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Cyclophilin, a primary molecular target for cyclosporine. Structural and functional implications
M W Harding1, R E Handschumacher
1Department of Pharmacology, Yale University School of Medicine, New Haven, Connecticut 06510.
Cyclophilin (CYP) is identified as the primary cellular receptor for cyclosporine (CsA), a crucial immunosuppressant. This finding implicates CYP in regulating T and B cell activation and cellular signaling pathways.
Area of Science:
- Immunology
- Molecular Biology
- Biochemistry
Background:
- Cyclosporine (CsA) is a vital immunosuppressive drug, but its precise molecular mechanism of action remains incompletely understood.
- Identifying the cellular targets of CsA is essential for elucidating its immunosuppressive effects and potential therapeutic applications.
Purpose of the Study:
- To identify and functionally characterize the molecular target(s) of cyclosporine (CsA) within the cell.
- To investigate the role of cyclophilin (CYP) as a potential cytosolic receptor for CsA.
Main Methods:
- Evidence presented suggests cyclophilin (CYP) as the primary cytosolic receptor for CsA.
- Characterization of CYP's high affinity (Kd 30 nM) and specificity for CsA and its analogs.
Main Results:
- Cyclophilin (CYP) is a low-molecular-weight, basic protein abundant in the cytosol (0.05%–0.4% of total protein).
- CYP exists in at least two isoforms, is conserved across eukaryotic organisms, and is a member of a multigene family.
- CYP's interaction with CsA suggests its pivotal role in regulating T and B cell activation.
Conclusions:
- Cyclophilin (CYP) is strongly implicated as the primary cytosolic receptor for cyclosporine (CsA).
- CYP likely plays a crucial role in lymphocyte activation and potentially broader cellular physiology.
- CYP may function within signaling pathways linking receptor stimulation to gene regulation in lymphocytes and other cell types.
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