Golgi Disruption and Early Embryonic Lethality in Mice Lacking USO1

Susie Kim,Patrick Smits,Matthew L Warman,Adele Hill,Julie G Donaldson

doi:10.1371/journal.pone.0050530

Abstract

Golgins are a family of long rod-like proteins characterized by the presence of central coiled-coil domains. Members of the golgin family have important roles in membrane trafficking, where they function as tethering factors that capture transport vesicles and facilitate membrane fusion. Golgin family members also have essential roles in maintaining the organization of the Golgi apparatus. Knockdown of individual golgins in cultured cells resulted in the disruption of the Golgi structure and the dispersal of Golgi marker proteins throughout the cytoplasm. However, these cellular phenotypes have not always been recapitulated in vivo. For example, embryonic development proceeds much further than expected and Golgi disruption was observed in only a subset of cell types in mice lacking the ubiquitously expressed golgin GMAP-210. Cell-type specific functional compensation among golgins may explain the absence of global cell lethality when a ubiquitously expressed golgin is missing. In this study we show that functional compensation does not occur for the golgin USO1. Mice lacking this ubiquitously expressed protein exhibit disruption of Golgi structure and early embryonic lethality, indicating that USO1 is indispensable for early embryonic development.

Highlights

Communication between different membrane bound compartments within a eukaryotic cell and between the cell and its extracellular environment is accomplished in large part by the membrane trafficking process
Sequence tag information obtained by RT-PCR using ES cell RNA had previously suggested that the AW0562 gene traps (GT) spliced to Uso1 exon 10 and the YTA025 GT spliced to Uso1 exon 12
We confirmed our hypotheses by using forward primers located in exons 10 or 12 of Uso1 and a reverse primer located in the GT to PCR amplify genomic DNA from mice derived from AW0562 and YTA025 ES cells, respectively

Summary

Introduction

Communication between different membrane bound compartments within a eukaryotic cell and between the cell and its extracellular environment is accomplished in large part by the membrane trafficking process ( known as vesicular trafficking). Two major but interconnecting trafficking pathways exist within the cell. The exocytic pathway is responsible for transporting proteins and lipids from their place of synthesis to their site of function in or outside the cell. The endocytic, or retrograde, pathway is responsible for transport of internalized cargo from the extracellular environment towards endosomes and lysosomes. The endocytic pathway is responsible for the recycling of proteins involved in exocytic transport [1,2,3,4]. (1) Cargo is selected, and a vesicular or tubular transport intermediate forms at a donor compartment. (2) The transport intermediate is delivered to the target membrane using molecular motors that travel along the cell’s microtubule or actin filament system. (3) Tethering brings the transport intermediate and target membranes in close proximity. Membrane trafficking occurs in four steps. (1) Cargo is selected, and a vesicular or tubular transport intermediate forms at a donor compartment. (2) The transport intermediate is delivered to the target membrane using molecular motors that travel along the cell’s microtubule or actin filament system. (3) Tethering brings the transport intermediate and target membranes in close proximity. (4) Fusion of the two membranes leads to the transfer of cargo [5]

Methods

Results

Conclusion