Intracellular membrane trafficking among organelles occurs through vesicular or tubular intermediates that selectively deliver proteins and lipids from one compartment to another. The Rab proteins are small GTPases that function as master regulators of this process. All Rabs localize at specific subcellular compartments and their distribution is crucial for the specificity and directionality of membrane traffic (i.e. secretion, endocytosis, recycling etc.). In particular, Rab14, one of the recently discovered members of the Rab family is localized at the Golgi/trans-Golgi network (TGN) and endosomes and has been associated with different steps of the endosomal recycling pathway. Here we have identified Rab14 as a novel substrate of PARP12, a mono-ADP-ribosyl transferase mainly localized at the Golgi complex. The physiological functions of PARP12 are not yet completely elucidated. With this study we demonstrate that PARP12 is able to interact and modify Rab14 and that its depletion impairs Rab14 functions. Inhibition of ADP-ribosylation alters Rab14 localization, which in turn affects membrane flow through the recycling endosomes. Using bioinformatics and mutagenesis approaches, we have generated a Rab14 mutant that cannot be ADP-ribosylated by PARP12. The analysis of the mutant suggests that Rab14 participates in a cascade of events controlling the maturation of recycling endosomes and that the ADP-ribosylation of Rab14 is essential for this step. Overall our data identify mono-ADP-ribosylation as a novel post-translation modification of the small GTPase Rab14 that may be used to modulate the spatial-temporal regulation of the Rab14-GTPase activation cycle. In addition our data highlight a novel role of PARP12 in the progression of intracellular membrane traffic.
The mono-ADP-ribosylation of Rab14 by PARP12 is involved in the regulation of Rab14-driven membrane traffic
2017
Abstract
Intracellular membrane trafficking among organelles occurs through vesicular or tubular intermediates that selectively deliver proteins and lipids from one compartment to another. The Rab proteins are small GTPases that function as master regulators of this process. All Rabs localize at specific subcellular compartments and their distribution is crucial for the specificity and directionality of membrane traffic (i.e. secretion, endocytosis, recycling etc.). In particular, Rab14, one of the recently discovered members of the Rab family is localized at the Golgi/trans-Golgi network (TGN) and endosomes and has been associated with different steps of the endosomal recycling pathway. Here we have identified Rab14 as a novel substrate of PARP12, a mono-ADP-ribosyl transferase mainly localized at the Golgi complex. The physiological functions of PARP12 are not yet completely elucidated. With this study we demonstrate that PARP12 is able to interact and modify Rab14 and that its depletion impairs Rab14 functions. Inhibition of ADP-ribosylation alters Rab14 localization, which in turn affects membrane flow through the recycling endosomes. Using bioinformatics and mutagenesis approaches, we have generated a Rab14 mutant that cannot be ADP-ribosylated by PARP12. The analysis of the mutant suggests that Rab14 participates in a cascade of events controlling the maturation of recycling endosomes and that the ADP-ribosylation of Rab14 is essential for this step. Overall our data identify mono-ADP-ribosylation as a novel post-translation modification of the small GTPase Rab14 that may be used to modulate the spatial-temporal regulation of the Rab14-GTPase activation cycle. In addition our data highlight a novel role of PARP12 in the progression of intracellular membrane traffic.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
