Targeting ERK3/MK5 complex for treatment of obesity and diabetes.

Kinases represent one of the largest druggable families of proteins. Importantly, many kinases are aberrantly activated/de-activated in multiple organs during obesity, which contributes to the development of diabetes and associated diseases. Previous results indicate that the complex between Extracellular-regulated kinase 3 (ERK3) and Mitogen-Activated Protein Kinase (MAPK)-activated protein kinase 5 (MK5) suppresses energy dissipation and promotes fatty acids (FAs) output in adipose tissue and, therefore promotes obesity and diabetes. However, the therapeutic potential of targeting this complex at the systemic level has not been fully explored. Here we applied a translational approach to target the ERK3/MK5 complex in mice. Importantly, deletion of ERK3 in the whole body or administration of MK5-specific inhibitor protects against obesity and promotes insulin sensitivity. Finally, we show that the expression of ERK3 and MK5 correlates with the degree of obesity and that ERK3/MK5 complex regulates energy dissipation in human adipocytes. Altogether, we demonstrate that ERK3/MK5 complex can be targeted in vivo to preserve metabolic health and combat obesity and diabetes.This study was funded by European Research Council (ERC) Starting Grant SicMetabol (no.678119), Emmy Noether Grant Su820/1-1 from the German Research Foundation (DFG), EMBO Installation Grant from European Molecular Biology Organization (EMBO), the Dioscuri Centre of Scientific Excellenced The program initiated by the Max Planck Society (MPG), managed jointly with the National Science Centre, and mutually funded by the Ministry of Science and Higher Education (MNiSW) and the German Federal Ministry of Education and Research (BMBF), and Sonata bis grant (2020/38/E/NZ4/00314) from National Science Centre.S

Orphan GPR116 mediates the insulin sensitizing effects of the hepatokine FNDC4 in adipose tissue

The proper functional interaction between different tissues represents a key component in systemic metabolic control. Indeed, disruption of endocrine inter-tissue communication is a hallmark of severe metabolic dysfunction in obesity and diabetes. Here, we show that the FNDC4-GPR116, liver-white adipose tissue endocrine axis controls glucose homeostasis. We found that the liver primarily controlled the circulating levels of soluble FNDC4 (sFNDC4) and lowering of the hepatokine FNDC4 led to prediabetes in mice. Further, we identified the orphan adhesion GPCR GPR116 as a receptor of sFNDC4 in the white adipose tissue. Upon direct and high affinity binding of sFNDC4 to GPR116, sFNDC4 promoted insulin signaling and insulin-mediated glucose uptake in white adipocytes. Indeed, supplementation with FcsFNDC4 in prediabetic mice improved glucose tolerance and inflammatory markers in a white-adipocyte selective and GPR116-dependent manner. Of note, the sFNDC4-GPR116, liver-adipose tissue axis was dampened in (pre) diabetic human patients. Thus our findings will now allow for harnessing this endocrine circuit for alternative therapeutic strategies in obesity-related pre-diabetes. The soluble bioactive form of the transmembrane protein fibronectin type III domain containing 4 (sFNDC4) has anti-inflammatory effects and improves insulin sensitivity. Here the authors show that liver derived sFNDC4 signals through adipose tissue GPCR GPR116 to promote insulin-mediated glucose uptake.Peer reviewe

Der adrenerge induzierte ERK3-Signalweg verstärkt Lipolyse und unterdrückt Energiedissipation

Obesity-induced diabetes affects over 400 million people worldwide. Obesity is a complex metabolic disease and is associated with several co-morbidities, all of which negatively affect the individual’s quality of life. It is commonly considered that obesity is a result of a positive energy misbalance, as increased food intake and lower expenditure eventually lead to the development of this disease. Moreover, the pathology of obesity is attributed to several genetic and epigenetic factors that put an individual at high risk compared to another. Adipose tissue is the main site of the organism’s energy storage. During the time when the nutrients are available in excess, adipocytes acquire triglycerides, which are released during the time of food deprivation in the process of lipolysis (free fatty acids and glycerol released from adipocytes). Uncontrolled lipolysis is the consequent event that contributes to the development of diabetes and paradoxically obesity. To identify the genetic factors aiming for future therapeutic avenues targeting this pathway, we performed a high-throughput screen and identified the Extracellular-regulated kinase 3 (ERK3) as a hit. We demonstrate that β-adrenergic stimulation stabilizes ERK3 leading to the formation of a complex with the co-factor MAP kinase-activated protein kinase 5 (MK5) thereby driving lipolysis. Mechanistically, we identify a downstream target of the ERK3/MK5 pathway, the transcription factor FOXO1, which promotes the expression of the major lipolytic enzyme ATGL. Finally, we provide evidence that targeted deletion of ERK3 in mouse adipocytes inhibits lipolysis, but elevates energy dissipation, promoting lean phenotype and ameliorating diabetes. Moreover, we shed the light on our pharmacological approach in targeting ERK3/MK5 pathways using MK5 specific inhibitor. Already after 1 week of administering the inhibitor, mice showed signs of improvement of their metabolic fitness as showed here by a reduction in induced lipolysis and the elevation in the expression of thermogenic genes. Taken together, our data suggest that targeting the ERK3/MK5 pathway, a previously unrecognized signaling axis in adipose tissue, could be an attractive target for future therapies aiming to combat obesity-induced diabetes.Adipositas-induzierter Diabetes betrifft weltweit über 400 Millionen Menschen. Adipositas ist eine komplexe Stoffwechselerkrankung und geht mit mehreren Komorbiditäten einher, die sich alle negativ auf die Lebensqualität der Betroffenen auswirken. Es wird generell angenommen, dass Adipositas aus einem positiven Energieungleichgewicht resultiert, da eine erhöhte Nahrungsaufnahme und ein geringerer Verbrauch zu der Ausbildung dieser Krankheit führen. Darüber hinaus ist die Pathologie von Adipositas auf mehrere genetische und epigenetische Faktoren zurückzuführen, wodurch Individuen einem erhöhtem Risiko ausgesetzt sein können. Das Fettgewebe ist der vorwiegende Energiespeicher des Organismus. In Zeiten eines Nährstoffüberschusses speichern Adipozyten Triglyceride, die im Falle eines Nahrungsmangels durch den Prozess der Lipolyse in Form von freien Fettsäuren und Glycerin freigesetzt werden. Unkontrollierte Lipolyse ist ein Folgeereignis, welches zur Entwicklung von Diabetes und paradoxerweise zu Adipositas beiträgt. Um die genetischen Faktoren zu identifizieren, die in Zukunft therapeutische Angriffspunkte darstellen könnten, haben wir ein Hochdurchsatz-Screening durchgeführt und die extrazellulär regulierte Kinase 3 (ERK3) als Treffer identifiziert. Wir zeigen, dass β-adrenerge Stimulation ERK3 stabilisiert, was zur Bildung eines Komplexes mit dem Cofactor MAP-Kinase-aktivierte Proteinkinase 5 (MK5) führt und dadurch die Lipolyse vorantreibt. Mechanistisch identifizieren wir den Transkriptionsfaktor FOXO1, der dem ERK3/MK5-Signalweg nachgeschaltet ist und die Expression des wichtigsten lipolytischen Enzyms ATGL fördert. Darüber hinaus belegen wir, dass die gezielte Deletion von ERK3 in Maus-Adipozyten die Lipolyse hemmt, aber die Energiedissipation erhöht, den mageren Phänotyp fördert und Diabetes lindert. Außerdem nutzen wir einen pharmakologischen Ansatz durch Verwendung eines MK5 spezifischen Inhibitors, um auf den ERK3/MK5-Signalweg abzuzielen. Bereits eine Woche nach Verabreichung des Inhibitors zeigen Mäuse Anzeichen einer verbesserten metabolischen Fitness, die sich durch einer Verringerung der induzierten Lipolyse und eine verstärkte Expression von thermogenen Genen auszeichnet. Zusammenfassend legen unsere Daten nahe, dass der ERK3/MK5-Signalweg, eine zuvor nicht erkannte Signalachse im Fettgewebe, ein attraktiver Ansatzpunkt für zukünftige Therapien zur Bekämpfung von Adipositas-induziertem Diabetes sein könnte

Ndrg1 promotes adipocyte differentiation and sustains their function

Adipocytes play a central role in maintaining metabolic homeostasis in the body. Differentiation of adipocyte precursor cells requires the transcriptional activity of peroxisome proliferator-activated receptor-γ (Pparγ) and CCAAT/enhancer binding proteins (C/Ebps). Transcriptional activity is regulated by signaling modules activated by a plethora of hormones and nutrients. Mechanistic target of rapamacin complexes (mTORC) 1 and 2 are central for the coordination of hormonal and nutritional inputs in cells and are essential for adipogenesis. Serum glucocorticoid kinase 1 (Sgk1)-dependent phosphorylation of N-Myc downstream-regulated gene 1 (Ndrg1) is a hallmark of mTORC2 activation in cells. Moreover, Pparγ activation promotes Ndrg1 expression. However, the impact of Ndrg1 on adipocyte differentiation and function has not yet been defined. Here, we show that Ndrg1 expression and its Sgk1-dependent phosphorylation are induced during adipogenesis. Consistently, we demonstrate that Ndrg1 promotes adipocyte differentiation and function by inducing Pparγ expression. Additionally, our results indicate that Ndrg1 is required for C/Ebpα phosphorylation. Moreover, we found that Ndrg1 phosphorylation by Sgk1 promotes adipocyte formation. Taken together, we show that induction of Ndrg1 expression by Pparγ and its phosphorylation by Sgk1 kinase are required for the acquisition of adipocyte characteristics by precursor cells

A Unique Expression of Keratin 14 in a Subset of Trophoblast Cells.

The placenta, a transient organ in human, is essential for pregnancy maintenance and for fetal growth and development. Trophoblast and stromal cells are the main cell types present in human placenta. Trophoblast cells are present in different subtypes depending on their differentiation state and their temporal and spatial location during pregnancy. The stromal cells are of extraembryonic mesenchymal origin and are important for villous formation and maintenance. Interestingly, many pregnancy-related diseases are associated with defect in trophoblast differentiation and villous integrity. Therefore, it's crucial to specifically identify each type of placental cells using specific markers. Keratins (CK) are widely used as marker of epithelial cells, cancer origin identification and in some cases as marker of stem/progenitor cells. Vimentin is widely used as marker of mesenchymal cells. The aim of this study is to characterize the presence of different keratins in human trophoblast cells and vimentin in stromal cells. Using immunohistochemistry on term placental sections, our results show that vimentin is solely expressed in stromal-mesenchymal cells while keratins 5, 7, 8, 14 and 19 are expressed in trophoblast cells. Interestingly, all keratins tested, except for keratin 14, were evenly expressed in all trophoblast cells. Keratin 14 was expressed in a subset of CK7 positive cells. Moreover, the same results were obtained when using freshly isolated cytotrophoblast cells or BeWo cells. In conclusion, this study is a crucial step in the advancement of our knowledge in placental cell type identification and characterization

Deletion of <i>Pld1</i> or <i>Pld2</i> promotes food intake.

<p>A) 24 hours cumulative food intake of 20-weeks old mice with indicated genotypes. B) Oxygen consumption of mice with indicated genotypes at different time of the day. C) Average oxygen consumption during light and dark phase. D) Carbon dioxide production of mice with indicated genotypes at different time of the day. E) Average carbon dioxide during light and dark phase. F) Voluntary movements of mice with indicated genotypes at different time of the day. G) Average voluntary movements of mice during light and dark phase. H) Respiratory exchange rate of mice with indicated genotypes at different time of the day. I) Average respiratory exchange rate of mice during light and dark phase. Data represented as mean +/- S.E.M., n = 6 males for control (black), n = 4 males for <i>Pld1</i>^<i>-/-</i> (orange), n = 6 males for <i>Pld2</i>^<i>-/-</i> (green). *p<0.05, **p<0.01, ***p<0.001</p

Expression of keratin 14 in primary trophoblast cells.

<p>Representative immunofluorescent images of cytospin preparations of primary trophoblast cells, isolated from human term placenta, stained for the indicated antibodies and for Dapi are shown. The arrows indicate the presence of CK14. These experiments were repeated at least 3 times.</p

Phospholipases D1 and D2 Suppress Appetite and Protect against Overweight

<div><p>Obesity is a major risk factor predisposing to the development of peripheral insulin resistance and type 2 diabetes (T2D). Elevated food intake and/or decreased energy expenditure promotes body weight gain and acquisition of adipose tissue. Number of studies implicated phospholipase D (PLD) enzymes and their product, phosphatidic acid (PA), in regulation of signaling cascades controlling energy intake, energy dissipation and metabolic homeostasis. However, the impact of PLD enzymes on regulation of metabolism has not been directly determined so far. In this study we utilized mice deficient for two major PLD isoforms, PLD1 and PLD2, to assess the impact of these enzymes on regulation of metabolic homeostasis. We showed that mice lacking PLD1 or PLD2 consume more food than corresponding control animals. Moreover, mice deficient for PLD2, but not PLD1, present reduced energy expenditure. In addition, deletion of either of the PLD enzymes resulted in development of elevated body weight and increased adipose tissue content in aged animals. Consistent with the fact that elevated content of adipose tissue predisposes to the development of hyperlipidemia and insulin resistance, characteristic for the pre-diabetic state, we observed that <i>Pld1</i>^<i>-/-</i> and <i>Pld2</i>^<i>-/-</i> mice present elevated free fatty acids (FFA) levels and are insulin as well as glucose intolerant. In conclusion, our data suggest that deficiency of PLD1 or PLD2 activity promotes development of overweight and diabetes.</p></div

list of antibodies used in immunohistochemistry and immunofluorescence.

<p>NA: not available</p><p>list of antibodies used in immunohistochemistry and immunofluorescence.</p

Keratins expression in BeWo cells.

<p>Representative immunofluorescent images of BeWo cells stained for the indicated antibodies and for Dapi are shown. The arrow indicates the presence of CK14. These experiments were repeated at least 3 times.</p