Interleukin-6 requires JAK to stimulate inner cell mass expansion in bovine embryos
REPRODUCTION
Authors: Wooldridge, Lydia K.; Johnson, Sally E.; Cockrum, Rebecca R.; Ealy, Alan D.
Abstract
Supplementing interleukin-6 (IL6) to in vitro-produced bovine embryos increases inner cell mass (ICM) cell numbers in blastocysts. A series of studies were completed to further dissect this effect. Treatment with IL6 increased ICM cell numbers in early, regular and expanded blastocysts but had no effect on morulae total cell number. Treatment with IL6 for 30min induced signal transducer and activator of transcription 3 (STAT3) phosphorylation and nuclear translocation in all blastomeres in early morulae and specifically within the ICM in blastocysts. Also, IL6 supplementation increased SOCS3 mRNA abundance, a STAT3-responsive gene, in blastocysts. Chemical inhibition of Janus kinase (JAK) activity from day 5 to day 8 prevented STAT3 activation and the IL6-induced ICM cell number increase. Global transcriptome analysis of blastocysts found that transcripts for IL6 and its receptor subunits (IL6R and IL6ST) were the most abundantly expressed IL6 family ligand and receptors. These results indicate that IL6 increases ICM cell numbers as the ICM lineage emerges at the early blastocyst stage through a STAT3-dependent mechanism. Also, IL6 appears to be the primary IL6 cytokine family member utilized by bovine blastocysts to control ICM cell numbers.
No significant impact of IFN-gamma pathway gene variants on tuberculosis susceptibility in a West African population
EUROPEAN JOURNAL OF HUMAN GENETICS
Authors: Meyer, Christian G.; Intemann, Christopher D.; Foerster, Birgit; Owusu-Dabo, Ellis; Franke, Andre; Horstmann, Rolf D.; Thye, Thorsten
Abstract
The concept of interferon-gamma (IFN-gamma) having a central role in cell-mediated immune defence to Mycobacterium tuberculosis has long been proposed. Observations made through early candidate gene studies of constituents of the IFN-gamma pathway have identified moderately associated variants associated with resistance or susceptibility to tuberculosis (TB). By analysing 20 major genes whose proteins contribute to IFN-gamma signalling we have assessed a large fraction of the variability in genes that might contribute to susceptibility to TB. Genetic variants were identified by sequencing the promoter regions and all exons of IFNG, IFNGR1, IFNGR2, IRF1, IL12A, IL12B, IL12RB1, IL12RB2, IL23A, IL23R, IL27, EBI3, IL27RA, IL6ST, SOCS1, STAT1, STAT4, JAK2, TYK2 and TBX21 in 69 DNA samples from Ghana. In addition, we screened all exons of IFNGR1 in a Ghanaian study group comprising 1999 TB cases and 2589 controls by high-resolution melting point analysis. The fine-mapping approach allows for a detailed screening of all variants, common and rare. Statistical comparisons of cases and controls, however, did not yield significant results after correction for multiple testing with any of the 246 variants selected for genotyping in this investigation. Gene-wise haplotype tests and analysis of rare variants did not reveal any significant association with susceptibility to TB in our investigation as well. Although this analysis was applied on a plausible set of IFN-gamma pathway genes in the largest African TB cohort available so far, the lack of significant results challenges the view that genetic marker of the IFN-gamma pathway have an important impact on susceptibility to TB.