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J Biol Chem. 2019 Feb 15;294(7):2386-2396. doi: 10.1074/jbc.RA118.006226. Epub 2018 Dec 20.

Interleukin 34 (IL-34) cell-surface localization regulated by the molecular chaperone 78-kDa glucose-regulated protein facilitates the differentiation of monocytic cells.

Author information

1
From the Division of Medical Bioengineering, Graduate School of Natural Science and Technology.
2
the Department of Applied Chemistry and Biotechnology, Faculty of Engineering, and.
3
the Laboratory of Applied Cell Biology, Graduate School of Interdisciplinary Science and Engineering in Health Systems, Okayama University, Tsushima-Naka 3-1-1, Kita-ku, Okayama 700-8530, Japan.
4
From the Division of Medical Bioengineering, Graduate School of Natural Science and Technology, magari@cc.okayama-u.ac.jp.

Abstract

Interleukin 34 (IL-34) constitutes a cytokine that shares a common receptor, colony-stimulating factor-1 receptor (CSF-1R), with CSF-1. We recently identified a novel type of monocytic cell termed follicular dendritic cell-induced monocytic cells (FDMCs), whose differentiation depended on CSF-1R signaling through the IL-34 produced from a follicular dendritic cell line, FL-Y. Here, we report the functional mechanisms of the IL-34-mediated CSF-1R signaling underlying FDMC differentiation. CRIPSR/Cas9-mediated knockout of the Il34 gene confirmed that the ability of FL-Y cells to induce FDMCs completely depends on the IL-34 expressed by FL-Y cells. Transwell culture experiments revealed that FDMC differentiation requires a signal from a membrane-anchored form of IL-34 on the FL-Y cell surface, but not from a secreted form, in a direct interaction between FDMC precursor cells and FL-Y cells. Furthermore, flow cytometric analysis using an anti-IL-34 antibody indicated that IL-34 was also expressed on the FL-Y cell surface. Thus, we explored proteins interacting with IL-34 in FL-Y cells. Mass spectrometry analysis and pulldown assay identified that IL-34 was associated with the molecular chaperone 78-kDa glucose-regulated protein (GRP78) in the plasma membrane fraction of FL-Y cells. Consistent with this finding, GRP78-heterozygous FL-Y cells expressed a lower level of IL-34 protein on their cell surface and exhibited a reduced competency to induce FDMC differentiation compared with the original FL-Y cells. These results indicated a novel GRP78-dependent localization and specific function of IL-34 in FL-Y cells related to monocytic cell differentiation.

KEYWORDS:

CRISPR/Cas; GRP78; Western blot; cell differentiation; cell surface protein; chaperone; colony-stimulating factor-1 receptor; cytokine; follicular dendritic cell; interleukin; interleukin 34; monocyte; plasma membrane

PMID:
30573681
PMCID:
PMC6378969
[Available on 2020-02-15]
DOI:
10.1074/jbc.RA118.006226
[Indexed for MEDLINE]

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