l-Ornithine-l-Aspartate (LOLA) Normalizes Metabolic Parameters in Models of Steatosis, Insulin Resistance and Metabolic Syndrome.

l-Ornithine- l-aspartate (LOLA) reduces toxic ammonium (NH3) plasma levels in hepatic encephalopathy. NH3 detoxification/excretion is achieved by its incorporation into urea and glutamine via activation of carbamoyl phosphate synthetase 1 (CSP1) by l-ornithine and stimulation of arginase by l-aspartate. We aimed at identifying additional molecular targets of LOLA as a potential treatment option for non-alcoholic fatty liver disease (NAFLD). In primary hepatocytes from NAFLD patients, urea cycle enzymes CSP1 and ornithine transcarbamylase (OTC) increase, while the catabolism of branched-chain amino acids (BCAAs) decreases with disease severity. In contrast, LOLA increased the expression rates of the BCAA enzyme transcripts bcat2, bckdha, and bckdk. In untreated HepG2 hepatoblastoma cells and HepG2-based models of steatosis, insulin resistance, and metabolic syndrome (the latter for the first time established herein), LOLA reduced the release of NH3; beneficially modulated the expression of genes related to fatty acid import/transport (cd36, cpt1), synthesis (fasn, scd1, ACC1), and regulation (srbf1); reduced cellular ATP and acetyl-CoA; and favorably modulated the expression of master regulators/genes of energy balance/mitochondrial biogenesis (AMPK-α, pgc1α). Moreover, LOLA reconstituted the depolarized mitochondrial membrane potential, while retaining mitochondrial integrity and avoiding induction of superoxide production. Most effects were concentration-dependent at ≤40 mM LOLA. We demonstrate for l-ornithine-l-aspartate a broad range of reconstituting effects on metabolic carriers and targets of catabolism/energy metabolism impaired in NAFLD. These findings strongly advocate further investigations to establish LOLA as a safe, efficacious, and cost-effective basic medication for preventing and/or alleviating NAFLD.

DNA-Dependent Protein Kinase Mediates YB-1 (Y-Box Binding Protein)-Induced Double Strand Break Repair.

BACKGROUND: DNA-PK (DNA-dependent protein kinase) is a stress-activated serine/threonine kinase that plays a central role in vascular smooth muscle cell proliferation and vascular proliferative disease processes such as neointimal formation. In this study, we link the activation of DNA-PK to the function of the transcription factor YB-1 (Y-box binding protein). METHODS: To identify YB-1 phosphorylation by DNA-PK, we generated different YB-1-expressing vectors. YB-1 nuclear translocation was investigated using immunoblotting and immunofluorescence staining. For YB-1 activity, luciferase assays were performed. RESULTS: We show by mutational analysis and kinase assay that the transcriptional regulator YB-1 is a substrate of DNA-PK. Blockade of DNA-PK by specific inhibitors revealed its critical involvement in YB-1phosphorylation as demonstrated by inhibition of an overexpressed YB-1 reporter construct. Using DNA-PK-deficient cells, we demonstrate that the shuttling of YB-1 from the cytoplasm to the nucleus is dependent on DNA-PK and that the N-terminal domain of YB-1 is phosphorylated at threonine 89. Point mutation of YB-1 at this residue abrogated the translocation of YB-1 into the nucleus. The phosphorylation of YB-1 by DNA-PK increased cellular DNA repair after exposure to ionizing radiation. Atherosclerotic tissue specimens were analyzed by immunohistochemistry. The DNA-PK subunits and YB-1 phosphorylated at T89 were found colocalized suggesting their in vivo interaction. In mice, the local application of the specific DNA-PK inhibitor NU7026 via thermosensitive Pluronic F-127 gel around dilated arteries significantly reduced the phosphorylation of YB-1. CONCLUSIONS: DNA-PK directly phosphorylates YB-1 and, this way, modulates YB-1 function. This interaction could be demonstrated in vivo, and colocalization in human atherosclerotic plaques suggests clinical relevance of our finding. Phosphorylation of YB-1 by DNA-PK may represent a novel mechanism governing atherosclerotic plaque progression.

Normoxic HIF-1α Stabilization Caused by Local Inflammatory Factors and Its Consequences in Human Coronary Artery Endothelial Cells.

Knowledge about normoxic hypoxia-inducible factor (HIF)-1α stabilization is limited. We investigated normoxic HIF-1α stabilization and its consequences using live cell imaging, immunoblotting, Bio-Plex multiplex immunoassay, immunofluorescence staining, and barrier integrity assays. We demonstrate for the first time that IL-8 and M-CSF caused HIF-1α stabilization and translocation into the nucleus under normoxic conditions in both human coronary endothelial cells (HCAECs) and HIF-1α-mKate2-expressing HEK-293 cells. In line with the current literature, our data show significant normoxic HIF-1α stabilization caused by TNF-α, INF-γ, IL-1ß, and IGF-I in both cell lines, as well. Treatment with a cocktail consisting of TNF-α, INF-γ, and IL-1ß caused significantly stronger HIF-1α stabilization in comparison to single treatments. Interestingly, this cumulative effect was not observed during simultaneous treatment with IL-8, M-CSF, and IGF-I. Furthermore, we identified two different kinetics of HIF-1α stabilization under normoxic conditions. Our data demonstrate elevated protein levels of HIF-1α-related genes known to be involved in the development of atherosclerosis. Moreover, we demonstrate an endothelial barrier dysfunction in HCAECs upon our treatments and during normoxic HIF-1α stabilization comparable to that under hypoxia. This study expands the knowledge of normoxic HIF-1α stabilization and activation and its consequences on the endothelial secretome and barrier function. Our data imply an active role of HIF-1α in vivo in the vasculature in the absence of hypoxia.

NOX4 mRNA correlates with plaque stability in patients with carotid artery stenosis.

Carotid artery stenosis (CAS) develops from atherosclerotic lesions and plaques. Plaque rupture or stenosis may result in occlusion of the carotid artery. Accordingly, the asymptomatic disease becomes symptomatic, characterized by ischemic stroke or transient ischemic attacks, indicating an urgent need for better understanding of the underlying molecular mechanisms and eventually prevent symptomatic CAS. NOX4, a member of the NADPH oxidase family, has anti-atherosclerotic and anti-inflammatory properties in animal models of early atherosclerosis. We hypothesized that NOX4 mRNA expression is linked to protective mechanisms in CAS patients with advanced atherosclerotic lesions as well. Indeed, NOX4 mRNA expression is lower in patients with symptomatic CAS. A low NOX4 mRNA expression is associated with an increased risk of the development of clinical symptoms. In fact, NOX4 appears to be linked to plaque stability, apoptosis and plaque hemorrhage. This is supported by cleaved caspase-3 and glycophorin C and correlates inversely with plaque NOX4 mRNA expression. Even healing of a ruptured plaque appears to be connected to NOX4, as NOX4 mRNA expression correlates to fibrous cap collagen and is reciprocally related to MMP9 activity. In conclusion, low intra-plaque NOX4 mRNA expression is associated with an increased risk for symptomatic outcome and with reduced plaque stabilizing mechanisms suggesting protective effects of NOX4 in human advanced atherosclerosis.

IKKγ/NEMO Localization into Multivesicular Bodies.

The NF-κB pathway is central pathway for inflammatory and immune responses, and IKKγ/NEMO is essential for NF-κB activation. In a previous report, we identified the role of glycogen synthase kinase-3ß (GSK-3ß) in NF-κB activation by regulating IKKγ/NEMO. Here, we show that NEMO phosphorylation by GSK-3ß leads to NEMO localization into multivesicular bodies (MVBs). Using the endosome marker Rab5, we observed localization into endosomes. Using siRNA, we identified the AAA-ATPase Vps4A, which is involved in recycling the ESCRT machinery by facilitating its dissociation from endosomal membranes, which is necessary for NEMO stability and NF-κB activation. Co-immunoprecipitation studies of NEMO and mutated NEMO demonstrated its direct interaction with Vps4A, which requires NEMO phosphorylation. The transfection of cells by a mutated and constitutively active form of Vps4A, Vps4A-E233Q, resulted in the formation of large vacuoles and strong augmentation in NEMO expression compared to GFP-Vps4-WT. In addition, the overexpression of the mutated form of Vps4A led to increased NF-κB activation. The treatment of cells with the pharmacologic V-ATPase inhibitor bafilomycin A led to a dramatic downregulation of NEMO and, in this way, inhibited NF-κB signal transduction. These results reveal an unexpected role for GSK-3ß and V-ATPase in NF-κB signaling activation.

Cigarette Smoke Extract Disturbs Mitochondria-Regulated Airway Epithelial Cell Responses to Pneumococci.

Mitochondrial functionality is crucial for the execution of physiologic functions of metabolically active cells in the respiratory tract including airway epithelial cells (AECs). Cigarette smoke is known to impair mitochondrial function in AECs. However, the potential contribution of mitochondrial dysfunction in AECs to airway infection and airway epithelial barrier dysfunction is unknown. In this study, we used an in vitro model based on AECs exposed to cigarette smoke extract (CSE) followed by an infection with Streptococcus pneumoniae (Sp). The levels of oxidative stress as an indicator of mitochondrial stress were quantified upon CSE and Sp treatment. In addition, expression of proteins associated with mitophagy, mitochondrial content, and biogenesis as well as mitochondrial fission and fusion was quantified. Transcriptional AEC profiling was performed to identify the potential changes in innate immune pathways and correlate them with indices of mitochondrial function. We observed that CSE exposure substantially altered mitochondrial function in AECs by suppressing mitochondrial complex protein levels, reducing mitochondrial membrane potential and increasing mitochondrial stress and mitophagy. Moreover, CSE-induced mitochondrial dysfunction correlated with reduced enrichment of genes involved in apical junctions and innate immune responses to Sp, particularly type I interferon responses. Together, our results demonstrated that CSE-induced mitochondrial dysfunction may contribute to impaired innate immune responses to Sp.

YB-1 Mediates TNF-Induced Pro-Survival Signaling by Regulating NF-κB Activation.

Cell fate decisions regulating survival and death are essential for maintaining tissue homeostasis; dysregulation thereof can lead to tumor development. In some cases, survival and death are triggered by the same receptor, e.g., tumor necrosis factor (TNF)-receptor 1 (TNFR1). We identified a prominent role for the cold shock Y-box binding protein-1 (YB-1) in the TNF-induced activation and nuclear translocation of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB) p65. In the absence of YB-1, the expression of TNF receptor-associated factor 2 (TRAF2), a central component of the TNF receptor signaling complex required for NF-κB activation, is significantly reduced. Therefore, we hypothesized that the loss of YB-1 results in a destabilization of TRAF2. Consistent with this hypothesis, we observed that YB-1-deficient cells were more prone to TNF-induced apoptotic cell death. We observed enhanced effector caspase-3 activation and could successfully rescue the cells using the pan-caspase inhibitor zVAD-fmk, but not necrostatin-1. Taken together, our results indicate that YB-1 plays a central role in promoting cell survival through NF-κB activation and identifies a novel mechanism by which enhanced YB-1 expression may contribute to tumor development.

Expanding the genotypic and phenotypic spectrum of severe serine biosynthesis disorders.

Serine biosynthesis disorders comprise a spectrum of very rare autosomal recessive inborn errors of metabolism with wide phenotypic variability. Neu-Laxova syndrome represents the most severe expression and is characterized by multiple congenital anomalies and pre- or perinatal lethality. Here, we present the mutation spectrum and a detailed phenotypic analysis in 15 unrelated families with severe types of serine biosynthesis disorders. We identified likely disease-causing variants in the PHGDH and PSAT1 genes, several of which have not been reported previously. Phenotype analysis and a comprehensive review of the literature corroborates the evidence that serine biosynthesis disorders represent a continuum with varying degrees of phenotypic expression and suggest that even gradual differences at the severe end of the spectrum may be correlated with particular genotypes. We postulate that the individual residual enzyme activity of mutant proteins is the major determinant of the phenotypic variability, but further functional studies are needed to explore effects at the enzyme protein level.

DNA-PK: gatekeeper for IKKγ/NEMO nucleocytoplasmic shuttling in genotoxic stress-induced NF-kappaB activation.

The transcription factors of the nuclear factor κB (NF-κB) family play a pivotal role in the cellular response to DNA damage. Genotoxic stress-induced activation of NF-κB differs from the classical canonical pathway by shuttling of the NF-κB Essential Modifier (IKKγ/NEMO) subunit through the nucleus. Here, we show that DNA-dependent protein kinase (DNA-PK), an enzyme involved in DNA double-strand break (DSB) repair, triggers the phosphorylation of NEMO by genotoxic stress, thereby enabling shuttling of NEMO through the nucleus with subsequent NF-κB activation. We identified serine 43 of NEMO as a DNA-PK phosphorylation site and point mutation of this serine to alanine led to a complete block of NF-κB activation by ionizing radiation (IR). Blockade of DNA-PK by a specific shRNA or by DNA-PKcs-deficient cells abrogated NEMO entry into the nucleus, as well. Accordingly, SUMOylation of NEMO, a prerequisite of nuclear NEMO, was abolished. Based on these observations, we propose a model in which NEMO phosphorylation by DNA-PK provides the first step in the nucleocytoplasmic trafficking of NEMO.

G-Protein-Coupled Estrogen Receptor (GPER)-Specific Agonist G1 Induces ER Stress Leading to Cell Death in MCF-7 Cells.

The G-protein-coupled estrogen receptor (GPER) mediates rapid non-genomic effects of estrogen. Although GPER is able to induce proliferation, it is down-regulated in breast, ovarian and colorectal cancer. During cancer progression, high expression levels of GPER are favorable for patients' survival. The GPER-specific agonist G1 leads to an inhibition of cell proliferation and an elevated level of intracellular calcium (Ca2+). The purpose of this study is to elucidate the mechanism of G1-induced cell death by focusing on the connection between G1-induced Ca2+ depletion and endoplasmic reticulum (ER) stress in the estrogen receptor positive breast cancer cell line MCF-7. We found that G1-induced ER Ca2+ efflux led to the activation of the unfolded protein response (UPR), indicated by the phosphorylation of IRE1α and PERK and the cleavage of ATF6. The pro-survival UPR signaling was activated via up-regulation of the ER chaperon protein GRP78 and translational attenuation indicated by eIF2-α phosphorylation. However, the accompanying pro-death UPR signaling is profoundly activated and responsible for ER stress-induced cell death. Mechanistically, PERK-phosphorylation-induced JNK-phosphorylation and IRE1α-phosphorylation, which further triggered CAMKII-phosphorylation, are both implicated in G1-induced cell death. Our study indicates that loss of ER Ca2+ is responsible for G1-induced cell death via the pro-death UPR signaling.

A Secreted Phospholipase A2 Induces Formation of Smooth Muscle Foam Cells Which Transdifferentiate to Macrophage-Like State.

Vascular smooth muscle cells (VSMCs) loaded with lipid droplets (LDs) are markers of atherosclerosis. In this disease, inflammatory Group IIA-secreted phospholipase A2s (GIIA sPLA2s) are highly expressed in VSMCs, but their actions in these cells are unknown. Here, we investigated the ability of myotoxin III (MT-III), an ophidian GIIA sPLA2 sharing structural and functional features with mammalian GIIA sPLA2s, to induce LD formation and lipid metabolism factors involved in this effect. Modulation of VSMC phenotypes by this sPLA2 was also evaluated. Incubation of VSMCs with MT-III significantly increased the number of LDs. MT-III upregulated scavenger receptor type 1 (SR-A1) and lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) protein expression and enhanced acetylated-low density lipoprotein (acLDL) uptake by VSMCs, revealing the ability of a GIIA PLA2 to modulate scavenger receptor activities. MT-III induced translocation and protein expression of PPAR-γ and -ß/δ. Inhibition of peroxisome proliferator-activated receptors (PPARs) and diacylglycerol O-acyltransferase (DGAT) and acyl-CoA:cholesterolacyltransferase (ACAT) enzymes abrogated MT-III-induced LD formation. Moreover, in response to MT-III, VSMCs acquired phagocytic activity and expressed macrophage markers CD68 and MAC-2. In conclusion, MT-III is able to stimulate VSMCs and recruit factors involved in lipid uptake and metabolism, leading to the formation of VSMC-derived foam cells with acquisition of macrophage-like markers and functions.

Tafazzin-dependent cardiolipin composition in C6 glioma cells correlates with changes in mitochondrial and cellular functions, and cellular proliferation.

The mitochondrial phospholipid cardiolipin (CL) has been implicated with mitochondrial morphology, function and, more recently, with cellular proliferation. Tafazzin, an acyltransferase with key functions in CL remodeling determining actual CL composition, affects mitochondrial oxidative phosphorylation. Here, we show that the CRISPR-Cas9 mediated knock-out of tafazzin (Taz) is associated with substantial alterations of various mitochondrial and cellular characteristics in C6 glioma cells. The knock-out of tafazzin substantially changed the profile of fatty acids incorporated in CL and the distribution of molecular CL species. Taz knock-out was further associated with decreased capacity of oxidative phosphorylation that mainly originates from impaired complex I associated energy metabolism in C6 glioma cells. The lack of tafazzin switched energy metabolism from oxidative phosphorylation to glycolysis indicated by lower respiration rates, membrane potential and higher levels of mitochondria-derived reactive oxygen species but keeping the cellular ATP content unchanged. The impact of tafazzin on mitochondria was also indicated by altered morphology and arrangement in tafazzin deficient C6 glioma cells. In the cells we observed tafazzin-dependent changes in the distribution of cellular fatty acids as an indication of altered lipid metabolism as well as in stability/morphology. Most impressive is the dramatic reduction in cell proliferation in tafazzin deficient C6 glioma cells that is not mediated by reactive oxygen species. Our data clearly indicate that defects in CL phospholipid remodeling trigger a cascade of events including modifications in CL linked to subsequent alterations in mitochondrial and cellular functions.

A secreted phospholipase A2 induces formation of smooth muscle foam cells which transdifferentiate to macrophage-like state

Vascular smooth muscle cells (VSMCs) loaded with lipid droplets (LDs) are markers of atherosclerosis. In this disease, inflammatory Group IIA-secreted phospholipase A2s (GIIA sPLA2s) are highly expressed in VSMCs, but their actions in these cells are unknown. Here, we investigated the ability of myotoxin III (MT-III), an ophidian GIIA sPLA2 sharing structural and functional features with mammalian GIIA sPLA2s, to induce LD formation and lipid metabolism factors involved in this effect. Modulation of VSMC phenotypes by this sPLA2 was also evaluated. Incubation of VSMCs with MT-III significantly increased the number of LDs. MT-III upregulated scavenger receptor type 1 (SR-A1) and lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) protein expression and enhanced acetylated-low density lipoprotein (acLDL) uptake by VSMCs, revealing the ability of a GIIA PLA2 to modulate scavenger receptor activities. MT-III induced translocation and protein expression of PPAR-gama and -ß/d. Inhibition of peroxisome proliferator-activated receptors (PPARs) and diacylglycerol O-acyltransferase (DGAT) and acyl-CoA:cholesterolacyltransferase (ACAT) enzymes abrogated MT-III-induced LD formation. Moreover, in response to MT-III, VSMCs acquired phagocytic activity and expressed macrophage markers CD68 and MAC-2. In conclusion, MT-III is able to stimulate VSMCs and recruit factors involved in lipid uptake and metabolism, leading to the formation of VSMC-derived foam cells with acquisition of macrophage-like markers and functions.

A secreted phospholipase A2 induces formation of smooth muscle foam cells which transdifferentiate to macrophage-like state

Vascular smooth muscle cells (VSMCs) loaded with lipid droplets (LDs) are markers of atherosclerosis. In this disease, inflammatory Group IIA-secreted phospholipase A2s (GIIA sPLA2s) are highly expressed in VSMCs, but their actions in these cells are unknown. Here, we investigated the ability of myotoxin III (MT-III), an ophidian GIIA sPLA2 sharing structural and functional features with mammalian GIIA sPLA2s, to induce LD formation and lipid metabolism factors involved in this effect. Modulation of VSMC phenotypes by this sPLA2 was also evaluated. Incubation of VSMCs with MT-III significantly increased the number of LDs. MT-III upregulated scavenger receptor type 1 (SR-A1) and lectin-like oxidized low-density lipoprotein receptor-1 (LOX-1) protein expression and enhanced acetylated-low density lipoprotein (acLDL) uptake by VSMCs, revealing the ability of a GIIA PLA2 to modulate scavenger receptor activities. MT-III induced translocation and protein expression of PPAR-gama and -ß/d. Inhibition of peroxisome proliferator-activated receptors (PPARs) and diacylglycerol O-acyltransferase (DGAT) and acyl-CoA:cholesterolacyltransferase (ACAT) enzymes abrogated MT-III-induced LD formation. Moreover, in response to MT-III, VSMCs acquired phagocytic activity and expressed macrophage markers CD68 and MAC-2. In conclusion, MT-III is able to stimulate VSMCs and recruit factors involved in lipid uptake and metabolism, leading to the formation of VSMC-derived foam cells with acquisition of macrophage-like markers and functions.

Diverging impact of cell fate determinants Scrib and Llgl1 on adhesion and migration of hematopoietic stem cells.

PURPOSE: Cell fate determinants Scrib and Llgl1 influence self-renewal capacity of hematopoietic stem cells (HSCs). Scrib-deficient HSCs are functionally impaired and lack sufficient repopulation capacity during serial transplantation and stress. In contrast, loss of Llgl1 leads to increased HSC fitness, gain of self-renewal capacity and expansion of the stem cell pool. Here, we sought to assess for shared and unique molecular functions of Llgl1 and Scrib by analyzing their interactome in hematopoietic cells. METHODS: Interactome analysis was performed by affinity purification followed by mass spectrometry. Motility, migration and adhesion were assessed on primary murine HSCs, which were isolated by FACS sorting following conditional deletion of Scrib or Llgl1, respectively. Imaging of Scrib-deficient HSCs was performed by intravital 2-photon microscopy. RESULTS: Comparison of Scrib and Llgl1 interactome analyses revealed involvement in common and unique cellular functions. Migration and adhesion were among the cellular functions connected to Scrib but not to Llgl1. Functional validation of these findings confirmed alterations in cell adhesion and migration of Scrib-deficient HSCs in vitro and in vivo. In contrast, genetic inactivation of Llgl1 did not affect adhesion or migratory capacity of hematopoietic stem cells. CONCLUSION: Our data provide first evidence for an evolutionarily conserved role of the cell fate determinant Scrib in HSC adhesion and migration in vitro and in vivo, a unique function that is not shared with its putative complex partner Llgl1.

Generation of functional cardiomyocytes from rat embryonic and induced pluripotent stem cells using feeder-free expansion and differentiation in suspension culture.

The possibility to generate cardiomyocytes from pluripotent stem cells in vitro has enormous significance for basic research, disease modeling, drug development and heart repair. The concept of heart muscle reconstruction has been studied and optimized in the rat model using rat primary cardiovascular cells or xenogeneic pluripotent stem cell derived-cardiomyocytes for years. However, the lack of rat pluripotent stem cells (rPSCs) and their cardiovascular derivatives prevented the establishment of an authentic clinically relevant syngeneic or allogeneic rat heart regeneration model. In this study, we comparatively explored the potential of recently available rat embryonic stem cells (rESCs) and induced pluripotent stem cells (riPSCs) as a source for cardiomyocytes (CMs). We developed feeder cell-free culture conditions facilitating the expansion of undifferentiated rPSCs and initiated cardiac differentiation by embryoid body (EB)-formation in agarose microwell arrays, which substituted the robust but labor-intensive hanging drop (HD) method. Ascorbic acid was identified as an efficient enhancer of cardiac differentiation in both rPSC types by significantly increasing the number of beating EBs (3.6 ± 1.6-fold for rESCs and 17.6 ± 3.2-fold for riPSCs). These optimizations resulted in a differentiation efficiency of up to 20% cTnTpos rPSC-derived CMs. CMs showed spontaneous contractions, expressed cardiac markers and had typical morphological features. Electrophysiology of riPSC-CMs revealed different cardiac subtypes and physiological responses to cardio-active drugs. In conclusion, we describe rPSCs as a robust source of CMs, which is a prerequisite for detailed preclinical studies of myocardial reconstruction in a physiologically and immunologically relevant small animal model.

The cell fate determinant Scribble is required for maintenance of hematopoietic stem cell function.

Cell fate determinants influence self-renewal potential of hematopoietic stem cells. Scribble and Llgl1 belong to the Scribble polarity complex and reveal tumor-suppressor function in drosophila. In hematopoietic cells, genetic inactivation of Llgl1 leads to expansion of the stem cell pool and increases self-renewal capacity without conferring malignant transformation. Here we show that genetic inactivation of its putative complex partner Scribble results in functional impairment of hematopoietic stem cells (HSC) over serial transplantation and during stress. Although loss of Scribble deregulates transcriptional downstream effectors involved in stem cell proliferation, cell signaling, and cell motility, these effectors do not overlap with transcriptional targets of Llgl1. Binding partner analysis of Scribble in hematopoietic cells using affinity purification followed by mass spectometry confirms its role in cell signaling and motility but not for binding to polarity modules described in drosophila. Finally, requirement of Scribble for self-renewal capacity also affects leukemia stem cell function. Thus, Scribble is a regulator of adult HSCs, essential for maintenance of HSCs during phases of cell stress.

Endothelial Nitric Oxide Synthase-Induced Hypertrophy and Vascular Dysfunction Contribute to the Left Ventricular Dysfunction in Caveolin-1-/- Mice.

BACKGROUND: Caveolin-1 (Cav1)-/- mice display impaired development of left ventricular pressure and increased left ventricular wall thickness but no dilated ventricle; these are typical findings in patients with heart failure with preserved ejection fraction (HfpEF). Aiming to clarify if dysfunctional endothelial nitric oxide synthase (eNOS) influences cardiomyocyte contractility, cardiac conduction system, or afterload/vascular resistance, we studied Cav1-/-/eNOS-/- mice. METHODS: Cardiac function was assessed in vivo by pressure-volume-catheterization of the left ventricle, echocardiography and electrocardiography. In addition, isolated tissue experiments were performed to evaluate cardiomyocyte contractility (atria) and vessel morphology and function (aorta). Histology, immunoblotting and quantitative polymerase chain reaction were applied to characterise radical formation and oxidative stress in the heart. RESULTS: Cardiac hypertrophy was completely reversed in Cav1-/-/eNOS-/- mice. The impaired pump function in Cav1-/- mice was significantly improved in Cav1-/-/eNOS-/- mice, but no complete alignment with eNOS-/- controls was achieved, indicating an additional eNOS-independent mechanism contributing to HFpEF in Cav1-/- mice. It is unlikely that frequently occurring arrhythmias contributed to HFpEF in Cav1-/- mice. In contrast, numerous eNOS-dependent and eNOS-independent vascular abnomalities could explain the cardiac phenotypes of Cav1-/- mice. CONCLUSIONS: Synergistic effects between eNOS-related cardiac hypertrophy and vascular hypercontractility appear to underlie the left ventricular dysfunction in Cav1-/-mice. These findings provide insights relevant to the poorly understood pathophysiology of HFpEF.

Semiautomatic High-Content Analysis of Complex Images from Cocultures of Vascular Smooth Muscle Cells and Macrophages: A CellProfiler Showcase.

Automatization in microscopy, cell culture, and the ease of digital imagery allow obtainment of more information from single samples and upscaling of image-based analysis to high-content approaches. Simple segmentation algorithms of biological imagery are nowadays widely spread in biomedical research, but processing of complex sample structures, for example, variable sample compositions, cell shapes, and sizes, and rare events remains a difficult task. As there is no perfect method for image segmentation and fully automatic image analysis of complex content, we aimed to succeed by identification of unique and reliable features within the sample. Through exemplary use of a coculture of vascular smooth muscle cells (VSMCs) and macrophages (MPs), we demonstrate how rare interactions within this highly variable sample type can be analyzed. Because of limitations in immunocytochemistry in our specific setup, we developed a semiautomatic approach to examine the interaction of lipid-laden MPs with VSMCs under hypoxic conditions based on nuclei morphology by high-content analysis using the open-source software CellProfiler ( www.cellprofiler.org ). We provide evidence that, in comparison with fully automatic analysis, a low threshold within the analysis workflow and subsequent manual control save time, while providing more objective and reliable results.