotection in vivo. In light of these findings, we conclude that atheroprotective phenotype conferred by global Pfn1 haplo-insufficiency requires contributions of additional cell types that are relevant for atherosclerosis progression.

Canagliflozin protects against hyperglycemia-induced cerebrovascular injury by preventing blood-brain barrier (BBB) disruption via AMPK/Sp1/adenosine A2A receptor

Diabetes mellitus causes brain microvascular endothelial cell (MEC) damage, inducing dysfunctional angiogenic response and disruption of the blood-brain barrier (BBB). Canagliflozin is a revolutionary hypoglycemic drug that exerts neurologic and/or vascular-protective effects beyond glycemic control; however, its underlying mechanism remains unclear. In the present study, we hypothesize that canagliflozin ameliorates BBB permeability by preventing diabetes-induced brain MEC damage. Mice with high-fat diet/streptozotocin-induced diabetes received canagliflozin for 8 weeks. We assessed vascular integrity by measuring cerebrovascular neovascularization indices. The expression of specificity protein 1 (Sp1), as well as tight junction proteins (TJs), phosphorylated AMP-activated protein kinase (p-AMPK), and adenosine A2A receptors was examined. Mouse brain MECs were grown in high glucose (30 mM) to mimic diabetic conditions. They were treated with/without canagliflozin and assessed for migration and angiogenic ability. We also performed validation studies using AMPK activator (AICAR), inhibitor (Compound C), Sp1 small interfering RNA (siRNA), and adenosine A2A receptor siRNA. We observed that cerebral pathological neovascularization indices were significantly normalized in mice treated with canagliflozin. Increased Sp1 and adenosine A2A receptor expression and decreased p-AMPK and TJ expression were observed under diabetic conditions. Canagliflozin or AICAR treatment alleviated these changes. However, this alleviation effect of canagliflozin was diminished again after Compound C treatment. Either Sp1 siRNA or adenosine A2A receptor siRNA could increase the expression of TJs. Luciferase reporter assay confirmed that Sp1 could bind to the adenosine A2A receptor gene promoter. Our study identifies the AMPK/Sp1/adenosine A2A receptor pathway as a treatment target for diabetes-induced cerebrovascular injury.

Haplo-insufficiency of Profilin1 in vascular endothelial cells is beneficial but not sufficient to confer protection against experimentally induced atherosclerosis

Actin cytoskeleton plays an important role in various aspects of atherosclerosis, a key driver of ischemic heart disease. Actin-binding protein Profilin1 (Pfn1) is overexpressed in atherosclerotic plaques in human disease, and Pfn1, when partially depleted globally in all cell types, confers atheroprotection in vivo . This study investigates the impact of endothelial cell (EC)-specific partial loss of Pfn1 expression in atherosclerosis development. We utilized mice engineered for conditional heterozygous knockout of the Pfn1 gene in ECs, with atherosclerosis induced by depletion of hepatic LDL receptor by gene delivery of PCSK9 combined with high-cholesterol diet. Our studies show that partial depletion of EC Pfn1 has certain beneficial effects marked by dampening of select pro-atherogenic cytokines (CXCL10 and IL7) with concomitant reduction in cytotoxic T cell abundance but is not sufficient to reduce hyperlipidemia and confer atheroprotection in vivo . In light of these findings, we conclude that atheroprotective phenotype conferred by global Pfn1 haplo-insufficiency requires contributions of additional cell types that are relevant for atherosclerosis progression.

Vascular endothelial profilin-1 drives a protumorigenic tumor microenvironment and tumor progression in renal cancer

Overexpression of actin-binding protein profilin-1 (Pfn1) correlates with advanced disease features and adverse clinical outcome of patients with clear cell renal carcinoma, the most prevalent form of renal cancer. We previously reported that Pfn1 is predominantly overexpressed in tumor-associated vascular endothelial cells in human clear cell renal carcinoma. In this study, we combined in vivo strategies involving endothelial cell-specific depletion and overexpression of Pfn1 to demonstrate a role of vascular endothelial Pfn1 in promoting tumorigenicity and enabling progressive growth and metastasis of renal carcinoma cells in a syngeneic orthotopic mouse model of kidney cancer. We established an important role of endothelial Pfn1 in tumor angiogenesis and further identified endothelial Pfn1-dependent regulation of several pro- (VEGF, SERPINE1, CCL2) and anti-angiogenic factors (platelet factor 4) in vivo. Endothelial Pfn1 overexpression increases tumor infiltration by macrophages and concomitantly diminishes tumor infiltration by T cells including CD8+ T cells in vivo, correlating with the pattern of endothelial Pfn1-dependent changes in tumor abundance of several prominent immunomodulatory cytokines. These data were also corroborated by multiplexed quantitative immunohistochemistry and immune deconvolution analyses of RNA-seq data of clinical samples. Guided by Upstream Regulator Analysis of tumor transcriptome data, we further established endothelial Pfn1-induced Hif1α elevation and suppression of STAT1 activation. In conclusion, this study demonstrates for the first time a direct causal relationship between vascular endothelial Pfn1 dysregulation, immunosuppressive tumor microenvironment, and disease progression with mechanistic insights in kidney cancer. Our study also provides a conceptual basis for targeting Pfn1 for therapeutic benefit in kidney cancer.

Rho/SRF Inhibitor Modulates Mitochondrial Functions

CCG-1423 is a Rho A pathway inhibitor that has been reported to inhibit Rho/SRF-mediated transcriptional regulation. Serum response factor and its cofactors, which include ternary complex factors and myocardin-related transcription factors, regulate various cellular functions. In this study, we observed that CCG-1423 modulates the mitochondrial functions. The effect of this small molecule drug was determined by measuring mitochondrial function using an XFe96 Analyzer and an Oxygraph 2k (O2k) high-resolution respirometer. CCG-1423 treatment significantly reduced oxidative phosphorylation in a dose-dependent manner. However, CCG-1423 increased the glycolytic rate. We also observed that histone 4 at lysine-16 underwent hyperacetylation with the treatment of this drug. Immunolabeling with F-actin and MitoTracker revealed the alteration in the actin cytoskeleton and mitochondria. Taken together, our findings highlight a critical role of CCG-1423 in inhibiting the transcription of SRF/p49 and PGC-1α, β, resulting in the downregulation of mitochondrial genes, leading to the repression of mitochondrial oxidative phosphorylation and overall ATP reduction. This study provides a better understanding of the effects of CCG-1423 on mitochondria, which may be useful for the assessment of the potential clinical application of CCG-1423 and its derivatives.

Myocardin-related transcription factor's interaction with serum-response factor is critical for outgrowth initiation, progression, and metastatic colonization of breast cancer cells

Breast cancer (BC)-related mortality primarily results from metastatic colonization of disseminated cells. Actin polymerization plays an important role in driving post-extravasation metastatic outgrowth of tumor cells. This study examines the role of myocardin-related transcription factor (MRTF)/serum-response (SRF), a transcription system well known for regulation of cytoskeletal genes, in metastatic colonization of BC cells. We demonstrated that co-depletion of MRTF isoforms (MRTF-A and MRTF-B) dramatically impairs single-cell outgrowth ability of BC cells as well as retards growth progression of pre-established BC cell colonies in three-dimensional (3D) cultures. Conversely, overexpression of MRTF-A promotes initiation and progression of tumor-cell outgrowth in vitro, primary tumor formation, and metastatic outgrowth of seeded BC cells in vivo, and these changes can be dramatically blocked by molecular disruption of MRTF-A's interaction with SRF. Correlated with the outgrowth phenotypes, we further demonstrate MRTF's ability to augment the intrinsic cellular ability to polymerize actin and formation of F-actin-based protrusive structures requiring SRF's interaction. Pharmacological proof-of-concept studies show that small molecules capable of interfering with MRTF/SRF signaling robustly suppresses single-cell outgrowth and progression of pre-established outgrowth of BC cells in vitro as well as experimental metastatic burden of BC cells in vivo. Based on these data, we conclude that MRTF activity potentiates metastatic colonization of BC cells and therefore, targeting MRTF may be a promising strategy to diminish metastatic burden in BC.

Profilin-1 prevents psoriasis pathogenesis through IκBζ regulation

Profilin-1 (PFN-1) is an actin-binding protein that regulates actin polymerization, cell proliferation, apoptosis, angiogenesis, and carcinogenesis. Its dysregulation has been reported in diverse pathologic diseases; however, the role of PFN-1 in psoriasis has not yet been elucidated. In this study, we demonstrate that PFN-1 expression is increased in both skin and serum of patients with psoriasis. PFN-1 was markedly expressed in the epidermis of psoriatic lesions and its expression positively correlated with psoriasis severity. IL-17A treatment of keratinocytes increased the PFN-1 expression, whereas TNF-α induced the PFN-1 expression and secretion. In addition, knockdown of PFN-1 with shRNA resulted in an altered expression of psoriasis-associated inflammatory markers, HBD-2, S100A7, S100A9, and Ki67, and recombinant PFN-1 suppressed the IL-17A-induced inflammatory response in keratinocytes. Interestingly, recombinant PFN-1 also suppressed IL-17A-induced IκBζ, an important player in immune response in psoriasis. Collectively, our results show that PFN-1 acts as a negative regulator of psoriatic inflammation through suppression of IκBζ, and the balanced level of PFN-1 is important for the IκBζ regulation. Thus, the expression of PFN-1 can be used as a biomarker for psoriasis severity, and it can be considered as a possible target for the treatment of psoriasis.

Phosphorylation of MICAL2 by ARG promotes head and neck cancer tumorigenesis by regulating skeletal rearrangement

The actin cytoskeletal architecture provides the structural underpinnings for crucial cellular behaviors. In cancer cells, changes in the actin cytoskeleton may serve as prerequisites for proliferation, invasion, and metastatic dissemination. However, the underlying mechanisms remain largely unknown. Here, we show that MICAL2, which is increased in head and neck squamous cell carcinoma (HNSCC) and inversely associated with patient survival, promotes HNSCC growth, invasion, and migration. MICAL2 serves as a flavoprotein monooxygenase and directly induces actin filament depolymerization by specifically oxidizing the methionine 44 and 47 residues of F-actin. The kinase ARG interacts with MICAL2 and augments MICAL2-mediated actin disassembly. Direct phosphorylation assay and mass spectrometry confirmed that ARG phosphorylates MICAL2 at Tyr445, Tyr463, and Tyr488. Substitution of the Tyr445 or Tyr463 residue of purified recombinant MICAL2-redox with phenylalanine (generating a non-phosphorylatable mutant) abolishes the enhanced MICAL2-mediated F-actin disassembly induced by ARG. Consistently, ectopic expression of non-phosphorylatable MICAL2 mutants (MICAL2^Y445F and MICAL2^Y463F, not MICAL2^Y488F) failed to ameliorate HNSCC cell growth, whereas expression of wild-type MICAL2 or MICAL2^Y488F rescued the impaired proliferation induced by MICAL2 knockdown. Moreover, CCG-1423, an inhibitor of MICAL2, was shown to inhibit HNSCC cell proliferation, invasion, and migration. Taken together, our findings indicate that phosphorylation of MICAL2 at Tyr445 and Tyr463 by ARG mediates F-actin disassembly and promotes HNSCC progression.

Inhibition of ocular neovascularization by novel anti-angiogenic compound

Aberrant angiogenesis lies at the heart of a wide range of ocular pathologies such as proliferative diabetic retinopathy, wet age-related macular degeneration and retinopathy of prematurity. This study explores the anti-angiogenic activity of a novel small molecule investigative compound capable of inhibiting profilin1-actin interaction recently identified by our group. We demonstrate that our compound is capable of inhibiting migration, proliferation and angiogenic activity of microvascular endothelial cells in vitro as well as choroidal neovascularization (CNV) ex vivo. In mouse model of laser-injury induced CNV, intravitreal administration of this compound diminishes sub-retinal neovascularization. Finally, our preliminary structure-activity relationship study (SAR) demonstrates that this small molecule compound is amenable to improvement in biological activity through structural modifications.

MKL1 regulates hepatocellular carcinoma cell proliferation, migration and apoptosis via the COMPASS complex and NF-κB signaling

Background

Histone modification plays essential roles in hepatocellular carcinoma (HCC) pathogenesis, but the regulatory mechanisms remain poorly understood. In this study, we aimed to analyze the roles of Megakaryoblastic leukemia 1 (MKL1) and its regulation of COMPASS (complex of proteins associated with Set1) in HCC cells.

Methods

MKL1 expression in clinical tissues and cell lines were detected by bioinformatics, qRT-PCR and western blot. MKL1 expression in HCC cells were silenced with siRNA, followed by cell proliferation evaluation via Edu staining and colony formation, migration and invasion using the Transwell system, and apoptosis by Hoechst staining. HCC cell tumorigenesis was assessed by cancer cell line-based xenograft model, combined with H&E staining and IHC assays.

Results

MKL1 expression was elevated in HCC cells and clinical tissues which was correlated with poor prognosis. MKL1 silencing significantly repressed proliferation, migration, invasion and colony formation but enhanced apoptosis in HepG2 and Huh-7 cells. MKL1 silencing also inhibited COMPASS components and p65 protein expression in HepG2 and Huh-7 cells. HepG2 cell tumorigenesis in nude mice was severely impaired by MKL1 knockdown, resulted into suppressed Ki67 expression and cell proliferation.

Conclusion

MKL1 promotes HCC pathogenesis by regulating hepatic cell proliferation, migration and apoptosis via the COMPASS complex and NF-κB signaling.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-021-08185-w.

Clinical Pathological Features and Current Animal Models of Type 3 Macular Neovascularization

Type 3 macular neovascularization (MNV3), or retinal angiomatous proliferation (RAP), is a distinct type of neovascular age-related macular degeneration (AMD), which is a leading cause of vision loss in older persons. During the past decade, systematic investigation into the clinical, multimodal imaging, and histopathological features and therapeutic outcomes has provided important new insight into this disease. These studies favor the retinal origin of MNV3 and suggest the involvement of retinal hypoxia, inflammation, von Hippel–Lindau (VHL)–hypoxia-inducible factor (HIF)–vascular endothelial growth factor (VEGF) pathway, and multiple cell types in the development and progression of MNV3. Several mouse models, including the recently built Rb/p107/Vhl triple knockout mouse model by our group, have induced many of the histological features of MNV3 and provided much insight into the underlying pathological mechanisms. These models have revealed the roles of retinal hypoxia, inflammation, lipid metabolism, VHL/HIF pathway, and retinoblastoma tumor suppressor (Rb)–E2F cell cycle pathway in the development of MNV3. This article will summarize the clinical, multimodal imaging, and pathological features of MNV3 and the diversity of animal models that exist for MNV3, as well as their strengths and limitations.

Static and dynamic culture of human endothelial cells encapsulated inside alginate-gelatin microspheres

This study aimed to explore the angiogenesis potential of human endothelial cells encapsulated inside alginate-gelatin microspheres under static and dynamic culture systems after 7 days. Human umbilical vein endothelial cells were encapsulated inside alginate (1%) and gelatin (1.2%) using an electrostatic encapsulation method. Cells were incubated for 7 days in vitro. The cell survival rate was measured using the MTT assay. The expression of VEGFR-2 and von Willebrand factor genes was studied by real-time PCR assay. Using western blot analysis, we monitored the protein contents of VEGFR-2, vWF, and Caspase 3. The levels of SOD and GPx enzymes were calculated using biochemical kits. Angiogenesis potential was assessed using in vitro Matrigel assay. Data showed an increased survival rate in encapsulated cells cultured under the static condition compared to the conventional 2D condition (p < 0.05). The culture of encapsulated cells under a dynamic bioreactor system did not alter cell viability. Compared to the dynamic culture system, the incubation of encapsulated cells in the static culture system swelled the microspheres (p < 0.05). Both dynamic and static culture models increased the expression of VEGFR-2 and von Willebrand factor in encapsulated cells compared to 2D culture (p < 0.05), showing enhanced functional maturation. Data showed a significant increase of vWF and reduction of apoptosis marker Caspase in the dynamic culture system (p < 0.05). The levels of SOD and GPx were significantly increased in dynamic and static culture models as compared to the control 2D group (p < 0.05). In vitro tubulogenesis assay showed significant induction of angiogenesis in dynamic encapsulated HUVECs indicated with a large number of vascular tubes and arborized ECs compared to the control and static encapsulated HUVECs (p < 0.05). The current study suggests a bioreactor dynamic system is a reliable approach, similar to a static condition, for the expansion of encapsulated human ECs in a 3D milieu.

The role of profilin-1 in cardiovascular diseases

Dynamic remodeling of the actin cytoskeleton is an essential feature for virtually all actin-dependent cellular processes, including cell migration, cell cycle progression, chromatin remodeling and gene expression, and even the DNA damage response. An altered actin cytoskeleton is a structural hallmark associated with numerous pathologies ranging from cardiovascular diseases to immune disorders, neurological diseases and cancer. The actin cytoskeleton in cells is regulated through the orchestrated actions of a myriad of actin-binding proteins. In this Review, we provide a brief overview of the structure and functions of the actin-monomer-binding protein profilin-1 (Pfn1) and then discuss how dysregulated expression of Pfn1 contributes to diseases associated with the cardiovascular system.

Migration arrest of chemoresistant leukemia cells mediated by MRTF-SRF pathway

Background

Dormant chemotherapy-resistant leukemia cells can survive for an extended period before relapse. Nevertheless, the mechanisms underlying the development of chemoresistance in vivo remain unclear.

Methods

Using intravital bone imaging, we characterized the behavior of murine acute myeloid leukemia (AML) cells (C1498) in the bone marrow before and after chemotherapy with cytarabine.

Results

Proliferative C1498 cells exhibited high motility in the bone marrow. Cytarabine treatment impaired the motility of residual C1498 cells. However, C1498 cells regained their migration potential after relapse. RNA sequencing revealed that cytarabine treatment promoted MRTF-SRF pathway activation. MRTF inhibition using CCG-203971 augmented the anti-tumor effects of chemotherapy in our AML mouse model, as well as suppressed the migration of chemoresistant C1498 cells.

Conclusions

These results provide novel insight into the role of cell migration arrest on the development of chemoresistance in AML, as well as provide a strong rationale for the modulation of cellular motility as a therapeutic target for refractory AML.

Profilin: many facets of a small protein

Profilin is a ubiquitously expressed protein well known as a key regulator of actin polymerisation. The actin cytoskeleton is involved in almost all cellular processes including motility, endocytosis, metabolism, signal transduction and gene transcription. Hence, profilin's role in the cell goes beyond its direct and essential function in regulating actin dynamics. This review will focus on the interactions of Profilin 1 and its ligands at the plasma membrane, in the cytoplasm and the nucleus of the cells and the regulation of profilin activity within those cell compartments. We will discuss the interactions of profilin in cell signalling pathways and highlight the importance of the cell context in the multiple functions that this small essential protein has in conjunction with its role in cytoskeletal organisation and dynamics. We will review some of the mechanisms that control profilin expression and the implications of changed expression of profilin in the light of cancer biology and other pathologies.

Disruption of profilin1 function suppresses developmental and pathological retinal neovascularization

Angiogenesis-mediated neovascularization in the eye is usually associated with visual complications. Pathological angiogenesis is particularly prominent in the retina in the settings of proliferative diabetic retinopathy, in which it can lead to permanent loss of vision. In this study, by bioinformatics analyses, we provide evidence for elevated expression of actin-binding protein PFN1 (profilin1) in the retinal vascular endothelial cells (VECs) of individuals with proliferative diabetic retinopathy, findings further supported by gene expression analyses for PFN1 in experimentally induced abnormal retinal neovascularization in an oxygen-induced retinopathy murine model. We observed that in a conditional knockout mouse model, postnatal deletion of the Pfn1 gene in VECs leads to defects in tip cell activity (marked by impaired filopodial protrusions) and reduced vascular sprouting, resulting in hypovascularization during developmental angiogenesis in the retina. Consistent with these findings, an investigative small molecule compound targeting the PFN1-actin interaction reduced random motility, proliferation, and cord morphogenesis of retinal VECs in vitro and experimentally induced abnormal retinal neovascularization in vivo In summary, these findings provide the first direct in vivo evidence that PFN1 is required for formation of actin-based protrusive structures and developmental angiogenesis in the retina. The proof of concept of susceptibility of abnormal angiogenesis to small molecule intervention of PFN1-actin interaction reported here lays a conceptual foundation for targeting PFN1 as a possible strategy in angiogenesis-dependent retinal diseases.

Alpha-lipoic acid inhibits proliferation and migration of human vascular endothelial cells through downregulating HSPA12B/VEGF signaling axis

Endothelial cells play essential roles in angiogenesis. Heat shock protein A12B (HSPA12B), a novel member of the multigene Hsp70 family, expresses specifically in endothelial cells. Alpha-lipoic acid (LA) has been used for the treatment of human diabetic complications for more than 20 years. However, little is known whether LA impacts endothelial proliferation and migration. To address these questions, primary human umbilical vein endothelial cells (HUVECs) were isolated and treated with LA. We found that LA reduced viable HUVECs but not caused LDH leakage and nuclear condensation, suggesting an inhibitory effect of LA on HUVEC proliferation. We also noticed that LA impeded wound closure of HUVEC monolayers. The expressions of C-Myc, VEGF, and eNOS and phosphorylation of focal adhesion kinase were reduced by LA. Moreover, LA decreased the expression of heat shock protein A12B (HSPA12B). Notably, overexpression of HSPA12B in endothelial cells prevented the LA-induced loss of VEGF. More importantly, HSPA12B overexpression attenuated the LA-induced inhibition of endothelial proliferation and migration. Collectively, the results demonstrated that LA inhibited proliferative and migratory abilities in human vascular endothelial cells through the downregulation of the HSPA12B/VEGF signaling axis. The data suggest that besides the treatment in diabetic complications, LA might represent a viable therapeutic potential for human diseases that involve high angiogenic activities such as cancers.

Identification of Pirin as a Molecular Target of the CCG-1423/CCG-203971 Series of Antifibrotic and Antimetastatic Compounds

A series of compounds (including CCG-1423 and CCG-203971) discovered through an MRTF/SRF-dependent luciferase screen has shown remarkable efficacy in a variety of in vitro and in vivo models, including significant reduction of melanoma metastasis and bleomycin- induced fibrosis. Although these compounds are efficacious in these disease models, the molecular target is unknown. Here, we describe affinity isolation-based target identification efforts which yielded pirin, an iron-dependent cotranscription factor, as a target of this series of compounds. Using biophysical techniques including isothermal titration calorimetry and X-ray crystallography, we verify that pirin binds these compounds in vitro. We also show with genetic approaches that pirin modulates MRTF- dependent luciferase reporter activity. Finally, using both siRNA and a previously validated pirin inhibitor, we show a role for pirin in TGF-β- induced gene expression in primary dermal fibroblasts. A recently developed analog, CCG-257081, which co crystallizes with pirin, is also effective in the prevention of bleomycin-induced dermal fibrosis.

Research on the establishment of chronic stress-induced premature ovarian failure the rat model and effects of Chinese medicine Muniziqi treatment

The purposes of this study were to establish and to explore the biological basis of the chronic stress-induced premature ovarian failure (POF) model and to explore the therapeutic effects of the traditional Chinese medicine Muniziqi. Sexually matured female Sprague-Dawley rats were fed with spinach and cilantro in cold and wet conditions for about 20 weeks until a chronic stress (CS) model was established. The CS rats were divided into a POF stress model group and a stress model group according to weekly biological characteristics and hormone level detection ( luteinizing hormone [LH], follicle stimulating hormone [FSH], and estrogen [E2]). To investigate the therapeutic effect of Muniziqi, the POF disease stress model group was divided into the high-, medium-, and low-drug intervention groups. The results showed that chronic stresses (special food, cold, damp) can lead to POF disease. The traditional Chinese medicine Muniziqi could not only improve the reproductive hormone level disorder, but also improve the function of the hypothalamus-pituitary-ovarian axis. The underlying mechanism may be a change in the E2, LH, and FSH hormone levels in serum and lower expression of ovarian premature aging-related protein PFN-1.

Applications of Ruthenium Complex in Tumor Diagnosis and Therapy

Ruthenium complexes are a new generation of metal antitumor drugs that are currently of great interest in multidisciplinary research. In this review article, we introduce the applications of ruthenium complexes in the diagnosis and therapy of tumors. We focus on the actions of ruthenium complexes on DNA, mitochondria, and endoplasmic reticulum of cells, as well as signaling pathways that induce tumor cell apoptosis, autophagy, and inhibition of angiogenesis. Furthermore, we highlight the use of ruthenium complexes as specific tumor cell probes to dynamically monitor the active biological component of the microenvironment and as excellent photosensitizer, catalyst, and bioimaging agents for phototherapies that significantly enhance the diagnosis and therapeutic effect on tumors. Finally, the combinational use of ruthenium complexes with existing clinical antitumor drugs to synergistically treat tumors is discussed.

SRF'ing and SAP'ing - the role of MRTF proteins in cell migration

Actin-based cell migration is a fundamental cellular activity that plays a crucial role in a wide range of physiological and pathological processes. An essential feature of the remodeling of actin cytoskeleton during cell motility is the de novo synthesis of factors involved in the regulation of the actin cytoskeleton and cell adhesion in response to growth-factor signaling, and this aspect of cell migration is critically regulated by serum-response factor (SRF)-mediated gene transcription. Myocardin-related transcription factors (MRTFs) are key coactivators of SRF that link actin dynamics to SRF-mediated gene transcription. In this Review, we provide a comprehensive overview of the role of MRTF in both normal and cancer cell migration by discussing its canonical SRF-dependent as well as its recently emerged SRF-independent functions, exerted through its SAP domain, in the context of cell migration. We conclude by highlighting outstanding questions for future research in this field.

Consensus guidelines for the use and interpretation of angiogenesis assays

The formation of new blood vessels, or angiogenesis, is a complex process that plays important roles in growth and development, tissue and organ regeneration, as well as numerous pathological conditions. Angiogenesis undergoes multiple discrete steps that can be individually evaluated and quantified by a large number of bioassays. These independent assessments hold advantages but also have limitations. This article describes in vivo, ex vivo, and in vitro bioassays that are available for the evaluation of angiogenesis and highlights critical aspects that are relevant for their execution and proper interpretation. As such, this collaborative work is the first edition of consensus guidelines on angiogenesis bioassays to serve for current and future reference.

Structure-based virtual screening identifies a small-molecule inhibitor of the profilin 1-actin interaction

Profilin 1 (Pfn1) is an important regulator of the actin cytoskeleton and plays a vital role in many actin-based cellular processes. Therefore, identification of a small-molecule intervention strategy targeted against the Pfn1-actin interaction could have broad utility in cytoskeletal research and further our understanding of the role of Pfn1 in actin-mediated biological processes. Based on an already resolved Pfn1-actin complex crystal structure, we performed structure-based virtual screening of small-molecule libraries to seek inhibitors of the Pfn1-actin interaction. We identified compounds that match the pharmacophore of the key actin residues of Pfn1-actin interaction and therefore have the potential to act as competitive inhibitors of this interaction. Subsequent biochemical assays identified two candidate compounds with nearly identical structures that can mitigate the effect of Pfn1 on actin polymerization in vitro As a further proof-of-concept test for cellular effects of these compounds, we performed proximity ligation assays in endothelial cells (ECs) to demonstrate compound-induced inhibition of Pfn1-actin interaction. Consistent with the important role of Pfn1 in regulating actin polymerization and various fundamental actin-based cellular activities (migration and proliferation), treatment of these compounds reduced the overall level of cellular filamentous (F) actin, slowed EC migration and proliferation, and inhibited the angiogenic ability of ECs both in vitro and ex vivo In summary, this study provides the first proof of principle of small-molecule-mediated interference with the Pfn1-actin interaction. Our findings may have potential general utility for perturbing actin-mediated cellular activities and biological processes.

Anti-angiogenic activity and mechanism of a chemically sulfated natural glucan from Phellinus ribis

A sulfated polysaccharide named PRP-S16 was obtained by sulfation of a glucan from Phellinus ribis using the chlorosulfonic acid method. PRP-S16 could significantly block the formation of new vessels in chicken chorioallantoic membrane (CAM). It could also inhibit the proliferation, migration, and tube formation and significantly reduced the mRNA expression of vascular endothelial growth factor (VEGF) in EA.hy926 endothelial cells. Western blotting indicated that PRP-S16 down regulated the protein expression of VEGF and VEGF receptor-1 (VEGFR-1), and inhibited the phosphorylation of VEGFR-2, protein kinase B (Akt) and extracellular signal-regulated kinase (ERK1/2) in EA.hy926 cells. These findings suggest that the mechanism of action of the anti-angiogenesis activity of PRP-S16 is related to the inhibition of VEGF-induced signaling pathway. PRP-S16 might be utilized as an effective antagonist in combating diseases associated with angiogenesis.