scholarly journals Protein Kinase A-Dependent Suppression of Reactive Oxygen Species in Transient Focal Ischemia in Adrenomedullin-Deficient Mice

2009 ◽  
Vol 29 (11) ◽  
pp. 1769-1779 ◽  
Author(s):  
Nobukazu Miyamoto ◽  
Ryota Tanaka ◽  
Tatsuo Shimosawa ◽  
Yutaka Yatomi ◽  
Toshiro Fujita ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Cyclic Amp ◽  
Protein Kinase A ◽  
Infarct Volume ◽  
Focal Ischemia ◽  
Neurologic Deficit ◽  
Oxygen Species ◽  
Wild Type ◽  
Transient Focal Ischemia ◽  
Kinase A

This study was designed to examine the effect of adrenomedullin deficiency on cerebral infarction and the relationship between adrenomedullin and cyclic AMP–protein kinase A pathway in regulating reactive oxygen species (ROS). Adrenomedullin heterozygous and wild-type mice were subjected to 60-mins focal ischemia. We used adrenomedullin heterozygous mice because adrenomedullin homozygotes die in utero. Infarct volume, neurologic deficit scores, and immunohistochemical analyses were evaluated at several time points after ischemia. The infarct volume and neurologic deficit scores were significantly worse in adrenomedullin heterozygous mice. Significant accumulation of inducible nitric oxide, oxidative DNA damage, and lipid peroxidation was noted after reperfusion in adrenomedullin heterozygous mice. Treatment of wild-type mice with H89, a protein kinase A inhibitor, resulted in increased infarct size, and worsening of neurologic deficit score and other parameters to levels comparable to those of adrenomedullin heterozygous mice. In contrast, cilostazol, which increases cyclic AMP, rescued neurologic deficit and ROS accumulation in adrenomedullin heterozygous mice. This study showed that adrenomedullin downregulation results in increase in ROS after transient focal ischemia in mice. The results also indicated that adrenomedullin has an important function against ischemic injury through the cyclic AMP–protein kinase A pathway.

scholarly journals Cross Talk between the Cell Wall Integrity and Cyclic AMP/Protein Kinase A Pathways in Cryptococcus neoformans

mBio ◽  
2014 ◽  
Vol 5 (4) ◽  
Author(s):  
Maureen J. Donlin ◽  
Rajendra Upadhya ◽  
Kimberly J. Gerik ◽  
Woei Lam ◽  
Laura G. VanArendonk ◽  
...  
Keyword(s):  
Cell Wall ◽  
Protein Kinase ◽  
Cyclic Amp ◽  
Protein Kinase A ◽  
Cryptococcus Neoformans ◽  
Signaling Pathway ◽  
Cell Wall Integrity ◽  
Wild Type ◽  
Content Type ◽  
Kinase A

ABSTRACTCryptococcus neoformans is a fungal pathogen of immunocompromised people that causes fatal meningitis. The fungal cell wall is essential to viability and pathogenesis ofC. neoformans, and biosynthesis and repair of the wall is primarily controlled by the cell wall integrity (CWI) signaling pathway. Previous work has shown that deletion of genes encoding the four major kinases in the CWI signaling pathway, namely,PKC1,BCK1,MKK2, andMPK1results in severe cell wall phenotypes, sensitivity to a variety of cell wall stressors, and for Mpk1, reduced virulence in a mouse model. Here, we examined the global transcriptional responses to gene deletions ofBCK1,MKK2, andMPK1compared to wild-type cells. We found that over 1,000 genes were differentially expressed in one or more of the deletion strains, with 115 genes differentially expressed in all three strains, many of which have been identified as genes regulated by the cyclic AMP (cAMP)/protein kinase A (PKA) pathway. Biochemical measurements of cAMP levels in the kinase deletion strains revealed significantly less cAMP in all of the deletion strains compared to the wild-type strain. The deletion strains also produced significantly smaller capsules than the wild-type KN99 strain did under capsule-inducing conditions, although the levels of capsule they shed were similar to those shed by the wild type. Finally, addition of exogenous cAMP led to reduced sensitivity to cell wall stress and restored surface capsule to levels near those of wild type. Thus, we have direct evidence of cross talk between the CWI and cAMP/PKA pathways that may have important implications for regulation of cell wall and capsule homeostasis.IMPORTANCECryptococcus neoformans is a fungal pathogen of immunocompromised people that causes fatal meningitis. The fungal cell wall is essential to viability and pathogenesis ofC. neoformans, and biosynthesis and repair of the wall are primarily controlled by the cell wall integrity (CWI) signaling pathway. In this study, we demonstrate that deletion of any of three core kinases in the CWI pathway impacts not only the cell wall but also the amount of surface capsule. Deletion of any of the kinases results in significantly reduced cellular cyclic AMP (cAMP) levels, and addition of exogenous cAMP rescues the capsule defect and some cell wall defects, supporting a direct role for the CWI pathway in regulation of capsule in conjunction with the cAMP/protein kinase A pathway.

scholarly journals Involvement of Salmonella Pathogenicity Island 2 in the Up-Regulation of Interleukin-10 Expression in Macrophages: Role of Protein Kinase A Signal Pathway

2004 ◽  
Vol 72 (4) ◽  
pp. 1964-1973 ◽  
Author(s):  
Kei-ichi Uchiya ◽  
Eduardo A. Groisman ◽  
Toshiaki Nikai
Keyword(s):  
Protein Kinase ◽  
Cyclic Amp ◽  
Protein Kinase A ◽  
Signal Transduction Pathway ◽  
Pathogenicity Island ◽  
Interleukin 10 ◽  
Wild Type ◽  
Necrosis Factor Alpha ◽  
Creb Phosphorylation ◽  
Kinase A

ABSTRACT Salmonellae are facultative intracellular bacteria capable of surviving within macrophages. Salmonella pathogenicity island 2 (SPI-2) is required for growth within macrophages and for virulence in mice. In this study, we show the involvement of SPI-2 in a signal transduction pathway that induces cytokine expression in Salmonella-infected macrophages. High levels of interleukin-10 (IL-10) mRNA were induced in macrophages by infection with wild-type salmonellae compared to a strain carrying a mutation in the spiC gene, which is encoded within SPI-2. The two strains had the same effect on the expression of proinflammatory cytokines such as IL-1α, IL-6, and tumor necrosis factor alpha. IL-10 expression was dose dependently blocked by treatment of infected macrophages with the protein kinase A (PKA) inhibitor H-89, while IL-10 expression was increased by the PKA activator dibutyryl cyclic AMP. Cyclic AMP-dependent PKA activity was higher in macrophages infected with wild-type salmonellae compared to the spiC mutant, and Ser132 phosphorylation of cyclic AMP response element-binding protein (CREB), which is an important mediator of PKA activation, correlated with the levels of PKA activity. Taken together, these results indicate that salmonellae cause an SPI-2-dependent increase in PKA activity that leads to CREB phosphorylation, resulting in up-regulation of IL-10 expression in Salmonella-infected macrophages. Suppression of IL-10 expression by an antisense oligonucleotide did not affect the growth of wild-type salmonellae within macrophages, whereas growth was dose dependently inhibited by H-89, suggesting that the PKA signaling pathway plays a significant role in intramacrophage Salmonella survival.

scholarly journals Evidence that glucocorticoid- and cyclic AMP-induced apoptotic pathways in lymphocytes share distal events

1992 ◽  
Vol 12 (8) ◽  
pp. 3600-3608
Author(s):  
D R Dowd ◽  
R L Miesfeld
Keyword(s):  
Protein Kinase ◽  
Cyclic Amp ◽  
Protein Kinase A ◽  
Protein Product ◽  
Single Step ◽  
Mitochondrial Activity ◽  
Isolation And Characterization ◽  
Resistant Phenotype ◽  
Apoptotic Pathways ◽  
Kinase A

WEHI7.2 murine lymphocytes undergo apoptotic death when exposed to glucocorticoids or elevated levels of intracellular cyclic AMP (cAMP), and these pathways are initiated by the glucocorticoid receptor (GR) and protein kinase A, respectively. We report the isolation and characterization of a novel WEHI7.2 variant cell line, WR256, which was selected in a single step for growth in the presence of dexamethasone and arose at a frequency of approximately 10(-10). The defect was not GR-related, as WR256 expressed functional GR and underwent GR-dependent events associated with apoptosis, such as hormone-dependent gene transcription and inhibition of cell proliferation. Moreover, the glucocorticoid-resistant phenotype was stable in culture and did not revert after treatment with 5-azacytidine or upon stable expression of GR cDNA. In addition, WR256 did not exhibit the diminished mitochondrial activity commonly associated with apoptosis. Interestingly, WR256 was also found to be resistant to 8-bromo-cAMP and forskolin despite having normal levels of protein kinase A activity and the ability to induce cAMP-dependent transcription. We examined the steady-state transcript levels of bcl-2, a gene whose protein product acts dominantly to inhibit thymocyte apoptosis, to determine whether elevated bcl-2 expression could account for the resistant phenotype. Our data showed that bcl-2 RNA levels were similar in the two cell lines and not altered by either dexamethasone or 8-bromo-cAMP treatment. These results suggest that WR256 exhibits a "deathless" phenotype and has a unique defect in a step of the apoptotic cascade that may be common to the glucocorticoid- and cAMP-mediated cell death pathways.

scholarly journals Terbutaline, forskolin and cAMP reduce secretion of aqueous humour in the isolated bovine eye

PLoS ONE ◽  
2020 ◽  
Vol 15 (12) ◽  
pp. e0244253
Author(s):  
Mohammad Shahidullah ◽  
William Stuart Wilson ◽  
Kazi Rafiq ◽  
Mahmudul Hasan Sikder ◽  
Jannatul Ferdous ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Cyclic Amp ◽  
Protein Kinase A ◽  
Aqueous Humour ◽  
Calcium Release ◽  
Drug Effects ◽  
Inhibitory Effect ◽  
Plateau Phase ◽  
Intracellular Ca ◽  
Kinase A

In order to elucidate involvement of cyclic AMP and intracellular Ca2+,[Ca2+]i, in the modulation of aqueous humour formation (AHF), we studied the effects of terbutaline, forskolin and 8-Br-cAMP in the isolated bovine eye. We also studied the interaction of cAMP on calcium signaling in cultured ciliary epithelial (CE) cells. Drug effects on AHF were measured by fluorescein dilution. Drug effects on [Ca2+]i were studied by the fura-2 fluorescence ratio technique. Terbutaline (100 nmol-100 M), forskolin (30 nM-100 M) or 8-Br-cAMP (100 nM– 10 μM), administered in the arterial perfusate produced significant reductions in AHF. The AH reducing effect of terbutaline was blocked by a selective inhibitor of protein kinase A (KT-5720). ATP (100 M) caused a rapid, transient (peak) increase in [Ca2+]i followed by a sustained plateau phase lasting more than 5 minutes. Preincubation of the cells (6 min) with terbutaline, forskolin or 8-Br-cAMP significantly reduced the peak calcium response to ATP. The sustained plateau phase of the response, on the other hand, was augmented by each of the agents. KT-5720 partially reversed the inhibitory effect of terbutaline on the peak and totally inhibited its effect on the plateau phase. These data indicate: (a) that AHF in the bovine eye can be manipulated through cyclic AMP, operating via protein kinase A, (b) that protein kinase A can affect [Ca2+]i homeostasis, (c) that calcium release from the intracellular store, not the entry, affects AHF, and (d) that interaction of [Ca2+]i with cAMP plays a role in modulating AH secretion.

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