Extracellular matrix regulates apoptosis in mammary epithelium through a control on insulin signaling

Organophosphate flame retardants tris (2-butoxyethyl) phosphate (TBEP) and tris (2-chloroethyl) phosphate (TCEP) disrupt human motor neuron development by differentially affecting their survival and differentiation

Mounting evidence in animal experiments proves that early life stage exposure to organophosphate flame retardants (OPFRs) affects the locomotor behavior and changes the transcriptions of central nervous system genes. Unfortunately, their effect on human motor neuron (MN) development, which is necessary for body locomotion and survival, has not yet characterized. Here, we utilized a spinal cord MN differentiation model from human embryonic stem cells (ESCs) and adopted this model to test the effects of two typical OPFRs tris (2-butoxyethyl) phosphate (TBEP) and tris (2-chloroethyl) phosphate (TCEP), on MN development and the possible mechanisms underlying. Our findings revealed TBEP exerted a much more inhibitory effect on MN survival, while TCEP exhibited a stronger stimulatory effect on ESCs differentiation into MN, and thus TBEP exhibited a stronger inhibition on MN development than TCEP. RNA sequencing analysis identified TBEP and TCEP inhibited MN survival mainly by disrupting extracellular matrix (ECM)-receptor interaction. Focusing on the pathway guided MN differentiation, we found both TBEP and TCEP activated BMP signaling, whereas TCEP simultaneously downregulated Wnt signaling. Collectively, this is the first study demonstrated TBEP and TCEP disrupted human MN development by affecting their survival and differentiation, thereby raising concern about their potential harm in causing MN disorders.

Synergistic effects of bee venom, hesperidin, and piperine with tamoxifen on apoptotic and angiogenesis biomarker molecules against xerographic MCF-7 injected rats

Breast cancer ranks as the second leading most significant of mortality for women. Studies have demonstrated the potential benefits of natural compounds in cancer treatment and prevention, either in isolation or in conjunction with chemotherapy. In order to improve Tamoxifen's therapeutic efficacy in in-vivo studies, our research sought to determine the effects of hesperidin, piperine, and bee venom as natural compounds, as well as their combination effect with or without Tamoxifen. First, 132 female albino rats were equally divided into six groups and five subgroups, and breast cancer was induced in the selected groups by xenografting of MCF7 cells. Second, the effect of single and best ratio combinations treatment from previous in vitro studies were selected. Next, tumorous mammary glands were collected for apoptotic and antiapoptotic biomarkers and cell cycle analysis. Single or combined natural products with or without Tamoxifen revealed a significant up-regulation in apoptotic genes Bax and Casp3 and a downregulation of antiapoptotic and angiogenesis genes Bcl-2 and VEGF genes. We found that cell cycle arrest in the G0/G1 phase was exclusively caused by Tamoxifen and/ or hesperidin. However, the cell cycle arrest in the G2/M phase is a result of the combination of piperine and bee venom, with or without Tamoxifen by using the flow cytometric technique. Our research concludes that bee venom, hesperidin, and piperine can synergistically enhance to increase Tamoxifen's efficiency in the management of breast cancer.

Cell-extracellular matrix mechanotransduction in 3D

Mechanical properties of extracellular matrices (ECMs) regulate essential cell behaviours, including differentiation, migration and proliferation, through mechanotransduction. Studies of cell-ECM mechanotransduction have largely focused on cells cultured in 2D, on top of elastic substrates with a range of stiffnesses. However, cells often interact with ECMs in vivo in a 3D context, and cell-ECM interactions and mechanisms of mechanotransduction in 3D can differ from those in 2D. The ECM exhibits various structural features as well as complex mechanical properties. In 3D, mechanical confinement by the surrounding ECM restricts changes in cell volume and cell shape but allows cells to generate force on the matrix by extending protrusions and regulating cell volume as well as through actomyosin-based contractility. Furthermore, cell-matrix interactions are dynamic owing to matrix remodelling. Accordingly, ECM stiffness, viscoelasticity and degradability often play a critical role in regulating cell behaviours in 3D. Mechanisms of 3D mechanotransduction include traditional integrin-mediated pathways that sense mechanical properties and more recently described mechanosensitive ion channel-mediated pathways that sense 3D confinement, with both converging on the nucleus for downstream control of transcription and phenotype. Mechanotransduction is involved in tissues from development to cancer and is being increasingly harnessed towards mechanotherapy. Here we discuss recent progress in our understanding of cell-ECM mechanotransduction in 3D.

Protection of transplants against antibody-mediated injuries: from xenotransplantation to allogeneic transplantation, mechanisms and therapeutic insights

Long-term allograft survival in allotransplantation, especially in kidney and heart transplantation, is mainly limited by the occurrence of antibody-mediated rejection due to anti-Human Leukocyte Antigen antibodies. These types of rejection are difficult to handle and chronic endothelial damages are often irreversible. In the settings of ABO-incompatible transplantation and xenotransplantation, the presence of antibodies targeting graft antigens is not always associated with rejection. This resistance to antibodies toxicity seems to associate changes in endothelial cells phenotype and modification of the immune response. We describe here these mechanisms with a special focus on endothelial cells resistance to antibodies. Endothelial protection against anti-HLA antibodies has been described in vitro and in animal models, but do not seem to be a common feature in immunized allograft recipients. Complement regulation and anti-apoptotic molecules expression appear to be common features in all these settings. Lastly, pharmacological interventions that may promote endothelial cell protection against donor specific antibodies will be described.

Into the Tissues: Extracellular Matrix and Its Artificial Substitutes: Cell Signalling Mechanisms

The existence of orderly structures, such as tissues and organs is made possible by cell adhesion, i.e., the process by which cells attach to neighbouring cells and a supporting substance in the form of the extracellular matrix. The extracellular matrix is a three-dimensional structure composed of collagens, elastin, and various proteoglycans and glycoproteins. It is a storehouse for multiple signalling factors. Cells are informed of their correct connection to the matrix via receptors. Tissue disruption often prevents the natural reconstitution of the matrix. The use of appropriate implants is then required. This review is a compilation of crucial information on the structural and functional features of the extracellular matrix and the complex mechanisms of cell-cell connectivity. The possibilities of regenerating damaged tissues using an artificial matrix substitute are described, detailing the host response to the implant. An important issue is the surface properties of such an implant and the possibilities of their modification.

The Multiple Faces of Integrin-ECM Interactions in Inflammatory Bowel Disease

Inflammatory Bowel Disease (IBD) comprises a series of chronic and relapsing intestinal diseases, with Crohn's disease and ulcerative colitis being the most common. The abundant and uncontrolled deposition of extracellular matrix, namely fibrosis, is one of the major hallmarks of IBD and is responsible for the progressive narrowing and closure of the intestine, defined as stenosis. Although fibrosis is usually considered the product of chronic inflammation, the substantial failure of anti-inflammatory therapies to target and reduce fibrosis in IBD suggests that fibrosis might be sustained in an inflammation-independent manner. Pharmacological therapies targeting integrins have recently shown great promise in the treatment of IBD. The efficacy of these therapies mainly relies on their capacity to target the integrin-mediated recruitment and functionality of the immune cells at the damage site. However, by nature, integrins also act as mechanosensitive molecules involved in the intracellular transduction of signals and modifications originating from the extracellular matrix. Therefore, understanding integrin signaling in the context of IBD may offer important insights into mechanisms of matrix remodeling, which are uncoupled from inflammation and could underlie the onset and persistency of intestinal fibrosis. In this review, we present the currently available knowledge on the role of integrins in the etiopathogenesis of IBD, highlighting their role in the context of immune-dependent and independent mechanisms.

Anoikis resistance in mammary epithelial cells is mediated by semaphorin 7a

Semaphorin-7a (SEMA7A), best known as a neuroimmune molecule, plays a diverse role in many cellular processes and pathologies. Here, we show that SEMA7A promotes anoikis resistance in cultured mammary epithelial cells through integrins and activation of pro-survival kinase AKT, which led us to investigate a role for SEMA7A during postpartum mammary gland involution-a normal developmental process where cells die by anoikis. Our results reveal that SEMA7A is expressed on live mammary epithelial cells during involution, that SEMA7A expression is primarily observed in α6-integrin expressing cells, and that luminal progenitor cells, specifically, are decreased in mammary glands of SEMA7A-/- mice during involution. We further identify a SEMA7A-α6/β1-integrin dependent mechanism of mammosphere formation and chemoresistance in mammary epithelial cells and suggest that this mechanism is relevant for recurrence in breast cancer patients.

Quantitative Proteomics Reveals a Novel Role of the E3 Ubiquitin-Protein Ligase FANCL in the Activation of the Innate Immune Response through Regulation of TBK1 Phosphorylation during Peste des Petits Ruminants Virus Infection

Peste des petits ruminants virus (PPRV) infection causes considerable innate immunosuppression in its host, which promotes viral replication. However, how the host rescues the innate immune response to counteract this immunosuppression during viral replication remains largely unknown. To explore the mechanisms of how a host counteracts PPRV-mediated innate immunosuppression, a high-throughput quantitation proteomic approach (isobaric tags for relative and absolute quantitation in conjunction with LC-MS/MS) was used to investigate the proteome landscape of goat fetal fibroblasts (GFFs) in response to PPRV infection. Eventually, 497 upregulated proteins and 358 downregulated proteins were identified. Many of the differentially expressed proteins were enriched in immune-related pathways. Blocking the activation of the innate immune response with a specific inhibitor BX795 in GFFs remarkably promoted PPRV replication, suggesting the significant antiviral role of the enriched immune-related pathways. The GO enrichment analysis showed that the host protein FANCL revealed a similar expression pattern to these innate immune-related proteins. In addition, the analysis of protein-protein interaction networks reveals a potential relationship between FANCL and the innate immune pathway. We determined that FANCL inhibited PPRV infection by enhancing type I interferon (IFN) and IFN-stimulated gene expression. Further investigation determined that FANCL induced type I IFN production by promoting TBK1 phosphorylation, thus impairing PPRV-mediated immunosuppression.

Effect of feed restriction on dairy cow milk production: a review

In the dairy cow, negative energy balance affects milk yield and composition as well as animal health. Studying the effects of negative energy balance on dairy cow milk production is thus essential. Feed restriction (FR) experiments attempting to reproduce negative energy balance by reducing the quantity or quality of the diet were conducted in order to better describe the animal physiology changes. The study of FR is also of interest since with climate change issues, cows may be increasingly faced with periods of drought leading to a shortage of forages. The aim of this article is to review the effects of FR during lactation in dairy cows to obtain a better understanding of metabolism changes and how it affects mammary gland activity and milk production and composition. A total of 41 papers studying FR in lactating cows were used to investigate physiological changes induced by these protocols. FR protocols affect the entire animal metabolism as indicated by changes in blood metabolites such as a decrease in glucose concentration and an increase in non-esterified fatty acid or β-hydroxybutyrate concentrations; hormonal regulations such as a decrease in insulin and insulin-like growth factor I or an increase in growth hormone concentrations. These variations indicated a mobilization of body reserve in most studies. FR also affects mammary gland activity through changes in gene expression and could affect mammary cell turnover through cell apoptosis, cell proliferation, and exfoliation of mammary epithelial cells into milk. Because of modifications of the mammary gland and general metabolism, FR decreases milk production and can affect milk composition with decreased lactose and protein concentrations and increased fat concentration. These effects, however, can vary widely depending on the type of restriction, its duration and intensity, or the stage of lactation in which it takes place. Finally, to avoid yield loss and metabolic disorders, it is important to identify reliable biomarkers to monitor energy balance.

Mechanisms of Regulated Cell Death: Current Perspectives

Balancing cell survival and cell death is fundamental to development and homeostasis. Cell death is regulated by multiple interconnected signaling pathways and molecular mechanisms. Regulated cell death (RCD) is implicated in fundamental processes such as organogenesis and tissue remodeling, removal of unnecessary structures or cells, and regulation of cell numbers. RCD can also be triggered by exogenous perturbations of the intracellular or extracellular microenvironment when the adaptive processes that respond to stress fail. During the past few years, many novel forms of non-apoptotic RCD have been identified, and the characterization of RCD mechanisms at a molecular level has deepened our understanding of diseases encountered in human and veterinary medicine. Given the complexity of these processes, it has become clear that the identification of RCD cannot be based simply on morphologic characteristics and that descriptive and diagnostic terms presently used by pathologists-such as individual cell apoptosis or necrosis-appear inadequate and possibly misleading. In this review, the current understanding of the molecular machinery of each type of non-apoptotic RCD mechanisms is outlined. Due to the continuous discovery of new mechanisms or nuances of previously described processes, the limitations of the terms apoptosis and necrosis to indicate microscopic findings are also reported. In addition, the need for a standard panel of biomarkers and functional tests to adequately characterize the underlying RCD and its role as a mechanism of disease is considered.

Functions of the extracellular matrix in development: Lessons from Caenorhabditis elegans

Cell-extracellular matrix interactions are crucial for the development of an organism from the earliest stages of embryogenesis. The main constituents of the extracellular matrix are collagens, laminins, proteoglycans and glycosaminoglycans that form a network of interactions. The extracellular matrix and its associated molecules provide developmental cues and structural support from the outside of cells during development. The complex nature of the extracellular matrix and its ability for continuous remodeling poses challenges when investigating extracellular matrix-based signaling during development. One way to address these challenges is to employ invertebrate models such as Caenorhabditis elegans, which are easy to genetically manipulate and have an invariant developmental program. C. elegans also expresses fewer extracellular matrix protein isoforms and exhibits reduced redundancy compared to mammalian models, thus providing a simpler platform for exploring development. This review summarizes our current understanding of how the extracellular matrix controls the development of neurons, muscles and the germline in C. elegans.

Mechanical Regulation of Apoptosis in the Cardiovascular System

Apoptosis is a highly conserved physiological process of programmed cell death which is critical for proper organism development, tissue maintenance, and overall organism homeostasis. Proper regulation of cell removal is crucial, as both excessive and reduced apoptotic rates can lead to the onset of a variety of diseases. Apoptosis can be induced in cells in response to biochemical, electrical, and mechanical stimuli. Here, we review literature on specific mechanical stimuli that regulate apoptosis and the current understanding of how mechanotransduction plays a role in apoptotic signaling. We focus on how insufficient or excessive mechanical forces may induce apoptosis in the cardiovascular system and thus contribute to cardiovascular disease. Although studies have demonstrated that a broad range of mechanical stimuli initiate and/or potentiate apoptosis, they are predominantly correlative, and no mechanisms have been established. In this review, we attempt to establish a unifying mechanism for how various mechanical stimuli initiate a single cellular response, i.e. apoptosis. We hypothesize that the cytoskeleton plays a central role in this process as it does in determining myriad cell behaviors in response to mechanical inputs. We also describe potential approaches of using mechanomedicines to treat various diseases by altering apoptotic rates in specific cells. The goal of this review is to summarize the current state of the mechanobiology field and suggest potential avenues where future research can explore.

Roles and mechanisms of MFG-E8 in vascular aging-related diseases

The aging of the vasculature plays a crucial role in the pathological progression of various vascular aging-related diseases. As endothelial cells (ECs) and vascular smooth muscle cells (VSMCs) are essential parts in the inner and medial layers of vessel wall, respectively, the structural and functional alterations of ECs and VSMCs are the major causes of vascular aging. Milk fat globule-epidermal growth factor 8 (MFG-E8) is a multifunctional glycoprotein which exerts a regulatory role in the intercellular interactions involved in a variety of biological and pathological processes. Emerging evidence suggests that MFG-E8 is a novel and outstanding modulator for vascular aging via targeting at ECs and VSMCs. In this review, we will summarise the cumulative roles and mechanisms of MFG-E8 in vascular aging and vascular aging-related diseases with special emphasis on the functions of ECs and VSMCs. In addition, we also aim to focus on the promising diagnostic function as a biomarker and the potential therapeutic application of MFG-E8 in vascular aging and the clinical evaluation of vascular aging-related diseases.

In vivo survival strategies for cellular adaptation to hypoxia: HIF1α-dependent suppression of mitochondrial oxygen consumption and decrease of intracellular hypoxia are critical for survival of hypoxic chondrocytes

Hypoxia occurs not only in pathological conditions like cancer and ischemia and in a variety of physiological settings in the adult organism, but also during normal embryonic development. In the inner portion of the fetal growth plate, which is an avascular tissue originating from mesenchymal progenitor cells, chondrocytes experience physiological hypoxia. Hypoxia-Inducible Transcription Factor-1α (HIF1α), a crucial mediator of cellular adaptation to hypoxia, is an essential survival factor for fetal growth plate chondrocytes. This brief review summarizes our current understanding of the survival function of HIF1α during endochondral bone development.

Artesunate alleviates myocardial ischemia/reperfusion-induced myocardial necrosis in rats and hypoxia/reoxygenation-induced apoptosis in H9C2 cells via regulating the FAK/PI3K/Akt pathway

Background

The various anti-inflammatory, anti-apoptotic, and antioxidant effects of Artesunate (Art) have been explored in numerous studies. This study aimed to evaluate the function of Art on myocardial necrosis in apoptotic cardiomyocytes in vivo and in vitro.

Methods

Sprague Dawley (SD) rats were randomly divided into groups: a control group, a myocardial ischemia reperfusion (MI/R) group, and MI/R+ Art groups. To establish a MI/R model, rats were subjected to left anterior descending artery ischemia for 45 minutes, and then reperfusion for 2 hours. Hypoxia was induced in H9C2 cells by subjecting them to hypoxic conditions at 37 °C for 4 hours, before placing them in a normoxic chamber for 2 hours. The test methods were used in this test, such as echocardiography, enzyme-linked immunosorbent assay (ELISA), HE staining, TUNEL staining, immunohistochemistry, flow cytometry, western blot, and CCK-8 assay.

Results

Art improved myocardial systolic function caused by MI/R injury in vivo. Simultaneously, Art reduced the levels of cardiac troponin I (cTnl), creatine kinase-MB (CK-MB) and myohemoglobin (Mb) in vivo and in vitro. Moreover, Art inhibited cardiomyocyte apoptosis in vivo and in vitro. The focal adhesion kinase (FAK)/phosphatidylinositide-3 kinases (PI3K)/AKT signaling pathway was also activated by Art in vivo and in vitro. Furthermore, after inhibitor PF573228 was added, Art inhibited apoptosis in H9C2 cells via activation of the FAK/PI3K/AKT signaling pathway in vitro.

Conclusions

This study confirms that Art alleviated MI/R injury and inhibited cardiomyocyte apoptosis in vivo and in vitro. Art exerted an inhibitory effect on cardiomyocyte apoptosis by activating the FAK/PI3K/AKT signaling pathway. Therefore, Art may serve as an alternative treatment for MI/R injury.

Boolean model of anchorage dependence and contact inhibition points to coordinated inhibition but semi-independent induction of proliferation and migration

Epithelial cells respond to their physical neighborhood with mechano-sensitive behaviors required for development and tissue maintenance. These include anchorage dependence, matrix stiffness-dependent proliferation, contact inhibition of proliferation and migration, and collective migration that balances cell crawling with the maintenance of cell junctions. While required for development and tissue repair, these coordinated responses to the microenvironment also contribute to cancer metastasis. Predictive models of the signaling networks that coordinate these behaviors are critical in controlling cell behavior to halt disease. Here we propose a Boolean regulatory network model that synthesizes mechanosensitive signaling that links anchorage to a matrix of varying stiffness and cell density sensing to contact inhibition, proliferation, migration, and apoptosis. Our model can reproduce anchorage dependence and anoikis, detachment-induced cytokinesis errors, the effect of matrix stiffness on proliferation, and contact inhibition of proliferation and migration by two mechanisms that converge on the YAP transcription factor. In addition, we offer testable predictions related to cell cycle-dependent anoikis sensitivity, the molecular requirements for abolishing contact inhibition, and substrate stiffness dependent expression of the catalytic subunit of PI3K. Moreover, our model predicts heterogeneity in migratory vs. non-migratory phenotypes in sub-confluent monolayers, and co-inhibition but semi-independent induction of proliferation vs. migration as a function of cell density and mitogenic stimulation. Our model serves as a stepping-stone towards modeling mechanosensitive routes to the epithelial to mesenchymal transition, capturing the effects of the mesenchymal state on anoikis resistance, and understanding the balance between migration versus proliferation at each stage of the epithelial to mesenchymal transition.

Matrix decoded - A pancreatic extracellular matrix with organ specific cues guiding human iPSC differentiation

The extracellular matrix represents a dynamic microenvironment regulating essential cell functions in vivo. Tissue engineering approaches aim to recreate the native niche in vitro using biological scaffolds generated by organ decellularization. So far, the organ specific origin of such scaffolds was less considered and potential consequences for in vitro cell culture remain largely elusive. Here, we show that organ specific cues of biological scaffolds affect cellular behavior. In detail, we report on the generation of a well-preserved pancreatic bioscaffold and introduce a scoring system allowing standardized inter-study quality assessment. Using multiple analysis tools for in-depth-characterization of the biological scaffold, we reveal unique compositional, physico-structural, and biophysical properties. Finally, we prove the functional relevance of the biological origin by demonstrating a regulatory effect of the matrix on multi-lineage differentiation of human induced pluripotent stem cells emphasizing the significance of matrix specificity for cellular behavior in artificial microenvironments.

Substrate curvature induces fallopian tube epithelial cell invasion via cell-cell tension in a model of ovarian cortical inclusion cysts

Throughout the body, epithelial tissues contain curved features (e.g. cysts, ducts and crypts) that influence cell behaviors. These structures have varied curvature, with flat structures having zero curvature and structures such as crypts having large curvature. In the ovary, cortical inclusion cysts (CICs) of varying curvatures are found, and fallopian tube epithelial (FTE) cells have been found trapped within these cysts. FTE are the precursor for ovarian cancer, and the CIC niche has been proposed to play a role in ovarian cancer progression. We hypothesized that variations in ovarian CIC curvature that occur during cyst resolution impact the ability of trapped FTE cells to invade into the surrounding stroma. Using a lumen model in collagen gels, we determined that increased curvature resulted in more invasions of mouse FTE cells. To isolate curvature as a system parameter, we developed a novel technique to pattern concave curvatures into collagen gels. When FTE cells were seeded to confluency on curved substrates, increases in curvature increased the number of invading FTE cells and the invasion distance. FTE invasion into collagen substrates with higher curvature depended on matrix metalloproteinases (MMPs), but expression of collagen I degrading Mmps was not different on curved and flat regions. A finite-element model predicted that contractility and cell-cell connections were essential for increased invasion on substrates with higher curvature, while cell-substrate interactions had minimal effect. Experiments supported these predictions, with invasion decreased by blebbistatin, ethylene glycol-bis(β-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA) or N-cadherin-blocking antibody, but with no effect from a focal adhesion kinase inhibitor. Finally, experimental evidence supports that cell invasion on curved substrates occurs in two phases-a cell-cell-dependent initiation phase where individual cells break away from the monolayer and an MMP-dependent phase as cells migrate further into the collagen matrix.

Invited review: Accelerating mammary gland involution after drying-off in dairy cattle

Bovine mammary gland involution, as a part of the reproductive cycle in dairy cows, is a very important remodeling transformation of the mammary gland for the subsequent lactation. There is considerable incentive to accelerate mammary gland involution to improve udder health, shorten the dry period, and simplify the management process by reducing dietary changes. The complex process of mammary involution is characterized by morphological changes in the epithelial cells and mammary tissue, changes in the composition of mammary secretions, and changes in the integrity of tight junctions. Involution is facilitated by elements of the immune system and several types of proteases and is coordinated by various types of hormones. This review first describes the involution process and then argues for the need to accelerate it. Last, this review focuses on various intervention methods for accelerating involution. Our aim is to provide a comprehensive overview of bovine mammary gland involution as well as potential techniques and new opinions for dry cow management.

Biometric Alterations of Mouse Embryonic Eye Structures Due to Short-Term Folic Acid Deficiency

PURPOSE

Folic acid (FA) is an essential nutrient for normal embryonic development. FA deficiency (FAD) in maternal diet increases the risk of several defects among the progeny, especially, neural tube defects. The eye begins its development from the neural tube; however, the relationship between FAD and ocular development in the offspring has been little explored and it isn't known how the FAD affects the formation of the eye. Our objective was to analyze the effect of maternal FAD on mouse embryos ocular biometry.

METHODS

Female mice C57/BL/6J were distributed into three different groups, according to the assigned diet: control group fed a standard FA diet (2 mg FA/kg), FAD group for short term fed (0 mg FA/kg + 1% succinylsulfathiazole) from the day after mating until day 14.5 of gestation, and FAD group for long term fed the same FA-deficient diet for 6 weeks prior mating and continued with this diet during gestation. A total of 57 embryos (19 embryos of each dietary group) at 14.5 gestational days were evaluated. As indicators of changes in ocular biometry, we analyze two parameters: area and circularity of the lens and whole eye, and the area of the retina. The program used in the treatment and selection of the areas of interest was ImageJ. The statistical analysis was performed by IBM SPSS Statistics 19.

RESULTS

Regarding the measures of the area, FA-deficient lenses and eyes were smaller than that of controls. We have also observed increase in the size of the neural retina, spatially, in embryos from females fed FAD diet during long term. On the other hand, as regard to circularity measures, we have seen that eyes and lenses were more circular than control.

CONCLUSION

Maternal FAD diet for a very short term generates morphological changes in ocular structures to the offspring.

Recombinant milk fat globule-EGF factor-8 reduces apoptosis via integrin β3/FAK/PI3K/AKT signaling pathway in rats after traumatic brain injury

Accumulating evidence suggests neuronal apoptosis has the potential to lead to more harmful effects in the pathological processes following traumatic brain injury (TBI). Previous studies have established that milk fat globule-EGF factor-8 (MFG-E8) provides neuroprotection through modulation of inflammation, oxidative stress, and especially apoptosis in cerebral ischemia and neurodegenerative disease. However, the effects of MFG-E8 on neuronal apoptosis in TBI have not yet been investigated. Therefore, we explored the role of MFG-E8 on anti-apoptosis and its potential mechanism following TBI. In the first set of experiments, adult male Sprague–Dawley (SD) rats were randomly divided into Sham and TBI groups that were each further divided into five groups representing different time points (6 h, 24 h, 72 h, and 7 days) (n = 9 each). Western blotting, quantitative real-time PCR, and immunofluorescence staining were performed to identify the expression and cellular localization of MFG-E8. In the second set of experiments, four groups were randomly assigned: Sham group, TBI + Vehicle group, and TBI + rhMFG-E8 (1 and 3 µg) (n = 15). Recombinant human MFGE8 (rhMFG-E8) was administrated as two concentrations through intracerebroventricular (i.c.v.) injection at 1 h after TBI induction. Brain water content, neurological severity score, western blotting, and immunofluorescence staining were measured at 24 and 72 h following TBI. In the final set of experiments, MFG-E8 siRNA (500 pmol/3 µl), integrin β3 siRNA (500 pmol/3 µl), and PI3K inhibitor LY294002 (5 and 20 µM) were injected i.c.v. and thereafter rats exposed to TBI. Western blotting, immunofluorescence staining, brain water content, neurological severity score, and Fluoro-Jade C (FJC) staining were used to investigate the effect of the integrin-β3/FAK/PI3K/AKT signaling pathway on MFG-E8-mediated anti-apoptosis after TBI. The expression of MFG-E8 was mainly located in microglial cells and increased to peak at 24 h after TBI. Treatment with rhMFG-E8 (3 µg) markedly decreased brain water content, improved neurological deficits, and reduced neuronal apoptosis at 24 and 72 h after TBI. rhMFG-E8 significantly enhanced the expression of integrin-β3/FAK/PI3K/AKT pathway-related components. Administration of integrin-β3 siRNA and LY294002 (5 and 20 µM) abolished the effect of rhMFG-E8 on anti-apoptosis and neuroprotection after TBI. This study demonstrated for the first time that rhMFG-E8 inhibits neuronal apoptosis and offers neuroprotection. This is suggested to occur through the modulation of the integrin-β3/FAK/PI3K/AKT signaling pathway, highlighting rhMFG-E8 as a potentially promising therapeutic strategy for TBI patients.

Insulin regulates multiple signaling pathways leading to monocyte/macrophage chemotaxis into the wound tissue

Wound healing is a complex process that involves sequential phases that overlap in time and space and affect each other dynamically at the gene and protein levels. We previously showed that insulin accelerates wound healing by stimulating faster and regenerative healing. One of the processes that insulin stimulates is an increase in monocyte/macrophage chemotaxis. In this study, we performed experiments in vivo and in vitro to elucidate the signaling transduction pathways that are involved in insulin-induced monocyte/macrophage chemotaxis. We found that insulin stimulates THP-1 cell chemotaxis in a dose-dependent and insulin receptor-dependent manner. We also show that the kinases PI3K-Akt, SPAK/JNK, and p38 MAPK are key molecules in the insulin-induced signaling pathways that lead to chemoattraction of the THP-1 cell. Furthermore, both PI3K-Akt and SPAK/JNK signaling involve Rac1 activation, an important molecule in regulating cell motility. Indeed, topical application of Rac1 inhibitor at an early stage during the healing process caused delayed and impaired healing even in the presence of insulin. These results delineate cell and molecular mechanisms involved in insulin-induced chemotaxis of monocyte/macrophage, cells that are critical for proper healing.

Summary: Insulin regulates multiple signaling pathways leading to monocyte/macrophage chemotaxis into the wound tissue, involving -Akt, SPAK/JNK, and p38 MAPK which in turn are involved in Rac1 activation. Furthermore, these results augment our understanding of the insulin-regulated wound inflammatory response.

Differentiation of Human Induced Pluripotent Stem Cells to Mammary-like Organoids

Human induced pluripotent stem cells (iPSCs) can give rise to multiple cell types and hold great promise in regenerative medicine and disease-modeling applications. We have developed a reliable two-step protocol to generate human mammary-like organoids from iPSCs. Non-neural ectoderm-cell-containing spheres, referred to as mEBs, were first differentiated and enriched from iPSCs using MammoCult medium. Gene expression profile analysis suggested that mammary gland function-associated signaling pathways were hallmarks of 10-day differentiated mEBs. We then generated mammary-like organoids from 10-day mEBs using 3D floating mixed gel culture and a three-stage differentiation procedure. These organoids expressed common breast tissue, luminal, and basal markers, including estrogen receptor, and could be induced to produce milk protein. These results demonstrate that human iPSCs can be directed in vitro toward mammary lineage differentiation. Our findings provide an iPSC-based model for studying regulation of normal mammary cell fate and function as well as breast disease development.

Serotoninergic and Circadian Systems: Driving Mammary Gland Development and Function

Since lactation is one of the most metabolically demanding states in adult female mammals, beautifully complex regulatory mechanisms are in place to time lactation to begin after birth and cease when the neonate is weaned. Lactation is regulated by numerous different homeorhetic factors, all of them tightly coordinated with the demands of milk production. Emerging evidence support that among these factors are the serotonergic and circadian clock systems. Here we review the serotoninergic and circadian clock systems and their roles in the regulation of mammary gland development and lactation physiology. We conclude by presenting our hypothesis that these two systems interact to accommodate the metabolic demands of lactation and thus adaptive changes in these systems occur to maintain mammary and systemic homeostasis through the reproductive cycles of female mammals.

Clonal culturing of human embryonic stem cells on laminin-521/E-cadherin matrix in defined and xeno-free environment

Lack of robust methods for establishment and expansion of pluripotent human embryonic stem (hES) cells still hampers development of cell therapy. Laminins (LN) are a family of highly cell-type specific basement membrane proteins important for cell adhesion, differentiation, migration and phenotype stability. Here we produce and isolate a human recombinant LN-521 isoform and develop a cell culture matrix containing LN-521 and E-cadherin, which both localize to stem cell niches in vivo. This matrix allows clonal derivation, clonal survival and long-term self-renewal of hES cells under completely chemically defined and xeno-free conditions without ROCK inhibitors. Neither LN-521 nor E-cadherin alone enable clonal survival of hES cells. The LN-521/E-cadherin matrix allows hES cell line derivation from blastocyst inner cell mass and single blastomere cells without a need to destroy the embryo. This method can facilitate the generation of hES cell lines for development of different cell types for regenerative medicine purposes.

Loss of anchorage primarily induces non-apoptotic cell death in a human mammary epithelial cell line under atypical focal adhesion kinase signaling

Anchorage dependence of cellular growth and survival prevents inappropriate cell growth or survival in ectopic environments, and serves as a potential barrier to metastasis of cancer cells. Therefore, obtaining a better understanding of anchorage-dependent responses in normal cells is the first step to understand and impede anchorage independence of growth and survival in cancer cells and finally to eradicate cancer cells during metastasis. Anoikis, a type of apoptosis specifically induced by lack of appropriate cell-extracellular matrix adhesion, has been established as the dominant response of normal epithelial cells to anchorage loss. For example, under detached conditions, the untransformed mammary epithelial cell (MEC) line MCF-10 A, which exhibits myoepithelial characteristics, underwent anoikis dependent on classical ERK signaling. On the other hand, recent studies have revealed a variety of phenotypes resulting in cell death modalities distinct from anoikis, such as autophagy, necrosis, and cornification, in detached epithelial cells. In the present study, we characterized detachment-induced cell death (DICD) in primary human MECs immortalized with hTERT (^TertHMECs), which are bipotent progenitor-like cells with a differentiating phenotype to luminal cells. In contrast to MCF-10 A cells, apoptosis was not observed in detached ^TertHMECs; instead, non-apoptotic cell death marked by features of entosis, cornification, and necrosis was observed along with downregulation of focal adhesion kinase (FAK) signaling. Cell death was overcome by anchorage-independent activities of FAK but not PI3K/AKT, SRC, and MEK/ERK, suggesting critical roles of atypical FAK signaling pathways in the regulation of non-apoptotic cell death. Further analysis revealed an important role of TRAIL (tumor necrosis factor (TNF)-related apoptosis-inducing ligand) as a mediator of FAK signaling in regulation of entosis and necrosis and a role of p38 MAPK in the induction of necrosis. Overall, the present study highlighted outstanding cell subtype or differentiation stage specificity in cell death phenotypes induced upon anchorage loss in human MECs.

Up-regulation of integrin α6β4 expression by mitogens involved in dairy cow mammary development

In dairy cows, the extracellular microenvironment varies significantly from the virgin state to lactation. The function of integrin α6β4 is dependent on cell type and extracellular microenvironment, and the precise expression profile of α6β4 and its effects on mammary development remain to be determined. In the present study, real-time PCR and immunohistochemistry were used to analyze the expression and localization of integrin α6β4 in Holstein dairy cow mammary glands. The effects of integrin α6β4 on the proliferation induced by mammogenic mitogens were identified by blocking integrin function in purified dairy cow mammary epithelial cells (DCMECs). The results showed that the localization of β4 subunit and its exclusive partner the α6 subunit were not consistent but were co-localized in basal luminal cells and myoepithelial cells, appearing to prefer the basal surface of the plasma membrane. Moreover, α6 and β4 subunit messenger RNA (mRNA) levels changed throughout the stages of dairy cow mammary development, reflected well by protein levels, and remained higher in the virgin and pregnancy states, with duct/alveolus morphogenesis and active cell proliferation, than during lactation, when growth arrest is essential for mammary epithelial cell differentiation. Finally, the upregulation of integrin expression by both mammogenic growth hormone and insulin-like growth factor-1 and the inhibited growth of DCMECs by function-blocking integrin antibodies confirmed that integrin α6β4 was indeed involved in dairy cow mammary development.

Rodent animal models: from mild to advanced stages of diabetic nephropathy

Diabetic nephropathy (DN) is a secondary complication of both type 1 and type 2 diabetes, resulting from uncontrolled high blood sugar. 30-40% of diabetic patients develop DN associated with a poor life expectancy and end-stage renal disease, causing serious socioeconomic problems. Although an exact pathogenesis of DN is still unknown, several factors such as hyperglycemia, hyperlipidemia, hypertension and proteinuria may contribute to the progression of renal damage in diabetic nephropathy. DN is confirmed by measuring blood urea nitrogen, serum creatinine, creatinine clearance and proteinuria. Clinical studies show that intensive control of hyperglycemia and blood pressure could successfully reduce proteinuria, which is the main sign of glomerular lesions in DN, and improve the renal prognosis in patients with DN. Diabetic rodent models have traditionally been used for doing research on pathogenesis and developing novel therapeutic strategies, but have limitations for translational research. Diabetes in animal models such as rodents are induced either spontaneously or by using chemical, surgical, genetic, or other techniques and depicts many clinical features or related phenotypes of the disease. This review discusses the merits and demerits of the models, which are used for many reasons in the research of diabetes and diabetic complications.

Suppression of prolactin signaling by pyrrolidine dithiocarbamate is alleviated by N-acetylcysteine in mammary epithelial cells

Prolactin is the key hormone to stimulate milk synthesis in mammary epithelial cells. It signals through the Jak2-Stat5 pathway to induce the expression of β-casein, a milk protein which is often used as a marker for mammary differentiation. Here we examined the effect of pyrrolidine dithiocarbamate (PDTC) on prolactin signaling. Our results show that PDTC downregulates prolactin receptor levels, and inhibits prolactin-induced Stat5 tyrosine phosphorylation and β-casein expression. This is not due to its inhibitory action on NF-κB since application of another NF-κB inhibitor, BAY 11-7082, and overexpression of I-κBα super-repressor do not lead to the same results. Instead, the pro-oxidant activity of PDTC is involved as inclusion of the antioxidant N-acetylcysteine restores prolactin signaling. PDTC triggers great extents of activation of ERK and JNK in mammary epithelial cells. These do not cause suppression of prolactin signaling but confer serine phosphorylation of insulin receptor substrate-1, thereby perturbing insulin signal propagation. As insulin facilitates optimal β-casein expression, blocking insulin signaling by PDTC might pose additional impediment to β-casein expression. Our results thus imply that lactation will be compromised when the cellular redox balance is dysregulated, such as during mastitis.

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.

Reduction of decoy receptor 3 enhances TRAIL-mediated apoptosis in pancreatic cancer

Most human pancreatic cancer cells are resistant to tumor necrosis factor (TNF)-related apoptosis-inducing ligand (TRAIL)-mediated apoptosis. However, the mechanisms by which pancreatic cancer cells utilize their extracellular molecules to counteract the proapoptotic signaling mediated by the TNF family are largely unknown. In this study, we demonstrate for the first time that DcR3, a secreted decoy receptor that malignant pancreatic cancer cells express at a high level, acts as an extracellular antiapoptotic molecule by binding to TRAIL and counteracting its death-promoting function. The reduction of DcR3 with siRNA unmasked TRAIL and greatly enhanced TRAIL-induced apoptosis. Gemcitabine, a first-line drug for pancreatic cancer, also reduced the level of DcR3. The addition of DcR3 siRNA further enhanced gemcitabine-induced apoptosis. Notably, our in vivo study demonstrated that the therapeutic effect of gemcitabine could be enhanced via further reduction of DcR3, suggesting that downregulation of DcR3 in tumor cells could tip the balance of pancreatic cells towards apoptosis and potentially serve as a new strategy for pancreatic cancer therapy.

Antibody against integrin lymphocyte function-associated antigen 1 inhibits HIV type 1 infection in primary cells through caspase-8-mediated apoptosis

HIV-1 infection induces formation of a virological synapse wherein CD4, chemokine receptors, and cell-adhesion molecules such as lymphocyte function-associated antigen 1 (LFA-1) form localized domains on the cell surface. Studies show that LFA-1 on the surface of HIV-1 particles retains its adhesion function and enhances virus attachment to susceptible cells by binding its counterreceptor intercellular adhesion molecule 1 (ICAM-1). This virus-cell interaction augments virus infectivity by facilitating binding and entry events. In this study, we demonstrate that inhibition of the LFA-1/ICAM-1 interaction by a monoclonal antibody leads to decreased virus production and spread in association with increased apoptosis of HIV-infected primary T cells. The data indicate that the LFA-1/ICAM-1 interaction may limit apoptosis in HIV-1-infected T cells. This phenomenon appears similar to anoikis wherein epithelial cells are protected from apoptosis conferred by ligand-bound integrins. These results have implications for further understanding HIV pathogenesis and replication in peripheral compartments and lymphoid organs.

Mammary gland development is delayed in mice deficient for aminopeptidase N

Development of the mammary gland requires the coordinated action of proteolytic enzymes during two phases of remodelling. Firstly, new ducts and side-branches thereof need to be established during pregnancy to generate an extensive ductal tree allowing the secretion and transport of milk. A second wave of remodelling occurs during mammary involution after weaning. We have analysed the role of the cell surface protease aminopeptidase N (Anpep, APN, CD13) during these processes using Anpep deficient and Anpep over-expressing mice. We find that APN deficiency significantly delays mammary gland morphogenesis during gestation. The defect is characterised by a reduction in alveolar buds and duct branching at mid-pregnancy. Conversely over-expression of Anpep leads to accelerated ductal development. This indicates that Anpep plays a critical role in the proteolytic remodelling of mammary tissue during adult mammary development.

The RhoA-Rok-myosin II pathway is involved in extracellular matrix-mediated regulation of prolactin signaling in mammary epithelial cells

In mammary epithelial cells (MECs), prolactin-induced signaling and gene expression requires integrin-mediated cell adhesion to basement membrane (BM). In the absence of proper cell-BM interactions, for example, culturing cells on collagen-coated plastic dishes, signal propagation is substantially impaired. Here we demonstrate that the RhoA-Rok-myosin II pathway accounts for the ineffectiveness of prolactin signaling in MECs cultured on collagen I. Under these culture conditions, the RhoA pathway is activated, leading to downregulation of prolactin receptor expression and reduced prolactin signaling. Enforced activation of RhoA in MECs cultured on BM suppresses prolactin receptor levels, and prevents prolactin-induced Stat5 tyrosine phosphorylation and β-casein expression. Overexpression of dominant negative RhoA in MECs cultured on collagen I, or inhibiting Rok activity, increases prolactin receptor expression, and enhances prolactin signaling. In addition, inhibition of myosin II ATPase activity by blebbistatin also exerts a beneficial effect on prolactin receptor expression and prolactin signaling, suggesting that tension exerted by the collagen substratum, in collaboration with the RhoA-Rok-myosin II pathway, contributes to the failure of prolactin signaling. Furthermore, MECs cultured on laminin-coated plastic have similar morphology and response to prolactin as those cultured on collagen I. They display high levels of RhoA activity and are inefficient in prolactin signaling, stressing the importance of matrix stiffness in signal transduction. Our results reveal that RhoA has a central role in determining the fate decisions of MECs in response to cell-matrix interactions.

Glucocorticoid alternative effects on proliferating and differentiated mammary epithelium are associated to opposite regulation of cell-cycle inhibitor expression

Glucocorticoids influence post-natal mammary gland development by sequentially controlling cell proliferation, differentiation, and apoptosis. In the mammary gland, it has been demonstrated that glucocorticoid treatment inhibits epithelial apoptosis in post-lactating glands. In this study, our first goal was to identify new glucocorticoid target genes that could be involved in generating this effect. Expression profiling, by microarray analysis, revealed that expression of several cell-cycle control genes was altered by dexamethasone (DEX) treatment after lactation. Importantly, it was determined that not only the exogenous synthetic hormone, but also the endogenous glucocorticoids regulated the expression of these genes. Particularly, we found that the expression of cell cycle inhibitors p21CIP1, p18INK4c, and Atm was differentially regulated by glucocorticoids through the successive stages of mammary gland development. In undifferentiated cells, DEX treatment induced their expression and reduced cell proliferation, while in differentiated cells this hormone repressed expression of those cell cycle inhibitors and promoted survival. Therefore, differentiation status determined the effect of glucocorticoids on mammary cell fate. Particularly, we have determined that p21CIP1 inhibition would mediate the activity of these hormones in differentiated mammary cells because over-expression of this protein blocked DEX-induced apoptosis protection. Together, our data suggest that the multiple roles played by glucocorticoids in mammary gland development and function might be at least partially due to the alternative roles that these hormones play on the expression of cell cycle regulators.

Histone deacetylase inhibitors upregulate MMP11 gene expression through Sp1/Smad complexes in human colon adenocarcinoma cells

MMP-11 (stromelysin-3) is a matrix metalloproteinase associated with tumor progression and poor prognosis. Its expression was initially described exclusively in stromal cells surrounding tumors, but more recently it has also been detected in macrophages and hepatocarcinoma cells. Here we show MMP-11 expression in human epithelial colon adenocarcinoma cell lines (Caco-2, HT-29 and BCS-TC2). Treatment of BCS-TC2 cells with butyrate and trichostatin A (TSA) (histone deacetylase inhibitors) increases MMP11 promoter activity and protein expression. Using electrophoretic mobility shift assay (EMSA) and supershift assays, we demonstrate for the first time that Sp1 is able to bind to the GC-boxes within the MMP11 proximal promoter region; this binding has been confirmed by chromatin immunoprecipitation. Sp1 is involved in MMP11 basal expression and it is essential for the upregulation of transcription by histone deacetylase inhibitors as deduced from mutant constructs lacking the Sp1 sites and by inhibition of its binding to the promoter with mithramycin. This regulation requires the formation of Sp1/Smad2 heterocomplexes, which is stimulated by an increase in the acetylation status of Smad after butyrate or TSA treatments. We have also found that ERK1/2-mitogen-activated protein kinase (MAPK), but not p38-MAPK or JNK, is involved in the upregulation of MMP11 by HDAC inhibitors.

Integrins α2β1 and α11β1 regulate the survival of mesenchymal stem cells on collagen I

Although mesenchymal stem cells (MSCs) are the natural source for bone regeneration, the exact mechanisms governing MSC crosstalk with collagen I have not yet been uncovered. Cell adhesion to collagen I is mostly mediated by three integrin receptors - α1β1, α2β1 and α11β1. Using human MSC (hMSC), we show that α11 subunit exhibited the highest basal expression levels but on osteogenic stimulation, both α2 and α11 integrins were significantly upregulated. To elucidate the possible roles of collagen-binding integrins, we applied short hairpin RNA (shRNA)-mediated knockdown in hMSC and found that α2 or α11 deficiency, but not α1, results in a tremendous reduction of hMSC numbers owing to mitochondrial leakage accompanied by Bcl-2-associated X protein upregulation. In order to clarify the signaling conveyed by the collagen-binding integrins in hMSC, we analyzed the activation of focal adhesion kinase, extracellular signal-regulated protein kinase and serine/threonine protein kinase B (PKB/Akt) kinases and detected significantly reduced Akt phosphorylation only in α2- and α11-shRNA hMSC. Finally, experiments with hMSC from osteoporotic patients revealed a significant downregulation of α2 integrin concomitant with an augmented mitochondrial permeability. In conclusion, our study describes for the first time that disturbance of α2β1- or α11β1-mediated interactions to collagen I results in the cell death of MSCs and urges for further investigations examining the impact of MSCs in bone conditions with abnormal collagen I.

Immunological function of the endothelial cell within the setting of organ transplantation

In organ transplantation, development of immunosuppressive treatment and improved diagnosis of allograft rejection has resulted in increased allograft survival in recent years. Nevertheless, rejection remains a major cause of graft loss and a better understanding of the characteristics of the allo-immune response is required to identify new diagnostic and therapeutic tools. The allogeneic immune response depends upon a major family of antigenic targets: the Major Histocompatibility Complex molecules (MHC) which are present on donor cells. These molecules are targets of both the humoral and cellular arms of the graft recipient's immune system: T lymphocytes which are implicated in acute cellular rejection and antibodies which are implicated in antibody-mediated rejection (AMR). Allo-recognition of allograft MHC antigens by either T cells or allo-antibodies is the primary event which can ultimately lead to graft rejection. Although immunosuppressive strategies have mainly focused on the T cell response and acute cellular rejection has therefore become relatively rare, antibody mediated rejection (AMR) remains resistant to conventional immunosuppressive treatment and results in frequent graft loss. Damage to the endothelium is a prominent histological feature of AMR underlining the involvement of endothelial cells in initiating the allo-immune response. Furthermore, endothelial cells express both HLA class I and class II molecules in the context of organ transplantation endowing them with the capacity to present antigen to the recipient T cells. The endothelium should therefore be viewed both as a stimulator of, and as a target for allo-immune responses. In this review, we will summarize current knowledge about the implication of endothelial cells in the allo-immune response in the context of organ transplantation.

The contribution of adhesion signaling to lactogenesis

The mammary gland undergoes hormonally controlled cycles of pubertal maturation, pregnancy, lactation, and involution, and these processes rely on complex signaling mechanisms, many of which are controlled by cell-cell and cell-matrix adhesion. The adhesion of epithelial cells to the extracellular matrix initiates signaling mechanisms that have an impact on cell proliferation, survival, and differentiation throughout lactation. The control of integrin expression on the mammary epithelial cells, the composition of the extracellular matrix and the presence of secreted matricellular proteins all contribute to essential adhesion signaling during lactogenesis. In vitro and in vivo studies, including the results from genetically engineered mice, have shed light on the regulation of these processes at the cell and tissue level and have led to increased understanding of the essential signaling components that are regulated in temporal and cell specific manner during lactogenesis. Recent studies suggest that a secreted matricellular protein, CTGF/CCN2, may play a role in lactogenic differentiation through binding to β1 integrin complexes, enhancing the production of extracellular matrix components and contributions to cell adhesion signaling.

Rac1 is essential for basement membrane-dependent epiblast survival

During murine peri-implantation development, the egg cylinder forms from a solid cell mass by the apoptotic removal of inner cells that do not contact the basement membrane (BM) and the selective survival of the epiblast epithelium, which does. The signaling pathways that mediate this fundamental biological process are largely unknown. Here we demonstrate that Rac1 ablation in embryonic stem cell-derived embryoid bodies (EBs) leads to massive apoptosis of epiblast cells in contact with the BM. Expression of wild-type Rac1 in the mutant EBs rescues the BM-contacting epiblast, while expression of a constitutively active Rac1 additionally blocks the apoptosis of inner cells and cavitation, indicating that the spatially regulated activation of Rac1 is required for epithelial cyst formation. We further show that Rac1 is activated through integrin-mediated recruitment of the Crk-DOCK180 complex and mediates BM-dependent epiblast survival through activating the phosphatidylinositol 3-kinase (PI3K)-Akt signaling pathway. Our results reveal a signaling cascade triggered by cell-BM interactions essential for epithelial morphogenesis.

IGF-I induced genes in stromal fibroblasts predict the clinical outcome of breast and lung cancer patients

BACKGROUND

Insulin-like growth factor-1 (IGF-I) signalling is important for cancer initiation and progression. Given the emerging evidence for the role of the stroma in these processes, we aimed to characterize the effects of IGF-I on cancer cells and stromal cells separately.

METHODS

We used an ex vivo culture model and measured gene expression changes after IGF-I stimulation with cDNA microarrays. In vitro data were correlated with in vivo findings by comparing the results with published expression datasets on human cancer biopsies.

RESULTS

Upon stimulation with IGF-I, breast cancer cells and stromal fibroblasts show some common and other distinct response patterns. Among the up-regulated genes in the stromal fibroblasts we observed a significant enrichment in proliferation associated genes. The expression of the IGF-I induced genes was coherent and it provided a basis for the segregation of the patients into two groups. Patients with tumours with highly expressed IGF-I induced genes had a significantly lower survival rate than patients whose tumours showed lower levels of IGF-I induced gene expression (P = 0.029 - Norway/Stanford and P = 7.96e-09 - NKI dataset). Furthermore, based on an IGF-I induced gene expression signature derived from primary lung fibroblasts, a separation of prognostically different lung cancers was possible (P = 0.007 - Bhattacharjee and P = 0.008 - Garber dataset).

CONCLUSION

Expression patterns of genes induced by IGF-I in primary breast and lung fibroblasts accurately predict outcomes in breast and lung cancer patients. Furthermore, these IGF-I induced gene signatures derived from stromal fibroblasts might be promising predictors for the response to IGF-I targeted therapies. See the related commentary by Werner and Bruchim: http://www.biomedcentral.com/1741-7015/8/2.

Effect of antibodies on endothelium

Patients developing posttransplant antibodies against HLA and non-HLA antigens expressed by the endothelium of the graft undergo more frequent episodes of rejection and have decreased long-term graft survival. Antibodies against the endothelium can alter/damage the cells of the graft through several mechanisms. Historically, antibodies were thought to elicit endothelial cell injury via complement-dependent mechanisms. New research has shown that antibodies can also contribute to the process of transplant rejection by stimulating proinflammatory and proproliferation signals. Antibody ligation leads to several functional alterations in EC including Weibel Palade body exocytosis, leukocyte recruitment, growth factor expression and cell proliferation. In contrast, under certain circumstances, antibodies may induce prosurvival signals and graft accommodation. The signaling events regulating accommodation vs. rejection appear to be influenced by the specificity and concentration of the anti-HLA antibody and the degree of molecular aggregation. Knowledge of the HLA and non-HLA antibody-mediated signaling pathways has the potential to identify new therapeutic targets to promote accommodation and prevent acute and chronic antibody-mediated rejection.

Crown formation during tooth development and tissue engineering

Considering tooth crown engineering, three main parameters have to be taken into account: (1) the relationship between crown morphology and tooth functionality, (2) the growth of the organ, which is hardly compatible with the use of preformed scaffolds, and (3) the need for easily available nondental competent cell sources. In vitro reassociation experiments using either dental tissues or bone marrow-derived cells (BMDC) have been designed to get information about the mechanisms to be preserved in order to allow crown engineering. As the primary enamel knot (PEK) is involved in signaling crown morphogenesis, the formation and fate of this structure was investigated (1) in heterotopic reassociations between embryonic day 14 (ED14) incisor and molar enamel organs and mesenchymes, and (2) in reassociations between ED14 molar enamel organs and BMDC. A PEK formed in cultured heterotopic dental tissue reassociations. The mesenchyme controls the fate of the EK cells, incisor or molar-specific using apoptosis as criterion, and functionality to drive single/multiple cusps tooth development. Although previous investigations showed that they might differentiate as odontoblast- or ameloblast-like cells, BMDC reassociated to an enamel organ could not support the development of multicusp teeth. These cells apparently could neither maintain nor stimulate the formation of a PEK.

T-lymphocyte-induced, Fas-mediated apoptosis is associated with early keratinocyte differentiation

The development of eczematous lesions is thought to be due in part to a breakdown in skin barrier function as a result of T lymphocytes (T cells) invading the skin causing epidermal keratinocyte apoptosis. In this study, we investigated the interaction of T cells and keratinocytes on apoptosis and terminal differentiation using an in vitro co-culture system. Experiments were performed using the HaCaT keratinocyte cell line or normal human epidermal keratinocytes. Activated human peripheral blood-derived T cells were found to induce Fas-dependent keratinocyte apoptosis by up to sixfold. Increased Fas was associated with increased IFN-gamma. The T-cell apoptotic signal was found to target preferentially keratinocytes in the very early stages of terminal differentiation, such as those with low levels of alpha 6-integrin expression, and result in subsequent increased caspase 3 activity. This observation was accompanied by a marked increase in keratinocyte ICAM-1 expression and its ligand LFA-1 on T cells. Our data suggest that T cells may initiate the onset of keratinocyte terminal differentiation making them more susceptible to Fas-dependent cell death signals delivered by the T cells.

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.