Gene disruption of tissue transglutaminase

V. De Laurenzi, G. Melino

Research output: Contribution to journalArticle

274 Citations (Scopus)

Abstract

Transglutaminase 2 (TGase 2), or tissue transglutaminase, catalyzes either ε-(γ-glutamyl)lysine or N1,N8-(γ-glutamyl)spermidine isopeptide bonds. TGase 2 expression has been associated with apoptosis, and it has been proposed that its activation should lead to the irreversible assembly of a cross-linked protein scaffold in dead cells. Thus, TGase 2-catalyzed protein polymerization contributes to the ultrastructural changes typical of dying apoptotic cells; it stabilizes the integrity of the apoptotic cells, preventing the release of harmful intracellular components into the extracellular space and, consequently, inflammation and scar formation. In order to perform a targeted disruption of the enzyme, we prepared a construct deleting part of exons 5 and 6, containing the active site, and intron 5. Complete absence of TGase 2 was demonstrated by reverse transcription-PCR and Western blot analysis. TGase activity measured on liver and thymus extracts showed, however, a minimal residual activity in TGase 2(-/-) mice. PCR analysis of mRNA extracted from the same tissues demonstrated that at least TGase 1 (normally present in the skin) is also expressed in these tissues and contributes to this residual activity. TGase 2(-/-) mice showed no major developmental abnormalities, and histological examination of the major organs appeared normal. Induction of apoptosis ex vivo in TGase 2(-/-) thymocytes (by CD95, dexamethasone, etoposide, and H2O2) and in vitro on TGase 2(-/-) mouse embryonal fibroblasts (by retinoids, UV, and H2O2) showed no significant differences. A reduction in cross-linked apoptotic bodies with a modestly increased release of lactate dehydrogenase has been detected in some cases. Together our results show that TGase 2 is not a crucial component of the main pathway of the apoptotic program. It is possible that the residual enzymatic activity, due to TGase 1 or redundancy of other still-unidentified TGases, can compensate for the lack of TGase 2.

Original languageEnglish
Pages (from-to)148-155
Number of pages8
JournalMolecular and Cellular Biology
Volume21
Issue number1
DOIs
Publication statusPublished - 2001

Fingerprint

Genes
transglutaminase 2
Thymus Extracts
Apoptosis
Liver Extracts
Polymerase Chain Reaction
Spermidine
Retinoids
Extracellular Space
Etoposide
Thymocytes
L-Lactate Dehydrogenase
Polymerization
Introns
Dexamethasone
Lysine
Reverse Transcription
Cicatrix
Exons
Catalytic Domain

ASJC Scopus subject areas

  • Molecular Biology
  • Genetics
  • Cell Biology

Cite this

Gene disruption of tissue transglutaminase. / De Laurenzi, V.; Melino, G.

In: Molecular and Cellular Biology, Vol. 21, No. 1, 2001, p. 148-155.

Research output: Contribution to journalArticle

De Laurenzi, V. ; Melino, G. / Gene disruption of tissue transglutaminase. In: Molecular and Cellular Biology. 2001 ; Vol. 21, No. 1. pp. 148-155.
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