Development of the anterior pituitary gland involves proliferation and differentiation of ectodermal cells in Rathke's pouch to generate five distinct cell types that are defined by the trophic hormones they produce. A detailed ontogenetic analysis of specific gene expression has revealed novel aspects of organogenesis in this model system. The expression of transcripts encoding the alpha-subunit common to three pituitary glycoprotein hormones in the single layer of somatic ectoderm on embryonic day 11 established that primordial pituitary cell commitment occurs prior to formation of a definitive Rathke's pouch. Activation of Pit-1 gene expression occurs as an organ-specific event, with Pit-1 transcripts initially detected in anterior pituitary cells on embryonic day 15. Levels of Pit-1 protein closely parallel those of Pit-1 transcripts without a significant lag. Unexpectedly, Pit-1 transcripts remain highly expressed in all five cell types of the mature pituitary gland, but the Pit-1 protein is detected in only three cell types--lactotrophs, somatotrophs, and thyrotrophs and not in gonadotrophs or corticotrophs. The presence of Pit-1 protein in thyrotrophs suggests that combinatorial actions of specific activating and restricting factors act to confine prolactin and growth hormone gene expression to lactotrophs and somatotrophs, respectively. A linkage between the initial appearance of Pit-1 protein and the surprising coactivation of prolactin and growth hormone gene expression is consistent with the model that Pit-1 is responsible for the initial transcriptional activation of both genes. The estrogen receptor, which has been reported to be activated in a stereotypic fashion subsequent to the appearance of Pit-1, appears to be capable, in part, of mediating the progressive increase in prolactin gene expression characteristic of the mature lactotroph phenotype. This is a consequence of synergistic transcriptional effects with Pit-1, on the basis of binding of the estrogen receptor to a response element in the prolactin gene distal enhancer. These data imply that both transcriptional and post-transcriptional regulation of Pit-1 gene expression and combinatorial actions with other classes of transcription factors activated in distinct temporal patterns, are required for the mature physiological patterns of gene expression that define distinct cell types within the anterior pituitary gland.

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Background Anti-cytokine therapies such as adalimumab, tocilizumab, and the small molecule JAK inhibitor tofacitinib have proven that cytokines and their subsequent downstream signaling processes are important in the pathogenesis of rheumatoid arthritis. Tofacitinib, a pan-JAK inhibitor, is the first approved JAK inhibitor for the treatment of RA and has been shown to be effective in managing disease. However, in phase 2 dose-ranging studies tofacitinib was associated with dose-limiting tolerability and safety issues such as anemia. Upadacitinib (ABT-494) is a selective JAK1 inhibitor that was engineered to address the hypothesis that greater JAK1 selectivity over other JAK family members will translate into a more favorable benefit:risk profile. Upadacitinib selectively targets JAK1 dependent disease drivers such as IL-6 and IFNγ, while reducing effects on reticulocytes and natural killer (NK) cells, which potentially contributed to the tolerability issues of tofacitinib. Methods Structure-based hypotheses were used to design the JAK1 selective inhibitor upadacitinib. JAK family selectivity was defined with in vitro assays including biochemical assessments, engineered cell lines, and cytokine stimulation. In vivo selectivity was defined by the efficacy of upadacitinib and tofacitinib in a rat adjuvant induced arthritis model, activity on reticulocyte deployment, and effect on circulating NK cells. The translation of the preclinical JAK1 selectivity was assessed in healthy volunteers using ex vivo stimulation with JAK-dependent cytokines. Results Here, we show the structural basis for the JAK1 selectivity of upadacitinib, along with the in vitro JAK family selectivity profile and subsequent in vivo physiological consequences. Upadacitinib is ~ 60 fold selective for JAK1 over JAK2, and > 100 fold selective over JAK3 in cellular assays. While both upadacitinib and tofacitinib demonstrated efficacy in a rat model of arthritis, the increased selectivity of upadacitinib for JAK1 resulted in a reduced effect on reticulocyte deployment and NK cell depletion relative to efficacy. Ex vivo pharmacodynamic data obtained from Phase I healthy volunteers confirmed the JAK1 selectivity of upadactinib in a clinical setting. Conclusions The data presented here highlight the JAK1 selectivity of upadacinitinib and supports its use as an effective therapy for the treatment of RA with the potential for an improved benefit:risk profile. Electronic supplementary material The online version of this article (10.1186/s41927-018-0031-x) contains supplementary material, which is available to authorized users.

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Background: Janus kinase 3 (Jak3) inhibitors hold promise for treatment of autoimmunity, but developing selective inhibitors is challenging. Results: We designed Jak3 inhibitors that avoid inhibition of the other JAKs. Conclusion: Our inhibitors possess high selectivity against other kinases and can potently inhibit Jak3 activity in cell-based assays. Significance: This class of irreversible inhibitors may be useful as selective agents of Jak3 inhibition.

Many immunoglobulin (Ig)-producing cells retain the DNA that separates Ig variable (V) and constant (C) region genes in the germline. This "remnant" DNA must be moved during the recombination process that joins V and C genes via a joining (J) segment. We have analyzed remnant DNAs in several Ig-producing cell lines. The nucleotide sequences of kappa (kappa) light chain remnant DNAs indicate close relationships to V-J joining. We find fused V kappa and J kappa recognition sequences in five remnant DNAs, suggesting reciprocal relationships to the fused V kappa and J kappa segments produced by V-J joining. However, of sixteen plasmacytoma remnant DNAs analyzed, all involve only recombination with J kappa l. Thus, in most cell lines, remnant DNAs are not directly reciprocal to recombined kappa-genes. On the other hand, our analyses of some myelomas do indicate indirect relationships between remnant DNAs and kappa-genes. Our results suggest that multiple steps of DNA recombination occur during Ig-gene rearrangement. Because remnant DNA joining sites do not exhibit the flexibility that has been observed in Ig-gene V-J joining, our findings also suggest that the joining mechanism may involve endonuclease, exonuclease and ligase activities.

Background Anti-cytokine therapies have become the mainstay of treatment for rheumatoid arthritis (RA) disease symptoms and can arrest disease progression. Despite numerous treatment options there are still many RA patients who fail to experience substantial decreases in disease activity. Recently, Jak kinase blockade was shown clinically to be effective in managing disease and in some cases achieving remission. However, these first generation Jak inhibitors have failed to meet expectations due to dose-limiting tolerability and safety issues. ABT-494 is a second generation Jak kinase inhibitor with high selectivity for Jak1 thereby minimizing the potential for side effects related to Jak2 and Jak3 inhibition. Here we describe preclinical and early clinical data that suggest ABT-494 has potential to address some of the current unmet medical needs of RA patients. Methods ABT-494 was engineered for increased selectivity for Jak1 using structural predictions that indicated the potential for differential binding interactions outside the ATP-binding active site of Jak1 but not Jak2. The efficacy and selectivity of ABT-494 were tested in a battery of relevant cellular and in vivo pharmacology assays including bone marrow colony formation, adjuvant induced arthritis (AIA), erythropoietin induced reticulocyte deployment and NK/NKT cell suppression. The potency of ABT-494 in a variety of complementary pharmacodynamic assays was also assessed at multiple dosages in healthy human subjects administered orally for 14 days. Results ABT-494 demonstrates approximately 74 fold selectivity for Jak1 over Jak2 in cellular assays dependent on specific, relevant cytokines. ABT-494 is a potent inhibitor of inflammation and bone loss in rat AIA and, compared to Tofacitinib, spares relevant essential physiological processes such as erythropoietin signaling and peripheral NK cell counts at similarly efficacious doses in rats. When dosed orally for 14 days in healthy human subjects ABT-494 did not decrease reticulocyte or NK cell counts at predicted efficacious doses consistent with its pharmacodynamic properties in rats. Conclusions ABT-494 is a Jak1-selective inhibitor that demonstrates efficacy in rat arthritis models. Preliminary evidence suggests that pharmacodynamic properties of ABT-494 are consistent between those observed in rodent models and in healthy human subjects. Taken together, these encouraging observations support further testing of ABT-494 in RA patients in Phase II randomized placebo controlled trials and indicate it may have increased potential to address patient needs over existing agents. Disclosure of Interest : J. Voss Employee of: AbbVie, C. Graff Employee of: AbbVie, A. Schwartz Employee of: AbbVie, D. Hyland Employee of: AbbVie, M. Argiriadi Employee of: AbbVie, H. Camp Employee of: AbbVie, L. Dowding Employee of: AbbVie, M. Friedman Employee of: AbbVie, K. Frank Employee of: AbbVie, J. George Employee of: AbbVie, E. Goedken Employee of: AbbVie, G. Lo Schiavo: None declared, M. Morytko Employee of: AbbVi...