Related Experiment Video
Updated: Jul 30, 2026
09:40
Co-immunoprecipitation Assay for Studying Functional Interactions Between Receptors and Enzymes
Published on: September 28, 2018
Multiple high-affinity cAMP-phosphodiesterases in human T-lymphocytes
S A Robicsek1, D K Blanchard, J Y Djeu
1Department of Pharmacology, College of Medicine, University of South Florida, Tampa 33612-4799.
Biochemical Pharmacology
|July 25, 1991
Summary
Human T-lymphocytes contain two high-affinity cyclic nucleotide phosphodiesterase (cAMP-PDE) isozymes. Inhibiting both isozymes synergistically suppresses T-lymphocyte blastogenesis, offering potential for immune modulation.
Area of Science:
- Immunology
- Pharmacology
- Molecular Biology
Background:
- Cyclic nucleotide phosphodiesterases (PDEs) regulate intracellular cyclic adenosine monophosphate (cAMP) levels.
- T-lymphocyte functions are modulated by cAMP, making PDE isozymes potential targets for immunomodulatory drugs.
- Two distinct high-affinity cAMP-PDE isozyme families exist in mammals, inhibited by specific compounds.
Purpose of the Study:
- To determine the presence of pharmacologically distinguishable high-affinity cAMP-PDEs in human T-lymphocytes.
- To investigate the effects of selective PDE inhibitors on lymphocyte blastogenesis.
Main Methods:
- Analysis of high-affinity cAMP-PDE activity in soluble and particulate fractions of T-lymphocyte sonicates.
- Assessment of inhibition by cyclic GMP, CI-930, and Ro 20-1724.
- Evaluation of the impact of these inhibitors, alone and in combination, on T-lymphocyte blastogenesis.
Main Results:
- Human T-lymphocytes possess both CI-930- and Ro 20-1724-inhibitable high-affinity cAMP-PDE isozymes.
- PDEs were found in both soluble and particulate fractions, with differential sensitivity to inhibitors.
- Individual inhibitors partially attenuated blastogenesis, while combined inhibition resulted in synergistic suppression.
Conclusions:
- Human T-lymphocytes express both major high-affinity cAMP-PDE isozymes.
- Both isozymes play a role in modulating T-lymphocyte blastogenesis.
- Simultaneous inhibition of both PDE isozymes yields synergistic antiblastogenic effects, suggesting therapeutic potential for immune regulation.
Related Concept Videos
02:54Protein Kinases and Phosphatases
Proteins undergo chemical modifications that trigger changes in the charge, structure, and conformation of the proteins. Phosphorylation, acetylation, glycosylation, nitrosylation, ubiquitination, lipidation, methylation, and proteolysis are various protein modifications that regulate protein activity. Such modifications are usually enzyme-driven.
Protein kinases
Many proteins in the cell are regulated by phosphorylation, the addition of a phosphate group. A family of enzymes called kinases...
Protein kinases
Many proteins in the cell are regulated by phosphorylation, the addition of a phosphate group. A family of enzymes called kinases...
01:42Phosphoinositides and PIPs
Phosphoinositides are a group of phospholipids containing a glycerol backbone with two fatty acid chains and a phosphate attached to a myoinositol sugar ring. The inositol head group extends into the cytoplasm, where it is modified by adding phosphate groups to form phosphatidylinositol phosphates or PIPs.
Different phosphoinositides are synthesized and recruited on the cytosolic face of the plasma membrane. The localization of specific phosphoinositides concentrated in separate membrane...
Different phosphoinositides are synthesized and recruited on the cytosolic face of the plasma membrane. The localization of specific phosphoinositides concentrated in separate membrane...
01:22Amplifying Signals via Enzymatic Cascade
When a ligand binds to a cell-surface receptor, the receptor's intracellular domain changes shape, which may either activate its enzyme function or allow its binding to other molecules. The initial signal is amplified by most signal transduction pathways. This means that a single ligand molecule can activate multiple molecules of a downstream target. Proteins that relay a signal are most commonly phosphorylated at one or more sites, activating or inactivating the protein. Kinases catalyze the...
01:25cAMP-dependent Protein Kinase Pathways
Cyclic Adenosine Monophosphate (cAMP) is an essential second messenger that activates protein kinase A (PKA) and regulates various biological processes. A single epinephrine molecule binds to GPCR and activates several heterotrimeric G proteins, each stimulating multiple adenylyl cyclase, amplifying the signal, and synthesizing large numbers of cAMP molecules. Small changes in cAMP concentration affect PKA activity. The binding of four cAMP molecules induces a conformational change in PKA,...
01:16Calmodulin-dependent Signaling
Calmodulin (CaM) is a calcium-binding protein in eukaryotes that controls various calcium-regulated cellular processes. It has four calcium-binding sites that bind calcium to form the calcium-calmodulin ( Ca2+-CaM) complex. GPCR stimulation increases the calcium levels in the cells that bind to CaM and induces a conformational change.
The Ca2+-CaM complex does not have enzymatic activity by itself. Instead, the complex binds downstream target proteins, including membrane proteins or enzymes,...
The Ca2+-CaM complex does not have enzymatic activity by itself. Instead, the complex binds downstream target proteins, including membrane proteins or enzymes,...
01:22T Cell Activation and Clonal Selection
T cells are integral to our adaptive immune system, recognizing and effectively responding to foreign antigens. T cell activation and clonal selection are pivotal in orchestrating this immune response. This article elucidates these mechanisms, detailing the roles of cluster of differentiation (CD) markers, major histocompatibility complex (MHC) molecules, costimulatory signals, and the process of clonal selection.
Naive T cells that have not yet encountered an antigen express two primary CD...
Naive T cells that have not yet encountered an antigen express two primary CD...