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Functional dissection of N-terminal nuclear trafficking signals of SETDB1

Authors :
Jaemin Eom
Kyuheum Jeon
Jung Sun Park
Yong-Kook Kang
Source :
Frontiers in Cell and Developmental Biology, Vol 10 (2022)
Publication Year :
2022
Publisher :
Frontiers Media S.A., 2022.

Abstract

SETDB1 is a histone H3-lysine 9-specific methyltransferase that fulfills epigenetic functions inside the nucleus; however, when overexpressed, SETDB1 majorily localizes in the cytoplasm. SETDB1 has a single nuclear-localization-signal (NLS) motif and two successive nuclear-export-signal (NES1 and NES2) motifs in the N-terminus, suggesting that SETDB1 localization is the consequence of a balance between the two antithetic motifs. Here, we performed a series of motif deletions to characterize their effects on the cellular movement of SETDB1. Given the cytoplasmic localization of GFP-SETDB1 in the whole form, without the NES motifs, GFP-SETDB1 was not nuclear, and 3xNLS addition plus NES removal held the majority of GFP-SETDB1 within the nucleus. The results indicated that the cytoplasmic localization of GFP-SETDB1 is the combined result of weak NLS and robust NESs. In ATF7IP-overexpressing cells, GFP-SETDB1 entered the nucleus only in the presence of the NES1 motif; neither the NES2 nor NLS motif was necessary. Since subcellular fractionation results showed that ATF7IP was nuclear-only, an intermediary protein may interact specifically with the NES1 motif after stimulation by ATF7IP. When GFP-SETDB1 had either NES1 or NES2, it was precipitated (in immunoprecipitation) and colocalized (in immunofluorescence) with ATF7IP, indicating that GFP-SETDB1 interacts with ATF7IP through the NES motifs in the nucleus. The regulated nuclear entry of SETDB1 is assumed to set a tight restriction on its abundance within the nucleus, thereby ensuring balanced nuclear SETDB1 levels.

Details

Language :
English
ISSN :
2296634X
Volume :
10
Database :
Directory of Open Access Journals
Journal :
Frontiers in Cell and Developmental Biology
Publication Type :
Academic Journal
Accession number :
edsdoj.7d5cff63cd214fcc957eb80155dc8691
Document Type :
article
Full Text :
https://doi.org/10.3389/fcell.2022.1069765