The microenvironment patterns the pluripotent mouse epiblast through paracrine Furin and Pace4 proteolytic activities

Abstract

The fate of pluripotent cells in early mouse embryos is controlled by graded Nodal signals that are activated by the endoproteases Furin and Pace4. Soluble forms of Furin and Pace4 cleave proNodal in vitro and after secretion in transfected cells, but direct evidence for paracrine activity in vivo is elusive. Here, we show that Furin and Pace4 are released by the extraembryonic microenvironment, and that they cleave a membrane-bound reporter substrate in adjacent epiblast cells and activate Nodal to maintain pluripotency. Secreted Pace4 and Furin also stimulated mesoderm formation, whereas endoderm was only induced by Pace4, correlating with a difference in the spatiotemporal distribution of these proteolytic activities. Our analysis of paracrine Furin and Pace4 activities and their in vivo functions significantly advances our understanding of how the epiblast is patterned by its microenvironment. Adding cell-cell communication to the pleiotropic portfolio of these proteases provides a new framework to study proprotein processing also in other relevant contexts.

Proprotein Convertase Subtilisin/Kexin Type 7 (PCSK7) Is Essential for the Zebrafish Development and Bioavailability of Transforming Growth Factor β1a (TGFβ1a)

“…In addition, a mutation in furinA causes significant embryonic lethality in zebrafish despite the duplication of the furin gene (24). These fundamental phenotypes can be explained by a lack of processing of PCSK substrate molecules; in early mouse development, the significance of the proper activation of the TGF␤ family cytokines, such as BMPs and NODAL (50), is particularly emphasized. In contrast, a thorough functional analysis of a mammalian model for PCSK7 is not available in the literature.…”

Ets2-dependent trophoblast signalling is required for gastrulation progression after primitive streak initiation

“…This work also demonstrates that trophoblast signalling is not only required for gastrulation initiation [3][4][5][6] , but also for gastrulation progression. The latter is defined here as all gastrulation process taking place between E6.5 (PS initiation stage) and E7.75 (the stage just prior to the period when the embryo begins somitogenesis).…”

“…Mammalian gastrulation requires signals from two extraembryonic tissues: the visceral endoderm (VE-progenitor of yolk-sac endoderm and minor contributor to DE) and the extraembryonic ectoderm (EXE) trophoblast (progenitor of placental trophoblast) 1,2 . Although EXE trophoblast signalling is required for gastrulation initiation [3][4][5][6] , it is currently unknown whether it also controls gastrulation progression after PS initiation. This issue was addressed here using Ets2 homozygous null (Ets2 À / À ) mice.…”

A Molecular Sensor To Characterize Arenavirus Envelope Glycoprotein Cleavage by Subtilisin Kexin Isozyme 1/Site 1 Protease

“…A unique feature of SKI-1/S1P is its ability to recognize and process substrates in distinct compartments of the secretory pathway. LASV GPC is already processed by SKI-1/S1P in the ER/cisGolgi, whereas endogenous substrates, such as sterol regulatory element-binding proteins (SREBPs) or activation transcription factor 6 (ATF-6), are processed in the median Golgi compartment, and LCMV GPC undergoes cleavage in late Golgi compartments (20,21). These observations suggest that the activity of the protease is somehow regulated in a compartment-specific manner.…”