The Experts below are selected from a list of 169587369 Experts worldwide ranked by ideXlab platform
Joseph A Beavo - One of the best experts on this subject based on the ideXlab platform.
-
pde3 and pde4 isozyme selective inhibitors are both required for synergistic activation of brown adipose tissue
Molecular Pharmacology, 2013Co-Authors: Stephen Kraynik, R S Miyaoka, Joseph A BeavoAbstract:Brown adipose tissue (BAT) is a highly thermogenic organ that converts lipids and glucose into heat. Many of the metabolic and gene transcriptional hallmarks of BAT activation, namely increased lipolysis, uncoupling protein-1 (UCP1) mRNA, and glucose uptake, are regulated by the adrenergic second messenger, cAMP. Cyclic nucleotide phosphodiesterases (PDEs) catalyze the breakdown of cAMP, thereby regulating the magnitude and duration of this signaling molecule. In the absence of adrenergic stimulus, we found that it required a combination of a PDE3 and a PDE4 inhibitor to fully induce UCP1 mRNA and lipolysis in brown adipocytes, whereas neither PDE inhibitor alone had any substantial effect under basal conditions. Under submaximal β-adrenoceptor stimulation of brown adipocytes, a PDE3 inhibitor alone could potentiate induction of UCP1 mRNA, whereas a PDE4 inhibitor alone could augment lipolysis, indicating differential roles for each of these two PDEs. Neither induction of UCP1 nor lipolysis was altered by inhibition of PDE1, PDE2, or PDE8A. Finally, when injected into mice, the combination of PDE3 and PDE4 inhibitors stimulated glucose uptake in BAT under thermoneutral and fasted conditions, a response that was further potentiated by the global ablation of PDE8A. Taken together, these data reveal that multiple PDEs work in concert to regulate three of the important pathways leading to BAT activation, a finding that may provide an improved conceptual basis for the development of therapies for obesity-related diseases.
-
cAMP-Specific Phosphodiesterases 8A and 8B, Essential Regulators of Leydig Cell Steroidogenesis□S
2011Co-Authors: Masami Shimizu-albergine, Li-chun Lisa Tsai, Enrico Patrucco, Joseph A BeavoAbstract:Phosphodiesterase (PDE) 8A and PDE8B are high-affinity, cAMP-specific phosphodiesterases that are highly expressed in Leydig cells. PDE8A is largely associated with mitochondria, whereas PDE8B is broadly distributed in the cytosol. We used a new, PDE8-selective inhibitor, PF-04957325, and genetically ab-lated PDE8A(/), PDE8B(/) and PDE8A(/)/B(/) mice to determine roles for these PDEs in the regulation of testosterone production. PF-04957325 treatment of WT Leydig cells or MA10 cells increased steroid production but had no effect in PDE8A (/)/B(/) double-knockout cells, confirming the selectivity of the drug. Moreover, under basal conditions, cotreatment with PF-04957325 plus rolipram, a PDE4-selective inhibitor, synergis-tically potentiated steroid production. These results suggest that the pool(s) of cAMP regulating androgen production are controlled by PDE8s working in conjunction with PDE4. Likewise, PDE8A (/)/B(/) cells had higher testosterone production than cells from either PDE8A(/) or PDE8B(/) mice, suggesting that both PDE8s work in concert to regulate steroid production. We further demonstrate that combined inhibition of PDE8s and PDE4 greatly increased PKA activity including phosphorylation of cho-lesterol-ester hydrolase (CEH)/hormone-sensitive lipase (HSL). CEH/HSL phosphorylation also was increased in PDE8A(/)/ B(/) cells compared with WT cells. Finally, combined inhibition of PDE8s and PDE4 increased the expression of steroidogenic acute regulatory (StAR) protein. Together these findings suggest that both PDE8A and PDE8B play essential roles to maintain low cAMP levels, thereby suppressing resting steroidogenesis by keeping CEH/HSL inactive and StAR protein expression low. They also suggest that in order for PDE inhibitor therapy to be an effective stimulator of steroidogenesis, both PDE8 isozymes and PDE4 need to be simultaneously targeted
-
solution structure of the cgmp binding gaf domain from phosphodiesterase 5 insights into nucleotide specificity dimerization and cgmp dependent conformational change
Journal of Biological Chemistry, 2008Co-Authors: Clemens C. Heikaus, Joseph R Stout, Monica Sekharan, Peter S Brzovic, Joseph A Beavo, Catherine M Eakin, Ponni Rajagopal, Rachel E. KlevitAbstract:Phosphodiesterase 5 (PDE5) controls intracellular levels of cGMP through its regulation of cGMP hydrolysis. Hydrolytic activity of the C-terminal catalytic domain is increased by cGMP binding to the N-terminal GAF A domain. We present the NMR solution structure of the cGMP-bound PDE5A GAF A domain. The cGMP orientation in the buried binding pocket was defined through 37 intermolecular nuclear Overhauser effects. Comparison with GAF domains from PDE2A and adenylyl cyclase cyaB2 reveals a conserved overall domain fold of a six-stranded β-sheet and four α-helices that form a well defined cGMP binding pocket. However, the nucleotide coordination is distinct with a series of altered binding contacts. The structure suggests that nucleotide binding specificity is provided by Asp-196, which is positioned to form two hydrogen bonds to the guanine ring of cGMP. An alanine mutation of Asp-196 disrupts cGMP binding and increases cAMP affinity in constructs containing only GAF A causing an altered cAMP-bound structural conformation. NMR studies on the tandem GAF domains reveal a flexible GAF A domain in the absence of cGMP, and indicate a large conformational change upon ligand binding. Furthermore, we identify a region of ∼20 residues directly N-terminal of GAF A as critical for tight dimerization of the tandem GAF domains. The features of the PDE5 regulatory domain revealed here provide an initial structural basis for future investigations of the regulatory mechanism of PDE5 and the design of GAF-specific regulators of PDE5 function.
-
phosphodiesterase type 5 expanding roles in cardiovascular regulation
Circulation Research, 2007Co-Authors: David A Kass, Hunter C Champion, Joseph A BeavoAbstract:Phosphodiesterase type 5A (PDE5A) selectively hydrolyzes cyclic GMP. Inhibitors of PDE5A such as sildenafil are widely used to treat erectile dysfunction, but growing evidence supports important roles for the enzyme in both the vasculature and heart. In disorders such as cardiac failure, PDE5A upregulation may contribute to a decline in cGMP and protein kinase G signaling, exacerbating dysfunction. PDE5A plays an important role in the pulmonary vasculature where its inhibition benefits patients with pulmonary hypertension. In the heart, PDE5A signaling appears compartmentalized, and its inhibition is cardioprotective against ischemia-reperfusion and antracycline toxicity, blunts acute adrenergic contractile stimulation, and can suppress chronic hypertrophy and dysfunction attributable to pressure-overload. In this review, we discuss the molecular biology, pharmacology, and physiology of PDE5A, mechanisms of vascular and cardiac regulation, and recent evidence supporting the utility of selective PDE5A inhibition for the treatment of cardiovascular disorders.
-
modulation of leydig cell function by cyclic nucleotide phosphodiesterase 8a
Proceedings of the National Academy of Sciences of the United States of America, 2006Co-Authors: Valeria Vasta, Masami Shimizualbergine, Joseph A BeavoAbstract:Leydig cells produce testosterone in the testes under the pulsatile control of pituitary luteinizing hormone (LH). cAMP is the intracellular messenger for LH action on steroidogenesis, and pharmacological evidence indicates that the response to LH can be modulated by cyclic nucleotide phosphodiesterases (PDEs). However the types and roles of the PDEs present in Leydig cells have not been fully defined. We report here that PDE8A is expressed in Leydig cells, and using PDE8A knockout mice we provide evidence that PDE8A is a key regulator of LH signaling and steroidogenesis. A 4-fold increase in the sensitivity to LH for testosterone production was detected in Leydig cells isolated from PDE8A knockout mice. In Leydig cells from wild-type mice, 3-isobutyl-1-methylxanthine, a compound that inhibits all cAMP PDEs except PDE8A, elicited only a small increase in the sensitivity of testosterone production to LH. However, in the PDE8-null mice, the effect of this inhibitor is much more pronounced. These observations indicate that PDE8A and at least one other PDE control the same or a complementary pool of cAMP that mediates LH-regulated steroidogenesis. Overall, these results suggest that pharmacological manipulation of PDE8A, alone or in combination with other PDEs present in Leydig cells, may be exploited to modulate testosterone synthesis and possibly to treat various conditions where the local levels of this androgen need to be altered.
Katsuzumi Okumura - One of the best experts on this subject based on the ideXlab platform.
-
human ca2 calmodulin dependent phosphodiesterase pde1a novel splice variants their specific expression genomic organization and chromosomal localization
Biochimica et Biophysica Acta, 2001Co-Authors: Hideo Michibata, Noriyuki Yanaka, Yutaka Kanoh, Katsuzumi Okumura, Kenji OmoriAbstract:Abstract We report here the identification of novel human PDE1A splice variants, their tissue distribution patterns, genomic structure, and chromosomal localization of the gene. We identified one N-terminus (N3) and one C-terminus (C3) by cDNA library screening and dbEST database search. These N- and C-termini, including the reported N-termini (N1 and N2) and C-termini (C1 and C2), combined to generate nine different PDE1A cDNAs. N1 and N2 are similar to the 5′ ends of the bovine PDE1A proteins of 61 kDa and 59 kDa, respectively, and C1 and C2 are the 3′ ends of the reported human PDE1A variants. The results of PCR and Southern blot analysis show that nine PDE1A splice variants exhibit distinctive tissue distribution patterns by the difference of the N-terminus. PDE1As with N2 were widely expressed in various tissues, mainly in the kidney, liver, and pancreas. On the other hand, PDE1As with N1 and N3 were particularly expressed at a high level in the brain and testis, respectively. These findings suggest that the distinct expression patterns among PDE1A variants depend on the several promoters situated upstream of exons encoding 5′ ends of the variants. The PDE1A gene spans over 120 kb of genomic DNA, and consists of at least 17 exons and 16 introns. The PDE1A gene was located on human chromosome 2q32 by fluorescent in situ hybridization analysis.
-
expression structure and chromosomal localization of the human cgmp binding cgmp specific phosphodiesterase pde5a gene
FEBS Journal, 1998Co-Authors: Noriyuki Yanaka, Hideo Michibata, Jun Kotera, Akio Ohtsuka, Hiroyuki Akatsuka, Yuji Imai, Kotomi Fujishige, Eri Kawai, Shinichiro Takebayashi, Katsuzumi OkumuraAbstract:cGMP-binding, cGMP-specific phosphodiesterase which is encoded by the PDE5A gene plays important roles in cardiovascular system, and is a significant target molecule of therapeutic agents. However, little is known about molecular characteristics of the human PDE5A gene. The 4.4-kb cDNA encoding human PDE5A was isolated from lung and placenta cDNA libraries. The deduced amino acid sequence analysis demonstrated that N-terminal amino acid sequence is dissimilar to that of rat PDE5A [Kotera, J., Yanaka, N., Fujishige, K., Imai, Y., Akatsuka, H., Ishizuka, T., Kawashima, K. & Omori, K. (1997) Eur. J. Biochem. 249, 434-442]. Human PDE5A mRNA is produced in high amounts in various tissues such as pancreas, skeletal muscle, placenta, heart, thyroid, adrenal cortex, testis, small intestine and stomach. In addition, the megakaryocyte-like cell line Dami cells and two types of human vascular smooth muscle cells also produce the mRNA. Over 100-kb chromosomal DNA corresponding to the human PDE5A gene was isolated and analyzed. The human PDE5A gene was revealed to contain 21 exons. Comparison of genomic organization with the rod photoreceptor phosphodiesterase beta-subunit gene (PDE6B), which is another kind of cGMP-specific phosphodiesterase, has shown that the PDE5A and PDE6B genes are very similar in their relative exon intron organization. In particular, the evolutionary relatedness of these genes was suggested in the catalytic domain. Furthermore, chromosomal location of the PDE5A gene was defined as being chromosome 4q26 by fluorescent in situ hybridization analysis.
Sandhya S Visweswariah - One of the best experts on this subject based on the ideXlab platform.
-
modeling and mutational analysis of the gaf domain of the cgmp binding cgmp specific phosphodiesterase pde5
FEBS Letters, 2003Co-Authors: S. Sopory, Sai A Balaji, Narayanaswamy Srinivasan, Sandhya S VisweswariahAbstract:The GAFa domain of the cGMP-binding, cGMP-specific phosphodiesterase (PDE5A) was modeled on the crystal structure of PDE2A GAF domain and residues involved in cGMP binding identified. Tandem GAFa and GAFb domains of PDE5A, expressed in Escherichia coli, bound cGMP (Kd 27 nM). Mutation of aspartate-299 in GAFa, suggested earlier to be critical for cGMP binding, did not abrogate cGMP binding, but mutation of F205, which formed a stacking interaction with the guanine ring of cGMP, led to complete loss of cGMP binding. Therefore, the GAFa domain of PDE5A adopts a structure similar to the GAFb domain of PDE2A, and provides the sole site for cGMP binding in PDE5A.
Noriyuki Yanaka - One of the best experts on this subject based on the ideXlab platform.
-
human ca2 calmodulin dependent phosphodiesterase pde1a novel splice variants their specific expression genomic organization and chromosomal localization
Biochimica et Biophysica Acta, 2001Co-Authors: Hideo Michibata, Noriyuki Yanaka, Yutaka Kanoh, Katsuzumi Okumura, Kenji OmoriAbstract:Abstract We report here the identification of novel human PDE1A splice variants, their tissue distribution patterns, genomic structure, and chromosomal localization of the gene. We identified one N-terminus (N3) and one C-terminus (C3) by cDNA library screening and dbEST database search. These N- and C-termini, including the reported N-termini (N1 and N2) and C-termini (C1 and C2), combined to generate nine different PDE1A cDNAs. N1 and N2 are similar to the 5′ ends of the bovine PDE1A proteins of 61 kDa and 59 kDa, respectively, and C1 and C2 are the 3′ ends of the reported human PDE1A variants. The results of PCR and Southern blot analysis show that nine PDE1A splice variants exhibit distinctive tissue distribution patterns by the difference of the N-terminus. PDE1As with N2 were widely expressed in various tissues, mainly in the kidney, liver, and pancreas. On the other hand, PDE1As with N1 and N3 were particularly expressed at a high level in the brain and testis, respectively. These findings suggest that the distinct expression patterns among PDE1A variants depend on the several promoters situated upstream of exons encoding 5′ ends of the variants. The PDE1A gene spans over 120 kb of genomic DNA, and consists of at least 17 exons and 16 introns. The PDE1A gene was located on human chromosome 2q32 by fluorescent in situ hybridization analysis.
-
expression structure and chromosomal localization of the human cgmp binding cgmp specific phosphodiesterase pde5a gene
FEBS Journal, 1998Co-Authors: Noriyuki Yanaka, Hideo Michibata, Jun Kotera, Akio Ohtsuka, Hiroyuki Akatsuka, Yuji Imai, Kotomi Fujishige, Eri Kawai, Shinichiro Takebayashi, Katsuzumi OkumuraAbstract:cGMP-binding, cGMP-specific phosphodiesterase which is encoded by the PDE5A gene plays important roles in cardiovascular system, and is a significant target molecule of therapeutic agents. However, little is known about molecular characteristics of the human PDE5A gene. The 4.4-kb cDNA encoding human PDE5A was isolated from lung and placenta cDNA libraries. The deduced amino acid sequence analysis demonstrated that N-terminal amino acid sequence is dissimilar to that of rat PDE5A [Kotera, J., Yanaka, N., Fujishige, K., Imai, Y., Akatsuka, H., Ishizuka, T., Kawashima, K. & Omori, K. (1997) Eur. J. Biochem. 249, 434-442]. Human PDE5A mRNA is produced in high amounts in various tissues such as pancreas, skeletal muscle, placenta, heart, thyroid, adrenal cortex, testis, small intestine and stomach. In addition, the megakaryocyte-like cell line Dami cells and two types of human vascular smooth muscle cells also produce the mRNA. Over 100-kb chromosomal DNA corresponding to the human PDE5A gene was isolated and analyzed. The human PDE5A gene was revealed to contain 21 exons. Comparison of genomic organization with the rod photoreceptor phosphodiesterase beta-subunit gene (PDE6B), which is another kind of cGMP-specific phosphodiesterase, has shown that the PDE5A and PDE6B genes are very similar in their relative exon intron organization. In particular, the evolutionary relatedness of these genes was suggested in the catalytic domain. Furthermore, chromosomal location of the PDE5A gene was defined as being chromosome 4q26 by fluorescent in situ hybridization analysis.
Eiki Takimoto - One of the best experts on this subject based on the ideXlab platform.
-
controlling myocyte cgmp pde1 joins the fray
Circulation Research, 2009Co-Authors: Eiki TakimotoAbstract:cGMP is a central intracellular second-messenger regulating numerous cellular functions. In the cardiac myocyte, cGMP mediates effects of nitric oxide and atrial natriuretic peptide, whereas its counterpart, cAMP, mediates catecholamine signaling. Each cyclic nucleotide has a corresponding primary targeted protein kinase, PKA for cAMP, and PKG for cGMP. PKA stimulation is associated with enhanced contractility and can stimulate growth, whereas PKG acts as a brake in the heart, capable of countering cAMP-PKA-contractile stimulation and inhibiting hypertrophy1. Importantly, the duration and magnitude of these signaling cascades are determined not only by generation of cyclic nucleotides, but also by their hydrolysis catalyzed by phosphodiesterases (PDEs). PDE regulation is quite potent – often suppressing an acute rise in a given cyclic nucleotide back to baseline within seconds to minutes2. It is also compartmentalized within the cell, so that specific targeted proteins can be regulated by the same “generic” cyclic nucleotide3. For many years, the only PDE in the crosshairs for cardiac biologists was PDE3, a principally cAMP-targeted PDE whose inhibition served as the basis for drugs such as milrinone as a heart failure therapy. However, this list was recently expanded with the recognition of PDE4 as a regulator of beta-receptor signaling and excitation-contraction coupling4, and PDE5 for its regulation of cardiac stress responses1. With the study of Miller et al5, in the current issue if Circulation Research, we can now add PDE1 to the list of hypertrophy regulators – via its modulation of cGMP in the myocyte. The mammalian PDEs comprise a 21 gene superfamily of enzymes grouped into 11 iso-enzymes (PDE1- PDE11) based on sequence homology, enzymatic properties and sensitivity to inhibitors2. These iso-enzymes harbor different specificities to cAMP, cGMP or both, and are also differentially expressed in a variety of tissues. PDE1, PDE2, PDE3, PDE4, PDE5 and PDE9 are expressed in the heart and among these, PDE5 and PDE9 are highly specific to cGMP2 (Table). Recent studies have demonstrated a role for cGMP modulation by PDE5 in the heart1, though the role for PDE9 is unknown at present. PDE5 is up-regulated in failing human6 and hypertrophied mice ventricles7. PDE5 inhibitor ameliorates cardiac hypertrophy in mice7, and genetic silencing of PDE5 inhibits cardiac myocyte hypertrophy in vitro8. Cardiac PDE5 over-expression leads to exacerbated remodeling after myocardial infarction6. Furthermore, the cardio-protective effects from PDE5 inhibitors have been reported in various animal models of cardiac pathology, including myocardial infarction, ischemia-reperfusion injury, doxorubicin cardiomyopathy, and cardiomyopathy associated with dystrophin deficiency1. Table PDEs in the heart PDE5 is not the only cGMP hydrolyzing PDE in myocardium, as basal activity represents ~30% of total myocardial cGMP-esterase activity in mice7 and dogs9. Although this activity can rise with chronic pathologic remodeling (e.g. increasing >50% of the total cGMP esterase activity in the pressure-overloaded mouse heart7), a large proportion of cGMP-esterase activity is still attributable to other PDEs. A primary candidate has been the dual substrate PDE1. Unlike PDE5 which is stimulated by cGMP binding and PKG phosphorylation, PDE1 is activated by calcium-calmodulin, thus is an appealing target for stress-stimulated regulation. Recent studies have proposed that PDE1 (particularly PDE1c) is a more prominent regulator of cGMP hydrolysis in vitro in human normal and failing myocardium 10, 11 – raising interest in defining its role in myocytes in greater detail. The study of Miller et al. has now revealed an important role of PDE1A in cardiac myocytes and its response to pro-hypertrophic stimulation. PDE1 has three primary isoforms, PDE1A-C. PDE1A and PDE1B preferentially hydrolyze cGMP with greater affinity than cAMP, while PDE1C hydrolyzes both cAMP and cGMP with equal affinity. Prior studies had revealed expression and in vitro enzyme activity10, 11, but to date, a physiologic role of PDE1 in myocytes and intact hearts has remained unknown, due to the lack of specific inhibitors for the enzyme. Using one such inhibitor (IC86340, developed by ICOS, and unfortunately no longer available), Miller et al. demonstrated an anti-hypertrophic effect in both isolated neonatal and adult rat cardiac myocytes stimulated with phenylephrine or isoproterenol. The IC50 of IC86340 shows high specificity for PDE1C (0.06μM), PDE1B (0.21μM), PDE1A (0.44μM) as compared to other myocyte PDEs (over 100μM for PDE2, 3, 4, 5, 9). Though prior reports had focused on PDE1C as the dominant isoform11, the current work clearly highlighted PDE1A. The anti-hypertrophic effect of IC 86340 was comparable to that using the PDE5 inhibitor sildenafil in neonatal rat cardiac myocytes, and intriguingly both combined resulted in a further silencing of the hypertrophic effect, suggesting different and likely compartmentalized targeted pools of cGMP and distal signaling are involved. The current study also showed up-regulation of PDE1A expression in mice exposed to sustained neurohormones or pressure-overload. Such upregulation, as has been observed with PDE5, could itself depress cGMP, contributing pathologic cardiac remodeling. The study by Miller et al. leaves open the underlying mechanisms by which PDE1 inhibition resulted in suppression of hypertrophy. However, some of the same pathways already reported from natriuretic peptide stimulation or PDE5 inhibition could play a role. These include inhibition of Gq-coupled signaling and in particular inhibition of the calcineurin-NFAT pathway by PKG. The key regulator appears to be regulator of G protein signaling (RGS) – both RGS2 and RGS4. These proteins are GTPase accelerators, functioning as negative regulators of Gq activation. Mice lacking RGS2 have exacerbated hypertrophic response to pressure-overload that is not inhibited by sildenafil12. Overexpression of RGS4 in mice lacking natriuretic peptide receptor type A rescues the hypertrophic phenotype in the latter coupled to calcineurin-NFAT inhibition13. The present study examined responses to isoproterenol which can stimulate Cn-NFAT pathway, but does not replicate Gq signaling presented by pressure-overload. More studies will be needed. Another unexplored question is whether and how different pools of cGMP are targeted in localized sub-cellular pools by PDE1 versus PDE5. Such compartmentation would be consistent with what is now recognized to be a general feature of PDE regulation3. Compartmentalized cGMP regulation in myocytes has already been demonstrated for PDE5 and another cGMP targeting (and dual esterase) PDE2. For example, nitric oxide stimulated soluble guanylyl cyclase generates cGMP that is hydrolyzed by PDE5 localized at Z-bands of adult cardiac myocytes, and inhibiting PDE5 blunts acute beta-adrenergic responses coupled to enhanced PKG activation14. In contrast, ANP stimulation of the receptor guanylyl cyclase generates cGMP that has no impact on beta-adrenergic responses14, and appears targeted more by PDE2 at the sarcolemmal membrane15. We do not yet know where PDE1 is localized intra-cellularly, whether it is differentially coupled to the two cGMP synthetic pathways, if it modulates acute adrenergic stimulation, and/or whether it targets different or overlapping pools of cGMP to that by PDE5. All are intriguing questions to pursue. There are some controversies at present regarding which PDE PDE5 or PDE1 is likely to be more dominant in human hearts for cGMP regulation. The discussions remain largely speculative, based purely on in vitro enzyme assays, with no functional data regarding PDE110 and some data regarding PDE516. Since signaling via PDEs is likely compartmentalized, activity measured in a test-tube from cell extracts may not reflect the in vivo activity. The only human functional data to date with a cGMP-PDE has been with sildenafil in normal volunteers, wherein Borlaug et al showed that acute PDE5 inhibition suppresses dobutamine stimulated contractility16, just as observed in dogs9 and in mice14. The role of PDE5 inhibition in ameliorating pathologic heart disease is currently being tested in the RELAX trial ({"type":"clinical-trial","attrs":{"text":"NCT00763867","term_id":"NCT00763867"}}NCT00763867), an NIH-sponsored multicenter trial of sildenafil for treating heart failure with preserved ejection fraction. The major limitation of PDE1 studies to date has been the very limited availability of selective inhibitors (none are commercially available). As noted, the drug used by Miller et al. has been available to some at very limited quantities and there is little left. New agents in amounts that facilitate whole animal and even human studies are needed. In summary, we can add PDE1 to PDE5 as a likely important regulator of cGMP-hydrolysis and mediator of cardiac hypertrophy. Both appear to contribute as regulatory “brakes” to pathological remodeling, though the relative role and targeted signaling which may be species dependent, remains to be sorted out. The potential to combine both inhibitors as a therapy is intriguing and worthy of further studies. Future in vivo studies employing both genetic manipulation of each cGMP-hydrolyzing PDEs and use of chronic selective suppression will hopefully provide needed insights.
-
chronic inhibition of cyclic gmp phosphodiesterase 5a prevents and reverses cardiac hypertrophy
Nature Medicine, 2005Co-Authors: Eiki Takimoto, Djahida Bedja, Hunter C Champion, Diego F Belardi, Shuxun Ren, Rene E Rodriguez, Kathleen L Gabrielson, Yibin Wang, David A KassAbstract:Sustained cardiac pressure overload induces hypertrophy and pathological remodeling, frequently leading to heart failure. Genetically engineered hyperstimulation of guanosine 3',5'-cyclic monophosphate (cGMP) synthesis counters this response. Here, we show that blocking the intrinsic catabolism of cGMP with an oral phosphodiesterase-5A (PDE5A) inhibitor (sildenafil) suppresses chamber and myocyte hypertrophy, and improves in vivo heart function in mice exposed to chronic pressure overload induced by transverse aortic constriction. Sildenafil also reverses pre-established hypertrophy induced by pressure load while restoring chamber function to normal. cGMP catabolism by PDE5A increases in pressure-loaded hearts, leading to activation of cGMP-dependent protein kinase with inhibition of PDE5A. PDE5A inhibition deactivates multiple hypertrophy signaling pathways triggered by pressure load (the calcineurin/NFAT, phosphoinositide-3 kinase (PI3K)/Akt, and ERK1/2 signaling pathways). But it does not suppress hypertrophy induced by overexpression of calcineurin in vitro or Akt in vivo, suggesting upstream targeting of these pathways. PDE5A inhibition may provide a new treatment strategy for cardiac hypertrophy and remodeling.
-
cgmp catabolism by phosphodiesterase 5a regulates cardiac adrenergic stimulation by nos3 dependent mechanism
Circulation Research, 2004Co-Authors: Eiki Takimoto, Hunter C Champion, Diego F Belardi, Javid Moslehi, Marco Mongillo, Evanthia Mergia, David C Montrose, Takayoshi Isoda, Kate Aufiero, Manuela ZaccoloAbstract:Beta-adrenergic agonists stimulate cardiac contractility and simultaneously blunt this response by coactivating NO synthase (NOS3) to enhance cGMP synthesis and activate protein kinase G (PKG-1). cGMP is also catabolically regulated by phosphodiesterase 5A (PDE5A). PDE5A inhibition by sildenafil (Viagra) increases cGMP and is used widely to treat erectile dysfunction; however, its role in the heart and its interaction with beta-adrenergic and NOS3/cGMP stimulation is largely unknown. In nontransgenic (control) murine in vivo hearts and isolated myocytes, PDE5A inhibition (sildenafil) minimally altered rest function. However, when the hearts or isolated myocytes were stimulated with isoproterenol, PDE5A inhibition was associated with a suppression of contractility that was coupled to elevated cGMP and increased PKG-1 activity. In contrast, NOS3-null hearts or controls with NOS inhibited by N(G)-nitro-L-arginine methyl ester, or soluble guanylate cyclase (sGC) inhibited by 1H-[1,2,4]oxadiazolo[4,3-a]quinoxaline-1-one, showed no effect of PDE5A inhibition on beta-stimulated contractility or PKG-1 activation. This lack of response was not attributable to altered PDE5A gene or protein expression or in vitro PDE5A activity, but rather to an absence of sGC-generated cGMP specifically targeted to PDE5A catabolism and to a loss of PDE5A localization to z-bands. Re-expression of active NOS3 in NOS3-null hearts by adenoviral gene transfer restored PDE5A z-band localization and the antiadrenergic efficacy of PDE5A inhibition. These data support a novel regulatory role of PDE5A in hearts under adrenergic stimulation and highlight specific coupling of PDE5A catabolic regulation with NOS3-derived cGMP attributable to protein subcellular localization and targeted synthetic/catabolic coupling.
-
cgmp catabolism by phosphodiesterase 5a regulates cardiac adrenergic stimulation by nos3 dependent mechanism
Circulation Research, 2004Co-Authors: Eiki Takimoto, Hunter C Champion, Diego F Belardi, Javid Moslehi, Marco Mongillo, Evanthia Mergia, David C Montrose, Takayoshi Isoda, Kate Aufiero, Manuela ZaccoloAbstract:β-Adrenergic agonists stimulate cardiac contractility and simultaneously blunt this response by coactivating NO synthase (NOS3) to enhance cGMP synthesis and activate protein kinase G (PKG-1). cGMP is also catabolically regulated by phosphodiesterase 5A (PDE5A). PDE5A inhibition by sildenafil (Viagra) increases cGMP and is used widely to treat erectile dysfunction; however, its role in the heart and its interaction with β-adrenergic and NOS3/cGMP stimulation is largely unknown. In nontransgenic (control) murine in vivo hearts and isolated myocytes, PDE5A inhibition (sildenafil) minimally altered rest function. However, when the hearts or isolated myocytes were stimulated with isoproterenol, PDE5A inhibition was associated with a suppression of contractility that was coupled to elevated cGMP and increased PKG-1 activity. In contrast, NOS3-null hearts or controls with NOS inhibited by NG-nitro-l-arginine methyl ester, or soluble guanylate cyclase (sGC) inhibited by 1H-[1,2,4]oxadiazolo[4,3-a]quinoxaline-1-o...