A calcium-dependent nuclease from apoptotic rat thymocytes is homologous with cyclophilin. Recombinant cyclophilins A, B, and C have nuclease activity.

  1. J W Montague,
  2. M L Gaido,
  3. C Frye and
  4. J A Cidlowski
  1. Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill 27599.

    Abstract

    Apoptosis is an important physiological process that involves the deletion of specific cells in a controlled and timely manner. A biochemical hallmark typifying apoptosis in normal lymphocytes is DNA cleavage caused by a calcium-dependent nuclease. We have previously identified and purified an 18-kDa nuclease (NUC18) from glucocorticoid-treated rat thymocytes whose activity is associated with this apoptotic DNA fragmentation. Partial protein sequencing of pure NUC18 has generated two peptide sequences that have a remarkable similarity to rat cyclophilin A and other members of the cyclophilin family. We report here that recombinant cyclophilins A, B, and C have a calcium/magnesium-dependent nuclease activity with biochemical and pharmacological properties similar to those of NUC18. Our results raise the intriguing possibility that cyclophilin or a cyclophilin-related protein may play a role in lymphocyte apoptosis.

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    1. July 22, 1994 The Journal of Biological Chemistry, 269, 18877-18880.
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