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Though it is well known that mammalian cardiomyocytes exit cell cycle soon after birth, the mechanisms that regulate proliferation remain to be fully elucidated. Recent studies reported that cardiomyocytes undergo dedifferentiation before proliferation, indicating the importance of dedifferentiation in cardiomyocyte proliferation. Since Runx1 is expressed in dedifferentiated cardiomyocytes, Runx1 is widely used as a dedifferentiation marker of cardiomyocytes; however, little is known about the role of Runx1 in the proliferation of cardiomyocytes. The purpose of this study was to clarify the functional significance of Runx1 in cardiomyocyte proliferation. qRT‐PCR analysis and immunoblot analysis demonstrated that Runx1 expression was upregulated in neonatal rat cardiomyocytes when cultured in the presence of FBS. Similarly, STAT3 was activated in the presence of FBS. Interestingly, knockdown of STAT3 significantly decreased Runx1 expression, indicating Runx1 is regulated by STAT3. We next investigated the effect of Runx1 on proliferation. Immunofluorescence microscopic analysis using an anti‐Ki‐67 antibody revealed that knockdown of Runx1 decreased the ratio of proliferating cardiomyocytes. Conversely, Runx1 overexpression using adenovirus vector induced cardiomyocyte proliferation in the absence of FBS. Finally, RNA‐sequencing analysis revealed that Runx1 overexpression induced upregulation of cardiac fetal genes and downregulation of genes associated with fatty acid oxidation. Collectively, Runx1 is regulated by STAT3 and induces cardiomyocyte proliferation by juvenilizing cardiomyocytes. [ABSTRACT FROM AUTHOR]

Tumor suppressor protein p53 plays crucial roles in the onset of heart failure. p53 activation results in cardiac dysfunction, at least partially by suppressing angiogenesis. Though p53 has been reported to reduce VEGF production by inhibiting hypoxia‐inducible factor, the anti‐angiogenic property of p53 remains to be fully elucidated in cardiomyocytes. To explore the molecular signals downstream of p53 that regulate vascular function, especially under normoxic conditions, DNA microarray was performed using p53‐overexpressing rat neonatal cardiomyocytes. Among genes induced by more than 2‐fold, we focused on CXCL10, an anti‐angiogenic chemokine. Real‐time PCR revealed that p53 upregulated the CXCL10 expression as well as p21, a well‐known downstream target of p53. Since p53 is known to be activated by doxorubicin (Doxo), we examined the effects of Doxo on the expression of CXCL10 and found that Doxo enhanced the CXCL10 expression, accompanied by p53 induction. Importantly, Doxo‐induced CXCL10 was abrogated by siRNA knockdown of p53, indicating that p53 activation is necessary for Doxo‐induced CXCL10. Next, we examined the effect of hypoxic condition on p53‐mediated induction of CXCL10. Interestingly, CXCL10 was induced by hypoxia and its induction was potentiated by the overexpression of p53. Finally, the conditioned media from cultured cardiomyocytes expressing p53 decreased the tube formation of endothelial cells compared with control, analyzed by angiogenesis assay. However, the inhibition of CXCR3, the receptor of CXCL10, restored the tube formation. These data indicate that CXCL10 is a novel anti‐angiogenic factor downstream of p53 in cardiomyocytes and could contribute to the suppression of vascular function by p53. [ABSTRACT FROM AUTHOR]

Because mammalian cardiomyocytes largely cease to proliferate immediately after birth, the regenerative activity of the heart is limited. To date, much effort has been made to clarify the regulatory mechanism of cardiomyocyte proliferation because the amplification of cardiomyocytes could be a promising strategy for heart regenerative therapy. Recently, it was reported that the inhibition of glycogen synthase kinase (GSK)‐3 promotes the proliferation of neonatal rat cardiomyocytes (NRCMs) and human iPS cell‐derived cardiomyocytes (hiPSC‐CMs). Additionally, Yes‐associated protein (YAP) induces cardiomyocyte proliferation. The purpose of this study was to address the importance of YAP activity in cardiomyocyte proliferation induced by GSK‐3 inhibitors (GSK‐3Is) to develop a novel strategy for cardiomyocyte amplification. Immunofluorescent microscopic analysis using an anti‐Ki‐67 antibody demonstrated that the treatment of NRCMs with GSK‐3Is, such as BIO and CHIR99021, increased the ratio of proliferative cardiomyocytes. YAP was localized in the nuclei of more than 95% of cardiomyocytes, either in the presence or absence of GSK‐3Is, indicating that YAP was endogenously activated. GSK‐3Is increased the expression of β‐catenin and promoted its translocation into the nucleus without influencing YAP activity. The knockdown of YAP using siRNA or pharmacological inhibition of YAP using verteporfin or CIL56 dramatically reduced GSK‐3I‐induced cardiomyocyte proliferation without suppressing β‐catenin activation. Interestingly, the inhibition of GSK‐3 also induced the proliferation of hiPSC‐CMs under sparse culture conditions, where YAP was constitutively activated. In contrast, under dense culture conditions, in which YAP activity was suppressed, the proliferative effects of GSK‐3Is on hiPSC‐CMs were not detected. Importantly, the activation of YAP by the knockdown of α‐catenin restored the proproliferative activity of GSK‐3Is. Collectively, YAP activation potentiates the GSK‐3I‐induced proliferation of cardiomyocytes. The blockade of GSK‐3 in combination with YAP activation resulted in remarkable amplification of cardiomyocytes. [ABSTRACT FROM AUTHOR]

Aim: We carried out a randomized controlled trial using ipragliflozin. We analyzed changes in diastolic function using echocardiography in patients with type 2 diabetes and heart failure with preserved ejection fraction. Methods: We carried out an open‐label, multicenter, randomized, two‐arm interventional trial. A total of eligible 68 participants were randomly assigned into two groups (ipragliflozin group n = 36; conventional treatment group n = 32). Primary end‐points were the change in E/e' and e'. Secondary end‐points were other parameters of echocardiography, plasma NT‐proBNP level, New York Heart Association class, hemoglobin A1c and blood pressure. Results: After 24 weeks of follow up, E/e' decreased in both groups (ipragliflozin: 11.0 vs 10.4; conventional treatment 10.5 vs 10.1; multivariate‐adjusted P = 0.95). There were no significant differences in the amount of change in E/e', e', echocardiography parameters, plasma NT‐proBNP level, New York Heart Association class, hemoglobin A1c and blood pressure between the two groups. In the subgroup analysis, ipragliflozin treatment decreased in left ventricular mass index in patients aged ≥70 years and also decreased in NT‐proBNP levels in patients with baseline NT‐proBNP ≥400 pg/mL. Conclusions: In this randomized controlled study carried out in patients with type 2 diabetes and heart failure with preserved ejection fraction, 24‐week ipragliflozin treatment did not improve left ventricular diastolic function compared with conventional treatment. As the subgroup, ipragliflozin treatment decreased in left ventricular mass index in participants aged ≥70 years. Geriatr Gerontol Int 2022; 22: 298–304. [ABSTRACT FROM AUTHOR]

Minesapride (drug code: DSP‐6952) is a potential gastrointestinal prokinetic agent with high selectivity for 5‐hydroxytryptamine 4 (5‐HT4) receptor that acts as a partial agonist. Although 5‐HT4 receptor agonists are expected to show efficacy in patients with irritable bowel syndrome with constipation, only tegaserod is available for female patients, with limitations, in the United States. Previously, another 5‐HT4 receptor agonist, cisapride, was widely used for the treatment of upper gastrointestinal diseases, but was withdrawn from the market because of arrhythmia with QT prolongation. Chemically, benzamide is one of the most common structures among 5‐HT4 receptor agonists. Some benzamide derivatives, such as cisapride, are responsible for QT prolongation, while some, such as mosapride, are not. Thus, we planned a thorough QT/QTc study to investigate the effects of minesapride, a newly designed benzamide derivative, on the QT/QTc. This was a randomized, placebo‐controlled, 4‐arm, 4‐period, crossover study conducted in healthy adults, with administration of single oral doses of minesapride (40 mg and 120 mg), placebo, and moxifloxacin in the fasted state. Minesapride and placebo were administered in a double‐blind fashion, while the positive control moxifloxacin was administered in an open‐label fashion. Japanese subjects (48 total: 24 males and 24 females) were randomized, and 47 subjects completed all treatment periods. A review of other electrocardiographic data revealed that neither therapeutic (40 mg) nor supratherapeutic (120 mg) doses of minesapride were associated with increased risk of prolonged QT interval. [ABSTRACT FROM AUTHOR]

Background and Purpose: In cardiovascular diseases, cardiac fibroblasts (CFs) participate in the myocardial inflammation by producing pro‐inflammatory cytokines, worsening the prognosis. β2‐adrenergic receptor (AR) and β3AR are expressed in CFs, and β‐adrenergic stimulation promotes CFs to produce pro‐inflammatory cytokines. However, the mechanism of the expression of pro‐inflammatory cytokines in response to β‐adrenergic stimulation remains to be fully elucidated. Experimental Approach: CFs were isolated from adult wild‐type or AT‐rich interactive domain‐containing protein 5A (Arid5a) knockout mice. The expression of mRNA was measured by real‐time RT‐PCR. Interleukin (IL)‐6 protein was measured by ELISA. The activity of nuclear factor‐κB (NF‐κB) and cyclic AMP (cAMP) response element binding protein (CREB) was assessed by ELISA‐like assay or Western blotting. Key Results: The β‐adrenergic stimulation remarkably induced IL‐6 mRNA and protein through β2AR in CFs. The activation of adenylate cyclase and the enhancement of intracellular cAMP resulted in the upregulation of IL‐6 mRNA expression. The induction of IL‐6 transcript by β2AR signaling was independent of NF‐κB. Concomitant with IL‐6, the expression of Arid5a, an IL‐6 mRNA stabilizing factor, was enhanced by β2‐adrenergic stimulation and by cAMP increase. Importantly, β2AR signaling‐mediated IL‐6 induction was suppressed in Arid5a knockout CFs. Finally, β2AR stimulation phosphorylated CREB via PKA pathway, and the activation of CREB was essential for the induction of Arid5a and IL‐6 mRNA. Conclusion and Implications: β2‐adrenergic stimulation post‐transcriptionally upregulates the expression of IL‐6 by the induction of Arid5a through cAMP/PKA/CREB pathway in adult CFs. β2AR/Arid5a/IL‐6 axis could be a therapeutic target against cardiac inflammation. [ABSTRACT FROM AUTHOR]

Aims We investigated the correlation of adrenergic receptor polymorphisms, α2cDel322–325, β1Ser49Gly and β1Arg389Gly, with the risk of heart failure in the Japanese population. Methods These polymorphisms were analysed by polymerase chain reaction-restriction fragment length polymorphism in patients with chronic heart failure due to idiopathic dilated cardiomyopathy (DCM) and compared with the control group. Results There were no differences or any trends in the allele and genotype frequencies of the β1Ser49Gly and β1Arg389Gly polymorphisms. The allele frequency of the α2cDel322–325 variant was lower in patients than in controls (0.11 vs. 0.04, P = 0.011 < 0.017, by Bonferroni correction), while the genotype frequency just failed to reach significance ( P = 0.022 > 0.017, by Bonferroni correction). Conclusions In this population, the variants β1Ser49, β1Arg389, and α2cDel322–325 do not appear to be risk factors for chronic heart failure due to DCM. The α2cDel322–325 variant may in fact confer some protection. [ABSTRACT FROM AUTHOR]

Abstract: In the process of atherosclerosis, platelet activating factor (PAF) promotes the infiltration of inflammatory cells into atherosclerotic plaque by modulating their cytoskeleton. Here, we examined whether Rho family proteins are involved in PAF-induced cytoskeletal reorganization in THP-1 macrophages. PAF stimulation rapidly induced cell elongation, accompanied by filopodia formation. The inhibition of Rho family proteins by the overexpression of Rho-GDI attenuated the PAF-mediated morphological changes. Both RhoA and Cdc42 were activated in response to PAF. Inhibition of RhoA or Cdc42 by dominant negative mutants abrogated morphological changes induced by PAF. Collectively, PAF regulates cytoarchitecture through Rho family proteins in macrophages. [Copyright &y& Elsevier]

Glycoprotein 130 (gp130), a common receptor of IL-6 family cytokines, plays critical roles in cardiac functions. Here, we demonstrate that the stimulation of gp130 with leukemia inhibitory factor (LIF) promoted cell adhesion in a cadherin-dependent manner in cultured cardiomyocytes. Wnt5a was upregulated by the stimulation of gp130 with IL-6 family cytokines, accompanied by N-cadherin protein upregulation. Wnt5a was not induced by LIF in cardiomyocytes expressing dominant-negative STAT3. Ablation of Wnt5a by antisense cDNA inhibited LIF-induced cell adhesion. Collectively, signals through gp130 upregulate Wnt5a through STAT3, promoting the N-cadherin-mediated cell adhesion. [Copyright &y& Elsevier]

Aldosterone is thought to regulate cardiac work independently of sodium retention, though the mechanisms remain to be known. In the present study, we have demonstrated that aldosterone reinforces endothelin-mediated cardiac hypertrophy with the increase in cell surface area and upregulation of the transcripts characteristic of hypertrophy. We have also shown that aldosterone augments c-Jun N-terminal kinase activation induced by endothelin-1. Taken together, it is suggested that aldosterone modulates cardiac hypertrophy, at least partially, synergistically with extracellular signals that have been shown to be involved in cardiac remodeling. [Copyright &y& Elsevier]

Terrestrial organisms have systems to escape from desiccation stresses. For example, tardigrades (also known as water bears) can survive severe dried and other extreme environments by anhydrobiosis. Although their extraordinary ability has enchanted people, little is known about the detailed molecular mechanisms of anhydrobiosis. Here, we focused on the tardigrade Ramazzottius varieornatus, one of the toughest animals on Earth. A transcriptome database of R. varieornatus shows that genes encoding a Ferritin‐like protein are upregulated during desiccation or ultraviolet radiation. This protein shows sequence similarity to enigmatic proteins in desiccation‐tolerant bacteria and plants, which are hypothesized to be desiccation‐related. However, because these proteins lack detailed biological information, their functions are relatively unknown. We determined an atomic (1.05 Å) resolution crystal structure of a Ferritin‐like protein from R. varieornatus. The structure revealed a dinuclear metal binding site, and we showed that this Ferritin‐like protein has phosphatase activity toward several metabolite compounds including unusual nucleotide phosphates produced by oxidative or radiation damage. We also found that a homologous protein from a desiccation‐ and ultraviolet‐tolerant bacterium Deinococcus radiodurans is a metabolite phosphatase. Our results indicate that through cleaning up damaged metabolites or regulation of metabolite levels, this phosphatase family can contribute to stress tolerances. This study provides a clue to one of the universal molecular bases of desiccation‐stress tolerance. [ABSTRACT FROM AUTHOR]

A letter to the editor is presented in response to the article concerning the warfarin dose requirement for patients with both VKORC1 3673A/A and CYP2C9*3/*3 genotypes that was published previously.

Aims: We investigated the correlation of adrenergic receptor polymorphisms, alpha(2c)Del322-325, beta(1)Ser49Gly and beta(1)Arg389Gly, with the risk of heart failure in the Japanese population., Methods: These polymorphisms were analysed by polymerase chain reaction-restriction fragment length polymorphism in patients with chronic heart failure due to idiopathic dilated cardiomyopathy (DCM) and compared with the control group., Results: There were no differences or any trends in the allele and genotype frequencies of the beta(1)Ser49Gly and beta(1)Arg389Gly polymorphisms. The allele frequency of the alpha(2c)Del322-325 variant was lower in patients than in controls (0.11 vs. 0.04, P = 0.011 < 0.017, by Bonferroni correction), while the genotype frequency just failed to reach significance (P = 0.022 > 0.017, by Bonferroni correction)., Conclusions: In this population, the variants beta(1)Ser49, beta(1)Arg389, and alpha(2c)Del322-325 do not appear to be risk factors for chronic heart failure due to DCM. The alpha(2c)Del322-325 variant may in fact confer some protection.