title: Mouse zygote-specific proteasome assembly chaperone important for maternal-to-zygotic transition.
abstract: During the maternal-to-zygotic transition (MZT), maternal proteins in oocytes are degraded by the ubiquitin-proteasome system (UPS), and new proteins are synthesized from the zygotic genome. However, the specific mechanisms underlying the UPS at the MZT are not well understood. We identified a molecule named zygote-specific proteasome assembly chaperone (ZPAC) that is specifically expressed in mouse gonads, and expression of ZPAC was transiently increased at the mouse MZT. ZPAC formed a complex with Ump1 and associated with precursor forms of 20S proteasomes. Transcription of ZPAC genes was also under the control of an autoregulatory feedback mechanism for the compensation of reduced proteasome activity similar to Ump1 and 20S proteasome subunit gene expression. Knockdown of ZPAC in early embryos caused a significant reduction of proteasome activity and decrease in Ump1 and mature proteasomes, leading to accumulation of proteins that need to be degraded at the MZT and early developmental arrest. Therefore, a unique proteasome assembly pathway mediated by ZPAC is important for progression of the mouse MZT.
authors: Division of Biological Science, Graduate School of Biology-Oriented Science and Technology, Kinki University ,  930 Nishimitani, Kinokawa, Wakayama 649-6493 ,  Japan ; Laboratory of Protein Metabolism, Graduate School of Pharmaceutical Sciences, The University of Tokyo ,  7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 ,  Japan.
authors: Seung-Wook
authors: SW
authors: Shin
authors: Natsumi
authors: N
authors: Shimizu
authors: Mikiko
authors: M
authors: Tokoro
authors: Satoshi
authors: S
authors: Nishikawa
authors: Yuki
authors: Y
authors: Hatanaka
authors: Masayuki
authors: M
authors: Anzai
authors: Jun
authors: J
authors: Hamazaki
authors: Satoshi
authors: S
authors: Kishigami
authors: Kazuhiro
authors: K
authors: Saeki
authors: Yoshihiko
authors: Y
authors: Hosoi
authors: Akira
authors: A
authors: Iritani
authors: Shigeo
authors: S
authors: Murata
authors: Kazuya
authors: K
authors: Matsumoto
keywords: Maternal-to-zygotic transition; Ubiquitin–proteasome system; ZPAC