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 language | English |
|---|---|
| Pages (from-to) | 148-155 |
| Number of pages | 8 |
| Journal | Molecular and Cellular Biology |
| Volume | 21 |
| Issue number | 1 |
| DOIs | |
| Publication status | Published - 2001 |
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ASJC Scopus subject areas
- Molecular Biology
- Genetics
- Cell Biology
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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 journal › Article
}
TY - JOUR
T1 - Gene disruption of tissue transglutaminase
AU - De Laurenzi, V.
AU - Melino, G.
PY - 2001
Y1 - 2001
N2 - 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.
AB - 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.
UR - http://www.scopus.com/inward/record.url?scp=0034747685&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=0034747685&partnerID=8YFLogxK
U2 - 10.1128/MCB.21.1.148-155.2001
DO - 10.1128/MCB.21.1.148-155.2001
M3 - Article
C2 - 11113189
AN - SCOPUS:0034747685
VL - 21
SP - 148
EP - 155
JO - Molecular and Cellular Biology
JF - Molecular and Cellular Biology
SN - 0270-7306
IS - 1
ER -