Comprehensive functional analysis of Rab GTPases in Drosophila nephrocytes.
The Drosophila nephrocyte is a critical component of the fly renal system and bears structural and functional homology to podocytes and proximal tubule cells of the mammalian kidney. Investigations of nephrocyte cell biological processes are fundamental to understanding the insect renal system. Nephrocytes are highly active in endocytosis and vesicle trafficking. Rab GTPases regulate endocytosis and trafficking but specific functions of nephrocyte Rabs remain undefined. We analyzed Rab GTPase expression and function in Drosophila nephrocytes and found that 11 out of 27 Drosophila Rabs were required for normal activity. Rabs 1, 5, 7, 11 and 35 were most important. Gene silencing of the nephrocyte-specific Rab5 eliminated all intracellular vesicles and the specialized plasma membrane structures essential for nephrocyte function. Rab7 silencing dramatically increased clear vacuoles and reduced lysosomes. Rab11 silencing increased lysosomes and reduced clear vacuoles. Our results suggest that Rab5 mediates endocytosis that is essential for the maintenance of functionally critical nephrocyte plasma membrane structures and that Rabs 7 and 11 mediate alternative downstream vesicle trafficking pathways leading to protein degradation and membrane recycling, respectively. Elucidating molecular pathways underlying nephrocyte function has the potential to yield important insights into human kidney cell physiology and mechanisms of cell injury that lead to disease. The Drosophila nephrocyte is emerging as a useful in vivo model system for molecular target identification and initial testing of therapeutic approaches in humans.
Center for Cancer and Immunology Research, Children's Research Institute, Children's National Medical Center, 111 Michigan Avenue NW, Washington, DC 20010, USA.
Yulong
Y
Fu
Center for Cancer and Immunology Research, Children's Research Institute, Children's National Medical Center, 111 Michigan Avenue NW, Washington, DC 20010, USA.
Jun-Yi
JY
Zhu
Division of Nephrology, Nanfang Hospital, Southern Medical University, Guangzhou, 510515, People's Republic of China.
Fujian
F
Zhang
Center for Cancer and Immunology Research, Children's Research Institute, Children's National Medical Center, 111 Michigan Avenue NW, Washington, DC 20010, USA.
Adam
A
Richman
Department of Nephrology, First Affiliated Hospital of Zhengzhou University, Zhengzhou, 450052, People's Republic of China.
Zhanzheng
Z
Zhao
Center for Cancer and Immunology Research, Children's Research Institute, Children's National Medical Center, 111 Michigan Avenue NW, Washington, DC 20010, USA. ZHan@childrensnational.org.
Zhe
Z
Han
D000818:Animals; D048429:Cell Size; D022162:Cytoplasmic Vesicles; D004330:Drosophila / Q000166:cytology / Q000201:enzymology* / Q000648:ultrastructure; D029721:Drosophila Proteins / Q000378:metabolism*; D005260:Female; D020868:Gene Silencing; D007668:Kidney / Q000166:cytology / Q000201:enzymology / Q000648:ultrastructure; D008247:Lysosomes / Q000201:enzymology; D008297:Male; D050199:Podocytes / Q000201:enzymology / Q000648:ultrastructure; D020691:rab GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*
D029721:Drosophila Proteins; D020691:rab GTP-Binding Proteins
Drosophila; Endosome; Nephrocyte; Rab; Vesicle trafficking