PT  - JOURNAL ARTICLE
AU  - Vijayakrishnan, Niranjana
AU  - Woodruff, Elvin A.
AU  - Broadie, Kendal
TI  - Rolling blackout is required for bulk endocytosis in non-neuronal cells and neuronal synapses
AID  - 10.1242/jcs.036673
DP  - 2009 Jan 01
TA  - Journal of Cell Science
PG  - 114--125
VI  - 122
IP  - 1
4099  - http://jcs.biologists.org/content/122/1/114.short
4100  - http://jcs.biologists.org/content/122/1/114.full
SO  - J. Cell Sci.2009 Jan 01; 122
AB  - Rolling blackout (RBO) is a Drosophila EFR3 integral membrane lipase. A conditional temperature-sensitive (TS) mutant (rbots) displays paralysis within minutes following a temperature shift from 25°C to 37°C, an impairment previously attributed solely to blocked synaptic-vesicle exocytosis. However, we found that rbots displays a strong synergistic interaction with the Syntaxin-1A TS allele syx3-69, recently shown to be a dominant positive mutant that increases Syntaxin-1A function. At neuromuscular synapses, rbots showed a strong defect in styryl-FM-dye (FM) endocytosis, and rbots;syx3-69 double mutants displayed a synergistic, more severe, endocytosis impairment. Similarly, central rbots synapses in primary brain culture showed severely defective FM endocytosis. Non-neuronal nephrocyte Garland cells showed the same endocytosis defect in tracer-uptake assays. Ultrastructurally, rbots displayed a specific defect in tracer uptake into endosomes in both neuronal and non-neuronal cells. At the rbots synapse, there was a total blockade of endosome formation via activity-dependent bulk endocytosis. Clathrin-mediated endocytosis was not affected; indeed, there was a significant increase in direct vesicle formation. Together, these results demonstrate that RBO is required for constitutive and/or bulk endocytosis and/or macropinocytosis in both neuronal and non-neuronal cells, and that, at the synapse, this mechanism is responsive to the rate of Syntaxin-1A-dependent exocytosis.