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Inner nuclear membrane protein Ima1 is dispensable for intranuclear positioning of centromeres
Author(s) -
Hiraoka Yasushi,
Maekawa Hiromi,
Asakawa Haruhiko,
Chikashige Yuji,
Kojidani Tomoko,
Osakada Hiroko,
Matsuda Atsushi,
Haraguchi Tokuko
Publication year - 2011
Publication title -
genes to cells
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.912
H-Index - 115
eISSN - 1365-2443
pISSN - 1356-9597
DOI - 10.1111/j.1365-2443.2011.01544.x
Subject(s) - biology , microbiology and biotechnology , mitosis , centromere , inner membrane , schizosaccharomyces pombe , prophase , spindle pole body , nuclear membrane , schizosaccharomyces , nuclear protein , genetics , meiosis , cell division , chromosome , cell , spindle apparatus , mutant , nucleus , gene , transcription factor , mitochondrion
Inner nuclear membrane (INM) proteins play a role in spatial organization of chromosomes within the nucleus. In the fission yeast Schizosaccharomyces pombe , Sad1, an INM protein of the conserved SUN‐domain family, plays an active role in moving chromosomes along the nuclear membranes during meiotic prophase. Ima1 is another conserved INM protein recently identified. A previous study claimed that Ima1 is essential for mitotic cell growth, linking centromeric heterochromatin to the spindle‐pole body. However, we obtained results contradictory to the previously proposed role for Ima1: Ima1 was dispensable for mitotic cell growth or centromere positioning. This discrepancy was attributed to incorrect ima1 deletion mutants used in the previous study. Our results show that Ima1 collaborates with two other conserved INM proteins of the LEM‐domain family that are homologous to human Man1 and Lem2. Loss of any one of three INM proteins has no effect on mitotic cell growth; however, loss of all these proteins causes severe defects in mitotic cell growth and nuclear membrane morphology. Considering that all three INM proteins interact with Sad1, these results suggest that Ima1, Lem2 and Man1 play at least partially redundant roles for nuclear membrane organization.