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Development 2019 Apr 23;1468:. doi: 10.1242/dev.172700.
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Novel functions of the ubiquitin-independent proteasome system in regulating Xenopus germline development.

Hwang H , Jin Z , Krishnamurthy VV , Saha A , Klein PS , Garcia B , Mei W , King ML , Zhang K , Yang J .

In most species, early germline development occurs in the absence of transcription with germline determinants subject to complex translational and post-translational regulations. Here, we report for the first time that early germline development is influenced by dynamic regulation of the proteasome system, previously thought to be ubiquitously expressed and to serve 'housekeeping' roles in controlling protein homeostasis. We show that proteasomes are present in a gradient with the highest levels in the animal hemisphere and extending into the vegetal hemisphere of Xenopus oocytes. This distribution changes dramatically during the oocyte-to-embryo transition, with proteasomes becoming enriched in and restricted to the animal hemisphere and therefore separated from vegetally localized germline determinants. We identify Dead-end1 (Dnd1), a master regulator of vertebrate germline development, as a novel substrate of the ubiquitin-independent proteasomes. In the oocyte, ubiquitin-independent proteasomal degradation acts together with translational repression to prevent premature accumulation of Dnd1 protein. In the embryo, artificially increasing ubiquitin-independent proteasomal degradation in the vegetal pole interferes with germline development. Our work thus reveals novel inhibitory functions and spatial regulation of the ubiquitin-independent proteasome during vertebrate germline development.

PubMed ID: 30910828
PMC ID: PMC6503979
Article link: Development
Grant support: [+]

Species referenced: Xenopus laevis
Genes referenced: dazl dnd1 eif4e hspa8 myc nanos1 pgat pgc psma2 psmc6 psme1 psme2 psme3 psme4 trim36
GO keywords: proteasome regulatory particle [+]
Antibodies: Dnd1 Ab1 FLAG Ab3 HSPA8 Ab1 Myc Ab2 Proteasome 20s Ab 1 Tubb3 Ab2

Phenotypes: Xla Wt + psme1 + psme2 (Fig. 7 Ac1 B) [+]

Article Images: [+] show captions
References [+] :
Aguero, Mechanisms of Vertebrate Germ Cell Determination. 2017, Pubmed, Xenbase