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Ca2+-stimulated adenylyl cyclases as therapeutic targets for psychiatric and neurodevelopmental disorders. Front Pharmacol 2022; 13:949384. [PMID: 36188604 PMCID: PMC9523369 DOI: 10.3389/fphar.2022.949384] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Accepted: 09/05/2022] [Indexed: 11/13/2022] Open
Abstract
As the main secondary messengers, cyclic AMP (cAMP) and Ca2+ trigger intracellular signal transduction cascade and, in turn, regulate many aspects of cellular function in developing and mature neurons. The group I adenylyl cyclase (ADCY, also known as AC) isoforms, including ADCY1, 3, and 8 (also known as AC1, AC3, and AC8), are stimulated by Ca2+ and thus functionally positioned to integrate cAMP and Ca2+ signaling. Emerging lines of evidence have suggested the association of the Ca2+-stimulated ADCYs with bipolar disorder, schizophrenia, major depressive disorder, post-traumatic stress disorder, and autism. In this review, we discuss the molecular and cellular features as well as the physiological functions of ADCY1, 3, and 8. We further discuss the recent therapeutic development to target the Ca2+-stimulated ADCYs for potential treatments of psychiatric and neurodevelopmental disorders.
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Abstract
Adenylyl cyclases (ACs) catalyze the conversion of ATP to the ubiquitous second messenger cAMP. Mammals possess nine isoforms of transmembrane ACs, dubbed AC1-9, that serve as major effector enzymes of G protein-coupled receptors. The transmembrane ACs display varying expression patterns across tissues, giving potential for them having a wide array of physiologic roles. Cells express multiple AC isoforms, implying that ACs have redundant functions. Furthermore, all transmembrane ACs are activated by Gαs so it was long assumed that all ACs are activated by Gαs-coupled GPCRs. AC isoforms partition to different microdomains of the plasma membrane and form prearranged signaling complexes with specific GPCRs that contribute to cAMP signaling compartments. This compartmentation allows for a diversity of cellular and physiological responses by enabling unique signaling events to be triggered by different pools of cAMP. Isoform specific pharmacological activators or inhibitors are lacking for most ACs, making knockdown and overexpression the primary tools for examining the physiological roles of a given isoform. Much progress has been made in understanding the physiological effects mediated through individual transmembrane ACs. GPCR-AC-cAMP signaling pathways play significant roles in regulating functions of every cell and tissue, so understanding each AC isoform's role holds potential for uncovering new approaches for treating a vast array of pathophysiological conditions.
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Expression pattern of type 3 adenylyl cyclase in rodent dorsal root ganglion and its primary afferent terminals. Neurosci Lett 2019; 692:16-22. [PMID: 30366013 DOI: 10.1016/j.neulet.2018.10.049] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Revised: 09/20/2018] [Accepted: 10/22/2018] [Indexed: 01/09/2023]
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How does your kidney smell? Emerging roles for olfactory receptors in renal function. Pediatr Nephrol 2016; 31:715-23. [PMID: 26264790 PMCID: PMC4752438 DOI: 10.1007/s00467-015-3181-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/21/2015] [Revised: 06/24/2015] [Accepted: 07/22/2015] [Indexed: 12/12/2022]
Abstract
Olfactory receptors (ORs) are chemosensors that are responsible for one's sense of smell. In addition to this specialized role in the nose, recent evidence suggests that ORs are also found in a variety of additional tissues including the kidney. As this list of renal ORs continues to expand, it is becoming clear that they play important roles in renal and whole-body physiology, including a novel role in blood pressure regulation. In this review, we highlight important considerations that are crucial when studying ORs and present the current literature on renal ORs and their emerging relevance in maintaining renal function.
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The type 3 adenylyl cyclase is required for the survival and maturation of newly generated granule cells in the olfactory bulb. PLoS One 2015; 10:e0122057. [PMID: 25807252 PMCID: PMC4373939 DOI: 10.1371/journal.pone.0122057] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2014] [Accepted: 02/06/2015] [Indexed: 01/14/2023] Open
Abstract
The type 3 adenylyl cyclase (AC3) is localized to olfactory cilia in the main olfactory epithelium (MOE) and primary cilia in the adult mouse brain. Although AC3 has been strongly implicated in odor perception and olfactory sensory neuron (OSN) targeting, its role in granule cells (GCs), the most abundant interneurons in the main olfactory bulb (MOB), remains largely unknown. Here, we report that the deletion of AC3 leads to a significant reduction in the size of the MOB as well as the level of adult neurogenesis. The cell proliferation and cell cycle in the subventricular zone (SVZ), however, are not suppressed in AC3-/- mice. Furthermore, AC3 deletion elevates the apoptosis of GCs and disrupts the maturation of newly formed GCs. Collectively, our results identify a fundamental role for AC3 in the development of adult-born GCs in the MOB.
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Extrasensory perception: odorant and taste receptors beyond the nose and mouth. Pharmacol Ther 2013; 142:41-61. [PMID: 24280065 DOI: 10.1016/j.pharmthera.2013.11.004] [Citation(s) in RCA: 80] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2013] [Accepted: 11/04/2013] [Indexed: 12/22/2022]
Abstract
G protein-coupled receptors (GPCRs) represent the largest family of transmembrane receptors and are prime therapeutic targets. The odorant and taste receptors account for over half of the GPCR repertoire, yet they are generally excluded from large-scale, drug candidate analyses. Accumulating molecular evidence indicates that the odorant and taste receptors are widely expressed throughout the body and functional beyond the oronasal cavity - with roles including nutrient sensing, autophagy, muscle regeneration, regulation of gut motility, protective airway reflexes, bronchodilation, and respiratory disease. Given this expanding array of actions, the restricted perception of these GPCRs as mere mediators of smell and taste is outdated. Moreover, delineation of the precise actions of odorant and taste GPCRs continues to be hampered by the relative paucity of selective and specific experimental tools, as well as the lack of defined receptor pharmacology. In this review, we summarize the evidence for expression and function of odorant and taste receptors in tissues beyond the nose and mouth, and we highlight their broad potential in physiology and pathophysiology.
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Interactions between intracellular free Ca2+ and cyclic AMP in neuroendocrine cells. Cell Calcium 2012; 51:260-6. [PMID: 22385836 DOI: 10.1016/j.ceca.2011.12.013] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2011] [Revised: 12/12/2011] [Accepted: 12/22/2011] [Indexed: 11/29/2022]
Abstract
Calcium ions and cyclic adenosine monophosphate (cAMP) are virtually ubiquitous intracellular signaling molecules in mammalian cells. This paper will focus on the cross-talk between Ca(2+) and cAMP mobilizing signaling pathways and summarize the underlying molecular mechanisms. Subsequently, workings of adenohypophyseal corticotrope cells will be reviewed to highlight the physiological relevance of a Ca(2+) cAMP interactions in neuroendocrinology.
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Is the lifetime of light-stimulated cGMP phosphodiesterase regulated by recoverin through its regulation of rhodopsin phosphorylation? Behav Brain Sci 2010. [DOI: 10.1017/s0140525x00039522] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Are pheromones detected through the main olfactory epithelium? Mol Neurobiol 2008; 35:317-23. [PMID: 17917120 DOI: 10.1007/s12035-007-0014-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2006] [Revised: 11/30/1999] [Accepted: 01/12/2007] [Indexed: 10/23/2022]
Abstract
A major sensory organ for the detection of pheromones by animals is the vomeronasal organ (VNO). Although pheromones control the behaviors of various species, the effect of pheromones on human behavior has been controversial because the VNO is not functional in adults. However, recent genetic, biochemical, and electrophysiological data suggest that some pheromone-based behaviors, including male sexual behavior in mice, are mediated through the main olfactory epithelium (MOE) and are coupled to the type 3 adenylyl cyclase (AC3) and a cyclic nucleotide-gated (CNG) ion channel. These recent discoveries suggest the provocative hypothesis that human pheromones may signal through the MOE.
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Introduction of bisecting GlcNAc in N-glycans of adenylyl cyclase III enhances its activity. Glycobiology 2007; 17:655-62. [PMID: 17324955 DOI: 10.1093/glycob/cwm022] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Adenylyl cyclases (ACs) catalyze the synthesis of cAMP in response to extracellular and intracellular signals and are responsible for a wide variety of biological activities including cell growth, differentiation, and metabolism. There are nine, currently known, isoforms of transmembrane ACs, and the primary structure of the catalytic unit and the potential N-glycosylation sites are highly conserved among them. The enzyme beta1,4-N-acetylglucosaminyltransferase III (GnT-III) catalyzes the addition of a bisecting N-acetylglucosamine (GlcNAc) to N-glycans. We have been studying the function of GnT-III on signaling molecules. In this study, we report on the effects of a bisecting GlcNAc on AC signaling. We established GnT-III stable expressing cell lines of Neuro-2a mouse neuroblastoma cells and B16 mouse melanoma cells. Forskolin-induced AC activation and downstream signaling, such as the synthesis of cAMP and the phosphorylation of transcriptional factor CRE-binding protein were upregulated in the GnT-III transfectants compared with mock transfectants or a dominant negative mutant of GnT-III-transfected cells. Since endogenous AC expression levels in Neuro-2a and B16 cells were too low to permit the glycosylation status to be examined, AC type III (ACIII) was overexpressed in a stable expression system using Flp-In-293 cells. The N-glycans of ACIII in the GnT-III transfectants were confirmed to be modified by the introduction of a bisecting GlcNAc, and AC activity was found to be significantly up-regulated in the GnT-III transfectants. Thus, the structure of N-glycans of ACIII regulates its enzymatic activity and downstream signaling.
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Pheromone detection in male mice depends on signaling through the type 3 adenylyl cyclase in the main olfactory epithelium. J Neurosci 2006; 26:7375-9. [PMID: 16837584 PMCID: PMC6674185 DOI: 10.1523/jneurosci.1967-06.2006] [Citation(s) in RCA: 122] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Terrestrial vertebrates have evolved two anatomically and mechanistically distinct chemosensory structures: the main olfactory epithelium (MOE) and the vomeronasal organ (VNO). Although it has been generally thought that pheromones are detected through the VNO, whereas other chemicals are sensed by the MOE, recent evidence suggests that some pheromones may be detected through the MOE. Odorant receptors in the MOE are coupled to the type 3 adenylyl cyclase (AC3), an enzyme not expressed in the VNO. Consequently, odorants and pheromones do not elicit electrophysiological responses in the MOE of AC3-/- mice, although VNO function is intact. Here we report that AC3-/- mice cannot detect mouse milk, urine, or mouse pheromones. Inter-male aggressiveness and male sexual behaviors are absent in AC3-/- mice. Furthermore, adenylyl cyclase activity in membranes prepared from the MOE of wild-type mice, but not AC3-/- mice, is stimulated by 2-heptanone, a mouse pheromone. We conclude that signaling through AC3 in the MOE is obligatory for male sexual behavior, male-male aggressiveness, and the detection of some pheromones.
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Abstract
Nerve growth factor (NGF) and the ubiquitous second messenger cyclic AMP (cAMP) are both implicated in neuronal differentiation. Multiple studies indicate that NGF signals to at least a subset of its targets via cAMP, but the link between NGF and cAMP has remained elusive. Here, we have described the use of small molecule inhibitors to differentiate between the two known sources of cAMP in mammalian cells, bicarbonate- and calcium-responsive soluble adenylyl cyclase (sAC) and G protein-regulated transmembrane adenylyl cyclases. These inhibitors, along with sAC-specific small interfering RNA, reveal that sAC is uniquely responsible for the NGF-elicited rise in cAMP and is essential for the NGF-induced activation of the small G protein Rap1 in PC12 cells. In contrast and as expected, transmembrane adenylyl cyclase-generated cAMP is responsible for Rap1 activation by the G protein-coupled receptor ligand PACAP (pituitary adenylyl cyclase-activating peptide). These results identify sAC as a mediator of NGF signaling and reveal the existence of distinct pathways leading to cAMP-dependent signal transduction.
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Abstract
Activation of receptors coupled to inhibitory G proteins (Galpha i/o) has opposing consequences for cyclic AMP accumulation and the activity of cyclic AMP-dependent protein kinase, depending on the duration of stimulation. Acute activation inhibits the activity of adenylate cyclase, thereby attenuating cyclic AMP accumulation; in contrast, persistent activation of Galpha i/o-coupled receptors produces a paradoxical enhancement of adenylate cyclase activity, thus increasing cyclic AMP accumulation when the action of the inhibitory receptor is terminated. This heterologous sensitization of cyclic AMP signaling, also called superactivation or supersensitization, likely represents a cellular adaptive response, a mechanism by which the cell compensates for chronic inhibitory input. Recent advances in our knowledge of G protein-mediated signaling, regulation of adenylate cyclase, and other cellular signaling mechanisms have extensively increased our insight into the mechanisms and significance of this phenomenon. In particular, recent evidence points to the Galpha(s)-adenylate cyclase interface as a locus for the expression of the sensitized adenylate cyclase response, and to isoform-specific phosphorylation of adenylate cyclase as one mechanism that can produce sensitization. Galpha i/o-coupled receptor-induced heterologous sensitization may contribute to enhanced Galpha(s)-coupled receptor signaling following neurotransmitter elevations induced by the administration of drugs of abuse and during other types of neuronal function or dysfunction. This review will focus on recent advances in our understanding of signaling pathways that are involved in sensitization and describe the potential role of sensitization in neuronal function.
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Calmodulin is required for vasopressin-stimulated increase in cyclic AMP production in inner medullary collecting duct. J Biol Chem 2005; 280:13624-30. [PMID: 15710610 PMCID: PMC1182701 DOI: 10.1074/jbc.m500040200] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Calmodulin plays a critical role in regulation of renal collecting duct water permeability by vasopressin. However, specific targets for calmodulin action have not been thoroughly addressed. In the present study, we investigated whether Ca2+/calmodulin regulates adenylyl cyclase activity in the renal inner medullary collecting duct. Rat inner medullary collecting duct suspensions were incubated in the presence or absence of 0.1 nM vasopressin and the calmodulin inhibitors, monodansylcadaverine, W-7, and trifluoperazine, followed by measurement of cAMP. Vasopressin-stimulated cAMP elevation was significantly attenuated in the presence of calmodulin inhibitors. Analysis of transglutaminase 2 knock-out mice confirmed that these compounds were not acting through inhibition of transglutaminase 2 activity. Calmodulin inhibitors also blocked both cholera toxin- and forskolin-stimulated cAMP accumulation. In isolated perfused tubules, W-7 reversibly blocked vasopressin-stimulated urea permeability, a process that requires a rise in intracellular cAMP but does not appear to involve protein trafficking to the apical plasma membrane. These results suggest that calmodulin is required for vasopressin-stimulated adenylyl cyclase activity in the intact inner medullary collecting duct. Reverse transcription-PCR, immunoblotting, and immunohistochemistry revealed the presence of the calmodulin-sensitive adenylyl cyclase type 3 in the rat collecting duct, an isoform previously not known to be expressed in the collecting duct. Long-term treatment of Brattleboro rats with a vasopressin analog markedly decreased adenylyl cyclase type 3 protein abundance, providing an explanation for long-term down-regulation of vasopressin response in the collecting duct. These studies demonstrate the importance of calmodulin in the regulation of collecting duct adenylyl cyclase activity and transport function.
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Long lasting inhibition of adenylyl cyclase selectively mediated by inositol 1,4,5-trisphosphate-evoked calcium release. J Biol Chem 2005; 280:8936-44. [PMID: 15632122 DOI: 10.1074/jbc.m410045200] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
In A7r5 smooth muscle cells, vasopressin stimulates release of Ca2+ from intracellular stores and Ca2+ entry, and it inhibits adenylyl cyclase (AC) activity. Inhibition of AC is prevented by inhibition of phospholipase C or when the increase in cytosolic [Ca2+] is prevented by the Ca2+ buffer, BAPTA. It is unaffected by pertussis toxin, inhibition of protein kinase C, or L-type Ca2+ channels or by removal of extracellular Ca2+. The independence of extracellular Ca2+ occurs despite inhibition of AC by vasopressin persisting for at least 15 min, whereas the cytosolic [Ca2+] returns to its basal level within 1-2 min in Ca2+-free medium. Although capacitative Ca2+ entry (CCE), activated by emptying stores with thapsigargin, inhibits AC, Ca2+ entry via CCE or L-type Ca2+ channels activated by vasopressin is ineffective. Temporally separating vasopressin-evoked Ca2+ release from the assessment of AC activity revealed that the transient Ca2+ signal resulting from Ca2+ mobilization causes a long lasting inhibition of AC. By contrast, inhibition of AC by thapsigargin-evoked CCE reverses rapidly after removal of extracellular Ca2+. Inhibition of AC by vasopressin is prevented by inhibition of Ca2+-calmodulin-dependent protein kinase II. We conclude that persistent inhibition of AC (probably AC-3) by vasopressin is mediated by inositol trisphosphate-evoked Ca2+ release causing activation of Ca2+-calmodulin-dependent protein kinase II. Our results establish that an important interaction between two ubiquitous signaling pathways is tuned selectively to Ca2+ release via inositol trisphosphate receptors and that the interaction transduces a transient Ca2+ signal into a long lasting inhibition of AC.
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Dopamine D2 receptor-activated Ca2+ signaling modulates voltage-sensitive sodium currents in rat nucleus accumbens neurons. J Neurophysiol 2004; 93:1406-17. [PMID: 15590733 DOI: 10.1152/jn.00771.2004] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Receptor-mediated dopamine (DA) modulation of neuronal excitability in the nucleus accumbens (NAc) has been shown to be critically involved in drug addiction and a variety of brain diseases. However, the mechanisms underlying the physiological or pathological molecular process of DA modulation remain largely elusive. Here, we demonstrate that stimulation of DA D2 class receptors (D2R) enhanced voltage-sensitive sodium currents (VSSCs, I(Na)) in freshly dissociated NAc neurons via suppressing tonic activity of the cyclic AMP/PKA cascade and facilitating intracellular Ca2+ signaling. D2R-mediated I(Na) enhancement depended on activation of G(i/o) proteins and was mimicked by direct inhibition of PKA. Furthermore, increasing free [Ca2+]in by activating inositol 1,4,5-triphosphate receptors (IP3Rs), blocking Ca2+ reuptake, or adding buffered Ca2+, all enhanced I(Na). Under these circumstances, D2R-mediated I(Na) enhancement was occluded. In contrast, D2R-mediated I(Na) enhancement was blocked by inhibition of IP3Rs, chelation of free Ca2+, or inhibition of Ca2(+)/calmodulin-activated calcineurin (CaN), but not by inhibition of phospholipase C (PLC). Although stimulation of muscarinic cholinergic receptors (mAChRs) also increased I(Na), this action was blocked by PLC inhibitors. Our findings indicate that D2Rs mediate an enhancement of VSSCs in NAc neurons, in which cytosolic free Ca2+ plays a crucial role. Our results also suggest that D2R-mediated reduction in tonic PKA activity may increase free [Ca2+]in, primarily via disinhibition of IP3Rs. IP3R activation then facilitates Ca2+ signaling and subsequently enhances VSSCs via decreasing PKA-induced phosphorylation and increasing CaN-induced dephosphorylation of Na+ channels. This study provides insight into the complex and dynamic role of D2Rs in the NAc.
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Endoplasmic reticulum degradation impedes olfactory G-protein coupled receptor functional expression. BMC Cell Biol 2004; 5:34. [PMID: 15369603 PMCID: PMC520810 DOI: 10.1186/1471-2121-5-34] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2004] [Accepted: 09/15/2004] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Research on olfactory G-protein coupled receptors (GPCRs) has been severely impeded by poor functional expression in heterologous systems. Previously, we demonstrated that inefficient olfactory receptor (OR) expression at the plasma membrane is attributable, in part, to degradation of endoplasmic reticulum (ER)-retained ORs by the ubiquitin-proteasome system and sequestration of ORs in ER aggregates that are degraded by autophagy. Thus, experiments were performed to test the hypothesis that attenuation of ER degradation improves OR functional expression in heterologous cells. RESULTS To develop means to increase the functional expression of ORs, we devised an approach to measure activation of the mOREG OR (Unigene # Mm.196680; Olfr73) through coupling to an olfactory cyclic nucleotide-gated cation channel (CNG). This system, which utilizes signal transduction machinery coupled to OR activation in native olfactory sensory neurons, was used to demonstrate that degradation, both by the ubiquitin-proteasome system and autophagy, limits mOREG functional expression. The stimulatory effects of proteasome and autophagy inhibitors on mOREG function required export from the ER and trafficking through the biosynthetic pathway. CONCLUSIONS These findings demonstrate that poor functional expression of mOREG in heterologous cells is improved by blocking proteolysis. Inhibition of ER degradation may improve the function of other ORs and assist future efforts to elucidate the molecular basis of odor discrimination.
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Particulate Adenylate Cyclase Plays a Key Role in Human Sperm Olfactory Receptor-mediated Chemotaxis. J Biol Chem 2004; 279:40194-203. [PMID: 15271985 DOI: 10.1074/jbc.m403913200] [Citation(s) in RCA: 113] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Human sperm chemotaxis is a critical component of the fertilization process, but the molecular basis for this behavior remains unclear. Recent evidence shows that chemotactic responses depend on activation of the sperm olfactory receptor, hOR17-4. Certain floral scents, including bourgeonal, activate hOR17-4, trigger pronounced Ca(2+) fluxes, and evoke chemotaxis. Here, we provide evidence that hOR17-4 activation is coupled to a cAMP-mediated signaling cascade. Multidimensional protein identification technology was used to identify potential components of a G-protein-coupled cAMP transduction pathway in human sperm. These products included various membrane-associated adenylate cyclase (mAC) isoforms and the G(olf)-subunit. Using immunocytochemistry, specific mAC isoforms were localized to particular cell regions. Whereas mAC III occurred in the sperm head and midpiece, mAC VIII was distributed predominantly in the flagellum. In contrast, G(olf) was found mostly in the flagellum and midpiece. The observed spatial distribution patterns largely correspond to the spatiotemporal character of hOR17-4-induced Ca(2+) changes. Behavioral and Ca(2+) signaling responses of human sperm to bourgeonal were bioassayed in the presence, or absence, of the adenylate cyclase antagonist SQ22536. This specific agent inhibits particulate AC, but not soluble AC, activation. Upon incubation with SQ22536, cells ceased to exhibit Ca(2+) signaling, chemotaxis, and hyperactivation (faster swim speed and flagellar beat rate) in response to bourgeonal. Particulate AC is therefore required for induction of hOR17-4-mediated human sperm behavior and represents a promising target for future design of contraceptive drugs.
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Abstract
The intracellular levels of cAMP play a critical role in the meiotic arrest of mammalian oocytes. However, it is debated whether this second messenger is produced endogenously by the oocytes or is maintained at levels inhibitory to meiotic resumption via diffusion from somatic cells. Here, we demonstrate that adenylyl cyclase genes and corresponding proteins are expressed in rodent oocytes. The mRNA coding for the AC3 isoform of adenylyl cyclase was detected in rat and mouse oocytes by RT-PCR and by in situ hybridization. The expression of AC3 protein was confirmed by immunocytochemistry and immunofluorescence analysis in oocytes in situ. Cyclic AMP accumulation in denuded oocytes was increased by incubation with forskolin, and this stimulation was abolished by increasing intraoocyte Ca(2+) with the ionophore A23187. The Ca(2+) effects were reversed by an inhibitor of Ca(2+), calmodulin-dependent kinase II. These regulations of cAMP levels indicate that the major cyclase that produces cAMP in the rat oocyte has properties identical to those of recombinant or endogenous AC3 expressed in somatic cells. Furthermore, mouse oocytes deficient in AC3 show signs of a defect in meiotic arrest in vivo and accelerated spontaneous maturation in vitro. Collectively, these data provide evidence that an adenylyl cyclase is functional in rodent oocytes and that its activity is involved in the control of oocyte meiotic arrest.
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Calmodulin-regulated adenylyl cyclases: cross-talk and plasticity in the central nervous system. Mol Pharmacol 2003; 63:463-8. [PMID: 12606751 DOI: 10.1124/mol.63.3.463] [Citation(s) in RCA: 170] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Gene disruption studies have shown that the Ca(2+)-stimulated adenylyl cyclases, AC1 and AC8, are critical for some forms of synaptic plasticity, including long-term potentiation as well as long-term memory formation (LTM). It is hypothesized that these enzymes are required for LTM to support the increased expression of a family of genes regulated through the cAMP/Ca(2+) response element-binding protein/cAMP response element transcriptional pathway. In contrast to AC1 and AC8, AC3 is a Ca(2+)-inhibited adenylyl cyclase that plays an essential role in olfactory signal transduction. Coupling of odorant receptors to AC3 stimulates cAMP transients that function as the major second messenger for olfactory signaling. These cAMP transients are caused, at least in part, by Ca(2+) inhibition of AC3, which is mediated through calmodulin-dependent protein kinase II. The unique structure and regulatory properties of these adenylyl cyclases make them attractive drug target sites for modulation of a number of physiological processes including memory formation and olfaction.
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Type-specific regulation of adenylyl cyclase. Selective pharmacological stimulation and inhibition of adenylyl cyclase isoforms. J Biol Chem 2001; 276:47785-93. [PMID: 11602596 DOI: 10.1074/jbc.m107233200] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Crystallographic studies have elucidated the binding mechanism of forskolin and P-site inhibitors to adenylyl cyclase. Accordingly, computer-assisted drug design has enabled us to identify isoform-selective regulators of adenylyl cyclase. After examining more than 200 newly synthesized derivatives of forskolin, we found that the modification at the positions of C6 and C7, in general, enhances isoform selectivity. The 6-(3-dimethylaminopropionyl) modification led to an enhanced selectivity for type V, whereas 6-[N-(2-isothiocyanatoethyl) aminocarbonyl] and 6-(4-acrylbutyryl) modification led to an enhanced selectivity for type II. In contrast, 2'-deoxyadenosine 3'-monophosphate, a classical and 3'-phosphate-substituted P-site inhibitor, demonstrated a 27-fold selectivity for inhibiting type V relative to type II, whereas 9-(tetrahydro-2-furyl) adenine, a ribose-substituted P-site ligand, showed a markedly increased, 130-fold selectivity for inhibiting type V. Consequently, on the basis of the pharmacophore analysis of 9-(tetrahydro-2-furyl) adenine and adenylyl cyclase, a novel non-nucleoside inhibitor, 2-amino-7-(2-furanyl)-7,8-dihydro-5(6H)-quinazolinone (NKY80), was identified after virtual screening of more than 850,000 compounds. NKY80 demonstrated a 210-fold selectivity for inhibiting type V relative to type II. More importantly, the combination of a type III-selective forskolin derivative and 9-(tetrahydro-2-furyl) adenine or NKY80 demonstrated a further enhanced selectivity for type III stimulation over other isoforms. Our data suggest the feasibility of adenylyl cyclase isoform-targeted regulation of cyclic AMP signaling by pharmacological reagents, either alone or in combination.
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Adenylyl cyclase 3 mediates prostaglandin E(2)-induced growth inhibition in arterial smooth muscle cells. J Biol Chem 2001; 276:34206-12. [PMID: 11432866 DOI: 10.1074/jbc.m103923200] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Arterial smooth muscle cell (SMC) proliferation contributes to a number of vascular pathologies. Prostaglandin E(2) (PGE(2)), produced by the endothelium and by SMCs themselves, acts as a potent SMC growth inhibitor. The growth-inhibitory effects of PGE(2) are mediated through activation of G-protein-coupled membrane receptors, activation of adenylyl cyclases (ACs), formation of cAMP, and subsequent inhibition of mitogenic signal transduction pathways in SMCs. Of the 10 different mammalian AC isoforms known today, seven isoforms (AC2-7 and AC9) are expressed in SMCs from various species. We show that, despite the presence of several different AC isoforms, the principal AC isoform activated by PGE(2) in human arterial SMCs is a calmodulin kinase II-inhibited AC with characteristics similar to those of AC3. AC3 is expressed in isolated human arterial SMCs and in intact aorta. We further show that arterial SMCs isolated from AC3-deficient mice are resistant to PGE(2)-induced growth inhibition. In summary, AC3 is the principal AC isoform activated by PGE(2) in arterial SMCs, and AC3 mediates the growth-inhibitory effects of PGE(2). Because AC3 activity is inhibited by intracellular calcium through calmodulin kinase II, AC3 may serve as an important integrator of growth-inhibitory signals that stimulate cAMP formation and growth factors that increase intracellular calcium.
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Abstract
At least nine closely related isoforms of adenylyl cyclases (ACs), the enzymes responsible for the synthesis of cyclic AMP (cAMP) from ATP, have been cloned and characterized in mammals. Depending on the properties and the relative levels of the isoforms expressed in a tissue or a cell type at a specific time, extracellular signals received through the G-protein-coupled receptors can be differentially integrated. The present review deals with various aspects of such regulations, emphasizing the role of calcium/calmodulin in activating AC1 and AC8 in the central nervous system, the potential inhibitory effect of calcium on AC5 and AC6, and the changes in the expression pattern of the isoforms during development. A particular emphasis is given to the role of cAMP during drug and ethanol dependency and to some experimental limitations (pitfalls in the interpretation of cellular transfection, scarcity of the invalidation models, existence of complex macromolecular structures, etc).
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Characterization of adenylyl cyclase isoforms in rat peripheral pulmonary arteries. Am J Physiol Lung Cell Mol Physiol 2001; 280:L1359-69. [PMID: 11350817 DOI: 10.1152/ajplung.2001.280.6.l1359] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Activation of adenylyl cyclase (AC), of which there are 10 diversely regulated isoforms, is important in regulating pulmonary vascular tone and remodeling. Immunohistochemistry in rat lungs demonstrated that AC2, AC3, and AC5/6 predominated in vascular and bronchial smooth muscle. Isoforms 1, 4, 7, and 8 localized to the bronchial epithelium. Exposure of animals to hypoxia did not change the pattern of isoform expression. RT-PCR confirmed mRNA expression of AC2, AC3, AC5, and AC6 and demonstrated AC7 and AC8 transcripts in smooth muscle. Western blotting confirmed the presence of AC2, AC3, and AC5/6 proteins. Functional studies provided evidence of cAMP regulation by Ca(2+) and protein kinase C-activated but not G(i)-inhibited pathways, supporting a role for AC2 and a Ca(2+)-stimulated isoform, AC8. However, NKH-477, an AC5-selective activator, was more potent than forskolin in elevating cAMP and inhibiting serum-stimulated [(3)H]thymidine incorporation, supporting the presence of AC5. These studies demonstrate differential expression of AC isoforms in rat lungs and provide evidence that AC2, AC5, and AC8 are functionally important in cAMP regulation and growth pathways in pulmonary artery myocytes.
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MESH Headings
- Adenylyl Cyclases/chemistry
- Adenylyl Cyclases/genetics
- Adenylyl Cyclases/metabolism
- Animals
- Blotting, Western
- Cell Division/drug effects
- Cells, Cultured
- Colforsin/analogs & derivatives
- Colforsin/pharmacology
- Cyclic AMP/metabolism
- Dose-Response Relationship, Drug
- Enzyme Activation/drug effects
- Enzyme Activators/pharmacology
- Enzyme Inhibitors/pharmacology
- Hypertension, Pulmonary/metabolism
- Hypoxia/enzymology
- Immunohistochemistry
- Isoenzymes/chemistry
- Isoenzymes/metabolism
- Male
- Muscle, Smooth, Vascular/cytology
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/enzymology
- Organ Specificity
- Protein Kinase C/antagonists & inhibitors
- Protein Kinase C/metabolism
- Pulmonary Artery/cytology
- Pulmonary Artery/enzymology
- RNA, Messenger/biosynthesis
- Rats
- Rats, Inbred WKY
- Reverse Transcriptase Polymerase Chain Reaction
- Vasodilator Agents/pharmacology
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Adenylyl cyclase type 7 is the predominant isoform in the bovine retinal pigment epithelium. ACTA ANATOMICA 2000; 162:157-62. [PMID: 9831763 DOI: 10.1159/000046481] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The retinal pigment epithelium (RPE) fulfills important supporting tasks to maintain the visual functions of the sensorineural retina. One major signalling mechanism by which adjacent tissues impinge on the RPE is the adenylyl cyclase (AC)/cAMP pathway. In the RPE, cAMP seems to modulate unique functions such as the phagocytosis of discs shed from the rod outer segments, transport of vitamin A or the ion and fluid control in the subretinal space. We analyzed the AC expression pattern in the retina and the RPE and found AC type 7 to be almost the only isoform expressed in the RPE. We cloned AC type 7 from a cDNA library established with fresh bovine RPE, expressed this isoform in eukaryotic cells and characterized some of its properties.
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Tissue specificity and physiological relevance of various isoforms of adenylyl cyclase. Am J Physiol Renal Physiol 2000; 279:F400-16. [PMID: 10966920 DOI: 10.1152/ajprenal.2000.279.3.f400] [Citation(s) in RCA: 286] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The present review focuses on the potential physiological regulations involving different isoforms of adenylyl cyclase (AC), the enzymatic activity responsible for the synthesis of cAMP from ATP. Depending on the properties and the relative level of the isoforms expressed in a tissue or a cell type at a specific time, extracellular signals received by the G protein-coupled receptors can be differently integrated. We report here on various aspects of such regulations, emphasizing the role of Ca(2+)/calmodulin in activating AC1 and AC8 in the central nervous system, the potential inhibitory effect of Ca(2+) on AC5 and AC6, and the changes in the expression pattern of the isoforms during development. A particular emphasis is given to the role of cAMP during drug dependence. Present experimental limitations are also underlined (pitfalls in the interpretation of cellular transfection, scarcity of the invalidation models, and so on).
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Abstract
Several neuroendocrine control systems are prominently controlled by G-protein coupled receptors that activate the cAMP signal transduction pathway. The discovery of multiple genes that encode the molecular machinery of cAMP metabolism has revolutionized our knowledge of cAMP mediated processes. This perhaps all too familiar second messenger can be generated by nine different membrane enzymes in the context of varied levels of activation of G proteins as well as Ca(2+)- and protein kinase C-dependent processes. The amplitude, length and subcellular distribution of the cAMP signal are further modulated by over twenty functionally distinct isotypes of cAMP-degrading phosphodiesterases in a cell- and stimulus-specific manner. The present review summarizes the key properties of the molecular machinery that generates the cAMP signal and highlights how it is deployed in neuroendocrine systems.
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Expression pattern of adenylyl cyclase isoforms in the inner ear of the rat by RT-PCR and immunochemical localization of calcineurin in the organ of Corti. Hear Res 1999; 132:69-75. [PMID: 10392549 DOI: 10.1016/s0378-5955(99)00035-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Most studies concerning adenylyl cyclases in the inner ear were carried out before the advent of molecular biology. In a PCR approach using cDNAs of six inner ear tissues (stria vascularis, endolymphatic sac, organ of Corti, vestibulum, cochlear and vestibular nerve) we found tissue specific expression of adenylyl cyclase isoforms. Adenylyl cyclases types 2 and 4 are predominant in the fluid controlling tissues, i.e. in the stria vascularis and endolymphatic sac. In the organ of Corti and vestibulum the Ca2+-modulated isoforms types 1, 6 and 9 were expressed. The regulation of adenylyl cyclase 9, which is the major isoform expressed in the organ of Corti, proceeds via the Ca2+-activated protein phosphatase 2B (calcineurin, PPP3). PCR with specific primers for calcineurin demonstrated its abundant expression in the organ of Corti. Using a monoclonal antibody we localized calcineurin immunochemically to the cochlear nerve, the nerve fibers and the inner hair cells. In the cochlear and vestibular nerves a characteristic neuronal expression pattern of adenylyl cyclase isoforms was observed, i.e. adenylyl cyclases types 2, 3 and 8. The functional consequences of the adenylyl cyclase expression pattern in the inner ear are discussed in conjunction with its unique sensory performance.
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The 5'-flanking region of the mouse adenylyl cyclase type VIII gene imparts tissue-specific expression in transgenic mice. J Neurosci 1999. [PMID: 10066258 DOI: 10.1523/jneurosci.19-06-02051.1999] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The calcium-stimulated adenylyl cyclases (ACs) play a central role in stimulus-dependent modification of synaptic function. The type VIII AC (AC8) is one of three mammalian calcium-stimulated isoforms, each of which is expressed in a region-specific manner in the CNS. To delineate the DNA sequences responsible for appropriate targeting of AC8 expression, we report here the complete structure of the AC8 gene and define the pattern of expression of the full-length cDNA and its splice variants. In addition to expression within the brain, robust expression of AC8 was also found in the lung. By in situ hybridization, we have found the highest expression of AC8 mRNA within the olfactory bulb, thalamus, habenula, cerebral cortex, and hypothalamic supraoptic and paraventricular nuclei. By generating transgenic mice whose expression of beta-galactosidase is controlled by the AC8 5'-flanking DNA sequences, we demonstrate that the DNA sequences within the 10 kb preceding exon 1 are critical for establishment of this region-specific pattern. This spectrum of sites of production is unique to AC8 among the calcium-stimulated adenylyl cyclases and suggests nonredundant functions with other adenylyl cyclases in neuroendocrine regulation and/or behavior.
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Abstract
Adenylate cyclase integrates positive and negative signals that act through G protein-coupled cell-surface receptors with other extracellular stimuli to finely regulate levels of cAMP within the cell. Recently, the structures of the cyclase catalytic core complexed with the plant diterpene forskolin, and a cyclase-forskolin complex bound to an activated form of the stimulatory G protein subunit Gs alpha have been solved by X-ray crystallography. These structures provide a wealth of detail about how different signals could converge at the core cyclase domains to regulate catalysis. In this article, William Simonds reviews recent advances in the molecular and structural biology of this key regulatory enzyme, which provide new insight into its ability to integrate multiple signals in diverse cellular contexts.
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Molecular cloning of a full-length cDNA for human type 3 adenylyl cyclase and its expression in human islets. Biochem Biophys Res Commun 1999; 254:548-51. [PMID: 9920776 DOI: 10.1006/bbrc.1998.9983] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The GK (Goto-Kakizaki) rat is a lean model of type 2 diabetes in which the diabetic state was spontaneously induced. We recently demonstrated the presence in GK rats of two functional point mutations in the promoter region of the type 3 adenylyl cyclase (AC3) gene that resulted in overexpression of AC3 mRNA associated with increased cAMP generation. The AC3 gene promoter mutations are the first molecular changes to be described in any specific gene in the GK rat. Here we report cloning of a full-length cDNA encoding human AC3 from a human fetal brain cDNA library using a PCR-based screening method. This 4142-bp cDNA predicts an open reading frame encoding 1144 amino acids containing putative 12 transmembrane-spanning domains which are typically found in other mammalian AC isoforms. Comparison of the translated amino acid sequence of the AC3 gene between human and rat shows 95% homology. Using RT-PCR, clear AC3 expression was detected in isolated human islets as well as a cDNA panel containing templates from eight different tissues (brain, heart, kidney, liver, lung, pancreas, placenta, and skeletal muscle). This wide distribution of AC3 expression may involve a number of physiological and pathophysiological metabolic processes.
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Ca2+/calcineurin-inhibited adenylyl cyclase, highly abundant in forebrain regions, is important for learning and memory. J Neurosci 1998. [PMID: 9822726 DOI: 10.1523/jneurosci.18-23-09650.1998] [Citation(s) in RCA: 73] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Activation of cAMP synthesis by intracellular Ca2+ is thought to be the main mode of cAMP generation in the brain. Accordingly, the Ca2+-activated adenylyl cyclases I and VIII are expressed prominently in forebrain neurons. The present study shows that the novel adenylyl cyclase type IX is inhibited by Ca2+ and that this effect is blocked selectively by inhibitors of calcineurin such as FK506 and cyclosporin A. Moreover, adenylyl cyclase IX is inhibited by the same range of intracellular free Ca2+ concentrations that stimulate adenylyl cyclase I. Adenylyl cyclase IX is expressed prominently in the forebrain. Substantial arrays of neurons positive for AC9 mRNA were found in the olfactory lobe, in limbic and neocortical areas, in the striatum, and in the cerebellar system. These data show that the initiation of the cAMP signal by adenylyl cyclase may be controlled by Ca2+/calcineurin and thus provide evidence for a novel mode of tuning the cAMP signal by protein phosphorylation/dephosphorylation cascades.
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Mammalian G
s
‐Stimulated Adenylyl Cyclases. Compr Physiol 1998. [DOI: 10.1002/cphy.cp070108] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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40
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Abstract
The second messengers cAMP and inositol-1,4,5-triphosphate have been implicated in olfaction in various species. The odorant-induced cGMP response was investigated using cilia preparations and olfactory primary cultures. Odorants cause a delayed and sustained elevation of cGMP. A component of this cGMP response is attributable to the activation of one of two kinetically distinct cilial receptor guanylyl cyclases by calcium and a guanylyl cyclase-activating protein (GCAP). cGMP thus formed serves to augment the cAMP signal in a cGMP-dependent protein kinase (PKG) manner by direct activation of adenylate cyclase. cAMP, in turn, activates cAMP-dependent protein kinase (PKA) to negatively regulate guanylyl cyclase, limiting the cGMP signal. These data demonstrate the existence of a regulatory loop in which cGMP can augment a cAMP signal, and in turn cAMP negatively regulates cGMP production via PKA. Thus, a small, localized, odorant-induced cAMP response may be amplified to modulate downstream transduction enzymes or transcriptional events.
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The second messenger cAMP elicits eating by an anatomically specific action in the perifornical hypothalamus. J Neurosci 1998. [PMID: 9502822 DOI: 10.1523/jneurosci.18-07-02646.1998] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
We have previously shown that a membrane-permeant analog of cAMP, 8-bromo-cAMP (8-br-cAMP), elicits a vigorous eating response when microinjected into the perifornical hypothalamus (PFH) or lateral hypothalamus (LH) of satiated rats, suggesting that increases in cAMP in these areas may be important in the neural control of eating. To determine the locus of this effect, we compared the ability of 8-br-cAMP (1-100 nmol/0.3 microl) to elicit eating after microinjection into the PFH, LH, or the following bracketing areas: the anterior and posterior LH, paraventricular nucleus of the hypothalamus, thalamus, and amygdala. 8-br-cAMP at 50 nmol elicited eating (>/=3.4 gm in 2 hr) exclusively in the PFH and LH. At 100 nmol, 8-br-cAMP elicited a larger response in these areas and elicited a smaller, more variable response in the thalamus. We similarly mapped the feeding-stimulatory effects of compounds that increase endogenous cellular cAMP in naive rats. Combined microinjection of matched doses (300 nmol) of 3-isobutyl-1-methylxanthine and 7-deacetyl-7-O-(N-methylpiperazino)-gamma-butyryl-forskolin was effective exclusively in the PFH, eliciting an average 2 hr food intake of 8.4 +/- 2.0 gm. Collectively, these results suggest that increases in cellular cAMP within a specific brain site, the PFH, may play a role in the neural stimulation of eating.
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Abstract
Polymerase chain reaction (PCR) was used to clone an intronless cDNA encoding a new member (named OL2) of the G protein-coupled receptor superfamily. The coding region of the rat OL2 receptor gene predicts a seven transmembrane domain receptor of 315 amino acids. OL2 has 46.4 percent amino acid identity with OL1, an olfactory receptor expressed in the developing rat heart, and slightly lower percent indentities with several other olfactory receptors. PCR analysis reveals that the transcript is present mainly in the rat spleen and in a mouse insulin-secreting cell line (MIN6). No correlation was found between the tissue distribution of OL2 and that of the olfaction-related GTP-binding protein Golf alpha subunit. These findings suggest a role for this new hypothetical G-protein coupled receptor and for its still unknown ligand in the spleen and in the insulin-secreting beta cells.
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Type-specific regulation of mammalian adenylyl cyclases by G protein pathways. ADVANCES IN SECOND MESSENGER AND PHOSPHOPROTEIN RESEARCH 1998; 32:81-98. [PMID: 9421586 DOI: 10.1016/s1040-7952(98)80006-2] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
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45
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47
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Phosphorylation and inhibition of type III adenylyl cyclase by calmodulin-dependent protein kinase II in vivo. J Biol Chem 1996; 271:24231-5. [PMID: 8798667 DOI: 10.1074/jbc.271.39.24231] [Citation(s) in RCA: 129] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
Inhibition of type III adenylyl cyclase (III-AC) by intracellular Ca2+ in vivo provides a mechanism for attenuation of hormone-stimulated cAMP signals in olfactory epithelium, heart, and other tissues (Wayman, G. A., Impey, S., and Storm, D. R. (1995) J. Biol. Chem. 270, 21480-21486). Although the mechanism for Ca2+ inhibition of III-AC in vivo has not been defined, inhibition is not mediated by Gi, cAMP-dependent protein kinase, or protein kinase C. However, Ca2+ inhibition of III-AC is antagonized by KN-62, a CaM-dependent kinase inhibitor. In addition, constitutively activated CaM kinase II inhibits the enzyme. These data suggest that CaM kinase II regulates the activity of III-AC by direct phosphorylation or by an indirect mechanism involving phosphorylation of a protein that inhibits III-AC. Here we report that III-AC is phosphorylated in vivo when intracellular Ca2+ is increased and that phosphorylation is prevented by CaM-dependent kinase inhibitors. Site-directed mutagenesis of a CaM kinase II consensus site (Ser-1076 to Ala-1076) in III-AC greatly reduced Ca2+-stimulated phosphorylation and inhibition of III-AC in vivo. These data support the hypothesis that Ca2+ inhibition of III-AC is due to direct phosphorylation of the enzyme by CaM kinase II in vivo.
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Evidence for distinct signaling mechanisms in two mammalian olfactory sense organs. Proc Natl Acad Sci U S A 1996; 93:2365-9. [PMID: 8637879 PMCID: PMC39802 DOI: 10.1073/pnas.93.6.2365] [Citation(s) in RCA: 103] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
In mammals, olfactory stimuli are detected by sensory neurons at two distinct sites: the olfactory epithelium (OE) of the nasal cavity and the neuroepithelium of the vomeronasal organ (VNO). While the OE can detect volatile chemicals released from numerous sources, the VNO appears to be specialized to detect pheromones that are emitted by other animals and that convey information of behavioral or physiological importance. The mechanisms underlying sensory transduction in the OE have been well studied and a number of components of the transduction cascade have been cloned. Here, we investigated sensory transduction in the VNO by asking whether VNO neurons express molecules that have been implicated in sensory transduction in the OE. Using in situ hybridization and Northern blot analyses, we found that most of the olfactory transduction components examined, including the guanine nucleotide binding protein alpha subunit (G-alpha-olf), adenylyl cyclase type III, and an olfactory cyclic nucleotide-gated (CNG) channel subunit (oCNC1), are not expressed by VNO sensory neurons. In contrast, VNO neurons do express a second olfactory CNG channel subunit (oCNC2). These results indicate that VNO sensory transduction is distinct from that in the OE but raise the possibility that, like OE sensory transduction, sensory transduction in the VNO might involve cyclic nucleotide-gated ion channels.
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[2] Analysis of adenylylcyclase subspecies gene expression in brain by in Situ hybridization histochemistry. ACTA ACUST UNITED AC 1996. [DOI: 10.1016/s1043-9471(96)80038-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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50
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Abstract
Current findings show that adenylate cyclases comprise a heterogeneous multigene family, members of which are variously regulated by the alpha and beta gamma subunits of G proteins, by Ca2+ and by protein kinases. In the CNS, individual isoforms of adenylate cyclase are expressed discretely in select regions of the brain. At the subcellular level, adenylate cyclases can be concentrated into dendritic spines, thereby increasing their susceptibility to multiple regulatory influences. Altogether, such findings greatly expand knowledge of the potential role of this archetypical signaling system in the modulation of neuronal function.
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