Transglutaminase 2 inhibits Rb binding of human papillomavirus E7 by incorporating polyamine

Abstract

Transglutaminase 2 (TGase 2) is one of a family of enzymes that catalyze protein modi®cation through the incorporation of polyamines into substrates or the formation of protein crosslinks. However, the physiological roles of TGase 2 are largely unknown. To elucidate the functions of TGase 2, we have searched for its interacting proteins. Here we show that TGase 2 interacts with E7 oncoprotein of human papillomavirus type 18 (HPV18) in vitro and in vivo. TGase 2 incorporates polyamines into a conserved glutamine residue in the zinc-binding domain of HPV18 E7 protein. This modi®cation mediates the inhibition of E7's Rb binding ability. In contrast, TGase 2 does not affect HPV16 E7, due to absence of a glutamine residue at this polyamination site. Using E7 mutants, we demonstrate that TGase 2-dependent inhibition of HPV E7 function correlates with the presence of the polyamination site. Our results indicate that TGase 2 is an important cellular interfering factor and de®ne a novel host±virus interaction, suggesting that the inability of TGase 2 to inactivate HPV16 E7 could explain the high prevalence of HPV16 in cervical cancer.

Identification of New Amine Acceptor Protein Substrate Candidates of Transglutaminase in Rat Liver Extract: Use of 5-(Biotinamido) Pentylamine as a Probe

“…Since polyamines serve as good amine substrates, TG might modulate the functions of AI and FBPase by catalyzing the incorporation of polyamines into these enzymes, as has been suggested for other proteins. [30][31][32][33] AI, FBPase, BHMT, GAPDH, and GST, which were identified as TG protein substrate candidates in the present and our previous studies, are all cytosolic enzyme proteins. Although TG might contribute the regulation of these enzymatic activities by post-translational modification, the physiological significance of these cytosolic enzymes modified post-translationally by TG is unknown at present.…”

Transglutaminase 2 suppresses apoptosis by modulating caspase 3 and NF-κB activity in hypoxic tumor cells

“…Western blot analysis and subcellular fractionation experiments were performed as previously described (Jeon et al, 2003b). To detect caspase 3, the samples were treated with urea-containing lysis buffer (50 mM Tris-Cl, pH 6.8, 6 M urea, 40 mM dithiothreitol and 2% sodiumdodecyl sulphate).…”

“…To detect caspase 3, the samples were treated with urea-containing lysis buffer (50 mM Tris-Cl, pH 6.8, 6 M urea, 40 mM dithiothreitol and 2% sodiumdodecyl sulphate). Monoclonal antibody to TG2 was prepared as previously described (Jeon et al, 2003b). Monoclonal antibodies to actin and HIF1a were purchased from Sigma (Carlsbad, CA, USA) and BD Biosciences (San Jose, CA, USA), respectively.…”

Differential alternative splicing of human transglutaminase 4 in benign prostate hyperplasia and prostate cancer

“…Each transglutaminase 4 isoform was tagged with hemagglutinin epitope for detection of protein. For yeast expression, INVsc1 cells (Invitrogen) were transformed by Lithium acetate/single stranded-DNA/Polyethylglycol method (Jeon et al, 2003) and grown in SD medium (0.67% Yeast nitrogen base without amino acids, 2% glucose and 0.065% CSM-URA). Expression of protein was induced by incubation with YPG medium (1% yeast extract, 2% bacto-peptone and 2% galactose) for 4 h. For mammalian cell expression, HeLa cells were transfected with transglutaminase 4 isoforms in pcDNA3 using LipofectAMINE reagent (Invitrogen) according to manufacturer's instructions.…”