Calcium ions function as a booster of chromosome condensation

Abstract

Chromosome condensation is essential for the faithful transmission of genetic information to daughter cells during cell division. The depletion of chromosome scaffold proteins does not prevent chromosome condensation despite structural defects. This suggests that other factors contribute to condensation. Here we investigated the contribution of divalent cations, particularly Ca2+, to chromosome condensation in vitro and in vivo. Ca2+ depletion caused defects in proper mitotic progression, particularly in chromosome condensation after the breakdown of the nuclear envelope. Fluorescence lifetime imaging microscopy-Förster resonance energy transfer and electron microscopy demonstrated that chromosome condensation is influenced by Ca2+. Chromosomes had compact globular structures when exposed to Ca2+ and expanded fibrous structures without Ca2+. Therefore, we have clearly demonstrated a role for Ca2+ in the compaction of chromatin fibres.

Condensin II plays an essential role in reversible assembly of mitotic chromosomes in situ

“…Cation concentration-dependent, morphological changes had been reported at various levels of chromosome structure, including nucleosomal arrays to bulk chromatin masses (Hansen, 2002; Marko, 2008; Maeshima et al , 2014; Pepenella et al , 2014; Phengchat et al , 2016). These observations were explained by the fact that negative charges of DNA, which are not fully neutralized by positively charged histones, are shielded by cations, thereby allowing compaction of the DNA-containing structures.…”

The Winner Takes It All: Auxin—The Main Player during Plant Embryogenesis

“…Another explanation of asymmetric MAPK distribution may come from regulation of chromatin structure or segregation of molecules in cytoplasm. Chromosomes exposed to calcium ions display compact structure [134], thus it is possible that the level of chromatin condensation might differ between groups of chromatids due to calcium gradients, and in this way calcium ions could facilitate or reduce DNA accessibility for MAPKs. Thus, auxin-induced calcium fluxes might regulate the number of phosphorylated MPAKs in the vicinity of chromosomes, as they might trigger the activation of phosphatases or they might control chromatin compaction which reduces accessibility of DNA for MAPKs.…”

First proteomic analysis of diestrus and anestrus canine oocytes at the germinal vesicle reveals candidate proteins involved in oocyte meiotic competence

“…Calcium/calmodulin‐stimulated protein kinase II (CaMKII) is Ca 2+ ‐sensing protein that regulates cell cycle progression. According to Phengchat et al (), the activity of this protein is required for entry into mitosis and transition to metaphase. Ca 2+ depletion may inhibit CaMKII activation by affecting effector proteins causing chromosome decompression.…”