#Shun-ichi Suto 1, #Koh-ichi Teraoka1, #Ichiro Kawasaki 1, Kenta Sugiura 1, Taeko Sasaki 2, Ikuko Maejima 1, Hidetaka Kosako 3, *Miyuki Sato 2 & *Ken Sato 1 (1. Laboratory of Molecular Traffic, Institute for Molecular and Cellular Regulation, Gunma University; 2. Laboratory of Molecular Membrane Biology, Institute for Molecular and Cellular Regulation, Gunma University; 3. Division of Cell Signaling, Institute of Advanced Medical Sciences, Tokushima University) ; #Co-first author; *Corresponding author)
About
Fertilization—the fusion of an oocyte and a sperm—is a pivotal biological phenomenon in sexually reproducing organisms, marking the birth of a brand-new life from mature individuals. At this critical juncture, fertilized eggs and embryos undergo the degradation of proteins and organelles derived from the egg and sperm. Concurrently, the embryo initiates its own gene expression, triggering a massive overhaul of intracellular protein composition and cellular functions to prepare for embryonic development.
In this study, we identified HERD-1, a component of germline-specific Z granules, as an essential factor for the selective degradation of these obsolete maternal membrane proteins. Normally, after fertilization, these proteins are transported via endosomes to lysosomes for degradation via the multivesicular body (MVB) pathway. However, we found that the loss of HERD-1 leads to a reduction in key regulators of the multivesicular body pathway that mediates this process. Interestingly, this degradation defect was suppressed by the loss of DEPS-1 or PRG-1, proteins involved in small RNA synthesis. These results suggest that maternal germ granule components actively trigger endosomal activation (“endosomal switching”) in the early embryo (the offspring) via small RNA pathways, thereby precisely controlling organelle remodeling.
Paper information
Shun-ichi Suto, Koh-ichi Teraoka, Ichiro Kawasaki, Kenta Sugiura, Taeko Sasaki, Ikuko Maejima, Hidetaka Kosako, Miyuki Sato & Ken Sato. Germ granule components regulate endosomal switching during the oocyte-to-embryo transition in Caenorhabditis elegans. Commun Biol. 2026 May 7 ; 9, 952
Online URL
https://www.nature.com/articles/s42003-026-10193-0#citeas
