scholarly journals Mechanical Compression of Cartilage Explants Induces Multiple Time-dependent Gene Expression Patterns and Involves Intracellular Calcium and Cyclic AMP

2004 ◽  
Vol 279 (19) ◽  
pp. 19502-19511 ◽  
Author(s):  
Jonathan B. Fitzgerald ◽  
Moonsoo Jin ◽  
Delphine Dean ◽  
David J. Wood ◽  
Ming H. Zheng ◽  
...  
Keyword(s):  
Extracellular Matrix ◽  
Protein Kinase ◽  
Cyclic Amp ◽  
Intracellular Calcium ◽  
Protein Kinase A ◽  
Expression Patterns ◽  
Cartilage Explants ◽  
Mechanical Forces ◽  
Amp Activated Protein Kinase ◽  
Kinase A

Chondrocytes are influenced by mechanical forces to remodel cartilage extracellular matrix. Previous studies have demonstrated the effects of mechanical forces on changes in biosynthesis and mRNA levels of particular extracellular matrix molecules, and have identified certain signaling pathways that may be involved. However, the broad extent and kinetics of mechano-regulation of gene transcription has not been studied in depth. We applied static compressive strains to bovine cartilage explants for periods between 1 and 24 h and measured the response of 28 genes using real time PCR. Compression time courses were also performed in the presence of an intracellular calcium chelator or an inhibitor of cyclic AMP-activated protein kinase A. Cluster analysis of the data revealed four main expression patterns: two groups containing either transiently up-regulated or duration-enhanced expression profiles could each be subdivided into genes that did or did not require intracellular calcium release and cyclic AMP-activated protein kinase A for their mechano-regulation. Transcription levels for aggrecan, type II collagen, and link protein were up-regulated ∼2–3-fold during the first 8 h of 50% compression and subsequently down-regulated to levels below that of free-swelling controls by 24 h. Transcription levels of matrix metalloproteinases-3, -9, and -13, aggrecanase-1, and the matrix protease regulator cyclooxygenase-2 increased with the duration of 50% compression 2–16-fold by 24 h. Thus, transcription of proteins involved in matrix remodeling and catabolism dominated over anabolic matrix proteins as the duration of static compression increased. Immediate early genes c-fosand c-junwere dramatically up-regulated 6–30-fold, respectively, during the first 8 h of 50% compression and remained up-regulated after 24 h.

scholarly journals AMP-activated protein kinase: a remarkable contributor to preserve a healthy heart against ROS injury

2021 ◽  
Author(s):  
Alice Marino ◽  
Derek J. Hausenloy ◽  
Ioanna Andreadou ◽  
Sandrine Horman ◽  
Luc Bertrand ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Protein Kinase A ◽  
Amp Activated Protein Kinase ◽  
Kinase A

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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