Starvation- induced autophagy causes a re-distribution of Vamp7 vesicles to focal adhesions in HeLa cells

FADER CM

Cancun

Conferencia; Zing Conference of Autophagy; 2011

Zing

Autophagy is a normal degradative pathway that involves the sequestration of cytoplasmic components and organelles in a vacuole called autophagosome which finally fuses with the lysosome to degrade the sequestered material. The protein LC3 is an autophagic marker present in eukaryotic cells as a soluble form (LC3-I) and a membrane-associated form (LC3-II), which localizes to autophagosomes. SNAREs are key molecules of the vesicle fusion machinery. Our results indicate that a subset of Vamp7 (V-SNARE)-positive vacuoles colocalize with LC3 at the cell periphery upon starvation. Moreover, we have demonstrated that these Vamp7-positive structures are labeled by paxillin and vinculin (focal adhesion markers), indicating that the Vamp7-positive autophagosomes are present in these structures. We have also shown that the Vamp7 structures close to plasma membrane have late endosomal characteristics. Interestingly, the re-distribution of Vamp7 positive structures is a microtubule-dependent event, with the participation of the motor protein Kif5 and a Rab7 effector RILP. Furthermore, we have observed an increased number of ATP vesicles labeled with Vamp7 at the focal adhesions upon starvation. Taken together, our results suggest that VAMP7 is involved in the trafficking of amphisomes which contain ATP to the focal adhesions. It is likely that these structures may fuse with plasma membrane to release the nucleotide to the extracellular medium.