Induction of terminal differentiation of Dictyostelium by cAMP-dependent protein kinase and opposing effects of intracellulr and extracellular cAMP on stalk cell differentiation

Development ◽  
1993 ◽  
Vol 119 (1) ◽  
pp. 147-154 ◽  
Author(s):  
N.A. Hopper ◽  
C. Anjard ◽  
C.D. Reymond ◽  
J.G. Williams
Keyword(s):  
Cell Differentiation ◽  
Protein Kinase ◽  
Terminal Differentiation ◽  
Stalk Cell ◽  
Specific Gene ◽  
Intracellular Camp ◽  
Dependent Protein Kinase ◽  
Camp Dependent Protein Kinase ◽  
Dependent Protein ◽  
Extracellular Camp

Expression of the catalytic (C) subunit of the cAMP-dependent protein kinase (PKA) of Dictyostelium under the control of heterologous, cell-type-specific promoters causes ectopic terminal differentiation. When expressed under the control of a prespore-specific promoter, development is accelerated, to yield highly aberrant fruiting bodies that contain a basal mass of spore cells surrounding a central stalk-like structure. When expressed under the control of a prestalk-specific promoter, development arrests much earlier, at the tight mound stage. Prestalk cells move to the apices of these mounds, apparently normally, but no tip is formed. Most of the prestalk cells remain arrested in their development but there are a few isolated stalk cells scattered within such mounds. We show that extracellular cAMP represses stalk cell-specific gene expression in cells where the kinase is constitutively active, suggesting that inhibition of stalk cell differentiation by cAMP in normal cells (Berks and Kay, 1988) occurs because of an effect of extracellular cAMP on an intracellular signalling pathway independent of PKA. We propose a scheme whereby two separate events, a rise in intracellular cAMP levels and a fall in extracellular cAMP concentration, are required to induce stalk cell differentiation.

Regulation of Dictyostelium morphogenesis by cAMP-dependent protein kinase

1993 ◽  
Vol 340 (1293) ◽  
pp. 305-313 ◽  
Keyword(s):  
Cell Differentiation ◽  
Protein Kinase ◽  
Gene Activation ◽  
Stalk Cell ◽  
Dependent Protein Kinase ◽  
Camp Dependent Protein Kinase ◽  
Extracellular Signal ◽  
Dependent Protein ◽  
Extracellular Camp ◽  
Spore Cell

During formation of the Dictyostelium slug extracellular cAMP signals direct the differentiation of prespore cells and DIF, a chlorinated hexaphenone, induces the differentiation of prestalk cells. At culmination the slug transforms into a fruiting body, composed of a stalk supporting a ball of spores. A dominant inhibitor of cAMP-dependent protein kinase (PKA) expressed under the control of a prestalk-specific promoter blocks the differentiation of prestalk cells into stalk cells. Analysis of a gene specifically expressed in stalk cells suggests that PKA acts to remove a repressor that prevents the premature induction of stalk cell differentiation by DIF during slug migration. PKA is also necessary for the morphogenetic movement of prestalk cells at culmination. Expression of the PKA inhibitor under control of a prespore-specific promoter blocks the accumulation of prespore mRNA sequences and prevents terminal spore cell differentiation. Thus PKA is essential for progression along both pathways of terminal differentiation but with different mechanisms of action. On the stalk cell pathway it acts to regulate the action of DIF while on the spore cell pathway PKA itself seems to act as the inducer of spore cell maturation. Ammonia, the extracellular signal which regulates the entry into culmination, acts by controlling the intracellular concentration of cAMP and thus exerts its effects via PKA. The fact that PKA is necessary for both prespore and spore gene expression leads us to postulate the existence of a signalling mechanism which converts the progressive rise in cAMP concentration during development into discrete, PKA-regulated gene activation events.

scholarly journals Movement of the free catalytic subunit of cAMP-dependent protein kinase into and out of the nucleus can be explained by diffusion.

1993 ◽  
Vol 4 (10) ◽  
pp. 993-1002 ◽  
Author(s):  
A T Harootunian ◽  
S R Adams ◽  
W Wen ◽  
J L Meinkoth ◽  
S S Taylor ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Nuclear Translocation ◽  
Nuclear Accumulation ◽  
Intracellular Camp ◽  
Dependent Protein Kinase ◽  
Regulatory Subunits ◽  
Camp Dependent Protein Kinase ◽  
Block Movement ◽  
C Subunit ◽  
Dependent Protein

The catalytic (C) subunit of cyclic AMP (cAMP) dependent protein kinase (PKA) has previously been shown to enter and exit the nucleus of cells when intracellular cAMP is raised and lowered, respectively. To determine the mechanism of nuclear translocation, fluorescently labeled C subunit was injected into living REF52 fibroblasts either as free C subunit or in the form of holoenzyme (PKA) in which the catalytic and regulatory subunits were labeled with fluorescein and rhodamine, respectively. Quantification of nuclear and cytoplasmic fluorescence intensities revealed that free C subunit nuclear accumulation was most similar to that of macromolecules that diffuse into the nucleus. A glutathione S-transferase-C subunit fusion protein did not enter the nucleus following cytoplasmic microinjection. Puncturing the nuclear membrane did not decrease the nuclear concentration of C subunit, and C subunit entry into the nucleus did not appear to be saturable. Cooling or depleting cells of energy failed to block movement of C subunit into the nucleus. Photobleaching experiments showed that even after reaching equilibrium at high [cAMP], individual molecules of C subunit continued to leave the nucleus at approximately the same rate that they had originally entered. These results indicate that diffusion is sufficient to explain most aspects of C subunit subcellular localization.

scholarly journals Regulation of jun-B expression by a cyclic AMP (cAMP)-dependent mechanism in human myeloid cells

Blood ◽  
1991 ◽  
Vol 78 (1) ◽  
pp. 83-88 ◽  
Author(s):  
R Datta ◽  
T Nakamura ◽  
ML Sherman ◽  
D Kufe
Keyword(s):  
Protein Kinase ◽  
Cyclic Amp ◽  
Myeloid Leukemia ◽  
Leukemia Cells ◽  
Intracellular Camp ◽  
Dependent Protein Kinase ◽  
Cyclic Monophosphate ◽  
Camp Dependent Protein Kinase ◽  
Dependent Protein ◽  
Jun B

Abstract The present studies have examined the regulation of the jun-B early response gene by cyclic AMP (cAMP)-dependent signaling pathways. The 2.0-kb jun-B transcript was at low but detectable levels in uninduced human HL-60 myeloid leukemia cells. In contrast, treatment with 1 mmol/L8-bromo-adenosine 3′,5′-cyclic monophosphate (8-Br-cAMP) in the presence of isobutylmethylxanthine, an inhibitor of cAMP-dependent phosphodiesterase, was associated with increases in jun-B transcripts that were maximal by 1 hour and then decreased to near pretreatment levels by 6 hours. Similar findings were obtained with 8–(4- chlorophenylthio)-adenosine 3′,5′-cyclic monophosphate (8-CPT-cAMP) and N6,2′–0-dibutyryladenosine 3′,5′-cyclic monophosphate (dBt-cAMP). jun-B transcripts were also increased with other agents that increase intracellular cAMP levels, such as prostaglandin E2 (PGE2) and forskolin. Moreover, inhibition of cAMP-dependent protein kinase by the isoquinolinesulfonamide H-8 blocked 8-Br-cAMP-induced increases in jun- B expression. The results of nuclear run-on assays demonstrate that treatment of HL-60 cells with PGE2, forskolin, 8-Br-cAMP, and dBt-cAMP is associated with increases in the rate of jun-B transcription. The present findings also demonstrate that the related jun-D gene is similarly regulated by a cAMP-dependent pathway. Taken together, these findings suggest that stimulation of cAMP-dependent protein kinase is involved in the induction of jun gene expression in myeloid leukemia cells.

Extracellular cAMP-dependent protein kinase (ECPKA) in melanoma

2004 ◽  
Vol 208 (2) ◽  
pp. 187-191 ◽  
Author(s):  
Tsunekazu Kita ◽  
James Goydos ◽  
Elena Reitman ◽  
Roald Ravatn ◽  
Yong Lin ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Dependent Protein Kinase ◽  
Camp Dependent Protein Kinase ◽  
Dependent Protein ◽  
Extracellular Camp
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