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. 2015 Feb 3;16(3):297–311. doi: 10.15252/embr.201439464

Figure 2.

Figure 2

Rab21 and Sbf/MTMR13 have a conserved function required for autophagosome–lysosome fusion

Rab21 and Sbf/MTMR13 are required for autophagic flux.
  • A-D GFP:mCherry:Atg8 in Drosophila starved fat body. (A) Control (LacZ) shows predominantly autolysosomes (red punctae). (B, C) RNAi depletion of (B) Rab21 or (C) Sbf leads to an accumulation of autophagosomes (yellow punctae) and a depletion of autolysosomes (red punctae). (D) Percentage of autophagosomes (yellow) to total autophagic vacuoles (red + yellow) normalized to fat body area; SEM.
  • E-H Transmission electron microscopy of starved larval fat body. (E) Control. (F) Rab21RNAi or (G) SbfRNAi leads to accumulation of autophagosomes (arrowheads). (H) Number of autophagosomes normalized to cytoplasmic area; SEM.
  • I-M Stably expressed GFP:LC3 in HeLa cells grown in full media with siRNA. (I) Scramble (control). (J) RAB21 siRNA or (K) MTMR13 siRNA results in accumulation of GFP:LC3 autophagosomes. (L, M) Average number GFP:LC3 objects per cell from two independent siRNAs against (L) RAB21 or (M) MTMR13; SEM.
  • N-Q RAB21 (N, O) and MTMR13 (P, Q) are required for LC3-II flux in HeLa cells. Anti-LC3 immunoblot of (N) RAB21 or (P) MTMR13 siRNA-depleted HeLa cells grown in full media with or without bafilomycin A1. (O, Q) Ratio of LC3-II to tubulin integrated densities from (O) five or (Q) seven independent experiments; SEM. See also Supplementary Figs S1 and S2.