Nuclear Import of the LIKE HETEROCHROMATIN PROTEIN1 is redundantly mediated by Importinα−1, Importinα−2, and Importinα−3

• Published in: The Plant journal : for cell and molecular biology 2020-06, Vol.103 (3), p.1205-1214
• Main Authors: Chen, Chong, Kim, Daewon, Yun, Hee Rang, Lee, Yun Mi, Yogendra, Bordiya, Bo, Zhao, Kim, Hae Eun, Min, Jun Hong, Lee, Yong-Suk, Rim, Yeong Gil, Kim, Hyun Uk, Sung, Sibum, Heo, Jae Bok
• Format: Article
• Language: English
• ISSN: 0960-7412; 1365-313X
• DOI: 10.1111/tpj.14796

LIKE HETEROCHROMATIN PROTEIN1 (LHP1) encodes the only plant homologue of the metazoan HETEROCHROMATIN PROTEIN1 (HP1) protein family. LHP1 is necessary for proper epigenetic regulation of a range of developmental processes in plants. LHP1 is a transcriptional repressor of flowering related genes, such as FLOWERING LOCUS T ( FT ), FLOWERING LOCUS C ( FLC ), AGAMOUS ( AG ), and APETALA 3 ( AP3 ). We found that LHP1 interacts with importin [alpha]-1 (IMPα−1), importin [alpha]-2 (IMPα−2), and importin [alpha]-3 (IMPα−3), both in vitro and in vivo . A genetic approach revealed that triple mutation of impα−1 , impα−2 , and impα−3 resulted in Arabidopsis plants with a rapid flowering phenotype similar to that of plants with mutations in lhp1 due to the up-regulation of FT expression. Nuclear targeting of LHP1 was severely impaired in the impα triple mutant, resulting in the de-repression of LHP1 target genes AG, AP3 , and SHATTERPROOF 1 as well as FT . Therefore, the importin proteins IMPα−1, IMPα−2, and IMPα−3 are necessary for the nuclear import of LHP1.