Dataset Information

Glycogen Synthase Kinase 3? Promotes the Endocytosis of Transferrin in the African Trypanosome.

ABSTRACT: Human parasite Trypanosoma brucei proliferates in the blood of its host, where it takes up iron via receptor-mediated endocytosis of transferrin (Tf). Mechanisms of Tf endocytosis in the trypanosome are not fully understood. Small molecule lapatinib inhibits Tf endocytosis in T. brucei and associates with protein kinase GSK3? (TbGSK3?). Therefore, we hypothesized that Tf endocytosis may be regulated by TbGSK3?, and we used three approaches (both genetic and small molecule) to test this possibility. First, the RNAi knock-down of TbGSK3? reduced Tf endocytosis selectively, without affecting the uptake of haptaglobin-hemoglobin (Hp-Hb) or bovine serum albumin (BSA). Second, the overexpression of TbGSK3? increased the Tf uptake. Third, small-molecule inhibitors of TbGSK3?, TWS119 (IC50 = 600 nM), and GW8510 (IC50 = 8 nM) reduced Tf endocytosis. Furthermore, TWS119, but not GW8510, selectively blocked Tf uptake. Thus, TWS119 phenocopies the selective endocytosis effects of a TbGSK3? knockdown. Two new inhibitors of TbGSK3?, LY2784544 (IC50 = 0.6 ?M) and sorafenib (IC50 = 1.7 ?M), were discovered in a focused screen: at low micromolar concentrations, they prevented Tf endocytosis as well as trypanosome proliferation (GI50's were 1.0 and 3.1 ?M, respectively). These studies show that (a) TbGSK3? regulates Tf endocytosis, (b) TWS119 is a small-molecule tool for investigating the endocytosis of Tf,

SUBMITTER: Guyett PJ

PROVIDER: S-EPMC5025259 | biostudies-literature | 2016 Jul

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Glycogen Synthase Kinase 3β Promotes the Endocytosis of Transferrin in the African Trypanosome.

Guyett Paul J PJ Xia Shuangluo S Swinney David C DC Pollastri Michael P MP Mensa-Wilmot Kojo K

ACS infectious diseases 20160616 7

Human parasite Trypanosoma brucei proliferates in the blood of its host, where it takes up iron via receptor-mediated endocytosis of transferrin (Tf). Mechanisms of Tf endocytosis in the trypanosome are not fully understood. Small molecule lapatinib inhibits Tf endocytosis in T. brucei and associates with protein kinase GSK3β (TbGSK3β). Therefore, we hypothesized that Tf endocytosis may be regulated by TbGSK3β, and we used three approaches (both genetic and small molecule) to test this possibili ...[more]

PMID: 27626104

Similar Datasets

Project description:Background & aimsGlycogen synthase kinase 3β (Gsk3β [Gsk3b]) is a ubiquitously expressed kinase with distinctive functions in different types of cells. Although its roles in regulating innate immune activation and ischaemia and reperfusion injuries (IRIs) have been well documented, the underlying mechanisms remain ambiguous, in part because of the lack of cell-specific tools in vivo.MethodsWe created a myeloid-specific Gsk3b knockout (KO) strain to study the function of Gsk3β in macrophages in a murine liver partial warm ischaemia model.ResultsCompared with controls, myeloid Gsk3b KO mice were protected from IRI, with diminished proinflammatory but enhanced anti-inflammatory immune responses in livers. In bone marrow-derived macrophages, Gsk3β deficiency resulted in an early reduction of Tnf gene transcription but sustained increase of Il10 gene transcription on Toll-like receptor 4 stimulation in vitro. These effects were associated with enhanced AMP-activated protein kinase (AMPK) activation, which led to an accelerated and higher level of induction of the novel innate immune negative regulator small heterodimer partner (SHP [Nr0b2]). The regulatory function of Gsk3β on AMPK activation and SHP induction was confirmed in wild-type bone marrow-derived macrophages with a Gsk3 inhibitor. Furthermore, we found that this immune regulatory mechanism was independent of Gsk3β Ser9 phosphorylation and the phosphoinositide 3-kinase-Akt signalling pathway. In vivo, myeloid Gsk3β deficiency facilitated SHP upregulation by ischaemia-reperfusion in liver macrophages. Treatment of Gsk3b KO mice with either AMPK inhibitor or SHP small interfering RNA before the onset of liver ischaemia restored liver proinflammatory immune activation and IRI in these otherwise protected hosts. Additionally, pharmacological activation of AMPK protected wild-type mice from liver IRI, with reduced proinflammatory immune activation. Inhibition of the AMPK-SHP pathway by liver ischaemia was demonstrated in tumour resection patients.ConclusionsGsk3β promotes innate proinflammatory immune activation by restraining AMPK activation.Lay summaryGlycogen synthase kinase 3β promotes macrophage inflammatory activation by inhibiting the immune regulatory signalling of AMP-activated protein kinase and the induction of small heterodimer partner. Therefore, therapeutic targeting of glycogen synthase kinase 3β enhances innate immune regulation and protects liver from ischaemia and reperfusion injury.

Dataset Information

Glycogen Synthase Kinase 3? Promotes the Endocytosis of Transferrin in the African Trypanosome.

Publications

Glycogen Synthase Kinase 3β Promotes the Endocytosis of Transferrin in the African Trypanosome.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets