Two isoforms of tissue transglutaminase mediate opposing cellular fates

doi:10.1073/pnas.0604844103

Two isoforms of tissue transglutaminase mediate opposing cellular fates

Department of Molecular Medicine, Cornell University, Ithaca, NY 14853

Edited by Robert J. Lefkowitz, Duke University Medical Center, Durham, NC, and approved October 23, 2006 (received for review June 12, 2006)

Abstract

Opposing cellular responses are typically regulated by distinct sets of genes. However, tissue transglutaminase (TGase) provides an interesting example of a single gene product that has been implicated both in affording protection against cellular insults as well as in promoting cell death. Here, we shed some light on how these conflicting activities might be manifested by demonstrating that alternative transcripts of TGase differentially affect cell viability. We show that although the full-length TGase protein affords strong protection against cell death signals, a shorter version of TGase that is truncated at the 3′ end, and thus called TGase-short (TGase-S), is cytotoxic. The apoptotic activity of TGase-S is not dependent on its transamidation activity because the mutation of a cysteine residue that is essential for catalyzing this reaction does not compromise the ability of TGase-S to induce cell death. Intriguingly, TGase-S undergoes inappropriate oligomer formation in cells before cell death, suggesting a novel mechanism for the apoptotic effects of this protein.

Footnotes

*To whom correspondence should be addressed at:
Department of Molecular Medicine, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853-6401.
E-mail: rac1{at}cornell.edu
Author contributions: M.A.A. and R.A.C. designed research; M.A.A., J.M.J., A.M.M., and T.K.L. performed research; M.A.A. and M.E. contributed new reagents/analytic tools; M.A.A. and R.A.C. analyzed data; and M.A.A. and R.A.C. wrote the paper.
The authors declare no conflict of interest.
This article is a PNAS direct submission.
Abbreviations:

RA,

retinoic acid;

TGase,

tissue transglutaminase;

TGase-S,

TGase-short.
Freely available online through the PNAS open access option.