The proliferation-specific Forkhead Box m1 (Foxm1 or Foxm1b) transcription factor (previously called HFH-11B, Trident, Win, or MPP2) regulates expression of cell cycle genes essential for progression into DNA replication and mitosis. Expression of Foxm1 is found in a variety of distinct human cancers including hepatocellular carcinomas, intrahepatic cholangiocarcinomas, basal cell carcinomas, ductal breast carcinomas, and anaplastic astrocytomas and glioblastomas. In this study, we show that human Foxm1 protein is abundantly expressed in highly proliferative human nonsmall cell lung cancers (NSCLC) as well as in mouse lung tumors induced by urethane. To determine the role of Foxm1 during the development of mouse lung tumors, we used IFNinducible Mx-Cre recombinase transgene to delete mouse Foxm1 fl/fl-targeted allele before inducing lung tumors with urethane. We show that Mx-Cre Foxm1 À/À mice exhibit diminished proliferation of lung tumor cells causing a significant reduction in number and size of lung adenomas. Transient transfection experiments with A549 lung adenocarcinoma cells show that depletion of Foxm1 levels by short interfering RNA caused diminished DNA replication and mitosis and reduced anchorage-independent growth of cell colonies on soft agar. Foxm1-depleted A549 cells exhibit reduced expression of cell cycle-promoting cyclin A2 and cyclin B1 genes. These data show that Foxm1 stimulates the proliferation of tumor cells during progression of NSCLC.

Recent evidence suggests that binding of agonist to its cognate receptor initiates not only classical G protein-mediated signaling, but also ␤-arrestin-dependent signaling. One such ␤-arrestin-mediated pathway uses the ␤1-adrenergic receptor (␤1AR) to transactivate the EGFR. To determine whether ␤-adrenergic ligands that do not activate G protein signaling (i.e., ␤-blockers) can stabilize the ␤1AR in a signaling conformation, we screened 20 ␤-blockers for their ability to stimulate ␤-arrestin-mediated EGFR transactivation. Here we show that only alprenolol (Alp) and carvedilol (Car) induce ␤1AR-mediated transactivation of the EGFR and downstream ERK activation. By using mutants of the ␤1AR lacking G protein-coupled receptor kinase phosphorylation sites and siRNA directed against ␤-arrestin, we show that Alp-and Car-stimulated EGFR transactivation requires ␤1AR phosphorylation at consensus G protein-coupled receptor kinase sites and ␤-arrestin recruitment to the ligand-occupied receptor. Moreover, pharmacological inhibition of Src and EGFR blocked Alp-and Car-stimulated EGFR transactivation. Our findings demonstrate that Alp and Car are ligands that not only act as classical receptor antagonists, but can also stimulate signaling pathways in a G protein-independent, ␤-arrestin-dependent fashion.␤-adrenergic receptor ͉ G protein-coupled receptor ͉ signaling

Background/Objectives Induced pluripotent stem cells (iPS) exhibit enhanced survival and proliferation in ischemic tissues. However, the therapeutic application of iPS cells is limited by their tumorigenic potential. We hypothesized that iPS cells can transmit cytoprotective signals to cardiomyocytes via exosomes/microvesicles. Methods Exosomes/microvesicles secreted from mouse cardiac fibroblast (CF)-derived iPS cells (iPS-exo) were purified from conditioned medium and confirmed by electron micrograph, size distribution and zeta potential by particle tracking analyzer and protein expression of the exosome markers CD63 and Tsg101. Results We observed that exosomes are at low zeta potential, and easily aggregate. Temperature affects zeta potential (−14~−15mV at 23°C vs −24mV at 37°C). The uptake of iPS-exo protects H9C2 cells against H2O2-induced oxidative stress by inhibiting caspase 3/7 activation (P<0.05, n=6). Importantly, iPS-exo treatment can protect against myocardial ischemia/reperfusion (MIR) injury via intramyocardially injection into mouse ischemic myocardium before reperfusion. Furthermore, iPS-exo deliver cardioprotective miRNAs, including nanog-regulated miR-21 and HIF-1α-regulated miR-210, to H9C2 cardiomyocytes in vitro. Conclusions exosomes/microvesicles secreted by iPS cells are very effective at transmitting cytoprotective signals to cardiomyocytes in the setting of MIR. iPS-exo thus represent novel biological nanoparticles that offer the benefits of iPS cell therapy without the risk of tumorigenicity and can potentially serve as an “ off-the-shelf” therapy to rescue ischemic cardiomyocytes in conditions such as MIR.

Abstractβ-Arrestins, which were originally characterized as terminators of heterotrimeric guanine nucleotidebinding protein (G protein)-coupled receptor (GPCR) signaling, also act as important signal transducers. An emerging concept in GPCR signaling is β-arrestin-biased agonism, in which specific ligand-activated GPCR conformational states selectively signal through β-arrestins, rather than through G proteins. Here, we show that mechanical stretch induced β-arrestin-biased signaling downstream of angiotensin II type I receptors (AT1Rs) in the absence of ligand or G protein activation. Mechanical stretch triggered an AT1R-mediated conformational change in β-arrestin similar to that induced by a β-arrestin-biased ligand to selectively stimulate receptor signaling in the absence of detectable G protein activation. Hearts from mice lacking β-arrestin or AT1Rs failed to induce responses to mechanical stretch, as shown by blunted extra-cellular signal-regulated kinase and Akt activation, impaired transactivation of the epidermal growth factor receptor, and enhanced myocyte apoptosis. These data show that the heart responds to acute increases in mechanical stress by activating β-arrestin-mediated cell survival signals.

Transgenic and gene knock-out studies demonstrated that the mouse Forkhead Box m1 (Foxm1 or Foxm1b) transcription factor (previously called HFH-11B, Trident, Win, or MPP2) is essential for hepatocyte entry into mitosis during liver development, regeneration, and liver cancer. Targeted deletion of Foxm1 gene in mice produces an embryonic lethal phenotype due to severe abnormalities in the development of liver and heart. In this study, we show for the first time that Foxm1 ؊/؊ lungs exhibit severe hypertrophy of arteriolar smooth muscle cells and defects in the formation of peripheral pulmonary capillaries as evidenced by significant reduction in platelet endothelial cell adhesion molecule 1 staining of the distal lung. Consistent with these findings, significant reduction in proliferation of the embryonic Foxm1 ؊/؊ lung mesenchyme was found, yet proliferation levels were normal in the Foxm1-deficient epithelial cells. Severe abnormalities of the lung vasculature in Foxm1 ؊/؊ embryos were associated with diminished expression of the transforming growth factor ␤ receptor II, a disintegrin and metalloprotease domain 17 (ADAM-17), vascular endothelial growth factor receptors, Polo-like kinase 1, Aurora B kinase, laminin ␣4 (Lama4), and the Forkhead Box f1 transcription factor. Cotransfection studies demonstrated that Foxm1 stimulates transcription of the Lama4 promoter, and this stimulation requires the Foxm1 binding sites located between ؊1174 and ؊1145 bp of the mouse Lama4 promoter. In summary, development of mouse lungs depends on the Foxm1 transcription factor, which regulates expression of genes essential for mesenchyme proliferation, extracellular matrix remodeling, and vasculogenesis.

Abstract:Protein-coding genes account for only a small part of the human genome; in fact, the vast majority of transcripts are comprised of non-coding RNAs (ncRNAs) including long ncRNAs (lncRNAs) and small ncRNAs, microRNAs (miRs). Accumulating evidence indicates that ncRNAs could play critical roles in regulating many cellular processes which are often implicated in health and disease. For example, ncRNAs are aberrantly expressed in cancers, heart diseases, and many other diseases. LncRNAs and miRs are therefore novel and promising targets to be developed into biomarkers for diagnosis and prognosis as well as treatment options. The interaction between lncRNAs and miRs as well as its pathophysiological significance have recently been reported. Mechanistically, it is believed that lncRNAs exert "sponge-like" effects on various miRs, which subsequently inhibits miR-mediated functions. This crosstalk between two types of ncRNAs frequently contributes to the pathogenesis of the disease. In this review, we provide a summary of the recent studies highlighting the interaction between these ncRNAs and the effects of this interaction on disease pathogenesis and regulation.

These findings reveal a pivotal role for miR-150 as a regulator of cardiomyocyte survival during cardiac injury.

Cardiovascular disease is the leading cause of death in the United States, accounting for nearly one in every seven deaths. Over the last decade, various targeted therapeutics have been introduced, but there has been no corresponding improvement in patient survival. Since the mortality rate of cardiovascular disease has not been significantly decreased, efforts have been made to understand the link between heart disease and novel therapeutic targets such as non-coding RNAs. Among multiple non-coding RNAs, long non-coding RNA (lncRNA) has emerged as a novel therapeutic in cardiovascular medicine. LncRNAs are endogenous RNAs that contain over 200 nucleotides and regulate gene expression. Recent studies suggest critical roles of lncRNAs in modulating the initiation and progression of cardiovascular diseases. For example, aberrant lncRNA expression has been associated with the pathogenesis of ischemic heart failure. In this article, we present a synopsis of recent discoveries that link the roles and molecular interactions of lncRNAs to cardiovascular diseases. Moreover, we describe the prevalence of circulating lncRNAs and assess their potential utilities as biomarkers for diagnosis and prognosis of heart disease.