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  • JAK3 Is Expressed in the Nucleus of Malignant T Cells in Cutaneous T Cell Lymphoma (CTCL).

JAK3 Is Expressed in the Nucleus of Malignant T Cells in Cutaneous T Cell Lymphoma (CTCL).

Cancers (2021-01-21)
Chella Krishna Vadivel, Maria Gluud, Sara Torres-Rusillo, Lasse Boding, Andreas Willerslev-Olsen, Terkild B Buus, Tea Kirkegaard Nielsen, Jenny L Persson, Charlotte M Bonefeld, Carsten Geisler, Thorbjorn Krejsgaard, Anja T Fuglsang, Niels Odum, Anders Woetmann
ABSTRACT

Perturbation in JAK-STAT signaling has been reported in the pathogenesis of cutaneous T cell lymphoma (CTCL). JAK3 is predominantly associated with the intra-cytoplasmic part of IL-2Rγc located in the plasma membrane of hematopoietic cells. Here we demonstrate that JAK3 is also ectopically expressed in the nucleus of malignant T cells. We detected nuclear JAK3 in various CTCL cell lines and primary malignant T cells from patients with Sézary syndrome, a leukemic variant of CTCL. Nuclear localization of JAK3 was independent of its kinase activity whereas STAT3 had a modest effect on nuclear JAK3 expression. Moreover, JAK3 nuclear localization was only weakly affected by blockage of nuclear export. An inhibitor of the nuclear export protein CRM1, Leptomycin B, induced an increased expression of SOCS3 in the nucleus, but only a weak increase in nuclear JAK3. Importantly, immunoprecipitation experiments indicated that JAK3 interacts with the nuclear protein POLR2A, the catalytic subunit of RNA Polymerase II. Kinase assays showed tyrosine phosphorylation of recombinant human Histone H3 by JAK3 in vitro-an effect which was blocked by the JAK inhibitor (Tofacitinib citrate). In conclusion, we provide the first evidence of nuclear localization of JAK3 in malignant T cells. Our findings suggest that JAK3 may have a cytokine-receptor independent function in the nucleus of malignant T cells, and thus a novel non-canonical role in CTCL.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
StableCell RPMI-1640, With stable glutamine and sodium bicarbonate, liquid, sterile-filtered, suitable for cell culture
Sigma-Aldrich
Poly-L-lysine hydrobromide, mol wt 30,000-70,000
Sigma-Aldrich
Bovine Serum Albumin, lyophilized powder, ≥96% (agarose gel electrophoresis)
Sigma-Aldrich
Leptomycin B solution from Streptomyces sp., ≥95% (HPLC), Supplied in methanol: water (7:3)
Sigma-Aldrich
Methanol, suitable for HPLC, ≥99.9%
Sigma-Aldrich
Dimethyl sulfoxide, for molecular biology
Sigma-Aldrich
DAPI, for nucleic acid staining
Sigma-Aldrich
Penicillin–Streptomycin Solution Hybri-Max, with 10,000 units penicillin and 10mg/ml streptomycin in 0.9% NaCl, 0.1 μm filtered, BioReagent, suitable for hybridoma
Sigma-Aldrich
Tofacitinib citrate, ≥98% (HPLC)