Caenorhabditis eleganspolo-like kinase PLK-1 is required for merging parental genomes into a single nucleus

Abstract

Partial inactivation of PLK-1 in the embryo leads to the formation of two nuclei containing either maternal or paternal chromosomes. This is due to a defect in forming a nuclear envelope gap at the interface of the maternal and paternal pronuclei. Moreover, this gap formation is linked to proper chromosome alignment during the first mitosis.

Cell Biology of theCaenorhabditis elegansNucleus

“…Note that as the embryos progress through early development, their cells and nuclei become smaller. Adapted from Rahman et al (2015). Bar,10 mm. the NE are still present, the NE itself is no longer intact.…”

“…The chromosomes contributed by the oocyte and sperm are initially encapsulated by separate NEs, forming the maternal and paternal pronuclei, respectively. After pronuclear meeting, NPCs and the nuclear lamina largely disassemble, but the nuclear membranes between the two pronuclei still separate the maternal and paternal genomes ( Figure 6A, time 0; Audhya et al 2007;Rahman et al 2015). Mixing of parental genomes is initiated by the formation of a membrane gap ( Figure 7A).…”

“…The bright red spots at the bottom edge of the AB cell are the polar bodies. Adapted from Rahman et al (2015). Bar,10 mm. to as "twinned nuclei") in subsequent cell divisions, with one nucleus containing the maternal genome and the other containing the paternal one ( Figure 7B).…”

“…This phenotype is observed when lipid metabolism and ER structure are disrupted Golden et al 2009;Gorjanacz and Mattaj 2009;Bahmanyar et al 2014), when NPP-12/gp210 is downregulated Galy et al 2008), or when PLK-1 is partially inactivated (Rahman et al 2015). The formation of the membrane gap between the two pronuclei coincides with metaphase chromosome alignment; conditions that perturb alignment also abrogate the formation of the membrane gap (Rahman et al 2015). The exact structure of this membrane gap and the mechanism of its formation are unknown.…”

“…The membranous structures around centrosomes are indicated by arrows. Adapted from Rahman et al (2015). Bar, 10 mm.…”