Insulin resistance is associated with aging in mice and humans. We have previously shown that administration of recombinant GDF11 (rGDF11) to aged mice alters aging phenotypes in the brain, skeletal muscle, and heart. While the closely related protein GDF8 has a role in metabolism, limited data are available on the potential metabolic effects of GDF11 or GDF8 in aging. To determine the metabolic effects of these two ligands, we administered rGDF11 or rGDF8 protein to young or aged mice fed a standard chow diet, short-term high-fat diet (HFD), or long-term HFD. Under nearly all of these diet conditions, administration of exogenous rGDF11 reduced body weight by 3–17% and significantly improved glucose tolerance in aged mice fed a chow (~30% vs. saline) or HF (~50% vs. saline) diet and young mice fed a HFD (~30%). On the other hand, exogenous rGDF8 showed signifcantly lesser effect or no effect at all on glucose tolerance compared to rGDF11, consistent with data demonstrating that GFD11 is a more potent signaling ligand than GDF8. Collectively, our results show that administration of exogenous rGDF11, but not rGDF8, can reduce diet-induced weight gain and improve metabolic homeostasis.

Growth differentiation factor 11 (GDF11) and myostatin (or GDF8) are closely related members of the transforming growth factor β superfamily and are often perceived to serve similar or overlapping roles. Yet, despite commonalities in protein sequence, receptor utilization and signaling, accumulating evidence suggests that these 2 ligands can have distinct functions in many situations. GDF11 is essential for mammalian development and has been suggested to regulate aging of multiple tissues, whereas myostatin is a well-described negative regulator of postnatal skeletal and cardiac muscle mass and modulates metabolic processes. In this review, we discuss the biochemical regulation of GDF11 and myostatin and their functions in the heart, skeletal muscle, and brain. We also highlight recent clinical findings with respect to a potential role for GDF11 and/or myostatin in humans with heart disease. Finally, we address key outstanding questions related to GDF11 and myostatin dynamics and signaling during development, growth, and aging.

Nature Communications 7: Article number: 13542 (2016); Published: 6 December 2016; Updated: 5 January 2017 The original version of this Article contained an error in the spelling of the author Tommaso Poggioli, which was incorrectly given as Tommaso Pogglioli. This has now been corrected in both thePDF and HTML versions of the Article.

Circulation Research is available at http://circres.ahajournals.org DOI: 10.1161/CIRCRESAHA.116.308391 Abstract: Growth differentiation factor 11 (GDF11) and myostatin (or GDF8) are closely related members of the transforming growth factor β superfamily and are often perceived to serve similar or overlapping roles. Yet, despite commonalities in protein sequence, receptor utilization and signaling, accumulating evidence suggests that these 2 ligands can have distinct functions in many situations. GDF11 is essential for mammalian development and has been suggested to regulate aging of multiple tissues, whereas myostatin is a well-described negative regulator of postnatal skeletal and cardiac muscle mass and modulates metabolic processes. In this review, we discuss the biochemical regulation of GDF11 and myostatin and their functions in the heart, skeletal muscle, and brain. We also highlight recent clinical findings with respect to a potential role for GDF11 and/or myostatin in humans with heart disease. Finally, we address key outstanding questions related to GDF11 and myostatin dynamics and signaling during development, growth, and aging. (Circ Res. 2016;118:1125-1142. DOI: 10.1161/CIRCRESAHA.116.308391.)

Growth differentiation factor 11 (GDF11) and myostatin (or GDF8) are closely related members of the transforming growth factor β superfamily and are often perceived to serve similar or overlapping roles. Yet, despite commonalities in protein sequence, receptor utilization and signaling, accumulating evidence suggests that these 2 ligands can have distinct functions in many situations. GDF11 is essential for mammalian development and has been suggested to regulate aging of multiple tissues, whereas myostatin is a well-described negative regulator of postnatal skeletal and cardiac muscle mass and modulates metabolic processes. In this review, we discuss the biochemical regulation of GDF11 and myostatin and their functions in the heart, skeletal muscle, and brain. We also highlight recent clinical findings with respect to a potential role for GDF11 and/or myostatin in humans with heart disease. Finally, we address key outstanding questions related to GDF11 and myostatin dynamics and signaling during development, growth, and aging.(Circ Res. 2016; 118: 1125-1142. DOI: 10.1161/CIRCRESAHA. 116.308391.)

Electrophysiological studies of excitable organs usually focus on action potential (AP)-generating cells, whereas nonexcitable cells are generally considered as barriers to electrical conduction. Whether nonexcitable cells may modulate excitable cell function or even contribute to AP conduction via direct electrotonic coupling to AP-generating cells is unresolved in the heart: such coupling is present in vitro, but conclusive evidence in situ is lacking. We used genetically encoded voltage-sensitive fluorescent protein 2.3 (VSFP2.3) to monitor transmembrane potential in either myocytes or nonmyocytes of murine hearts. We confirm that VSFP2.3 allows measurement of cell type-specific electrical activity. We show that VSFP2.3, expressed solely in nonmyocytes, can report cardiomyocyte AP-like signals at the border of healed cryoinjuries. Using EM-based tomographic reconstruction, we further discovered tunneling nanotube connections between myocytes and nonmyocytes in cardiac scar border tissue. Our results provide direct electrophysiological evidence of heterocellular electrotonic coupling in native myocardium and identify tunneling nanotubes as a possible substrate for electrical cell coupling that may be in addition to previously discovered connexins at sites of myocyte-nonmyocyte contact in the heart. These findings call for reevaluation of cardiac nonmyocyte roles in electrical connectivity of the heterocellular heart.

RATIONALEGrowth differentiation factor 11 (GDF11) and GDF8 are members of the transforming growth factor-β superfamily sharing 89% protein sequence homology. We have previously shown that circulating GDF11 levels decrease with age in mice. However, a recent study by Egerman et al reported that GDF11/8 levels increase with age in mouse serum.OBJECTIVEHere, we clarify the direction of change of circulating GDF11/8 levels with age and investigate the effects of GDF11 administration on the murine heart.METHODS AND RESULTSWe validated our previous finding that circulating levels of GDF11/8 decline with age in mice, rats, horses, and sheep. Furthermore, we showed by Western analysis that the apparent age-dependent increase in GDF11 levels, as reported by Egerman et al, is attributable to cross-reactivity of the anti-GDF11 antibody with immunoglobulin, which is known to increase with age. GDF11 administration in mice rapidly activated SMAD2 and SMAD3 signaling in myocardium in vivo and decreased cardiac mass in both young (2-month-old) and old (22-month-old) mice in a dose-dependent manner after only 9 days.CONCLUSIONSOur study confirms an age-dependent decline in serum GDF11/8 levels in multiple mammalian species and that exogenous GDF11 rapidly activates SMAD signaling and reduces cardiomyocyte size. Unraveling the molecular basis for the age-dependent decline in GDF11/8 could yield insight into age-dependent cardiac pathologies.

Previous studies showed that cell delivery promotes cardiac function amelioration by release of cytokines and factors that increase cardiac tissue revascularization and cell survival. In addition, further observations revealed that specific stem cells, such as cardiac stem cells, mesenchymal stem cells and cardiospheres have the ability to integrate within the surrounding myocardium by differentiating into cardiomyocytes, smooth muscle cells and endothelial cells. Here, we present the materials and methods to reliably deliver noncontractile cells into the left ventricular wall of immunodepleted mice. The salient steps of this microsurgical procedure involve anesthesia and analgesia injection, intratracheal intubation, incision to open the chest and expose the heart and delivery of cells by a sterile 30-gauge needle and a precision microliter syringe. Tissue processing consisting of heart harvesting, embedding, sectioning and histological staining showed that intramyocardial cell injection produced a small damage in the epicardial area, as well as in the ventricular wall. Noncontractile cells were retained into the myocardial wall of immunocompromised mice and were surrounded by a layer of fibrotic tissue, likely to protect from cardiac pressure and mechanical load.

Introduction: Heterocellular electrotonic coupling of cardiac myocytes and non-myocytes is common in vitro , yet its presence, extent and role in vivo are debated. Optogenetic tools provide a unique means for cell-specific assessment of electrophysiology. Here, we utilise the genetically-encoded voltage-sensitive fluorescent protein 2.3 (VSFP2.3) to monitor transmembrane potential (Vm) in myocytes or fibroblasts of isolated murine hearts. Methods: Transgenic mice expressing VSFP2.3 under the control of either alpha-myosin heavy chain promoter (αMHC; myocytes) or Wilm’s tumor promoter (WT1; fibroblasts) were generated by Cre-LoxP recombination. Infarcts (left ventricular freewall) were caused by cryoablation, followed by 8 weeks recovery. Vm was measured in mechanically-uncoupled (10μM blebbistatin) Langendorff-perfused hearts by simultaneous collection of VSFP2.3 donor (mCerulean; CFP) and acceptor (citrine; YFP), or of VSFP2.3 YFP and voltage-sensitive dye (di-4-ANBDQPQ) signals, using an EMCCD camera (128х128 pixels, 511Hz) on an upright microscope (10х water-immersion lens). Cell-specificity of transgene expression was confirmed post hoc by immunohistochemistry (myomesin for myocytes, vimentin for fibroblasts) using confocal microscopy. Results: Cardiomyocyte action potentials (AP) were successfully measured in αMHC-VSFP2.3 mice by CFP/YFP ratiometry. After adding di-4-ANBDQPQ to these hearts, signal comparison reconfirmed slower AP upstroke and repolarisation kinetics of VSFP2.3 (Fig.A). Strikingly, myocyte-like AP were also recorded, in (dye-free) WT1-VSFP2.3 hearts, from fibroblasts at the infarct border zone (Fig.B). Conclusions: Results demonstrate the utility of VSFP2.3 for cell-specific cardiac electrophysiology research. In addition, observation of AP-like potentials in non-excitable cells confirms in vivo electrotonic coupling of cardiac myocytes and non-myocytes in healed murine infarct border tissue. ![][1] [1]: /embed/graphic-1.gif

Tamoxifen-inducible Cre-mediated manipulation of animal genomes has achieved wide acceptance over the last decade, with numerous important studies heavily relying on this technique. Recently, a number of groups have reported transient complications of using this protocol in the heart. In the present study we observed a previously unreported focal fibrosis and depressed left-ventricular function in tamoxifen-treated αMHC-MerCreMer-positive animals in a Tβ4shRNAflox × αMHC-MerCreMer cross at 6-7 weeks following standard tamoxifen treatment, regardless of the presence of the floxed transgene. The phenotype was reproduced by treating mice from the original αMHC-MerCreMer strain with tamoxifen. In the acute phase after tamoxifen treatment, cell infiltration into the myocardium was accompanied by increased expression of pro-inflammatory cytokines (IL-1β, IL-6, TNFα, IFNγ, Ccl2) and markers of hypertrophy (ANF, BNP, Col3a1). These observations highlight the requirement for including tamoxifen-treated MerCreMer littermate controls to avert misinterpretation of conditional mutant phenotypes. A survey of the field as well as the protocols presented here suggests that controlling the parameters of tamoxifen delivery is important in avoiding the chronic MerCreMer-mediated cardiac phenotype reported here.

Serum and glucocorticoid inducible kinase 1 (SGK1) plays a pivotal role in early angiogenesis during embryonic development. In this study, we sought to define the SGK1 downstream signalling pathways in the adult heart and to elucidate their role in cardiac neo-angiogenesis and wound healing after myocardial ischemia. To this end, we employed a viable SGK1 knockout mouse model generated in a 129/SvJ background. Ablation of SGK1 in these mice caused a significant decrease in phosphorylation of SGK1 target protein NDRG1, which correlated with alterations in NF-κB signalling and expression of its downstream target protein, VEGF-A. Disruption of these signalling pathways was accompanied by smaller heart and body size. Moreover, the lack of SGK1 led to defective endothelial cell (ECs) migration and tube formation in vitro, and increased scarring with decreased angiogenesis in vivo after myocardial infarct. This study underscores the importance of SGK1 signalling in cardiac neo-angiogenesis and wound healing after an ischemic insult in vivo.

Parkinson's disease (PD) is one of the most common neurodegenerative disorders whose etiology is multifactorial including both hereditary and environmental factors. Currently, pathogenic mutations in at least five genes have been implicated in familial PD generally accounting for less than 10 % of all PD cases in most populations. It has been suggested that polymorphisms in other genes such as those encoding enzymes involved in oxidative metabolism and detoxification could be involved in predisposition to PD since oxidative stress in dopaminergic neurons is thought to be of central importance in the pathogenesis of the disease. The aim of our work was to study the association of genetic polymorphisms in genes involved in oxidative metabolism and detoxification mechanism, namely GSTM1, GSTT1, GSTP1, and those involved in DNA damage repair, OGG1 and XRCC1, in an Italian cohort of sporadic PD patients. We did not detect any association between GSTT1 and GTTM1 null polymorphisms and PD, whereas the 104GSTP1 polymorphism was associated with PD in male patients but not in females. Furthermore, we detected a protective effect of wild type genotype of XRCC1 in women.

Background: Cardiovascular remodelling after myocardial infarction leads to cardiac function impairment due to left ventricle dilation, distortion of ventricular shape and mural hypertrophy. Therefore, ventricular remodelling can be considered a primary target for therapeutic treatment. We previously documented that cardiac-specific overexpression of the propeptide insulin-like growth factor 1Ea (IGF-1Ea) contributed to beneficial cardiac repair after ischemic damage by employing anti-inflammatory and antioxidant molecules, decreasing scar formation and enhancing cardiac function. The above benefits suggest that IGF-1 may be therapeutically important in cardiovascular diseases. However, the precise mechanisms in clinical-like procedures are not yet elucidated and IGF-1 family of growth factors are therefore poorly recognized pharmacologically. We hypothesized that IGF-1Ea-mediated delivery by allogeneic cell therapy could favour long-term decrease of left ventricle remodelling after myocardial infarction. Methods and Results: To support long-term expression of the propeptide IGF-1Ea, we infected pluripotent P19Cl6-MLC2vGFP cells with a lentivirus carrying the Igf-1Ea gene under the CMV promoter. These cells, which efficiently differentiate into cardiomyocytes activating a GFP transgene, were injected into the ventricular wall of C57BL/6 mice (n=11) after myocardial infarct induction in an allogeneic transplantation model. Mice injected with cells not expressing the transgene were used as control. IGF-1Ea delivery improved long-term local systolic function measured as percentage of anterior wall motion (60% vs 20%, p<0.01) and correlated with increased cell retention, decreased hypertrophic response through downregulation of the angiotensin signalling and activated pro-angiogenic program compared to mice transplanted with cells not expressing the transgene. Conclusions: this study indicates that allogeneic cell-mediated IGF-1Ea delivery is a good candidate in pharmacological and clinical studies to contribute to long-term beneficial remodelling of the heart in response to myocardial infarct.

The mammalian heart has a limited capability of physiological cardiomyocyte turnover during adult life to substitute aged or damaged cells. While this regenerative mechanism has been preserved throughout mammalian evolution, it is insufficient to counteract more extensive tissue loss, which results in scar formation at the expense of cardiac function. In recent years, regenerative medicine studies investigated the efficiency of stem cells to regenerate the heart via celltherapy, while pre-conditioning the hostile environment of the injured cardiac tissue by administration of cell survival and anti-inflammatory molecules. Indeed, post-infarct combinatorial therapies using cells and factors (including growth factors, chemokines and cytokines) increased cardiac function recovery and tissue regeneration. In addition, the use of factors and molecules capable of inducing adult cardiomyocytes to re-enter cell cycle was explored to overcome the intrinsic cell cycle block or the loss of mitogenic stimuli in the postnatal heart. Nevertheless, the field has yet to solve significant obstacles including the incomplete differentiation of stem cells (with the associated danger of tumor formation) and the paucity of tissue-specific stem cells (specifically in adult/aged organs). In this review, we describe the advances in cardiac regenerative studies and the patented designs of new tools to heal an injured heart. Keywords: Cardiac regeneration, cell therapy, growth factors, BONE MARROW STEM CELLS, c-KIT CARDIAC STEM CELLS, ISLET1 CARDIOVASCULAR PROGENITORS, PLURIPOTENT STEM CELLS, MAMMALIAN HEART, CARDIAC ENDOGENOUS Repair, GROWTH FACTOR THERAPY.

The aim of this study was to investigate whether supplemental IGF-1Ea transgene expression induces activation of local cardiac and bone marrow stem cell population to mediate mammalian heart repair. In physiologic conditions, cardiac overexpression of the IGF-1Ea propeptide is associated with an enrichment of c-Kit/Sca-1 positive side population cells in the bone marrow and the occurrence of an endothelial-primed CD34 positive side population in the heart. This cellular profile is shown here to correlate with the expression of cytokines involved in stem cell mobilization and vessel formation. This molecular and cellular interplay favored IGF-1Ea-mediated vessel formation in injured hearts. The physiologic and pathologic connection between cytokines and stem cells in response to IGF-1Ea may represent an important model to understand how to elicit endogenous reparative signaling.

Breast cancer (BC) is the most common type of malignancy in female patients and radio-treatment is the conventional therapy even if a great number of studies reported that enhanced sensitivity to ionizing radiation as measured as chromosome effects is present in a significant proportion of cancer patients, including breast cancer ones. In this study we analysed whether peripheral blood lymphocytes from sporadic BC patients and healthy subjects showed a different sensitivity to ionizing radiation and whether cytogenetic radiosensitivity may serve as a breast cancer risk biomarker. To test this hypothesis, the in vitro radiation sensitivity was measured by using both G(0) and G(2) chromosome radiosensitivity assays, on 46 subjects (23 BC patients and 23 healthy subjects). Results show that cancer patients are more radiosensitive than healthy controls and that G(2) assay could be more appropriate to define the individual radiosensitivity if compared to G(0) assay.