Potential Role of Protein Kinase B in Insulin-induced Glucose Transport, Glycogen Synthesis, and Protein Synthesis

Various biological responses stimulated by insulin have been thought to be regulated by phosphatidylinosi-tol 3-kinase, including glucose transport, glycogen syn-thesis, and protein synthesis. However, the molecular link between phosphatidylinositol 3-kinase and these biological responses has been poorly understood. Re-cently, it has been shown that protein kinase B (PKB/c-Akt/ Rac) lies immediately downstream from phosphati-dylinositol 3-kinase. Here, we show that expression of a constitutively active form of PKB induced glucose up-take, glycogen synthesis, and protein synthesis in L6 myotubes downstream of phosphatidylinositol 3-kinase and independent of Ras and mitogen-activated protein kinase activation. Introduction of constitutively active PKB induced glucose uptake and protein synthesis but not glycogen synthesis in 3T3L-1 adipocytes, which lack expression of glycogen synthase kinase 3 different from L6 myotubes. Furthermore, we show that deactivation of glycogen synthase kinase 3 and activation of rapamy-cin- sensitive serine/threonine kinase by PKB in L6 myo-tubes might be involved in the enhancement of glycogen synthesis and protein synthesis, respectively. These re-sults suggest that PKB acts as a key enzyme linking phosphatidylinositol 3-kinase activation to multiple bi-ological functions of insulin through regulation of downstream kinases in skeletal muscle, a major target tissue of insulin

Lower Cardiorenal Risk with Sodium-Glucose Cotransporter-2 Inhibitors versus Dipeptidyl Peptidase-4 Inhibitors in Type 2 Diabetes Patients without Cardiovascular and Renal Diseases: A large multinational observational study

BACKGROUND: We compared new use of sodium-glucose cotransporter-2 inhibitor (SGLT2i) vs. dipeptidyl peptidase-4 inhibitor (DPP4i) and the risk of cardiorenal disease, heart failure (HF) or chronic kidney disease (CKD), in type 2 diabetes patients without history of prevalent cardiovascular and renal disease, defined as cardiovascular- and renal disease (CVRD) free, managed in routine clinical practice. METHODS: In this observational cohort study, patients were identified in electronic health records in England, Germany, Japan, Norway, South Korea and Sweden, from 2012 to 2018. A total of 1 006 577 CVRD-free new users of SGLT2i or DPP4i were propensity score matched 1:1. Unadjusted Cox regression was used to estimate hazard ratios (HRs) for outcomes; cardiorenal disease, HF, CKD, stroke, myocardial infarction (MI) cardiovascular- and all-cause death. RESULTS: Baseline characteristics were well-balanced between the treatment groups (n = 105 130 in each group) with total follow up of 187 955 patient years. Patients were mean 56 years, 43% women and indexed between 2013 and 2018. The most commonly used agents were dapagliflozin (91.7% of exposure time) and sitagliptin/linagliptin (55.0%), in the SGLT2i and DPP4i groups respectively. SGLT2i was associated with lower risk of cardiorenal disease, HF, CKD, all-cause- and cardiovascular death; HR (95% CI) 0.56 (0.42-0.74), 0.71 (0.59-0.86), 0.44 (0.28-0.69), 0.67 (0.59-0.77) and 0.61 (0.44-0.85) respectively. No differences were observed for stroke (0.87 [0.69-1.09]) and MI (0.94 [0.80-1.11]). CONCLUSION: In this multinational observational study, SGLT2i was associated with lower risk of heart failure and chronic kidney disease versus DPP4i in T2D patients otherwise free from both cardiovascular and renal disease

Long-Term Survival of Resected Advanced Gastric Cancer with Hepatic and Pancreatic Invasion

A 64-year-old man was transferred to our division with a suspicion of gastric cancer. Computed tomography showed widespread irregular thickening of the stomach walls close to the liver and pancreas. Gastrointestinal fiberscopy showed a type 5 tumor in the upper to lower stomach, histologically diagnosed as tubular adenocarcinoma. Gastric cancer with hepatic and pancreatic invasion was diagnosed. Distant metastasis was not proven and complete resection was planned. At laparotomy, the tumor showed general expanding growth and invasion through the lateral segment of the liver and pancreas. Total gastrectomy and combined resection of the distal pancreas, spleen and left segment of the liver were performed. Hepatic and pancreatic invasion and lymph node metastasis were microscopically proven. Pancreatic fistula occurred postoperatively. On postoperative days 40, he was discharged. He received two cycles of adjuvant tegafur/gimeracil/oteracil chemotherapy. He has had no sign of recurrence for 7 years and 8 months

Bradykinin-induced microglial migration mediated by B1-bradykinin receptors depends on Ca2+ influx via reverse-mode activity of the Na+/Ca2+ exchanger

Bradykinin (BK) is produced and acts at the site of injury and inflammation. In the CNS, migration of microglia toward the lesion site plays an important role pathologically. In the present study, we investigated the effect of BK on microglial migration. Increased motility of cultured microglia was mimicked by B1 receptor agonists and markedly inhibited by a B1 antagonist but not by a B2 receptor antagonist. BK induced chemotaxis in microglia isolated from wild-type and B2-knock-out mice but not from B1-knock-out mice. BK-induced motility was not blocked by pertussis toxin but was blocked by chelating intracellular Ca2+ or by low extracellular Ca2+, implying that Ca2+ influx is prerequisite. Blocking the reverse mode of Na+/Ca2+ exchanger (NCX) completely inhibited BK-induced migration. The involvement of NCX was further confirmed by using NCX+/- mice; B1-agonist-induced motility and chemotaxis was decreased compared with that in NCX+/+ mice. Activation of NCX seemed to be dependent on protein kinase C and phosphoinositide 3-kinase, and resultant activation of intermediate-conductance (IK-type) Ca2+-dependent K+ currents (I(K(Ca))) was activated. Despite these effects, BK did not activate microglia, as judged from OX6 staining. Using in vivo lesion models and pharmacological injection to the brain, it was shown that microglial accumulation around the lesion was also dependent on B1 receptors and I(K(Ca)). These observations support the view that BK functions as a chemoattractant by using the distinct signal pathways in the brain and, thus, attracts microglia to the lesion site in vivo

Biological predictive factors in rectal cancer treated with preoperative radiotherapy or radiochemotherapy

We analysed the expression of microsatellite instability, p53, p21, vascular endothelial growth factor and thymidylate synthase (TS) in pretreatment biopsy specimens from 57 locally advanced rectal cancers. The aim of the study was to correlate the expression of these markers with pathological response. Nineteen patients were treated with preoperative concomitant radiotherapy (RT) and fluorouracil/oxaliplatin-based chemotherapy (RCT), while 38 had RT alone. Pathological complete remission (pCR) and microfoci residual tumour (micR) occurred more frequently in patients treated with RCT (P=0.002) and in N0 tumours (P=0.004). Among patients treated with RCT, high TS levels were associated with a higher response rate (pCR+micR; P=0.015). No such correlation was found in the RT group. The other molecular factors were of no predictive value. Multivariate analysis confirmed a significant interaction between nodal status and the probability of achieving a pathological response (P=0.023) and between TS expression and treatment, indicating that a high TS level is predictive of a higher pathological response in the RCT subset (P=0.007). This study shows that lymph node status is the most important predictive factor of tumour response to preoperative treatment. Thymidylate synthase expression assessed immunohistochemically from pretreatment tumour biopsies may be a useful predictive marker of rectal tumour response to preoperative RCT

Cardiac Transcription Factor Nkx2.5 Is Downregulated under Excessive O-GlcNAcylation Condition

Post-translational modification of proteins with O-linked N-acetylglucosamine (O-GlcNAc) is linked the development of diabetic cardiomyopathy. We investigated whether Nkx2.5 protein, a cardiac transcription factor, is regulated by O-GlcNAc. Recombinant Nkx2.5 (myc-Nkx2.5) proteins were reduced by treatment with the O-GlcNAcase inhibitors STZ and O-(2-acetamido-2-deoxy-D-glucopyroanosylidene)-amino-N-phenylcarbamate; PUGNAC) as well as the overexpression of recombinant O-GlcNAc transferase (OGT-flag). Co-immunoprecipitation analysis revealed that myc-Nkx2.5 and OGT-flag proteins interacted and myc-Nkx2.5 proteins were modified by O-GlcNAc. In addition, Nkx2.5 proteins were reduced in the heart tissue of streptozotocin (STZ)-induced diabetic mice and O-GlcNAc modification of Nkx2.5 protein increased in diabetic heart tissue compared with non-diabetic heart. Thus, excessive O-GlcNAcylation causes downregulation of Nkx2.5, which may be an underlying contributing factor for the development of diabetic cardiomyopathy

Removal of cell surface heparan sulfate increases TACE activity and cleavage of ErbB4 receptor

<p>Abstract</p> <p>Background</p> <p>Nuclear localization of proteolytically formed intracellular fragment of ErbB4 receptor tyrosine kinase has been shown to promote cell survival, and nuclear localization of ErbB4 receptor has been described in human breast cancer. Tumor necrosis factor alpha converting enzyme (TACE) initiates the proteolytic cascade leading to ErbB4 intracellular domain formation. Interactions between matrix metalloproteases and heparan sulfate have been described, but the effect of cell surface heparan sulfate on TACE activity has not been previously described.</p> <p>Results</p> <p>As indicated by immunodetection of increased ErbB4 intracellular domain formation and direct enzyme activity analysis, TACE activity was substantially amplified by enzymatic removal of cell surface heparan sulfate but not chondroitin sulfate.</p> <p>Conclusion</p> <p>In this communication, we suggest a novel role for cell surface heparan sulfate. Removal of cell surface heparan sulfate led to increased formation of ErbB4 intracellular domain. As ErbB4 intracellular domain has previously been shown to promote cell survival this finding may indicate a novel mechanism how HS degradation active in tumor tissue may favor cell survival.</p

Elevated miR-499 Levels Blunt the Cardiac Stress Response

The heart responds to myriad stresses by well-described transcriptional responses that involve long-term changes in gene expression as well as more immediate, transient adaptations. MicroRNAs quantitatively regulate mRNAs and thus may affect the cardiac transcriptional output and cardiac function. Here we investigate miR-499, a microRNA embedded within a ventricular-specific myosin heavy chain gene, which is expressed in heart and skeletal muscle.We assessed miR-499 expression in human tissue to confirm its potential relevance to human cardiac gene regulation. Using a transgenic mouse model, we found that elevated miR-499 levels caused cellular hypertrophy and cardiac dysfunction in a dose-dependent manner. Global gene expression profiling revealed altered levels of the immediate early stress response genes (Egr1, Egr2 and Fos), ß-myosin heavy chain (Myh7), and skeletal muscle actin (Acta1). We verified the effect of miR-499 on the immediate early response genes by miR-499 gain- and loss-of-function in vitro. Consistent with a role for miR-499 in blunting the response to cardiac stress, asymptomatic miR-499-expressing mice had an impaired response to pressure overload and accentuated cardiac dysfunction.Elevated miR-499 levels affect cardiac gene expression and predispose to cardiac stress-induced dysfunction. miR-499 may titrate the cardiac response to stress in part by regulating the immediate early gene response

Nkx2.7 and Nkx2.5 Function Redundantly and Are Required for Cardiac Morphogenesis of Zebrafish Embryos

Nkx2.7 is the tinman-related gene, as well as orthologs of Nkx2.5 and Nkx-2.3. Nkx2.7 and Nkx2.5 express in zebrafish heart fields of lateral plate mesoderm. The temporal and spatial expression patterns of Nkx2.7 are similar to those of Nkx2.5, but their functions during cardiogenesis remain unclear.Here, Nkx2.7 is demonstrated to compensate for Nkx2.5 loss of function and play a predominant role in the lateral development of the heart, including normal cardiac looping and chamber formation. Knocking down Nkx2.5 showed that heart development was normal from 24 to 72 hpf. However, when knocking down either Nkx2.7 or Nkx2.5 together with Nkx2.7, it appeared that the heart failed to undergo looping and showed defective chambers, although embryos developed normally before the early heart tube stage. Decreased ventricular myocardium proliferation and defective myocardial differentiation appeared to result from late-stage up-regulation of bmp4, versican, tbx5 and tbx20, which were all expressed normally in hearts at an early stage. We also found that tbx5 and tbx20 were modulated by Nkx2.7 through the heart maturation stage because an inducible overexpression of Nkx2.7 in the heart caused down-regulation of tbx5 and tbx20. Although heart defects were induced by overexpression of an injection of 150-pg Nkx2.5 or 5-pg Nkx2.7 mRNA, either Nkx2.5 or Nkx2.7 mRNA rescued the defects induced by Nkx2.7-morpholino(MO) and Nkx2.5-MO with Nkx2.7-MO.Therefore, we conclude that redundant activities of Nkx2.5 and Nkx2.7 are required for cardiac morphogenesis, but that Nkx2.7 plays a more critical function, specifically indicated by the gain-of-function and loss-of- function experiments where Nkx2.7 is observed to regulate the expressions of tbx5 and tbx20 through the maturation stage

In Vivo Tracking of Transplanted Mononuclear Cells Using Manganese-Enhanced Magnetic Resonance Imaging (MEMRI)

BACKGROUND: Transplantation of mononuclear cells (MNCs) has previously been tested as a method to induce therapeutic angiogenesis to treat limb ischemia in clinical trials. Non-invasive high resolution imaging is required to track the cells and evaluate clinical relevance after cell transplantation. The hypothesis that MRI can provide in vivo detection and long-term observation of MNCs labeled with manganese contrast-agent was investigated in ischemic rat legs. METHODS AND FINDINGS: The Mn-labeled MNCs were evaluated using 7-tesla high-field magnetic resonance imaging (MRI). Intramuscular transplanted Mn-labeled MNCs were visualized with MRI for at least 7 and up to 21 days after transplantation in the ischemic leg. The distribution of Mn-labeled MNCs was similar to that of ¹¹¹In-labeled MNCs measured with single-photon emission computed tomography (SPECT) and DiI-dyed MNCs with fluorescence microscopy. In addition, at 1-2 days after transplantation the volume of the site injected with intact Mn-labeled MNCs was significantly larger than that injected with dead MNCs, although the dead Mn-labeled MNCs were also found for approximately 2 weeks in the ischemic legs. The area covered by CD31-positive cells (as a marker of capillary endothelial cells) in the intact Mn-MNCs implanted site at 43 days was significantly larger than that at a site implanted with dead Mn-MNCs. CONCLUSIONS: The present Mn-enhanced MRI method enabled visualization of the transplanted area with a 150-175 µm in-plane spatial resolution and allowed the migration of labeled-MNCs to be observed for long periods in the same subject. After further optimization, MRI-based Mn-enhanced cell-tracking could be a useful technique for evaluation of cell therapy both in research and clinical applications