Implications of PDE4 structure on inhibitor selectivity across PDE families

Ke, Hengming

doi:10.1038/sj.ijir.3901211

Cited by 25 publications

(13 citation statements)

References 15 publications

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“…The nuclear staining dye TO-PRO-3 was from Invitrogen (Karlsruhe, Germany); tetramethyl-rhodamine-isothiocyanate (TRITC)-conjugated peanut agglutinin (TRITC-PNA), propidium iodide, the calcium ionophor A23187, percoll, Triton-100, Fura2-AM, laminin, poly-L-ornithine, laminin, aprotinin, DNAse, the phosphodiesterase inhibitor 3-isobutyl-1-methylxanthine (IBMX) [89], rolipram [124], zaprinast [89] as well as the taste stimuli L-glutamate sodium salt (MSG), inosine 5′-monophosphate disodium salt (IMP), saccharin and acesulfam K were purchased from Sigma Aldrich (Deisenhofen, Germany). The sweet-tasting plant protein thaumatin was kindly provided by E. Tareilus (Unilever, Rotterdam, Netherlands).…”

Section: Methodsmentioning

confidence: 99%

Expression of Tas1 Taste Receptors in Mammalian Spermatozoa: Functional Role of Tas1r1 in Regulating Basal Ca2+ and cAMP Concentrations in Spermatozoa

et al. 2012

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BackgroundDuring their transit through the female genital tract, sperm have to recognize and discriminate numerous chemical compounds. However, our current knowledge of the molecular identity of appropriate chemosensory receptor proteins in sperm is still rudimentary. Considering that members of the Tas1r family of taste receptors are able to discriminate between a broad diversity of hydrophilic chemosensory substances, the expression of taste receptors in mammalian spermatozoa was examined.Methodology/Principal FindingsThe present manuscript documents that Tas1r1 and Tas1r3, which form the functional receptor for monosodium glutamate (umami) in taste buds on the tongue, are expressed in murine and human spermatozoa, where their localization is restricted to distinct segments of the flagellum and the acrosomal cap of the sperm head. Employing a Tas1r1-deficient mCherry reporter mouse strain, we found that Tas1r1 gene deletion resulted in spermatogenic abnormalities. In addition, a significant increase in spontaneous acrosomal reaction was observed in Tas1r1 null mutant sperm whereas acrosomal secretion triggered by isolated zona pellucida or the Ca2+ ionophore A23187 was not different from wild-type spermatozoa. Remarkably, cytosolic Ca2+ levels in freshly isolated Tas1r1-deficient sperm were significantly higher compared to wild-type cells. Moreover, a significantly higher basal cAMP concentration was detected in freshly isolated Tas1r1-deficient epididymal spermatozoa, whereas upon inhibition of phosphodiesterase or sperm capacitation, the amount of cAMP was not different between both genotypes.Conclusions/SignificanceSince Ca2+ and cAMP control fundamental processes during the sequential process of fertilization, we propose that the identified taste receptors and coupled signaling cascades keep sperm in a chronically quiescent state until they arrive in the vicinity of the egg - either by constitutive receptor activity and/or by tonic receptor activation by gradients of diverse chemical compounds in different compartments of the female reproductive tract.

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Section: Methodsmentioning

confidence: 99%

Expression of Tas1 Taste Receptors in Mammalian Spermatozoa: Functional Role of Tas1r1 in Regulating Basal Ca2+ and cAMP Concentrations in Spermatozoa

et al. 2012

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“…This large superfamily of PDEs is subdivided into 11 distinct families based on structure, regulation, and kinetic properties. PDE families also are distinguished functionally by their unique pharmacological inhibitors (157,298,373,556). They share common structural features, having targeting domains and regulatory domains in the NH 2 -terminal region and a conserved catalytic domain consisting of 270 -300 amino acids, usually located toward the COOH-terminal half of the protein.…”

Section: B Phosphodiesterasesmentioning

confidence: 99%

PKA-Dependent and PKA-Independent Pathways for cAMP-Regulated Exocytosis

Seino¹,

Shibasaki²

2005

Physiological Reviews

512

447

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Stimulus-secretion coupling is an essential process in secretory cells in which regulated exocytosis occurs, including neuronal, neuroendocrine, endocrine, and exocrine cells. While an increase in intracellular Ca(2+) concentration ([Ca(2+)](i)) is the principal signal, other intracellular signals also are important in regulated exocytosis. In particular, the cAMP signaling system is well known to regulate and modulate exocytosis in a variety of secretory cells. Until recently, it was generally thought that the effects of cAMP in regulated exocytosis are mediated by activation of cAMP-dependent protein kinase (PKA), a major cAMP target, followed by phosphorylation of the relevant proteins. Although the involvement of PKA-independent mechanisms has been suggested in cAMP-regulated exocytosis by pharmacological approaches, the molecular mechanisms are unknown. Newly discovered cAMP-GEF/Epac, which belongs to the cAMP-binding protein family, exhibits guanine nucleotide exchange factor activities and exerts diverse effects on cellular functions including hormone/transmitter secretion, cell adhesion, and intracellular Ca(2+) mobilization. cAMP-GEF/Epac mediates the PKA-independent effects on cAMP-regulated exocytosis. Thus cAMP regulates and modulates exocytosis by coordinating both PKA-dependent and PKA-independent mechanisms. Localization of cAMP within intracellular compartments (cAMP compartmentation or compartmentalization) may be a key mechanism underlying the distinct effects of cAMP in different domains of the cell.

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“…There is as yet no crystal structure of any PDE1 holoenzyme either with or without calmodulin in complex, so the orientation of how the calmodulin molecules are bound, how the inhibitory region interacts with the catalytic region, or how the binding of calmodulin activates the enzyme is not known with any precision. However, the crystal structure of the PDE1B catalytic domain has been solved , and in general it is very similar to the other five PDE catalytic domain structures (Card et al, 2004;Ke, 2004). Biochemical data suggest that binding of Ca ϩ2 / CaM relieves an inhibition of activity (Sonnenburg et al, 1995).…”

Section: Overviewmentioning

confidence: 99%