Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.4.1 (phosphodiesterase)
 18,767 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The cAMP-specific phosphodiesterase (PDE) HSPDE 4A4B(pde46) selectively bound SH3 domains of SRC family tyrosyl kinases. Such an interaction profoundly changed the inhibition of PDE4 activity caused by the PDE4-selective inhibitor rolipram and mimicked the enhanced rolipram inhibition seen for particulate, compared with cytosolic pde46 expressed in COS7 cells. Particulate pde46 co-localized with LYN kinase in COS7 cells. The unique N-terminal and LR2 regions of pde46 contained the sites for SH3 binding. Altered rolipram inhibition was triggered by SH3 domain interaction with the LR2 region. Purified LYN SH3 and human PDE4A LR2 could be co-immunoprecipitated, indicating a direct interaction. Protein kinase A-phosphorylated pde46 remained able to bind LYN SH3. pde46 was found to be associated with SRC kinase in the cytosol of COS1 cells, leading to aberrant kinetics of rolipram inhibition. It is suggested that pde46 may be associated with SRC family tyrosyl kinases in intact cells and that the ensuing SH3 domain interaction with the LR2 region of pde46 alters the conformation of the PDE catalytic unit, as detected by altered rolipram inhibition. Interaction between pde46 and SRC family tyrosyl kinases highlights a potentially novel regulatory system and point of signaling system cross-talk.
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PMID:Association with the SRC family tyrosyl kinase LYN triggers a conformational change in the catalytic region of human cAMP-specific phosphodiesterase HSPDE4A4B. Consequences for rolipram inhibition. 1020 97

We describe the cloning and expression of HSPDE4A10, a novel long form splice variant of the human cAMP phosphodiesterase PDE4A gene. The 825 amino acid HSPDE4A10 contains a unique N terminus of 46 amino acids encoded by a unique 5' exon. Exon-1(4A10) lies approximately 11 kilobase pairs (kb) downstream of exon-1(4A4) and approximately 13.5 kb upstream of the PDE4A common exon 2. We identify a rat PDE4A10 ortholog and reveal a murine ortholog by nucleotide sequence database searching. PDE4A10 transcripts were detected in various human cell lines and tissues. The 5' sequence flanking exon-1(4A10) exhibited promoter activity with the minimal functional promoter region being highly conserved in the corresponding mouse genomic sequence. Transient expression of the engineered human PDE4A10 open reading frame in COS7 cells allowed detection of a 121-kDa protein in both soluble and particulate fractions. PDE4A10 was localized primarily to the perinuclear region of COS7 cells. Soluble and particulate forms exhibited similar K(m) values for cAMP hydrolysis (3-4 microM) and IC(50) values for inhibition by rolipram (50 nM) but the V(max) value of the soluble form was approximately 3-fold greater than that of the particulate form. At 55 degrees C, soluble HSPDE4A10 was more thermostable (T(0.5) = 11 min) than the particulate enzyme (T(0.5) = 5 min). HSPDE4A10 and HSPDE4A4B are shown here to be similar in size and exhibit similar maximal activities but differ with respect to sensitivity to inhibition by rolipram, thermostability, interaction with the SRC homology 3 domain of LYN, an SRC family tyrosyl kinase, and subcellular localization. We suggest that the unique N-terminal regions of PDE4A isoforms confer distinct properties upon them.
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PMID:Molecular cloning, genomic positioning, promoter identification, and characterization of the novel cyclic amp-specific phosphodiesterase PDE4A10. 1130 81

The long cyclic AMP (cAMP)-specific phosphodiesterase isoform, PDE4A5 (PDE4A subfamily isoform variant 5), when transiently expressed in COS-7 cells, was shown in subcellular fractionation studies to be associated with both membrane and cytosol fractions, with immunofluorescence analyses identifying PDE4A5 as associated both with ruffles at the cell margin and also at a distinct perinuclear localisation. Deletion of the first nine amino acids of PDE4A5 (1) ablated its ability to interact with the SH3 domain of the tyrosyl kinase, LYN; (2) reduced, but did not ablate, membrane association; and (3) disrupted the focus of PDE4A5 localisation within ruffles at the cell margin. This deleted region contained a Class I SH3 binding motif of similar sequence to those identified by screening a phage display library with the LYN-SH3 domain. Truncation to remove the PDE4A5 isoform-specific N-terminal region caused a further reduction in membrane association and ablated localisation at the cell margin. Progressive truncation to delete the PDE4A long isoform common region and then the long isoform-specific UCR1 did not cause any further change in membrane association or intracellular distribution. However, deletion up to the super-short form splice junction generated an entirely soluble 'core' PDE4A species. We propose that multiple sites in the N-terminal noncatalytic portion of PDE4A5 have the potential to associate with intracellular structures and thus define its intracellular localisation. At least two such sites lie within the PDE4A5 isoform-specific N-terminal region and these appear to be primarily responsible for targeting PDE4A5 to, and organising it within, the cell margin; one is an SH3 binding motif able to interact with LYN kinase and the other lies within the C-terminal portion of the PDE4A5 unique region. A third membrane association region is located within the N-terminal portion of UCR2 and appears to be primarily responsible for targeting to the perinuclear region. Progressive N-terminal truncation, to delete defined regions of PDE4A5, identified activity changes occurring upon deletion of the SH3 binding site region and then upon deletion of the membrane association site region located within UCR2. This suggests that certain of these anchor sites may not only determine intracellular targeting but may also transduce regulatory effects on PDE4A5 activity.
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PMID:In addition to the SH3 binding region, multiple regions within the N-terminal noncatalytic portion of the cAMP-specific phosphodiesterase, PDE4A5, contribute to its intracellular targeting. 1188 90