Supplementary Methods from Cancer-Associated Adipocytes Exhibit an Activated Phenotype and Contribute to Breast Cancer Invasion

Aims Deciphering the innate mechanisms governing the blockade of proliferation in adult cardiomyocytes (CMs) is challenging for mammalian heart regeneration. Despite the exit of CMs from the cell cycle during the postnatal maturation period coincides with their morphological switch to a typical adult rod-shape, whether these two processes are connected is unknown. Here, we examined the role of ephrin-B1, a CM rod-shape stabilizer, in adult CM proliferation and cardiac regeneration. Methods and results Transgenic- or AAV9-based ephrin-B1 repression in adult mouse heart led to substantial proliferation of resident CMs and tissue regeneration to compensate for apex resection, myocardial infarction (MI) and senescence. Interestingly, in the resting state, CMs lacking ephrin-B1 did not constitutively proliferate, indicative of no major cardiac defects. However, they exhibited proliferation-competent signature, as indicated by higher mononucleated state and a dramatic decrease of miR-195 mitotic blocker, which can be mobilized under neuregulin-1 stimulation in vitro and in vivo . Mechanistically, the post-mitotic state of the adult CM relies on ephrin-B1 sequestering of inactive phospho-Yap1, the effector of the Hippo-pathway, at the lateral membrane. Hence, ephrin-B1 repression leads to phospho-Yap1 release in the cytosol but CM quiescence at resting state. Upon cardiac stresses (apectomy, MI, senescence), Yap1 could be activated and translocated to the nucleus to induce proliferation-gene expression and consequent CM proliferation Conclusions Our results identified ephrin-B1 as a new natural locker of adult CM proliferation and emphasize that targeting ephrin-B1 may prove a future promising approach in cardiac regenerative medicine for HF treatment. Significance The mammalian adult heart is unable to regenerate due to the inability of cardiomyocytes (CMs) to proliferate and replace cardiac tissue lost. Exploiting CM-specific transgenic mice or AAV9-based gene therapy, this works identifies ephrin-B1, a specific rod-shape stabilizer of the adult CM, as a natural padlock of adult CM proliferation for compensatory adaptation to different cardiac stresses (apectomy, MI, senescence), thus emphasizing a new link between the adult CM morphology and their proliferation potential. Moreover, the study demonstrates proof-of-concept that targeting ephrin-B1 may be an innovative therapeutic approach for ischemic heart failure.

Aims:Tenascin-C (TNC) is an endogenous danger signal molecule strongly associated with inflammatory diseases and with poor outcome in patients with cardiomyopathies. Its function within pathological cardiac tissue during pressure overload remains poorly understood.Methods and results:We showed that TNC accumulates after 1 week of transverse aortic constriction (TAC) in the heart of 12-week-old male mice. By cross bone marrow transplantation experiments, we determined that TNC deposition relied on cardiac cells and not on haematopoietic cells. The expression of TNC induced by TAC, or by administration of a recombinant lentivector coding for TNC, triggered a pro-inflammatory cardiac microenvironment, monocyte/macrophage (MO/MΦ) accumulation, and systolic dysfunction. TNC modified macrophage polarization towards the pro-inflammatory phenotype and stimulated RhoA/Rho-associated protein kinase (ROCK) pathways to promote mesenchymal to amoeboid transition that enhanced macrophage migration into fibrillar collagen matrices. The amplification of inflammation and MO/MΦ recruitment by TNC was abrogated by genetic invalidation of TNC in knockout mice. These mice showed less ventricular remodelling and an improved cardiac function after TAC as compared with wild-type mice.Conclusions:By promoting a pro-inflammatory microenvironment and macrophage migration, TNC appears to be a key factor to enable the MO/MΦ accumulation within fibrotic hearts leading to cardiac dysfunction. As TNC is highly expressed during inflammation and sparsely during the steady state, its inhibition could be a promising therapeutic strategy to control inflammation and immune cell infiltration in heart disease.

Toll-like receptor 7 (TLR7) is critical to the induction of antiviral immunity, but TLR7 dosage is also a key pathogenic factor in systemic lupus erythematosus (SLE), an autoimmune disease with strong female bias. SLE prevalence is also elevated in individuals with Klinefelter syndrome, who carry one or more supernumerary X chromosomes, suggesting that the X chromosome complement contributes to SLE susceptibility. TLR7 is encoded by an X chromosome locus, and we examined here whether the TLR7 gene evades silencing by X chromosome inactivation in immune cells from women and Klinefelter syndrome males. Single-cell analyses of TLR7 allelic expression demonstrated that substantial fractions of primary B lymphocytes, monocytes, and plasmacytoid dendritic cells not only in women but also in Klinefelter syndrome males express TLR7 on both X chromosomes. Biallelic B lymphocytes from women displayed greater TLR7 transcriptional expression than the monoallelic cells, correlated with higher TLR7 protein expression in female than in male leukocyte populations. Biallelic B cells were preferentially enriched during the TLR7-driven proliferation of CD27(+) plasma cells. In addition, biallelic cells showed a greater than twofold increase over monoallelic cells in the propensity to immunoglobulin G class switch during the TLR7-driven, T cell-dependent differentiation of naive B lymphocytes into immunoglobulin-secreting cells. TLR7 escape from X inactivation endows the B cell compartment with added responsiveness to TLR7 ligands. This finding supports the hypothesis that enhanced TLR7 expression owing to biallelism contributes to the higher risk of developing SLE and other autoimmune disorders in women and in men with Klinefelter syndrome.

AIMS:Post-infarction remodelling is accompanied and influenced by perturbations in mitogen-activated protein kinase (MAPK) signalling. The growth arrest and DNA-damage-inducible 45 (Gadd45) proteins are small acidic proteins involved in DNA repair and modulation of MAPK activity. Little is known about the role of Gadd45 in the heart. Here, we explored the potential contribution of Gadd45 gamma (γ) isoform to the acute and late phase of heart failure (HF) after myocardial infarction (MI) and determined the mechanisms underlying Gadd45γ actions. METHODS AND RESULTS:The Gadd45γ isoform is up-regulated in murine cardiomyocytes subjected to simulated ischaemia and in the mouse heart during MI. To mimic the situation observed during MI, we enhanced Gadd45γ content in cardiomyocytes with a single injection of an adeno-associated viral (AAV9) vector encoding Gadd45γ under the cTNT promoter. Gadd45γ overexpression induces cardiomyocyte apoptosis, fibrosis, left ventricular dysfunction, and HF. On the other hand, genetic deletion of Gadd45γ in knockout mice confers resistance to ischaemic injury, at least in part by limiting cardiomyocyte apoptosis. Mechanistically, Gadd45γ activates receptor-interacting protein 1 (RIP1) and caspase-8 in a p38 MAPK-dependent manner to promote cardiomyocyte death. CONCLUSION:This work is the first to demonstrate that Gadd45γ accumulation during MI promotes the development and persistence of HF by inducing cardiomyocyte apoptosis in a p38 MAPK-dependent manner. We clearly identify Gadd45γ as a therapeutic target in the development of HF.

The mechanisms underlying the relationships between nutritional status and immunity remain to be fully characterized. The present study was undertaken to analyze by flow cytometry, in the context of diet-induced obesity, the status of immune cells in subcutaneous, and epididymal fat depots in wild-type and immunodeficient Rag2−/− mice submitted to nutritional challenge, i.e., 48-h fasting and 1-week refeeding. In parallel, the responsiveness of mature adipocytes and immune cells in bone marrow, lymph node, and liver were also analyzed. The results show that fasting in obese wild-type mice induces a prominent lipolysis in epididymal AT and immunosuppression restricted to both subcutaneous and epididymal AT, characterized by reduced number of CD4+ T and B lymphocytes and M1/M2 macrophages associated with reduced leptin and increased FGF21 expression in mature adipocytes. One-week refeeding was sufficient to reverse the fasting-induced effects. Obese immunodeficient mice under nutritional challenge exhibited no changes in adipocyte leptin expression and no marked trafficking of AT macrophages or NK cells, while the fasted-induced upregulation of FGF21 expression was maintained as well as the lipolytic responses. The present results demonstrate that, in a context of diet-induced obesity, fasting-induced immunosuppression is restricted to fat depots in immunocompetent mice. Lack of adipocyte leptin regulation and fasting-induced immunosuppression in obese immunodeficient mice strongly suggests that lymphocytes are involved in the modulation of adipocyte leptin expression on one hand and on the other that leptin is involved in the immune changes in AT according to nutritional status.

BACKGROUND & AIMS Glucose is absorbed into intestine cells via the sodium glucose transporter 1 (SGLT-1) and glucose transporter 2 (GLUT2); various peptides and hormones control this process. Apelin is a peptide that regulates glucose homeostasis and is produced by proximal digestive cells; we studied whether glucose modulates apelin secretion by enterocytes and the effects of apelin on intestinal glucose absorption. METHODS We characterized glucose-related luminal apelin secretion in vivo and ex vivo by mass spectroscopy and immunologic techniques. The effects of apelin on (14)C-labeled glucose transport were determined in jejunal loops and in mice following apelin gavage. We determined levels of GLUT2 and SGLT-1 proteins and phosphorylation of AMPKα2 by immunoblotting. The net effect of apelin on intestinal glucose transepithelial transport was determined in mice. RESULTS Glucose stimulated luminal secretion of the pyroglutaminated apelin-13 isoform ([Pyr-1]-apelin-13) in the small intestine of mice. Apelin increased specific glucose flux through the gastric epithelial barrier in jejunal loops and in vivo following oral glucose administration. Conversely, pharmacologic apelin blockade in the intestine reduced the increased glycemia that occurs following oral glucose administration. Apelin activity was associated with phosphorylation of AMPKα2 and a rapid increase of the GLUT2/SGLT-1 protein ratio in the brush border membrane. CONCLUSIONS Glucose amplifies its own transport from the intestinal lumen to the bloodstream by increasing luminal apelin secretion. In the lumen, active apelin regulates carbohydrate flux through enterocytes by promoting AMPKα2 phosphorylation and modifying the ratio of SGLT-1:GLUT2. The glucose-apelin cycle might be pharmacologically handled to regulate glucose absorption and assess better control of glucose homeostasis.

Both acute and chronic apelin treatment have been shown to improve insulin sensitivity in mice. However, the effects of apelin on fatty acid oxidation (FAO) during obesity-related insulin resistance have not yet been addressed. Thus, the aim of the current study was to determine the impact of chronic treatment on lipid use, especially in skeletal muscles. High-fat diet (HFD)-induced obese and insulin-resistant mice treated by an apelin injection (0.1 μmol/kg/day i.p.) during 4 weeks had decreased fat mass, glycemia, and plasma levels of triglycerides and were protected from hyperinsulinemia compared with HFD PBS-treated mice. Indirect calorimetry experiments showed that apelin-treated mice had a better use of lipids. The complete FAO, the oxidative capacity, and mitochondrial biogenesis were increased in soleus of apelin-treated mice. The action of apelin was AMP-activated protein kinase (AMPK) dependent since all the effects studied were abrogated in HFD apelin-treated mice with muscle-specific inactive AMPK. Finally, the apelin-stimulated improvement of oxidative capacity led to decreased levels of acylcarnitines and enhanced insulin-stimulated glucose uptake in soleus. Thus, by promoting complete lipid use in muscle of insulin-resistant mice through mitochondrial biogenesis and tighter matching between FAO and the tricarboxylic acid cycle, apelin treatment could contribute to insulin sensitivity improvement.

AbstractEarly local tumor invasion in breast cancer results in a likely encounter between cancer cells and mature adipocytes, but the role of these fat cells in tumor progression remains unclear. We show that murine and human tumor cells cocultivated with mature adipocytes exhibit increased invasive capacities in vitro and in vivo, using an original two-dimensional coculture system. Likewise, adipocytes cultivated with cancer cells also exhibit an altered phenotype in terms of delipidation and decreased adipocyte markers associated with the occurrence of an activated state characterized by overexpression of proteases, including matrix metalloproteinase-11, and proinflammatory cytokines [interleukin (IL)-6, IL-1β]. In the case of IL-6, we show that it plays a key role in the acquired proinvasive effect by tumor cells. Equally important, we confirm the presence of these modified adipocytes in human breast tumors by immunohistochemistry and quantitative PCR. Interestingly, the tumors of larger size and/or with lymph nodes involvement exhibit the higher levels of IL-6 in tumor surrounding adipocytes. Collectively, all our data provide in vitro and in vivo evidence that (i) invasive cancer cells dramatically impact surrounding adipocytes; (ii) peritumoral adipocytes exhibit a modified phenotype and specific biological features sufficient to be named cancer-associated adipocytes (CAA); and (iii) CAAs modify the cancer cell characteristics/phenotype leading to a more aggressive behavior. Our results strongly support the innovative concept that adipocytes participate in a highly complex vicious cycle orchestrated by cancer cells to promote tumor progression that might be amplified in obese patients. Cancer Res; 71(7); 2455–65. ©2011 AACR.

Apelin, an adipocyte-secreted factor upregulated by insulin, is increased in adipose tissue (AT) and plasma with obesity. Apelin was recently identified as a new player in the control of glucose homeostasis. However, the regulation of apelin and APJ (apelin receptor) expression in skeletal muscle in relation to insulin resistance or type 2 diabetes is not known. Thus we studied apelin and APJ expression in AT and muscle in different mice models of obesity and in type 2 diabetic patients. In insulin-resistant high-fat (HF)-fed mice, apelin and APJ expression were increased in AT compared with control. This was not the case in AT of highly insulin-resistant db/ db mice. In skeletal muscle, apelin expression was similar in control and HF-fed mice and decreased in db/ db mice. APJ expression was decreased in both HF-fed and db/ db mice. Control subjects and type 2 diabetic patients were subjected to a hyperinsulinemic-euglycemic clamp, and tissues biopsies were obtained before and at the end of the clamp. There was no significant difference in basal apelin and APJ expression in AT and muscle between control and diabetic patients. However, apelin plasma levels were significantly increased in diabetic patients. During the clamp, hyperinsulinemia increased apelin and APJ expression in AT of control but not in diabetic subjects. In muscle, only APJ mRNA levels were increased in control but also in diabetic patients. Taken together, these data show that apelin and APJ expression in mice and humans is regulated in a tissue-dependent manner and according to the severity of insulin resistance.

L’apeline est un peptide dont les formes les plus biologiquement actives sont de 13, 17 ou 36 acides amines. L’apeline et son recepteur membranaire APJ sont exprimes au niveau du systeme nerveux central, notamment dans l’hypothalamus, et en peripherie surtout dans le cœur, le tissu adipeux, les cellules endotheliales des vaisseaux sanguins et le muscle squelettique. L’apeline est impliquee dans la regulation de la prise hydrique, alimentaire, les phenomenes d’angiogenese et de proliferation cellulaire. Le systeme apeline/APJ est egalement un regulateur important de l’homeostasie cardiovasculaire. Ainsi, l’apeline induit une vasodilatation dependante du NO et augmente la contraction cardiaque. Dans differentes pathologies cardiaques, une diminution de l’expression et de l’activite du systeme apeline/APJ est observee mais l’apport exogene d’apeline produit une nette amelioration faisant de ce systeme une cible privilegiee. Recemment, des effets de l’apeline sur le metabolisme energetique ont ete mis en evidence. Des resultats obtenus dans notre equipe montrent qu’in vivo, chez la souris, une injection intraveineuse d’apeline diminue la glycemie et augmente l’utilisation du glucose dans les muscles squelettiques et le tissu adipeux. L’activation du transport du glucose par l’apeline dans le muscle implique une voie en partie independante de celle de l’insuline avec activation de l’AMP-activated protein kinase et de la NO-synthase endotheliale. Ainsi, l’apeline participe au controle de l’homeostasie glucidique. De facon tres interessante, ces effets perdurent chez des souris insulinoresistantes. Le cœur est aussi le siege d’une activite metabolique importante. Au cours du diabete, des alterations metaboliques sont observees. Le systeme apeline/APJ etant fortement exprime au niveau du cœur, les effets de l’apeline sur le metabolisme energetique ouvrent des perspectives interessantes.

European Journal of Endocrinology, but the version presented here has not yet been copy edited, formatted or proofed. Consequently, the journal accepts no responsibility for any errors or omissions it may contain. The definitive version is now freely available at

Apelin is a peptide known as the ligand of the G protein-coupled receptor APJ. Diverse active apelin peptides exist in the form of 13, 17 or 36 amino-acids originating from a 77-amino-acid precursor. Apelin and APJ are expressed in the central nervous system, particularly in the hypothalamus, and in peripheral tissues such as heart, adipose tissue, the endothelial cells of blood vessels and skeletal muscle. Apelin has been shown to be involved in the regulation of fluid homeostasis, food intake, cell proliferation and vessel formation. Apelin is also an important regulator of cardiovascular homeostasis by stimulating NO-dependent vasodilatation and increasing cardiac contractility. Down-regulation of apelin and APJ expression is associated with decreased cardiac performance but exogenous apelin restores it raising the possibility of investigating its therapeutic potential. Recently, apelin effects on energy metabolism have been demonstrated. Results obtained in our laboratory have shown that in vivo, in mice, intravenous injection of apelin decreases blood glucose and increases glucose utilization in skeletal muscle and adipose tissue. Activation of glucose transport by apelin in muscle implies a pathway partially independent of insulin signalling, involving the activation of AMP-activated protein- kinase and of endothelial NO-synthase. In obese and insulin-resistant mice, an intravenous injection of apelin improves glucose tolerance and stimulates the entry of glucose into insulin-sensitive tissues. Thus, apelin (acute treatment) regulates glucose homeostasis and is effective in insulin-resistant mice. The heart is also an important site of active metabolism and metabolic alterations are observed during diabetes. Since the apelin/APJ system is highly expressed in the heart, the effects of apelin on cardiac energy metabolism opens new interesting prospects.

OBJECTIVE:Apelin is a novel adipokine acting on APJ receptor, regulated by insulin and tumor necrosis factor-alpha (TNF-alpha) in adipose tissue (AT). Plasma apelin levels are increased in obese hyperinsulinemic subjects. The aim was to investigate whether the hypocaloric diet associated with weight loss modifies the elevated plasma apelin levels and the expression of apelin and APJ receptor in AT in obese women.DESIGN AND METHODS:Fasting plasma levels of apelin and TNF-alpha as well as mRNA levels of apelin and APJ in AT were measured before and after a 12-week hypocaloric weight-reducing diet in 20 obese women (body mass index (BMI) before diet 32.2+/-6.4 kg/m(2)). Twelve healthy women with a BMI of 20.7+/-0.6 kg/m(2) served as reference.RESULTS:Plasma levels of apelin and TNF-alpha were higher in obese compared with lean controls. The hypocaloric diet resulted in a significant decrease of BMI to 29.8+/-6.3 kg/m(2), plasma insulin (8.16+/-0.73 to 6.58+/-0.66 mU/l), apelin (369+/-25 pg/ml to 257+/-12 pg/ml), TNF-alpha levels (0.66+/-0.04 pg/ml to 0.56+/-0.04 pg/ml), and AT mRNAs of apelin and APJ. In addition, changes in AT mRNA apelin were related to changes in AT mRNA APJ levels.CONCLUSION:The hypocaloric diet associated with weight loss reduces the increased plasma and AT expression of apelin in obese women. This reduced apelin expression in AT could contribute to decreased circulating apelin levels.

By using pangenomic microarray, we identified apelin as a unique adipokine up regulated by the transcriptional co-activator peroxisome proliferator-activated receptor gamma (PPARgamma) co-activator 1alpha (PGC-1alpha) in human white adipocytes. We investigated its regulation in vitro and in vivo. Overexpression of PGC-1alpha by adenovirus in human adipocytes induces apelin expression and secretion. Pharmacological induction of cAMP, an upstream regulator of endogenous PGC-1alpha expression, up regulates apelin gene expression and also apelin secretion in human and mice adipocytes. Moreover, during cold exposure in mice, a physiological situation known to induce both cAMP and PGC-1alpha, apelin expression in adipocytes and plasma levels were increased. This is the first demonstration that PGC-1alpha is involved in the regulation of an adipokine gene expression and release.

Adipose tissue (AT) secretes several adipokines that influence insulin sensitivity and potentially link obesity to insulin resistance. Apelin, a peptide present in different tissues, is also secreted by adipocytes. Apelin is upregulated in obese and hyperinsulinemic humans and mice. Although a tight relation exists between the regulation of apelin and insulin, it remains largely unknown whether apelin affects whole-body glucose utilization. Herein, we show that in chow-fed mice, acute intravenous injection of apelin has a powerful glucose-lowering effect associated with enhanced glucose utilization in skeletal muscle and AT. Through in vivo and in vitro pharmacological and genetic approaches, we demonstrate the involvement of endothelial NO synthase, AMP-activated protein kinase, and Akt in apelin-stimulated glucose uptake in soleus muscle. Remarkably, in obese and insulin-resistant mice, apelin restored glucose tolerance and increased glucose utilization. Apelin could thus represent a promising target in the management of insulin resistance.

Little information is available on the ability of terminally differentiated cells to efficiently repair DNA double strand breaks (DSBs), and one might reasonably speculate that efficient DNA repair of these threatening DNA lesions, is needed in cells of long life span with no or limited regeneration from precursor. Few tissues are available besides neurons that allow the study of DNA DSBs repair activity in very long-lived cells. Adipocytes represent a suitable model since it is generally admitted that there is a very slow turnover of adipocytes in adult. Using both Pulse Field Gel Electrophoresis (PFGE) and the disappearance of the phosphorylated form of the histone variant H2AX, we demonstrated that the ability to repair DSBs is increased during adipocyte differentiation using the murine pre-adipocyte cell line, 3T3F442A. In mammalian cells, DSBs are mainly repaired by the non-homologous end-joining pathway (NHEJ) that relies on the DNA dependent protein kinase (DNA-PK) activity. During the first 24 h following the commitment into adipogenesis, we show an increase in the expression and activity of the catalytic sub-unit of the DNA-PK complex, DNA-PKcs. The increased in DNA DSBs repair activity observed in adipocytes was due to the increase in DNA-PK activity as shown by the use of DNA-PK inhibitor or sub-clones of 3T3F442A deficient in DNA-PKcs using long term RNA interference. Interestingly, the up-regulation of DNA-PK does not regulate the differentiation program itself. Finally, similar positive regulation of DNA-PKcs expression and activity was observed during differentiation of primary culture of pre-adipocytes isolated from human sub-cutaneous adipose tissue. Our results show that DNA DSBs repair activity is up regulated during the early commitment into adipogenesis due to an up-regulation of DNA-PK expression and activity. In opposition to the general view that DNA DSBs repair is decreased during differentiation, our results demonstrate that an up-regulation of this process might be observed in post-mitotic long-lived cells.

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A strong induction of semicarbazide-sensitive amine oxidase (SSAO) has previously been reported during murine preadipocyte lineage differentiation but it remains unknown whether this emergence also occurs during adipogenesis in man. Our aim was to compare SSAO and monoamine oxidase (MAO) expression during in vitro differentiation of human preadipocytes and in adipose and stroma-vascular fractions of human fat depots. A human preadipocyte cell strain from a patient with Simpson-Golabi-Behmel syndrome was first used to follow amine oxidase expression during in vitro differentiation. Then, human preadipocytes isolated from subcutaneous adipose tissues were cultured under conditions promoting ex vivo adipose differentiation and tested for MAO and SSAO expression. Lastly, human adipose tissue was separated into mature adipocyte and stroma-vascular fractions for analyses of MAO and SSAO at mRNA, protein and activity levels. Both SSAO and MAO were increased from undifferentiated preadipocytes to lipid-laden cells in all the models: 3T3-F442A and 3T3-L1 murine lineages, human SGBS cell strain or human preadipocytes in primary culture. In human subcutaneous adipose tissue, the adipocyte-enriched fraction exhibited seven-fold higher amine oxidase activity and contained three- to seven-fold higher levels of mRNAs encoded by MAO-A, MAO-B, AOC3 and AOC2 genes than the stroma-vascular fraction. MAO-A and AOC3 genes accounted for the majority of their respective MAO and SSAO activities in human adipose tissue. Most of the SSAO and MAO found in adipose tissue originated from mature adipocytes. Although the mechanism and role of adipogenesis-related increase in amine oxidase expression remain to be established, the resulting elevated levels of amine oxidase activities found in human adipocytes may be of potential interest for therapeutic intervention in obesity.