{beta}1 Integrin and IL-3R coordinately regulate STAT5 activation and anchorage-dependent proliferation

Single-nucleus RNA sequencing reveals heterogenous microenvironments and specific drug response between cervical squamous cell carcinoma and adenocarcinoma

BACKGROUND

Cervical squamous cell carcinoma (CSCC) and adenocarcinoma (CAde) are two major pathological types of cervical cancer (CC), but their high-resolution heterogeneity of tumor and immune microenvironment remains elusive.

METHODS

Here, we performed single-nucleus RNA sequencing (snRNA-seq) from five CSCC and three CAde samples, and systematically outlined their specific transcriptome atlas.

FINDINGS

We found CD8+ T cells in CSCC were more cytotoxic but lower exhausted compared to those in CAde, and phagocytic MRC1+ macrophages were specifically enriched in CSCC. Interestingly, we discovered that pro-tumoral cancer-associated myofibroblasts (myoCAFs) and cancer-associated vascular-fibroblasts (vCAFs) were more abundant in CSCC, and further verified their pro-metastatic roles in vitro. Furthermore, we also identified some specific chemotherapy drugs for CSCC (Dasatinib and Doramapimod) and CAde (Pyrimethamine and Lapatinib) by revealing their heterogeneity in transcriptomic profiles of malignant epithelial cells, and further verified their specific sensitivity in cell lines and constructed CC-derived organoids. Cell-cell communication networks revealed that the pathways of NRG1-ERBB2, and FN1-ITAG3 were specific for CAde and CSCC, respectively, which may partly explain the specificities of identified chemotherapy drugs.

INTERPRETATION

Our study described the immune heterogeneity and specific cellular interactions between CSCC and CAde, which could provide insights for uncovering pathogenesis and designing personalized treatment.

FUNDINGS

National Key R&D Program of China (2021YFC2701201), National Natural Science Foundation of China (82072895, 82141106, 82103134, 81903114).

Activated Stat5 trafficking Via Endothelial Cell-derived Extracellular Vesicles Controls IL-3 Pro-angiogenic Paracrine Action

Soluble factors and cell-derived extracellular vesicles (EVs) control vascular cell fate during inflammation. The present study investigates the impact of Interleukin 3 (IL-3) on EV release by endothelial cells (ECs), the mechanisms involved in EV release and paracrine actions. We found that IL-3 increases EV release, which is prevented by IL-3Ralpha blockade. EVs released upon IL-3 stimulation were able to induce pro-angiogenic signals as shown by chromatin immunoprecipitation (ChIP) assay performed on the promoter region of cyclin D1 and tridimensional tube-like structure formation. We herein demonstrate that these effects rely on the transfer of miR-126-3p, pre-miR-126 and, more importantly, of activated signal transduction and activator of transcription 5 (pSTAT5) from IL-3-EV cargo into recipient ECs. We show, using the dominant negative form (ΔN)STAT5 and an activated STAT5 (1*6STAT5) constructs, that STAT5 drives IL-3-mediated EV release, miR-126-3p and pSTAT5 content. Finally, using EVs recovered from ΔNSTAT5 expressing ECs, we provide evidence that miR-126-3p and pSTAT5 trafficking is relevant for IL-3-mediated paracrine pro-angiogenic signals. These results indicate that IL-3 regulates EC-EV release, cargo and IL-3 angiogenic paracrine action via STAT5. Moreover, these results provide evidence that EC-derived IL-3-EVs can serve as pro-angiogenic clinical delivery wound healing devices.

Importance of the stem cell microenvironment for ophthalmological cell-based therapy

Cell therapy is a promising treatment for diseases that are caused by cell degeneration or death. The cells for clinical transplantation are usually obtained by culturing healthy allogeneic or exogenous tissue in vitro. However, for diseases of the eye, obtaining the adequate number of cells for clinical transplantation is difficult due to the small size of tissue donors and the frequent needs of long-term amplification of cells in vitro, which results in low cell viability after transplantation. In addition, the transplanted cells often develop fibrosis or degrade and have very low survival. Embryonic stem cells (ESCs) and induced pluripotent stem cells (iPS) are also promising candidates for cell therapy. Unfortunately, the differentiation of ESCs can bring immune rejection, tumorigenicity and undesired differentiated cells, limiting its clinical application. Although iPS cells can avoid the risk of immune rejection caused by ES cell differentiation post-transplantation, the low conversion rate, the risk of tumor formation and the potentially unpredictable biological changes that could occur through genetic manipulation hinder its clinical application. Thus, the desired clinical effect of cell therapy is impaired by these factors. Recent research findings recognize that the reason for low survival of the implanted cells not only depends on the seeded cells, but also on the cell microenvironment, which determines the cell survival, proliferation and even reverse differentiation. When used for cell therapy, the transplanted cells need a specific three-dimensional structure to anchor and specific extra cellular matrix components in addition to relevant cytokine signaling to transfer the required information to support their growth. These structures present in the matrix in which the stem cells reside are known as the stem cell microenvironment. The microenvironment interaction with the stem cells provides the necessary homeostasis for cell maintenance and growth. A large number of studies suggest that to explore how to reconstruct the stem cell microenvironment and strengthen its combination with the transplanted cells are key steps to successful cell therapy. In this review, we will describe the interactions of the stem cell microenvironment with the stem cells, discuss the importance of the stem cell microenvironment for cell-based therapy in ocular diseases, and introduce the progress of stem cell-based therapy for ocular diseases.

Activation of integrin-ERBB2 signaling in undifferentiated thyroid cancer

Undifferentiated thyroid carcinoma is one of the most aggressive human cancers. Although genetic changes underlying this aggressive cancer remain to be elucidated, RAS mutations have been frequently identified in it. Mice harboring a mutant thyroid hormone receptor Thrb(PV) (Thrb(PV/PV) ) spontaneously develop differentiated follicular thyroid carcinoma similar to human thyroid cancer. We recently demonstrated that targeting a RAS mutation (Kras(G12D) ) to the thyroid of Thrb(PV/PV) mice (Thrb(PV/PV) Kras(G12D) mice) promotes initiation and progression of undifferentiated thyroid cancer. To uncover genes destined to drive the aggressive cancer phenotype, we used cDNA microarrays to compare the gene expression profiles of thyroid cells of Kras(G12D) mice and thyroid tumor lesions of Thrb(PV/PV) and Thrb(PV/PV) Kras(G12D) mice. Analyses of microarray data identified 14 upstream regulators that were significantly altered in thyroid tumors of Thrb(PV/PV) and Thrb(PV/PV) Kras(G12D) mice. Most of these genes with altered expression function as key regulators in growth factor-induced signaling. Further analysis identified gene expression profiles of markedly elevated integrin levels, acting as upstream activators to stimulate ERBB2-mediated downstream signaling in thyroid tumors of Thrb(PV/PV) Kras(G12D) mice. The present studies uncovered integrin-activated ERBB2 signaling as one of the mechanisms in synergy between TRβPV and KRASG12D signaling to promote aggressive tumor growth in undifferentiated thyroid cancer.

Integrins in development and cancer

The correct control of cell fate decisions is critical for metazoan development and tissue homeostasis. It is established that the integrin family of cell surface receptors regulate cell fate by mediating cell-cell and cell-extracellular matrix (ECM) interactions. However, our understanding of how the different family members control discrete aspects of cell biology, and how this varies between tissues and is temporally regulated, is still in its infancy. An emerging area of investigation aims to understand how integrins translate changes in tension in the surrounding microenvironment into biological responses. This is particularly pertinent due to changes in the mechanical properties of the ECM having been linked to diseases, such as cancer. In this review, we provide an overview of the roles integrins play in important developmental processes, such as proliferation, polarity, apoptosis, differentiation and maintenance of "stemness". We also discuss recent advances in integrin mechanobiology and highlight the involvement of integrins and aberrant ECM in cancer.

miR-221/222 control luminal breast cancer tumor progression by regulating different targets

α6β4 integrin is an adhesion molecule for laminin receptors involved in tumor progression. We present a link between β4 integrin expression and miR-221/222 in the most prevalent human mammary tumor: luminal invasive carcinomas (Lum-ICs). Using human primary tumors that display different β4 integrin expression and grade, we show that miR-221/222 expression inversely correlates with tumor proliferating index, Ki67. Interestingly, most high-grade tumors express β4 integrin and low miR-221/222 levels. We ectopically transfected miR-221/222 into a human-derived mammary tumor cell line that recapitulates the luminal subtype to investigate whether miR-221/222 regulates β4 expression. We demonstrate that miR-221/222 overexpression results in β4 expression downregulation, breast cancer cell proliferation, and invasion inhibition. The role of miR-221/222 in driving β4 integrin expression is also confirmed via mutating the miR-221/222 seed sequence for β4 integrin 3'UTR. Furthermore, we show that these 2 miRNAs are also key breast cancer cell proliferation and invasion regulators, via the post-transcriptional regulation of signal transducer and activator of transcription 5A (STAT5A) and of a disintegrin and metalloprotease-17 (ADAM-17). We further confirm these data by silencing ADAM-17, using a dominant-negative or an activated STAT5A form. miR-221/222-driven β4 integrin, STAT5A, and ADAM-17 did not occur in MCF-10A cells, denoted "normal" breast epithelial cells, indicating that the mechanism is cancer cell-specific.   These results provide the first evidence of a post-transcriptional mechanism that regulates β4 integrin, STAT5A, and ADAM-17 expression, thus controlling breast cancer cell proliferation and invasion. Pre-miR-221/222 use in the aggressive luminal subtype may be a powerful therapeutic anti-cancer strategy.

Extracellular matrix: a dynamic microenvironment for stem cell niche

Background

Extracellular matrix (ECM) is a dynamic and complex environment characterized by biophysical, mechanical and biochemical properties specific for each tissue and able to regulate cell behavior. Stem cells have a key role in the maintenance and regeneration of tissues and they are located in a specific microenvironment, defined as niche.

Scope of review

We overview the progresses that have been made in elucidating stem cell niches and discuss the mechanisms by which ECM affects stem cell behavior. We also summarize the current tools and experimental models for studying ECM–stem cell interactions.

Major conclusions

ECM represents an essential player in stem cell niche, since it can directly or indirectly modulate the maintenance, proliferation, self-renewal and differentiation of stem cells. Several ECM molecules play regulatory functions for different types of stem cells, and based on its molecular composition the ECM can be deposited and finely tuned for providing the most appropriate niche for stem cells in the various tissues. Engineered biomaterials able to mimic the in vivo characteristics of stem cell niche provide suitable in vitro tools for dissecting the different roles exerted by the ECM and its molecular components on stem cell behavior.

General significance

ECM is a key component of stem cell niches and is involved in various aspects of stem cell behavior, thus having a major impact on tissue homeostasis and regeneration under physiological and pathological conditions. This article is part of a Special Issue entitled Matrix-mediated cell behaviour and properties.

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Stem cells have a key role in the maintenance and regeneration of tissues.

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The extracellular matrix is a critical regulator of stem cell function.

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Stem cells reside in a dynamic and specialized microenvironment denoted as niche.

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The extracellular matrix represents an essential component of stem cell niches.

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Bioengineered niches can be used for investigating stem cell–matrix interactions.

Membrane-bound KIT ligand-targeting DNA vaccination inhibits mammary tumor growth

We have recently demonstrated that a DNA vaccine targeting membrane-bound KIT ligand (KITL) inhibits tumor growth by interfering with vessel stabilization/permeability and by disrupting the recruitment of inflammatory cells and regulatory T cells, the latter being an essential mechanism by which tumors resist available treatments. Combining KITL-targeting vaccines with conventional chemotherapy might avert drug resistance and improve the efficacy of standard-of-care therapeutic interventions.

CBAP functions as a novel component in chemokine-induced ZAP70-mediated T-cell adhesion and migration

Activated chemokine receptor initiates inside-out signaling to transiently trigger activation of integrins, a process involving multiple components that have not been fully characterized. Here we report that GM-CSF/IL-3/IL-5 receptor common beta-chain-associated protein (CBAP) is required to optimize this inside-out signaling and activation of integrins. First, knockdown of CBAP expression in human Jurkat T cells caused attenuated CXC chemokine ligand-12 (CXCL12)-induced cell migration and integrin α4β1- and αLβ2-mediated cell adhesion in vitro, which could be rescued sufficiently upon expression of murine CBAP proteins. Freshly isolated CBAP-deficient primary T cells also exhibited diminution of chemotaxis toward CC chemokine ligand-21 (CCL21) and CXCL12, and these chemokines-induced T-cell adhesions in vitro. Adoptive transfer of isolated naive T cells demonstrated that CBAP deficiency significantly reduced lymph node homing ability in vivo. Finally, migration of T cell-receptor-activated T cells induced by inflammatory chemokines was also attenuated in CBAP-deficient cells. Further analyses revealed that CBAP constitutively associated with both integrin β1 and ZAP70 and that CBAP is required for chemokine-induced initial binding of the talin-Vav1 complex to integrin β1 and to facilitate subsequent ZAP70-mediated dissociation of the talin-Vav1 complex and Vav1 phosphorylation. Within such an integrin signaling complex, CBAP likely functions as an adaptor and ultimately leads to activation of both integrin α4β1 and Rac1. Taken together, our data suggest that CBAP indeed can function as a novel signaling component within the ZAP70/Vav1/talin complex and plays an important role in regulating chemokine-promoted T-cell trafficking.

The GM-CSF/IL-3/IL-5 cytokine receptor family: from ligand recognition to initiation of signaling

Granulocyte-macrophage colony-stimulating factor (GM-CSF), interleukin-3 (IL-3), and IL-5 are members of a discrete family of cytokines that regulates the growth, differentiation, migration and effector function activities of many hematopoietic cells and immunocytes. These cytokines are involved in normal responses to infectious agents, bridging innate and adaptive immunity. However, in certain cases, the overexpression of these cytokines or their receptors can lead to excessive or aberrant initiation of signaling resulting in pathological conditions, with chronic inflammatory diseases and myeloid leukemias the most notable examples. Recent crystal structures of the GM-CSF receptor ternary complex and the IL-5 binary complex have revealed new paradigms of cytokine receptor activation. Together with a wealth of associated structure-function studies, they have significantly enhanced our understanding of how these receptors recognize cytokines and initiate signals across cell membranes. Importantly, these structures provide opportunities for structure-based approaches for the discovery of novel and disease-specific therapeutics. In addition, recent biochemical evidence has suggested that the GM-CSF/IL-3/IL-5 receptor family is capable of interacting productively with other membrane proteins at the cell surface. Such interactions may afford additional or unique biological activities and might be harnessed for selective modulation of the function of these receptors in disease.

Extracellular matrix, integrins, and growth factors as tailors of the stem cell niche

It is widely acknowledged that integrins, the major receptors for the extracellular matrix (ECM) proteins, exert an extensive crosstalk with many growth factor and cytokine receptors. Among them, growth factor receptors, such as the EGFR, MET, PDGFR and VEGFR, and the IL-3 receptor have been shown to be physically and functionally associated to integrins. The connection between integrins and other transmembrane receptors is bidirectional, integrins being essential for receptor signalling, and receptors being involved in regulation of integrin expression or activation. Moreover, there is accumulating evidence for direct binding of specific growth factors and morphogens to the ECM proteins, suggesting that ECM might spatially integrate different types of signals in a specific microenvironment, facilitating integrin/transmembrane receptors connection. These interactions are crucial in controlling a variety of cell behaviours including proliferation, survival and differentiation. The increasing interest for cell therapy in regenerative medicine has recently emphasized the role of cell-ECM adhesion as stem cell determinant. The relevance of ECM, integrins and growth factor receptor network in the establishment of stem cell niche, in maintenance of stem cells and in their differentiation will be analyzed in the present review.

Development of transgenic cloned pig models of skin inflammation by DNA transposon-directed ectopic expression of human β1 and α2 integrin

Integrins constitute a superfamily of transmembrane signaling receptors that play pivotal roles in cutaneous homeostasis by modulating cell growth and differentiation as well as inflammatory responses in the skin. Subrabasal expression of integrins α2 and/or β1 entails hyperproliferation and aberrant differentiation of keratinocytes and leads to dermal and epidermal influx of activated T-cells. The anatomical and physiological similarities between porcine and human skin make the pig a suitable model for human skin diseases. In efforts to generate a porcine model of cutaneous inflammation, we employed the Sleeping Beauty DNA transposon system for production of transgenic cloned Göttingen minipigs expressing human β1 or α2 integrin under the control of a promoter specific for subrabasal keratinocytes. Using pools of transgenic donor fibroblasts, cloning by somatic cell nuclear transfer was utilized to produce reconstructed embryos that were subsequently transferred to surrogate sows. The resulting pigs were all transgenic and harbored from one to six transgene integrants. Molecular analyses on skin biopsies and cultured keratinocytes showed ectopic expression of the human integrins and localization within the keratinocyte plasma membrane. Markers of perturbed skin homeostasis, including activation of the MAPK pathway, increased expression of the pro-inflammatory cytokine IL-1α, and enhanced expression of the transcription factor c-Fos, were identified in keratinocytes from β1 and α2 integrin-transgenic minipigs, suggesting the induction of a chronic inflammatory phenotype in the skin. Notably, cellular dysregulation obtained by overexpression of either β1 or α2 integrin occurred through different cellular signaling pathways. Our findings mark the creation of the first cloned pig models with molecular markers of skin inflammation. Despite the absence of an overt psoriatic phenotype, these animals may possess increased susceptibility to severe skin damage-induced inflammation and should be of great potential in studies aiming at the development and refinement of topical therapies for cutaneous inflammation including psoriasis.

Role of ITAM signaling module in signal integration

Diverse cell types use a small number of evolutionarily conserved signaling modules to integrate external cues and elicit distinct functions. A question thus arises as to how does a receptor, which contains a single signaling module, produce distinct outcomes to diverse signals, particularly if such module is shared amongst a family of receptors? Emerging data suggest that many immunoreceptors, all of which use a conserved ITAM-module for their signaling, can couple with members of additional classes of membrane receptors to deliver unique signal(s) to the cell. We discuss the possible biological purposes and mechanisms behind these interactions at the plasma membrane. We offer a conceptual framework to understand information processing within the immune system and discuss the new biology of old receptors involving their structural and functional collaborations that evolved to deliver unique signal(s) to the cell using a limited set of conserved signaling modules.

MIR221/MIR222-driven post-transcriptional regulation of P27KIP1 and P57KIP2 is crucial for high-glucose- and AGE-mediated vascular cell damage

AIMS/HYPOTHESIS

MicroRNAs (miRNAs) are a novel group of small non-coding RNAs that regulate gene expression at the post-transcriptional level and act on their target mRNAs in a tissue- and cell-type-specific manner. Herein, the relevance of MIR221/MIR222 in high-glucose- and AGE-mediated vascular damage was investigated.

METHODS

Functional studies were performed using human mature endothelial cells and endothelial progenitor cells subjected to high glucose or AGE. Quantitative real-time amplification was performed to analyse MIR221/MIR222 expression in these experimental conditions. Luciferase assay was used to identify MIR221/MIR222 targets. Functional studies were performed in vitro and in vivo in mice using gain- and loss-of-function approaches.

RESULTS

Using an in vivo mouse model we demonstrated that exposure to AGE and high glucose impaired vessel formation. Moreover, in vitro functional studies revealed that both high glucose and AGE inhibit cell-cycle progression by modulating the expression of P27KIP1 (also known as CDKN1B) and P57KIP2 (also known as CDKN1C), which encode cyclin-dependent kinase inhibitor 1B (p27, Kip1) (P27KIP1) and cyclin-dependent kinase inhibitor 1C (p57, Kip2) (P57KIP2), respectively. Crucial to AGE- and high-glucose-mediated cell-cycle arrest was the downregulation of MIR221/MIR222 expression. Luciferase assay showed that MIR221 and MIR222 specifically bind to the P27KIP1 and P57KIP2 mRNA 3'-untranslated regions, implicating P27KIP1 and P57KIP2 as MIR221/MIR222 targets. These results were confirmed by gain-of-function experiments in vitro, and by injecting mice with endothelial cells overexpressing MIR221 and MIR222.

CONCLUSIONS/INTERPRETATION

We provide evidence that high-glucose- and AGE-induced inhibition of vascular cell proliferation is controlled by MIR221/MIR222-driven post-transcriptional regulation of P27KIP1 and P57KIP2. These data add further insight to the possible contribution of miRNAs in vascular damage mediated by a high-glucose environment.

Fibronectin and beta-catenin act in a regulatory loop in dermal fibroblasts to modulate cutaneous healing

β-Catenin is an important regulator of dermal fibroblasts during cutaneous wound repair. However, the factors that modulate β-catenin activity in this process are not completely understood. We investigated the role of the extracellular matrix in regulating β-catenin and found an increase in β-catenin-mediated Tcf-dependent transcriptional activity in fibroblasts exposed to various extracellular matrix components. This occurs through an integrin-mediated GSK3β-dependent pathway. The physiologic role of this mechanism was demonstrated during wound repair in extra domain A-fibronectin-deficient mice, which exhibited decreased β-catenin-mediated signaling during the proliferative phase of healing. Extra domain A-fibronectin-deficient mice have wounds that fail at a lower tensile strength and contain fewer fibroblasts compared with wild type mice. This phenotype was rescued by genetic or pharmacologic activation of β-catenin signaling. Because fibronectin is a transcriptional target of β-catenin, this suggests the existence of a feedback loop between these two molecules that regulates dermal fibroblast cell behavior during wound repair.

MIR221/MIR222-driven post-transcriptional regulation of P27KIP1 and P57KIP2 is crucial for high-glucose- and AGE-mediated vascular cell damage

AIMS/HYPOTHESIS

MicroRNAs (miRNAs) are a novel group of small non-coding RNAs that regulate gene expression at the post-transcriptional level and act on their target mRNAs in a tissue- and cell-type-specific manner. Herein, the relevance of MIR221/MIR222 in high-glucose- and AGE-mediated vascular damage was investigated.

METHODS

Functional studies were performed using human mature endothelial cells and endothelial progenitor cells subjected to high glucose or AGE. Quantitative real-time amplification was performed to analyse MIR221/MIR222 expression in these experimental conditions. Luciferase assay was used to identify MIR221/MIR222 targets. Functional studies were performed in vitro and in vivo in mice using gain- and loss-of-function approaches.

RESULTS

Using an in vivo mouse model we demonstrated that exposure to AGE and high glucose impaired vessel formation. Moreover, in vitro functional studies revealed that both high glucose and AGE inhibit cell-cycle progression by modulating the expression of P27KIP1 (also known as CDKN1B) and P57KIP2 (also known as CDKN1C), which encode cyclin-dependent kinase inhibitor 1B (p27, Kip1) (P27KIP1) and cyclin-dependent kinase inhibitor 1C (p57, Kip2) (P57KIP2), respectively. Crucial to AGE- and high-glucose-mediated cell-cycle arrest was the downregulation of MIR221/MIR222 expression. Luciferase assay showed that MIR221 and MIR222 specifically bind to the P27KIP1 and P57KIP2 mRNA 3'-untranslated regions, implicating P27KIP1 and P57KIP2 as MIR221/MIR222 targets. These results were confirmed by gain-of-function experiments in vitro, and by injecting mice with endothelial cells overexpressing MIR221 and MIR222.

CONCLUSIONS/INTERPRETATION

We provide evidence that high-glucose- and AGE-induced inhibition of vascular cell proliferation is controlled by MIR221/MIR222-driven post-transcriptional regulation of P27KIP1 and P57KIP2. These data add further insight to the possible contribution of miRNAs in vascular damage mediated by a high-glucose environment.

Integrin signalling adaptors: not only figurants in the cancer story

Current evidence highlights the ability of adaptor (or scaffold) proteins to create signalling platforms that drive cellular transformation upon integrin-dependent adhesion and growth factor receptor activation. The understanding of the biological effects that are regulated by these adaptors in tumours might be crucial for the identification of new targets and the development of innovative therapeutic strategies for human cancer. In this Review we discuss the relevance of adaptor proteins in signalling that originates from integrin-mediated cell-extracellular matrix (ECM) adhesion and growth factor stimulation in the context of cell transformation and tumour progression. We specifically underline the contribution of p130 Crk-associated substrate (p130CAS; also known as BCAR1), neural precursor cell expressed, developmentally down-regulated 9 (NEDD9; also known as HEF1), CRK and the integrin-linked kinase (ILK)-pinch-parvin (IPP) complex to cancer, along with the more recently identified p140 Cas-associated protein (p140CAP; also known as SRCIN1).

Integrins and signal transduction

Integrin signaling has a critical function in organizing cells in tissues during both embryonic development and tissue repair. Following their binding to the extracellular ligands, the intracellular signaling pathways triggered by integrins are directed to two major functions: organization of the actin cytoskeleton and regulation of cell behaviour including survival, differentiation and growth. Basic research conducted in the past twelve years has lead to remarkable breakthroughs in this field. Integrins are catalytically inactive and translate positional cues into biochemical signals by direct and/or functional association with intracellular adaptors, cytosolic tyrosine kinases or growth factor and cytokine receptors. The purpose of this chapter is to highlight recent experimental and conceptual advances in integrin signaling with particular emphasis on the ability of integrins to regulate Fak/Src family kinases (SFKs) activation and the cross-talk with soluble growth factors receptors and cytokines.

Erythropoietin accelerates smooth muscle cell-rich vascular lesion formation in mice through endothelial cell activation involving enhanced PDGF-BB release

In this study, the effect of human erythropoietin Delta (Epo) on smooth muscle cell (SMC)-rich lesions was evaluated. Mice, of which the left carotid artery was ligated, were treated with suberythropoietic as well as erythropoietic doses of Epo and both doses of Epo enhanced SMC-rich lesion formation. No association was observed between hemoglobin levels and lesion size. Moreover, endothelial progenitor cell (EPC) numbers in the peripheral blood increased only in the erythropoietic dosing group, indicating that EPC numbers did not correlate with lesion size. Immunohistochemical analysis revealed that Epo-mediated enhancement of lesion formation correlates with increased signal transducer and activator of transcription 5 (Stat5) phosphorylation in the vessel wall. Experiments performed in cultured vascular cells demonstrated that Epo robustly induced phosphorylation of Stat5 in human umbilical vein endothelial cells (HUVECs), but only very weakly in SMCs. In tumor necrosis factor-alpha (TNFalpha)-activated HUVECS, Epo induced expression of platelet-derived growth factor B (PDGF-B), which was at least partially responsible for the induction of Stat5 phosphorylation in SMCs by HUVEC-conditioned medium. In conclusion, in mice Epo accelerates SMC-rich neointima formation, which correlates with increased Stat5 phosphorylation in the vessel wall but is independent of erythrocyte and EPC numbers.

Signal co-operation between integrins and other receptor systems

The multicellular nature of metazoans means that all cellular processes need to be tuned by adhesive interactions between cells and their local microenvironment. The spatial organization of cells within tissues requires sophisticated networks of extracellular signals to control their survival and proliferation, movements and positioning, and differentiated function. These cellular characteristics are mediated by multiple inputs from adhesion systems in combination with soluble and developmental signals. In the present review we explore how one class of adhesion receptor, the integrins, co-operate with other types of receptor to control diverse aspects of cell fate. In particular we discuss: (i) how beta3 and beta1 integrins work together with growth factors to control angiogenesis; (ii) how alpha6beta4 integrin co-operates with receptor tyrosine kinases in normal epithelial function and cancer; (iii) the interplay between beta1 integrins and EGF (epidermal growth factor) receptor; (iv) signal integration connecting integrins and cytokine receptors for interleukins, prolactin and interferons; and (v) how integrins and syndecans co-operate in cell migration.

Integrins and cell-fate determination

All cellular processes are determined by adhesive interactions between cells and their local microenvironment. Integrins, which constitute one class of cell-adhesion receptor, are multifunctional proteins that link cells to the extracellular matrix and organise integrin adhesion complexes at the cell periphery. Integrin-based adhesions provide anchor points for assembling and organising the cytoskeleton and cell shape, and for orchestrating migration. Integrins also control the fate and function of cells by influencing their proliferation, apoptosis and differentiation. Moreover, new literature demonstrates that integrins control the cell-division axis at mitosis. This extends the influence of integrins over cell-fate decisions, as daughter cells are frequently located in new microenvironments that determine their behaviour following cell division. In this Commentary, I describe how integrins influence cell-fate determination, placing particular emphasis on their role in influencing the direction of cell division and the orientation of the mitotic spindle.

Signal co-operation between integrins and other receptor systems

The multicellular nature of metazoans means that all cellular processes need to be tuned by adhesive interactions between cells and their local microenvironment. The spatial organization of cells within tissues requires sophisticated networks of extracellular signals to control their survival and proliferation, movements and positioning, and differentiated function. These cellular characteristics are mediated by multiple inputs from adhesion systems in combination with soluble and developmental signals. In the present review we explore how one class of adhesion receptor, the integrins, co-operate with other types of receptor to control diverse aspects of cell fate. In particular we discuss: (i) how β3 and β1 integrins work together with growth factors to control angiogenesis; (ii) how α6β4 integrin co-operates with receptor tyrosine kinases in normal epithelial function and cancer; (iii) the interplay between β1 integrins and EGF (epidermal growth factor) receptor; (iv) signal integration connecting integrins and cytokine receptors for interleukins, prolactin and interferons; and (v) how integrins and syndecans co-operate in cell migration.

Beta1 integrin adhesion enhances IL-6-mediated STAT3 signaling in myeloma cells: implications for microenvironment influence on tumor survival and proliferation

The bone marrow microenvironmental components interleukin (IL)-6 and fibronectin (FN) individually influence the proliferation and survival of multiple myeloma (MM) cells; however, in vivo, these effectors most likely work together. We examined signaling events, cell cycle progression, and levels of drug response in MM cells either adhered to FN via beta1 integrins, stimulated with IL-6, or treated with the two combined. Although G(1)-S cell cycle arrest associated with FN adhesion was overcome when IL-6 was added, the cell adhesion-mediated drug resistance (CAM-DR) was maintained in the presence of IL-6. Concomitant exposure of MM cells to IL-6 and FN adhesion revealed a dramatic increase in signal transducers and activators of transcription 3 (STAT3) phosphorylation, nuclear translocation, and DNA binding, compared with either IL-6 or FN adhesion alone in four MM cell lines. Importantly, this increase in STAT3 activation correlated with a novel association between STAT3 and gp130 in cells adhered to FN before stimulation with IL-6, relative to nonadherent cells. Taken together, these results suggest a mechanism by which collaborative signaling by beta1 integrin and gp130 confers an increased survival advantage to MM cells.

Formation of STAT5/PPARgamma transcriptional complex modulates angiogenic cell bioavailability in diabetes

OBJECTIVE

Circulating angiogenic cells (CACs) expansion is a multistage process requiring sequential activation of transcriptional factors, including STAT5. STAT5, in concert with peroxisome proliferator-activated receptors (PPARs), seems to induce discrete biological responses in different tissues. In the present study we investigated the role of STAT5 and PPARgamma in regulating CAC expansion in normal and diabetic settings.

METHODS AND RESULTS

Normal and diabetic CACs were used. siRNA technology, EMSA, and chromatin immunoprecipitation (ChIP) assay as well as site-directed mutagenesis of the STAT5 response element in the PPARgamma promoter enabled us to demonstrate that STAT5 transcriptional activity controls PPARgamma expression. Moreover, FACS analysis, coimmunoprecipitation experiments, and ChIP assay revealed that a STAT5/PPARgamma transcriptional complex controls cyclin D1 expression and CAC progression into the cell-cycle. Conversely, PPARgamma agonists, by preventing the expression of STAT5 and the formation of the STAT5/PPARgamma heterodimeric complex failed to promote CAC expansion. Finally, we demonstrated that diabetic CAC functional capability can be recovered by molecules able to activate the STAT5/PPARgamma transcriptional complex.

CONCLUSIONS

Our data identify the STAT5/PPARgamma heterodimers as landmark of CAC expansion and provide evidences for a mechanism that partially rescues CAC bioavailability in diabetic setting.

Interleukin-3 promotes expansion of hemopoietic-derived CD45+ angiogenic cells and their arterial commitment via STAT5 activation

Interleukin-3 (IL-3) released by infiltrating inflammatory cells in different pathologic settings contributes to organ and tumor angiogenesis. Here we demonstrate that IL-3 expands a subset of CD45+ circulating angiogenic cells clonally derived from the hemopoietic progenitors. Moreover, CD45+ cells exposed to IL-3 acquire arterial specification and contribute to the formation of vessels in vivo. Depletion of signal transducer and activator of transcription 5 (STAT5) provides evidence that IL-3–mediated cell expansion and arterial morphogenesis rely on STAT5 activation. In addition, by means of Tie2-transgenic mice, we demonstrate that STAT5 also regulates IL-3–induced expansion and arterial specification of bonemarrow–derived CD45+ cells. Thus, our data provide the first evidence that, in inflammatory microenvironments containing IL-3, angiogenic cells derived from hemopoietic precursors can act as adult vasculogenic cells. Moreover, the characterization of the signaling pathway regulating these events provides the rationale for therapeutically targeting STAT5 in these pathologic settings.

The Integrin alpha9beta1 contributes to granulopoiesis by enhancing granulocyte colony-stimulating factor receptor signaling

The integrin alpha9beta1 is widely expressed on neutrophils, smooth muscle, hepatocytes, endothelia, and some epithelia. We now show that mice lacking this integrin have a dramatic defect in neutrophil development, with decreased numbers of granulocyte precursors in bone marrow and impaired differentiation of bone marrow cells into granulocytes. In response to granulocyte colony-stimulating factor (G-CSF), alpha9-deficient bone marrow cells or human bone marrow cells incubated with alpha9beta1-blocking antibody demonstrated decreased phosphorylation of signal transducer and activator of transcription 3 and extracellular signal-regulated protein kinase. These effects depended on the alpha9 subunit cytoplasmic domain, which was required for formation of a physical complex between alpha9beta1 and ligated G-CSF receptor. Integrin alpha9beta1 was required for granulopoiesis and played a permissive role in the G-CSF-signaling pathway, suggesting that this integrin could play an important role in disorders of granulocyte development and other conditions characterized by defective G-CSF signaling.

Mesenchymal progenitor cells communicate via alpha and beta integrins with a three-dimensional collagen type I matrix

BACKGROUND/AIMS

The aim of our study was to investigate interactions of mesenchymal progenitor cells (MPCs) with collagen matrices.

METHODS

Human bone-marrow-derived MPCs were cultivated in collagen type I gels with and without inhibition of beta(1)-integrin by a specific antibody. Collagen gel contraction, cell morphology, expression of integrin subunits and several genes related to matrix synthesis and turnover as well as MPC differentiation were analyzed over 14 days.

RESULTS

Human MPCs markedly contracted free-floating collagen gels. Contraction was nearly completely inhibited by blocking beta(1)-integrin. Cellular morphology was elongated in the absence and mostly round in the presence of the antibody. Expression of integrin alpha(1), alpha(2) and beta(1) subunits showed several changes partly dependent on beta(1)-integrin blocking. Expression of matrix metalloproteinase-1 was elevated irrespective of beta(1)-integrin blocking and tenascin-C was subsequently induced during gel contraction. Spontaneous induction of chondrogenic, osteogenic or adipogenic differentiation was observed neither in the presence nor in the absence of the beta(1)-integrin antibody.

CONCLUSION

Our results indicate that the interaction of human MPCs with fibrillar collagen type I involves beta(1)- and alpha-integrin subunits and induces changes in gene expression related to extracellular matrix synthesis and turnover but not differentiation to the chondrogenic, osteogenic or adipogenic phenotype.

Comparative SAGE analysis of the response to hypoxia in human pulmonary and aortic endothelial cells

We utilized serial analysis of gene expression (SAGE) to analyze the temporal response of human pulmonary artery endothelial cells (HPAECs) to short-term chronic hypoxia at the level of transcription. Primary cultures of HPAECs were exposed to 1% O2hypoxia for 8 and 24 h and compared with identical same-passage cells cultured under standard (5% CO2-95% air) conditions. Hierarchical clustering of significant hypoxia-responsive genes identified temporal changes in the expressions of a number of well-described gene families including those encoding proteins involved in thrombosis, stress response, apoptosis, angiogenesis, and cell proliferation. These experiments build on previously published data describing the transcriptomic response of human aortic endothelial cells (HAECs) obtained from the same donor and cultured under identical conditions, and we have thus taken advantage of the immortality of SAGE data to make direct comparisons between these two data sets. This approach revealed comprehensive information relating to the similarities and differences at the level of mRNA expression between HAECs and HPAECs. For example, we found differences in the cell type-specific response to hypoxia among genes encoding cytoskeletal factors, including paxillin, and proteins involved in metabolic energy production, the response to oxidative stress, and vasoreactivity (e.g., endothelin-1). These efforts contribute to the expanding collection of publicly available SAGE data and provide a foundation on which to base further efforts to understand the characteristics of the vascular response to hypoxia in the pulmonary circulation relative to systemic vasculature.

Lipoprotein p37 from Mycoplasma hyorhinis inhibiting mammalian cell adhesion

p37 protein is a membrane lipoprotein of Mycoplasma hyorhinis, and our previous work showed that there was high ratio of M. hyorhinis infection in human gastric carcinoma. To investigate the possible functions of p37 in cancer development, the nucleotide sequence of p37 gene was modified and expressed well in transfected cells. We found that p37 localized at the Golgi apparatus and could be secreted out of the cell. Human gastric cancer cells AGS, after being transfected with the p37 gene, were smaller, more spherical and easy to detach from each other. Their adhesion to matrix was also diminished and cytoskeleton in these stable p37 AGS cell was rearranged and transcription co-factor beta-actin was transferred to nucleolus with down-regulation of ICAM-1 and integrin beta1. These findings will be helpful for us to elucidate the effects of p37 on eukaryotic cells as well as to better understand the potential relationship between cancer and mycoplasma infection.