In this study, increased expression of an endopeptidase hydrolyzing β- endorphin (β-Ep) to γ-endorphin (γ-Ep, β-Ep1-17) was observed upon immobilized anti-CD3 stimulated activation of human peripheral blood CD4+ T cells (hCD4+ T cells). Although freshly isolated hCD4+ T cells are devoid of significant β-Ep endopeptidase activity (< 0.1 nmol h-1 106 cells- 1), activation of these cells with immobilized anti-CD3 results in a time dependent appearance of β-Ep endopeptidase activity which reaches a maximal value of 17.4 ± 0.48 nmol h-1 106 cells-1 after 48 h of culture. Significant up-regulation of both mRNA encoding IDE/γ-EpGE and immunoreactive protein are observed in anti-CD3 stimulated hCD4+ T cells, indicating transcription and translation of IDE/γ-EpGE may be elevated. No significant hydrolysis of exogenous β-Ep is observed with intact hCD4+ T cells whether quiescent or activated or from preparations of hCD4+ T cell membranes. Therefore, this activity appears to be intracellular. Immunoreactive IDE/γ-EpGE is detected inside activated hCD4+ T cells. Analysis of metabolites generated upon hydrolysis of β-Ep with lysed activated hCD4+ T cell preparations identified the presence of: β-Ep1-18, β-Ep2-18, β-Ep1-17, β-Ep2-17, β-Ep18-31, β-Ep19-31, β-Ep1-13, β-Ep2- 13, β-Ep18-26, and β-Ep20-31 as major metabolites and the majority of these are consistent with β-Ep hydrolytic activity attributable to IDE/γ-EpGE.
|Number of pages||10|
|Journal||Journal of Neuroimmunology|
|State||Published - May 1 1998|
Bibliographical noteFunding Information:
We thank Dr. Richard Roth (Stanford University) for the kind gift of the murine monoclonal antibody 9B12 specific for the human insulin degrading enzyme. We also thank Dr. Clive Slaughter and the Biopolymers Facility at the Howard Hughes Medical Institute at UT Southwestern Medical Center for their assistance performing the peptide microsequencing, mass spectral data and analysis. This work was supported in part by US Public Health Service Grants DA0762 (GLC, DT, LBH) and DA02243 (LBH).
- HCD4 T cells
- Insulin degrading enzyme (IDE)
- γ-Endorphin generating enzyme
ASJC Scopus subject areas
- Immunology and Allergy
- Clinical Neurology