Identification and characterization of PDE4A11, a novel, widely expressed long isoform encoded by the human PDE4A cAMP phosphodiesterase gene.
PDE4A11 is a novel cAMP-specific phosphodiesterase that is conserved in humans, mouse, rat, pig, and bat. Exon-1(4A11) encodes its unique, 81 amino acid N-terminal region. Reverse-transcriptase polymerase chain reaction performed across the splice junction, plus identification of expressed sequence tags, identifies PDE4A11 as a long isoform possessing UCR1 and UCR2 regulatory domains. Transcript analysis shows that PDE4A11 is widely expressed compared with PDE4A10 and PDE4A4B long isoforms. Truncation analysis identifies a putative promoter in a 250-base pair region located immediately upstream of the start site in Exon-1(4A11). Recombinant PDE4A11, expressed in COS-7 cells, is a 126-kDa protein localized predominantly around the nucleus and in membrane ruffles. PDE4A11 exhibits a K(m) for cAMP hydrolysis of 4 microM, with relative V(max) similar to that of PDE4A10 and PDE4A4B. PDE4A11 is dose-dependently inhibited by rolipram, 4-[(3-butoxy-4-methoxyphenyl)-methyl]-2-imidazolidinone (Ro 20-1724), cilomilast, roflumilast, and denbufylline, with IC(50) values of 0.7, 0.9, 0.03, 0.004, and 0.3 microM, respectively. Soluble and particulate PDE4A11 exhibit distinct rates of thermal inactivation (55 degrees C; T((0.5)) = 2.5 and 4.4 min, respectively). Elevating cAMP levels in COS-7 cells activates PDE4A11 concomitant with its phosphorylation at Ser119 by protein kinase A (PKA). PDE4A11 differs from PDE4A4 in sensitivity to cleavage by caspase-3, interaction with LYN SH3 domain, redistribution upon long-term rolipram challenge, and sensitivity to certain PDE4 inhibitors. PDE4A11, PDE4A10, and PDE4A4 all can interact with betaarrestin. PDE4A11 is a novel, widely expressed long isoform that is activated by PKA phosphorylation and shows a distinct intracellular localization, indicating that it may contribute to compartmentalized cAMP signaling in cells in which it is expressed.
Wallace
Derek A
DA
Molecular Pharmacology Group, Division of Biochemistry and Molecular Biology, Institute of Biomedical and Life Sciences, Wolfson Building, University Avenue, University of Glasgow, Glasgow G12 8QQ, Scotland, UK.
Johnston
Lee Ann
LA
Huston
Elaine
E
MacMaster
Douglas
D
Houslay
Thomas M
TM
Cheung
York-Fong
YF
Campbell
Lachlan
L
Millen
Jenni E
JE
Smith
Robin A
RA
Gall
Irene
I
Knowles
Richard G
RG
Sullivan
Michael
M
Houslay
Miles D
MD
D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000037:antagonists & inhibitors / Q000096:biosynthesis* / Q000235:genetics*; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D019556:COS Cells; D002522:Chlorocebus aethiops; D000242:Cyclic AMP / Q000502:physiology; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D054703:Cyclic Nucleotide Phosphodiesterases, Type 4; D004305:Dose-Response Relationship, Drug; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects / Q000502:physiology*; D006801:Humans; D007424:Intracellular Fluid / Q000201:enzymology; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000235:genetics; D051379:Mice; D008969:Molecular Sequence Data; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D015398:Signal Transduction
D007527:Isoenzymes; D010726:Phosphodiesterase Inhibitors; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D015105:3',5'-Cyclic-AMP Phosphodiesterases; D054703:Cyclic Nucleotide Phosphodiesterases, Type 4; C517355:PDE4A protein, human