Spatial-temporal study of Rab1b dynamics and function at the ER-Golgi interface

SAMPIERI, L; GARCIA IA; HERNÁN MARTINEZ; ALVAREZ, C

PLOS ONE

PUBLIC LIBRARY SCIENCE

Lugar: San Francisco; Año: 2016

1932-6203

The GTPase Rab1b is involved in ER to Golgi transport, withmultiple Rab1b effectors (located at ERES, VTCs and the Golgi complex) beingrequired for its function. In this study, we performed live-celldual-expression studies to analyze the dynamics of Rab1b and some effectorslocated at the ERES-Golgi interface. Rab1b occupied widely distributed mobile punctateand tubular structures, displaying a transient overlaps with its effectors and showingthat these overlaps occurred at the same time in spatially distinct steps of ERto Golgi transport. In addition, we assessed Rab1b dynamics during cargosorting by analyzing the concentration at ERES of a Golgi protein (SialT2-CFP)during Brefeldin A washout (BFA WO). Rab1b was associated to most of the ERESstructures, but at different times during BFA WO, and recurrently SialT2-CFP wassorted in the ERES-Rab1b positive structures. Furthermore, we reveal for firsttime that Rab1b localization time at ERES depended on GBF1, a Rab1b effectorthat acts as the guanine nucleotide exchange factor of Arf1, and that Rab1b membraneassociation/dissociation dynamics at ERES was dependent on the GBF1 membraneassociation and activity, which strongly suggests that GBF1 activity modulatesRab1b membrane cycling dynamic.