Cyclin-Dependent Kinase 5 (CDK5)-Mediated Phosphorylation of Upstream Stimulatory Factor 2 (USF2) Contributes to Carcinogenesis

The transcription factor USF2 is supposed to have an important role in tumor development. However, the regulatory mechanisms contributing to the function of USF2 are largely unknown. Cyclin-dependent kinase 5 (CDK5) seems to be of importance since high levels of CDK5 were found in different cancers associated with high USF2 expression. Here, we identified USF2 as a phosphorylation target of CDK5. USF2 is phosphorylated by CDK5 at two serine residues, serine 155 and serine 222. Further, phosphorylation of USF2 at these residues was shown to stabilize the protein and to regulate cellular growth and migration. Altogether, these results delineate the importance of the CDK5-USF2 interplay in cancer cells

HIF-P4H-2 inhibition enhances intestinal fructose metabolism and induces thermogenesis protecting against NAFLD

Non-alcoholic fatty liver disease (NAFLD) parallels the global obesity epidemic with unmet therapeutic needs. We investigated whether inhibition of hypoxia-inducible factor prolyl 4-hydroxylase-2 (HIF-P4H-2), a key cellular oxygen sensor whose inhibition stabilizes HIF, would protect from NAFLD by subjecting HIF-P4H-2-deficient (Hif-p4h-2(gt/gt)) mice to a high-fat, high-fructose (HFHF) or high-fat, methionine-choline-deficient (HF-MCD) diet. On both diets, the Hif-p4h-2(gt/gt) mice gained less weight and had less white adipose tissue (WAT) and its inflammation, lower serum cholesterol levels, and lighter livers with less steatosis and lower serum ALT levels than the wild type (WT). The intake of fructose in majority of the Hif-p4h-2(gt/gt) tissues, including the liver, was 15-35% less than in the WT. We found upregulation of the key fructose transporter and metabolizing enzyme mRNAs, Slc2a2, Khka, and Khkc, and higher ketohexokinase activity in the Hif-p4h-2(gt/gt) small intestine relative to the WT, suggesting enhanced metabolism of fructose in the former. On the HF-MCD diet, the Hif-p4h-2(gt/gt) mice showed more browning of the WAT and increased thermogenesis. A pharmacological pan-HIF-P4H inhibitor protected WT mice on both diets against obesity, metabolic dysfunction, and liver damage. These data suggest that HIF-P4H-2 inhibition could be studied as a novel, comprehensive treatment strategy for NAFLD. Key messages center dot HIF-P4H-2 inhibition enhances intestinal fructose metabolism protecting the liver. center dot HIF-P4H-2 inhibition downregulates hepatic lipogenesis. center dot Induced browning of WAT and increased thermogenesis can also mediate protection. center dot HIF-P4H-2 inhibition offers a novel, comprehensive treatment strategy for NAFLD.Peer reviewe

Exploring effects of remote ischemic preconditioning in a pig model of hypothermic circulatory arrest

Objectives. During aortic and cardiac surgery, risks for mortality and morbidity are inevitable. Surgical setups involving deep hypothermic circulatory arrest (DHCA) are effective to achieve organ protection against ischemic injury. The aim of this study was to identify humoural factors mediating additive protective effects of remote ischemic preconditioning (RIPC) in a porcine model of DHCA. Design. Twenty-two pigs were randomized into the RIPC group (n=11) and the control group (n=11). The RIPC group underwent four 5-minute hind limb ischemia-reperfusion cycles prior to cardiopulmonary bypass and DHCA. All animals underwent identical surgical procedures including 60min DHCA at 18 degrees C. Blood samples were collected from vena cava and sagittal sinus at several time points. After the 8-hour follow-up period, the brain, heart, and kidney tissue samples were collected for tissue analyses. Results. Serum levels of brain damage marker S100B recovered faster in the RIPC group, after 4hours of the arrest, (pPeer reviewe

The Pro-Oncogenic Adaptor CIN85 Acts as an Inhibitory Binding Partner of Hypoxia-Inducible Factor Prolyl Hydroxylase 2

The EGFR adaptor protein, CIN85, has been shown to promote breast cancer malignancy and hypoxia-inducible factor (HIF) stability. However, the mechanisms underlying cancer promotion remain ill defined. Here we show that CIN85 is a novel binding partner of the main HIF-prolyl hydroxylase, PHD2, but not of PHD1 or PHD3. Mechanistically, the N-terminal SRC homology 3 domains of CIN85 interacted with the proline-arginine-rich region within the N-terminus of PHD2, thereby inhibiting PHD2 activity and HIF degradation. This activity is essential in vivo, as specific loss of the CIN85-PHD2 interaction in CRISPR/Cas9-edited cells affected growth and migration properties, as well as tumor growth in mice. Overall, we discovered a previously unrecognized tumor growth checkpoint that is regulated by CIN85-PHD2 and uncovered an essential survival function in tumor cells by linking growth factor adaptors with hypoxia signaling. Significance: This study provides unprecedented evidence for an oxygen-independent mechanism of PHD2 regulation that has important implications in cancer cell survival.Peer reviewe

Systematic evaluation of the association between hemoglobin levels and metabolic profile implicates beneficial effects of hypoxia

Activation of the hypoxia-inducible factor (HIF) pathway reprograms energy metabolism. Hemoglobin (Hb) is the main carrier of oxygen. Using its normal variation as a surrogate measure for hypoxia, we explored whether lower Hb levels could lead to healthier metabolic profiles in mice and humans (n = 7175) and used Mendelian randomization (MR) to evaluate potential causality (n = 173,480). The results showed evidence for lower Hb levels being associated with lower body mass index, better glucose tolerance and other metabolic profiles, lower inflammatory load, and blood pressure. Expression of the key HIF target genes SLC2A4 and Slc2a1 in skeletal muscle and adipose tissue, respectively, associated with systolic blood pressure in MR analyses and body weight, liver weight, and adiposity in mice. Last, manipulation of murine Hb levels mediated changes to key metabolic parameters. In conclusion, low-end normal Hb levels may be favorable for metabolic health involving mild chronic activation of the HIF response

Genomveränderungen–CRISPR/Cas9 als Methode der Wahl oder Qual?

Abstract The last years showed the rise of CRISPR/Cas9 to stardom. Several features such as programmability, specificity, and efficiency, make it to be a technique of choice for genome editing even in processes where basic aspects are not understood. However, scientific, technical and society driven challenges remain. To cope with these challenges, further research, technological improvements, translational studies as well as an open exchange between laboratories and the society are required

Hypoxia-inducible factors (HIFs) and phosphorylation:impact on stability, localization, and transactivity

Abstract The hypoxia-inducible factor α-subunits (HIFα) are key transcription factors in the mammalian response to oxygen deficiency. The HIFα regulation in response to hypoxia occurs primarily on the level of protein stability due to posttranslational hydroxylation and proteasomal degradation. However, HIF α-subunits also respond to various growth factors, hormones, or cytokines under normoxia indicating involvement of different kinase pathways in their regulation. Because these proteins participate in angiogenesis, glycolysis, programmed cell death, cancer, and ischemia, HIFα regulating kinases are attractive therapeutic targets. Although numerous kinases were reported to regulate HIFα indirectly, direct phosphorylation of HIFα affects HIFα stability, nuclear localization, and transactivity. Herein, we review the role of phosphorylation-dependent HIFα regulation with emphasis on protein stability, subcellular localization, and transactivation

Cyclin-Dependent Kinase 5 (CDK5)-Mediated Phosphorylation of Upstream Stimulatory Factor 2 (USF2) Contributes to Carcinogenesis

The transcription factor USF2 is supposed to have an important role in tumor development. However, the regulatory mechanisms contributing to the function of USF2 are largely unknown. Cyclin-dependent kinase 5 (CDK5) seems to be of importance since high levels of CDK5 were found in different cancers associated with high USF2 expression. Here, we identified USF2 as a phosphorylation target of CDK5. USF2 is phosphorylated by CDK5 at two serine residues, serine 155 and serine 222. Further, phosphorylation of USF2 at these residues was shown to stabilize the protein and to regulate cellular growth and migration. Altogether, these results delineate the importance of the CDK5-USF2 interplay in cancer cells