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Analysis of tissue transglutaminase and its effect on apoptosis
Author(s) -
Wagner Rebecca Lynn,
Henry Amanda,
Birckbichler Paul J.
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.6.lb25-b
Tissue transglutaminase (tTg) is a multifunctional enzyme possessing two catalytic activities. One is a calcium‐dependent reaction leading to formation of intermolecular isodipeptide cross‐linkages. GTP, a negative regulator for this cross‐linking activity, shifts the enzyme’s catalytic activity to G‐protein activity. The cross‐linkages lead to the formation of a protein scaffold in cells undergoing apoptosis. Human embryonic fibroblast cells (WI‐38) demonstrate contact inhibition, while their simian virus‐transformed counterparts (VA13A) demonstrate constant proliferation. Quantification of tTg by inhibition ELISA demonstrated that WI‐38 cells contained 10‐fold higher tTg quantities then the VA13A cells. There was a 23‐fold increase in tTg in VA13A cells exposed to sodium butyrate. Preliminary studies with sodium butyrate (NaB) alone and in combination with calcium ionophore showed not only an increase in apoptosis, but also an increased tTg expression in VA13A cultures. On the other hand, NaB had no effect on tTg expression and apoptosis in the WI‐38 cells. NaB treatment induced growth arrest in both cell lines and produced a more “normal” morphology for VA13A cells. These results are indicative of a dual role for NaB; one involving growth arrest and the other apoptosis. The results of the differential effect allows potential for selective targeted chemotherapy.