Characterization of TCDD-inducible poly-ADP-ribose polymerase (TIPARP/ARTD14) catalytic activity

YesHere, we report the biochemical characterization of the mono-ADP-ribosyltransferase 2,3,7,8-tetrachlorodibenzo-p-dioxin poly-ADP-ribose polymerase (TIPARP/ARTD14/PARP7), which is known to repress aryl hydrocarbon receptor (AHR)-dependent transcription. We found that the nuclear localization of TIPARP was dependent on a short N-terminal sequence and its zinc finger domain. Deletion and in vitro ADP-ribosylation studies identified amino acids 400–657 as the minimum catalytically active region, which retained its ability to mono-ADP-ribosylate AHR. However, the ability of TIPARP to ADP-ribosylate and repress AHR in cells was dependent on both its catalytic activity and zinc finger domain. The catalytic activity of TIPARP was resistant to meta-iodobenzylguanidine but sensitive to iodoacetamide and hydroxylamine, implicating cysteines and acidic side chains as ADP-ribosylated target residues. Mass spectrometry identified multiple ADP-ribosylated peptides in TIPARP and AHR. Electron transfer dissociation analysis of the TIPARP peptide 33ITPLKTCFK41 revealed cysteine 39 as a site for mono-ADP-ribosylation. Mutation of cysteine 39 to alanine resulted in a small, but significant, reduction in TIPARP autoribosylation activity, suggesting that additional amino acid residues are modified, but loss of cysteine 39 did not prevent its ability to repress AHR. Our findings characterize the subcellular localization and mono-ADP-ribosyltransferase activity of TIPARP, identify cysteine as a mono-ADP-ribosylated residue targeted by this enzyme, and confirm the TIPARP-dependent mono-ADP-ribosylation of other protein targets, such as AHR.This work was supported by Canadian Institutes of Health Research (CIHR) operating grants [MOP-494265 and MOP-125919]; CIHR New Investigator Award; an Early Researcher Award from the Ontario Ministry of Innovation [ER10-07-028]; the Johan Throne Holst Foundation; Novo Nordic Foundation; and the Norwegian Cancer Society to J.M. This work was also funded by grants from the Johan Throne Holst Foundation; and the Novo Nordic Foundation to H.I.N

LXR beta deficient mice have reduced hepatic insulin clearance during hyperinsulinemic euglucemic clamp

The present study addresses the insulin sensitivity in mice deficient in LXR beta (LXR beta(-/-)) as well as in wild type (wt) mice assessed by hyperinsulinemic euglycemic clamp Wt and LXR beta(-/-) mice were fed either a normal chow diet or a high fat and high cholesterol diet (HFCD), and Insulin sensitivity was assessed by hyperinsulinemic euglycemic clamps We show that LXR beta(-/-) mice have reduced insulin clearance during hyperinsulinemic clamps upon feeding both HFCD and a regular chow diet Moreover we also observed reduced hepatic inflammation in LXR beta(-/-) mice compared to wt mice upon feeding an HFCD, despite equal levels of hepatic steatosis. In summary, our results indicate that LXR beta(-/-) mice have reduced insulin clearance during hyperinsulinemic euglycemic clamps and also reduced hepatic inflammation upon feeding an HFCD for 26 weeks (C) 2010 Elsevier Inc All rights reservedDiabetes mellitus: pathophysiological changes and therap

Genome-Wide Profiling of Liver X Receptor, Retinoid X Receptor, and Peroxisome Proliferator-Activated Receptor alpha in Mouse Liver Reveals Extensive Sharing of Binding Sites

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Tracking insulin secretion and sensitivity in children who subsequently develop diabetes:a seven year study

In the ACTION (A Coronary disease Trial Investigating Outcome with Nifedipine GITS) trial, the benefits of adding nifedipine GITS to the treatment of patients with stable symptomatic coronary artery disease were particularly apparent in those with concomitant hypertension. This further analysis has assessed whether or not the addition of nifedipine GITS is particularly beneficial in the treatment of patients with the combination of diabetes mellitus and chronic stable angina