TY - JOUR
T1 - Maturation of Lipophagic Organelles in Hepatocytes Is Dependent Upon a Rab10/Dynamin-2 Complex
AU - Li, Zhipeng
AU - Weller, Shaun G.
AU - Drizyte-Miller, Kristina
AU - Chen, Jing
AU - Krueger, Eugene W.
AU - Mehall, Bridget
AU - Casey, Carol A.
AU - Cao, Hong
AU - McNiven, Mark A.
N1 - Publisher Copyright:
© 2020 by the American Association for the Study of Liver Diseases.
PY - 2020/8/1
Y1 - 2020/8/1
N2 - Background and Aims: Hepatocytes play a central role in storage and utilization of fat by the liver. Selective breakdown of lipid droplets (LDs) by autophagy (also called lipophagy) is a key process utilized to catabolize these lipids as an energy source. How the autophagic machinery is selectively targeted to LDs, where it mediates membrane engulfment and subsequent degradation, is unclear. Recently, we have reported that two distinct GTPases, the mechanoenzyme, dynamin2 (Dyn2), and the small regulatory Rab GTPase, Rab10, work independently at distinct steps of lipophagy in hepatocytes. Approach and Results: In an attempt to understand how these proteins are regulated and recruited to autophagic organelles, we performed a nonbiased biochemical screen for Dyn2-binding partners and found that Dyn2 actually binds Rab10 directly through a defined effector domain of Rab10 and the middle domain of Dyn2. These two GTPases can be observed to interact transiently on membrane tubules in hepatoma cells and along LD-centric autophagic membranes. Most important, we found that a targeted disruption of this interaction leads to an inability of cells to trim tubulated cytoplasmic membranes, some of which extend from lipophagic organelles, resulting in LD accumulation. Conclusions: This study identifies a functional, and direct, interaction between Dyn2 and a regulatory Rab GTPase that may play an important role in hepatocellular metabolism.
AB - Background and Aims: Hepatocytes play a central role in storage and utilization of fat by the liver. Selective breakdown of lipid droplets (LDs) by autophagy (also called lipophagy) is a key process utilized to catabolize these lipids as an energy source. How the autophagic machinery is selectively targeted to LDs, where it mediates membrane engulfment and subsequent degradation, is unclear. Recently, we have reported that two distinct GTPases, the mechanoenzyme, dynamin2 (Dyn2), and the small regulatory Rab GTPase, Rab10, work independently at distinct steps of lipophagy in hepatocytes. Approach and Results: In an attempt to understand how these proteins are regulated and recruited to autophagic organelles, we performed a nonbiased biochemical screen for Dyn2-binding partners and found that Dyn2 actually binds Rab10 directly through a defined effector domain of Rab10 and the middle domain of Dyn2. These two GTPases can be observed to interact transiently on membrane tubules in hepatoma cells and along LD-centric autophagic membranes. Most important, we found that a targeted disruption of this interaction leads to an inability of cells to trim tubulated cytoplasmic membranes, some of which extend from lipophagic organelles, resulting in LD accumulation. Conclusions: This study identifies a functional, and direct, interaction between Dyn2 and a regulatory Rab GTPase that may play an important role in hepatocellular metabolism.
UR - http://www.scopus.com/inward/record.url?scp=85082196515&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85082196515&partnerID=8YFLogxK
U2 - 10.1002/hep.31059
DO - 10.1002/hep.31059
M3 - Article
C2 - 31808574
AN - SCOPUS:85082196515
SN - 0270-9139
VL - 72
SP - 486
EP - 502
JO - Hepatology
JF - Hepatology
IS - 2
ER -