Reactive oxygen species (ROS) produced by NAD(P)H oxidases (Nox) play a significant role in the pathophysiology of cardiovascular diseases. Expression and activity of NAD(P)H oxidases are regulated by growth factors such as angiotensin II and platelet-derived growth factor (PDGF). We characterized the effects of the novel Nox inhibitor VAS2870 on PDGF-dependent ROS liberation and cellular events in vascular smooth muscle cells (VSMC). PDGF-BB increased NAD(P)H oxidase activity (lucigenin-enhanced chemiluminescence) and intracellular ROS levels (detected by confocal laserscanning microscopy using 2,7-DCF) to 229+/-9% and 362+/-54% at 1 and 2 h, respectively. Preincubation with VAS2870 (10 and 20 microM) completely abolished PDGF-mediated NAD(P)H oxidase activation and ROS production. Since ROS are involved in various growth factor-induced cellular functions, the influence of VAS2870 on PDGF-induced DNA synthesis and chemotaxis was determined. PDGF promoted a 4.2+/-0.2-fold increase of VSMC migration (modified Boyden chamber, p<0.01) and increased DNA synthesis by maximally 3.2+/-0.4-fold (BrdU incorporation, p<0.01) in a concentration-dependent manner. Preincubation with VAS2870 (0.1-20 microM) did not affect PDGF-induced cell cycle progression. However, it abolished PDGF-dependent chemotaxis of VSMC in a concentration-dependent manner (100% inhibition at 10 microM). These findings were related to PDGF-dependent signaling events. Western blot analyses using phospho-specific antibodies revealed that the downstream signaling molecules Akt, Erk, and Src were activated by PDGF. However, VAS2870 blocked PDGF-dependent activation of Src, but not of Akt and Erk, in a concentration-dependent manner. VAS2870 effectively suppresses growth factor-mediated ROS liberation in VSMC. Furthermore, it completely inhibits PDGF-dependent VSMC migration, whereas it does not affect DNA synthesis. These divergent effects reflect the critical role of Src activity, which-in contrast to Akt and Erk-appears to be redox-sensitive and is absolutely required for PDGF-induced chemotaxis, but not cell cycle progression.

Background: Reduced exercise capacity in patients with heart failure (HF) could be partially explained by skeletal muscle dysfunction. We compared skeletal muscle function, structure, and metabolism among clinically stable outpatients with HF with preserved ejection fraction, HF with reduced ejection fraction, and healthy controls (HC). Furthermore, the molecular, metabolic, and clinical profile of patients with reduced muscle endurance was described. Methods: Fifty-five participants were recruited prospectively at the University Hospital Jena (17 HF with preserved ejection fraction, 18 HF with reduced ejection fraction, and 20 HC). All participants underwent echocardiography, cardiopulmonary exercise testing, 6-minute walking test, isokinetic muscle function, and skeletal muscle biopsies. Expression levels of fatty acid oxidation, glucose metabolism, atrophy genes, and proteins as well as inflammatory biomarkers were assessed. Mitochondria were evaluated using electron microscopy. Results: Patients with HF with preserved ejection fraction showed compared with HF with reduced ejection fraction and HC reduced muscle strength (eccentric extension: 13.3±5.0 versus 18.0±5.9 versus 17.9±5.1 Nm/kg, P =0.04), elevated levels of MSTN-2 (myostatin-2), FBXO-32 (F-box only protein 32 [Atrogin1]) gene and protein, and smaller mitochondrial size ( P <0.05). Mitochondrial function and fatty acid and glucose metabolism were impaired in HF-patients compared with HC ( P <0.05). In a multiple regression analysis, GDF-15 (growth and differentiation factor 15), CPT1B (carnitine palmitoyltransferase IB)-protein and oral anticoagulation were independent factors for predicting reduced muscle endurance after adjusting for age (log10 GDF-15 [pg/mL] [B, −54.3 (95% CI, −106 to −2.00), P =0.043], log10 CPT1B per fold increase [B, 49.3 (95% CI, 1.90–96.77), P =0.042]; oral anticoagulation present [B, 44.8 (95% CI, 27.90–61.78), P <0.001]). Conclusions: Patients with HF with preserved ejection fraction have worse muscle function and predominant muscle atrophy compared with those with HF with reduced ejection fraction and HC. Inflammatory biomarkers, fatty acid oxidation, and oral anticoagulation were independent factors for predicting reduced muscle endurance.

Pre–B cells undergo apoptosis unless they are rescued by pre–B cell receptor–dependent survival signals. We previously showed that the BCR-ABL1 kinase that is expressed in pre–B lymphoblastic leukemia bypasses selection for pre–B cell receptor–dependent survival signals. Investigating possible interference of BCR-ABL1 with pre–B cell receptor signaling, we found that neither SYK nor SLP65 can be phosphorylated in response to pre–B cell receptor engagement. Instead, Bruton9s tyrosine kinase (BTK) is constitutively phosphorylated by BCR-ABL1. Activated BTK is essential for survival signals that otherwise would arise from the pre–B cell receptor, including activation of PLCγ1, autonomous Ca²⁺ signaling, STAT5-phosphorylation, and up-regulation of BCLX_L. Inhibition of BTK activity specifically induces apoptosis in BCR-ABL1⁺ leukemia cells to a similar extent as inhibition of BCR-ABL1 kinase activity itself. However, BCR-ABL1 cannot directly bind to full-length BTK. Instead, BCR-ABL1 induces the expression of a truncated splice variant of BTK that acts as a linker between the two kinases. As opposed to full-length BTK, truncated BTK lacks kinase activity yet can bind to BCR-ABL1 through its SRC-homology domain 3. Acting as a linker, truncated BTK enables BCR-ABL1–dependent activation of full-length BTK, which initiates downstream survival signals and mimics a constitutively active pre–B cell receptor.

VEGF-, phosphoinositide 3-kinase (PI3K)- and protein kinase C (PKC)-regulated signaling in cardiac and vascular differentiation was investigated in mouse ES cells and in ES cell-derived Flk-1⁺ cardiovascular progenitor cells. Inhibition of PI3K by wortmannin and LY294002, disruption of PI3K catalytic subunits p110α and p110δ using short hairpin RNA (shRNA), or inhibition of p110α with compound 15e and of p110δ with IC-87114 impaired cardiac and vascular differentiation. By contrast, TGX-221, an inhibitor of p110β, and shRNA knockdown of p110β were without significant effects. Antagonists of the PKC family, i.e. bisindolylmaleimide-1 (BIM-1), GÖ 6976 (targeting PKCα/βII) and rottlerin (targeting PKCδ) abolished vasculogenesis, but not cardiomyogenesis. Inhibition of Akt blunted cardiac as well as vascular differentiation. VEGF induced phosphorylation of PKCα/βII and PKCδ but not PKCζ. This was abolished by PI3K inhibitors and the VEGFR-2 antagonist SU5614. Furthermore, phosphorylation of Akt and phosphoinositide-dependent kinase-1 (PDK1) was blunted upon inhibition of PI3K, but not upon inhibition of PKC by BIM-1, suggesting that activation of Akt and PDK1 by VEGF required PI3K but not PKC. In summary, we demonstrate that PI3K catalytic subunits p110α and p110δ are central to cardiovasculogenesis of ES cells. Akt downstream of PI3K is involved in both cardiomyogenesis and vasculogenesis, whereas PKC is involved only in vasculogenesis.