Experimental Animal Division

Essential role of condensins I and II
for early embryonic divisions in mice

B6.Cg-Ncaph<tm1.1Hiran> (RBRC06800)

B6.Cg-Ncaph2<tm1.1Hiran> (RBRC06801)

Courtesy of Tatsuya Hirano, Ph.D.

Summary of defective phenotypes observed in neural stem cells depleted of condensin I (ΔI), condensin II (ΔII) or both (ΔI&II). CP; cortical plate; VZ ventricular zone.

Condensin complexes are among the most conserved classes of chromosomal proteins. Most eukaryotes have two different types of complexes, condensin I and condensin II, which share a heterodimeric pair of structural maintenance of chromosomes (SMC) core subunits but have distinct sets of non-SMC subunits [1, 2]. Most of the neurons and their supporting cells in the brain originate from neural stem cells (NSCs). Since the role of condensins in NSC division during cortical development remained unclear, Hirano and colleagues generated conditional KO mice to deplete Ncaph (encoding condensin I-specific subunit CAP-H) and/or Ncaph2 (condensin II-specific subunit CAP-H2) in developing cerebral cortex [3]. Contrary to previous reports showing that condensin II is not essential for mitosis or has non-mitotic functions in several model organisms, they revealed that condensins I and II have overlapping and non-overlapping functions in NSC division and survival. Ncaph and Ncaph2 conditional KO strains will stimulate further in vivo research identifying new roles of two condensin complexes in chromosome organization.