2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD)-inducible poly-ADP-ribose polymerase (TIPARP/PARP7) catalytic mutant mice (TiparpH532A) have increased sensitivity to TCDD-induced hepatotoxicity and lethality

ABSTRACT: We previously reported that TCDD-inducible poly-ADP-ribose polymerase (TIPARP), an aryl hydrocarbon receptor (AHR) target gene and mono-ADP-ribosyltransferase, acts as part of a negative feedback loop to repress AHR signalling, a process that prevented by a single H532A mutation that destroys TIPARP catalytic activity. Moreover, whole body or hepatocyte specific-deletion of, increases the sensitivity of mice to dioxin-induced toxicities. Based on these findings, we hypothesized that the loss of TIPARP catalytic activity would increase sensitivity to TCDD-induced toxicity in vivo. To test the hypothesis, we created a catalytically deficient mouse line (TiparpH532A) by introducing a single H532A mutation in Tiparp. Treatment of mouse embryonic fibroblasts (MEFs) or hepatocytes isolated from TiparpH532A mice confirmed the increased TCDD-induced expression of the AHR target genes, Cyp1a1, Cyp1b1 and Tiparp. We also confirmed TCDD-dependent increases in Tiparp protein levels, as well as increased protein stabilization of TiparpH532A compared Tiparp+/+ protein. TiparpH532A mice given a single injection of 10 ug/kg dioxin, a non-lethal dose in Tiparp+/+ mice, did not survive beyond day 10. All Tiparp+/+ mice survived the 30-day treatment. Dioxin treated TiparpH532A mice displayed increased expression of Ahr target genes, increased steatohepatitis and hepatotoxicity as indicated by increased alanine aminotransferase activity compared with wildtypes. Taken together, these data further support TIPARP as a key negative regulator of AHR activity and its specific loss of its catalytic activity is sufficient to increase the sensitivity to dioxin-induced hepatosteatosis and lethality. TIPARP has recently emerged as a potential anti-cancer therapeutic; however, AHR signalling and toxicity will need to be carefully considered in determining the consequences of TIPARP inhibition.

ORGANISM(S): Mus musculus

PROVIDER: GSE167205 | GEO | 2021/09/08

REPOSITORIES: GEO