Ulcerative colitis and Crohn’s disease are the two main forms of inflammatory bowel disease (IBD). Here, we report the first trans-ethnic association study of IBD, with genome-wide or Immunochip genotype data from an extended cohort of 86,640 European individuals and Immunochip data from 9,846 individuals of East-Asian, Indian or Iranian descent. We implicate 38 loci in IBD risk for the first time. For the majority of IBD risk loci, the direction and magnitude of effect is consistent in European and non-European cohorts. Nevertheless, we observe genetic heterogeneity between divergent populations at several established risk loci driven by a combination of differences in allele frequencies (NOD2), effect sizes (TNFSF15, ATG16L1) or a combination of both (IL23R, IRGM). Our results provide biological insights into the pathogenesis of IBD, and demonstrate the utility of trans-ethnic association studies for mapping complex disease loci and understanding genetic architecture across diverse populations.

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Three interconvertible forms of the estrogen receptor have been identified in the oviduct of estrogen-stimulated chicks. The non-estradiol binding form (Rnb) can be converted to the lower affinity binding form (Ry, Kd = 0.8 nM) by a process requiring the gamma-phosphoryl moiety of ATP. The enzymatic activity (Fy) essential for this "receptor potentiation" has been isolated from oviduct cytosol using ammonium sulfate fractionation, DEAE chromatography, and HPLC size-exclusion chromatography. The potentiation appears to require both kinase and phosphatase activities. The Fy kinase characteristically phosphorylates casein, histones, and glycogen synthase. Comparison of the kinase with casein kinase II, which also phosphorylates casein and glycogen synthase, indicates that Fy represents a distinct protein kinase since its activity is not stimulated by spermine or inhibited by heparin. Fy-mediated conversion of Rnb to Ry is blocked by the phosphatase inhibitors vanadate, fluoride, and pyrophosphate. The substrate specificity of the Fy phosphatase activity is distinct from that of the two well-characterized protein phosphatases 1 and 2A. Moreover, the requirement for Fy phosphatase activity in converting Rnb to Ry could not be mimicked by its substitution with purified protein phosphatases 1 or 2A. The unique substrate specificity of the oviduct protein phosphatase and protein kinase, which are apparently necessary to confer estradiol binding characteristics to the receptor, implies that these enzymes play a key role in the control of the estrogen receptor in its function as a transcription factor.

We previously demonstrated that the chick oviduct estrogen receptor exists in three interconvertible forms. Two of these forms bind estradiol with high but distinct affinities. A third form exists as a non-estrogen binding recyclable form, Rnb, which upon treatment with ATP/Mg2+ is quantitatively converted to the lower affinity estradiol binding form. We now describe the isolation from chick oviduct cytosol of a factor involved in this conversion and its 1100-fold purification by ammonium sulfate fractionation, DEAE ion-exchange chromatography, and size-exclusion HPLC. The factor elutes from the size-exclusion column with an apparent molecular weight of 40,000. This highly purified factor potentiates estradiol binding in a dose-dependent manner in the presence of ATP/Mg2+. Its activity is destroyed by heating or by trypsin treatment but is relatively stable to freezing and thawing and is inert to treatment with reducing agents. ATP is an essential nucleotide substrate; GTP and cyclic nucleotides are inactive. Studies of cation dependence demonstrate that Mg2+ is also essential; Ca2+ alone is completely ineffective in catalyzing receptor potentiation and does not synergize with Mg2+. In the presence of excess ATP/Mg2+ and a fixed concentration of Fy, the Km for potentiation of estradiol binding is approximately 0.4 nM.