Effects of estradiol on very low density lipoprotein receptor mRNA levels in rabbit heart

AbstractThe VLDL receptor, a newly identified lipoprotein receptor, has a domain structure homologous with the LDL receptor but has one additional cysteine rich repeat in the ligand binding domain. To study the regulation of the VLDL receptor in vivo, we administered 17 α-ethinyl estradiol to rabbits and examined its effects on VLDL receptor mRNA levels in the heart, one of the organs with highly expressed VLDL receptors, by RNA blotting. The ventricular level of VLDL receptor mRNA increased dramatically after estradiol administration. We could not detect VLDL receptor mRNA in the liver even after estradiol administration. We have confirmed the enhanced expression of liver LDL receptor mRNA by estradiol, however, only weak expression of the LDL receptor was detected in the ventricle of the rabbit heart. These results suggest that estradiol exerts its effect on the VLDL receptor gene expression in the heart

PPAR-α transcriptional activity is required to combat doxorubicin-induced podocyte injury in mice.

Immunosuppressants and inhibitors of the renin angiotensin system are major reagents to treat nephrotic syndrome but their clinical effects are not necessarily satisfactory. Injection of doxorubicin in several strains of mice causes nephrotic syndrome-like disorder. Zhou et al. report that PPAR-α expression is downregulated in murine doxorubicin nephropathy and a PPAR-α agonist, fenofibrate, partially ameliorates the disorder induced likely through stabilization of nephrin expression and suppression of apoptosis in podocytes, providing a new preventive strategy

Establishment of leptin-Responsive cell lines from adult mouse hypothalamus

Leptin resistance is considered to be the primary cause of obesity. However, the cause of leptin resistance remains incompletely understood, and there is currently no cure for the leptin-resistant state. In order to identify novel drug-target molecules that could overcome leptin resistance, it would be useful to develop in vitro assay systems for evaluating leptin resistance. In this study, we established immortalized adult mouse hypothalamus-derived cell lines, termed adult mouse hypothalamus (AMH) cells, by developing transgenic mice in which SV40 Tag was overexpressed in chromogranin A-positive cells in a tamoxifendependent manner. In order to obtain leptin-responsive clones, we selected clones based on the phosphorylation levels of STAT3 induced by leptin. The selected clones were fairly responsive to leptin in terms of STAT3, ERK, and Akt phosphorylation and induction of c- Fos mRNA induction. Pretreatment with leptin, insulin, and palmitate attenuated the c-Fos mRNA response to leptin, suggesting that certain aspects of leptin resistance might be reconstituted in this cellular model. These cell lines are useful tools for understanding the molecular nature of the signal disturbance in the leptin-resistant state and for identifying potential target molecules for drugs that relieve leptin resistance, although they have drawbacks including de-differentiated nature and lack of long-time stability

Natriuretic Peptide Signaling via Guanylyl Cyclase (GC)-A: An Endogenous Protective Mechanism of the Heart

Atrial and brain natriuretic peptides (ANP and BNP, respectively) are cardiac hormones, secretions of which are markedly upregulated during cardiac failure, making their plasma levels clinically useful diagnostic markers. ANP and BNP exert potent diuretic, natriuretic and vasorelaxant effects, which are mediated via their common receptor, guanylyl cyclase (GC)-A (also called natriuretic peptide receptor (NPR)-A). Mice deficient for GC-A are mildly hypertensive and show marked cardiac hypertrophy and fibrosis that is disproportionately severe, given their modestly higher blood pressure. Indeed, the cardiac hypertrophy seen in these mice is enhanced in a blood pressure-independent manner and is suppressed by cardiomyocyte-specific overexpression of GC-A. These results suggest that the actions of a local cardiac ANP/BNP-GC-A system are essential for maintenance of normal cardiac architecture. In addition, GC-A was shown to exert its cardioprotective effects by inhibiting angiotensin II-induced hypertrophic signaling, and recent evidence suggests that regulator of G protein signaling (RGS) subtype 4 is involved in the GC-A-mediated inhibition of Gαq-coupled hypertrophic signal transduction. Furthermore, several different groups have reported that functional mutations in the promoter region of the human GC-A gene are associated with essential hypertension and ventricular hypertrophy. These findings suggest that endogenous GC-A protects the heart from pathological hypertrophic stimuli, and that humans who express only low levels of GC-A are genetically predisposed to cardiac remodeling and hypertension

Is Pulse Pressure a Predictor of New-Onset Diabetes in High-Risk Hypertensive Patients?: A subanalysis of the Candesartan Antihypertensive Survival Evaluation in Japan (CASE-J) trial

OBJECTIVE: Hypertensive patients have an increased risk of developing diabetes. Accumulating evidence suggests a close relation between metabolic disturbance and increased arterial stiffness. Here, we examined the association between pulse pressure and the risk of new-onset diabetes in high-risk Japanese hypertensive patients. RESEARCH DESIGN AND METHODS: The Candesartan Antihypertensive Survival Evaluation in Japan (CASE-J) trial examined the effects of candesartan and amlodipine on the incidence of cardiovascular events in 4, 728 high-risk Japanese hypertensive patients. In the present study, we analyzed the relationship between pulse pressure at baseline and new-onset diabetes in 2, 685 patients without diabetes at baseline (male 1, 471; mean age 63.7 years; mean BMI 24.8 kg/m(2)) as a subanalysis of the CASE-J trial. RESULTS: During 3.3 +/- 0.8 years of follow-up, 97 patients (3.6%) developed diabetes. In multiple Cox regression analysis, pulse pressure was an independent predictor for new-onset diabetes (hazard ratio [HR] per 1 SD increase 1.44 [95% CI 1.15-1.79]) as were male sex, BMI, and additional use of diuretics, whereas age and heart rate were not. Plots of HRs for new-onset diabetes considering both systolic and diastolic blood pressure (DBP) revealed that a higher pulse pressure with a lower DBP, indicating that the increased pulse pressure was largely due to increased arterial stiffness, was strongly associated with the risk of new-onset diabetes. CONCLUSIONS: Pulse pressure is an independent predictor of new-onset diabetes in high-risk Japanese hypertensive patients. Increased arterial stiffness may be involved in the development of diabetes

Differentiation of human embryonic stem cells and human induced pluripotent stem cells into steroid-producing cells.

Although there have been reports of the differentiation of mesenchymal stem cells and mouse embryonic stem (ES) cells into steroid-producing cells, the differentiation of human ES/induced pluripotent stem (iPS) cells into steroid-producing cells has not been reported. The purpose of our present study was to establish a method for inducing differentiation of human ES/iPS cells into steroid-producing cells. The first approach we tried was embryoid body formation and further culture on adherent plates. The resultant differentiated cells expressed mRNA encoding the steroidogenic enzymes steroidogenic acute regulatory protein, 3β-hydroxysteroid dehydrogenase, cytochrome P450-containing enzyme (CYP)-11A1, CYP17A1, and CYP19, and secreted progesterone was detected in the cell medium. However, expression of human chorionic gonadotropin was also detected, suggesting the differentiated cells were trophoblast like. We next tried a multistep approach. As a first step, human ES/iPS cells were induced to differentiate into the mesodermal lineage. After 7 d of differentiation induced by 6-bromoindirubin-3'-oxime (a glycogen synthase kinase-3β inhibitor), the human ES/iPS cells had differentiated into fetal liver kinase-1- and platelet derived growth factor receptor-α-expressing mesodermal lineage cells. As a second step, plasmid DNA encoding steroidogenic factor-1, a master regulator of steroidogenesis, was introduced into these mesodermal cells. The forced expression of steroidogenic factor-1 and subsequent addition of 8-bromoadenosine 3',5'-cyclic monophosphate induced the mesodermal cells to differentiate into the steroidogenic cell lineage, and expression of CYP21A2 and CYP11B1, in addition to steroidogenic acute regulatory protein, 3β-hydroxysteroid dehydrogenase, CYP11A1, and CYP17A1, was detected. Moreover, secreted cortisol was detected in the medium, but human chorionic gonadotropin was not. These findings indicate that the steroid-producing cells obtained through the described multistep method are not trophoblast like; instead, they exhibit characteristics of adrenal cortical cells

Somatic chromosomal translocation between Ewsr1 and Fli1 loci leads to dilated cardiomyopathy in a mouse model

A mouse model that recapitulates the human Ewing's sarcoma-specific chromosomal translocation was generated utilizing the Cre/loxP-mediated recombination technique. A cross between Ewsr1-loxP and Fli1-loxP mice and expression of ubiquitous Cre recombinase induced a specific translocation between Ewsr1 and Fli1 loci in systemic organs of both adult mice and embryos. As a result Ewsr1-Fli1 fusion transcripts were expressed, suggesting a functional Ews-Fli1 protein might be synthesized in vivo. However, by two years of age, none of the Ewsr1-loxP/Fli1-loxP/CAG-Cre (EFCC) mice developed any malignancies, including Ewing-like small round cell sarcoma. Unexpectedly, all the EFCC mice suffered from dilated cardiomyopathy and died of chronic cardiac failure. Genetic recombination between Ewsr1 and Fli1 was confirmed in the myocardial tissue and apoptotic cell death of cardiac myocytes was observed at significantly higher frequency in EFCC mice. Moreover, expression of Ews-Fli1 in the cultured cardiac myocytes induced apoptosis. Collectively, these results indicated that ectopic expression of the Ews-Fli1 oncogene stimulated apoptotic signals, and suggested an important relationship between oncogenic signals and cellular context in the cell-of-origin of Ewing's sarcoma

Cloning of cDNA and genomic DNA for human cytochrome P-45011β

AbstractA full-length cDNA clone encoding steroid 11β-hydroxylase (P-45011β) has been isolated from a cDNA library derived from human adrenal tumor. The insert of the clone contains an open reading frame encoding a protein of 503 amino acid residues together with a 4 bp 5'-untranslated region and a 576 bp 3'-untranslated region to which a poly(A) tract is attached. The promoter region of the P-45011β gene has also been isolated from a genomic library derived from human pre-B cells. It contains a TATA box, a putative cAMP-responsive element, several repeated sequences and two sequence elements similar to the consensus sequence for binding of AP-1. A transient expression assay in Y-1 adrenal tumor cells demonstrates that the promoter activity is remarkably enhanced by treatment of the cells with cAMP. In addition, analysis using deletion mutants containing various lengths of the 5'-flanking region of the gene suggests that several cis-acting elements participate in transcriptional regulation of human P-45011β gene