MICAL-L1 links EHD1 to tubular recycling endosomes and regulates receptor recycling.
Endocytic recycling of receptors and lipids occurs via a complex network of tubular and vesicular membranes. EHD1 is a key regulator of endocytosis and associates with tubular membranes to facilitate recycling. Although EHD proteins tubulate membranes in vitro, EHD1 primarily associates with preexisting tubules in vivo. How EHD1 is recruited to these tubular endosomes remains unclear. We have determined that the Rab8-interacting protein, MICAL-L1, associates with EHD1, with both proteins colocalizing to long tubular membranes, in vitro and in live cells. MICAL-L1 is a largely uncharacterized member of the MICAL-family of proteins that uniquely contains two asparagine-proline-phenylalanine motifs, sequences that typically interact with EH-domains. Our data show that the MICAL-L1 C-terminal coiled-coil region is necessary and sufficient for its localization to tubular membranes. Moreover, we provide unexpected evidence that endogenous MICAL-L1 can link both EHD1 and Rab8a to these structures, as its depletion leads to loss of the EHD1-Rab8a interaction and the absence of both of these proteins from the membrane tubules. Finally, we demonstrate that MICAL-L1 is essential for efficient endocytic recycling. These data implicate MICAL-L1 as an unusual type of Rab effector that regulates endocytic recycling by recruiting and linking EHD1 and Rab8a on membrane tubules.
Sharma
Mahak
M
Department of Biochemistry and Molecular Biology and Eppley Cancer Center, University of Nebraska Medical Center, Omaha, NE 68198-5870, USA.
Giridharan
Sai Srinivas Panapakkam
SS
Rahajeng
Juliati
J
Naslavsky
Naava
N
Caplan
Steve
S
D048868:Adaptor Proteins, Signal Transducing; D020816:Amino Acid Motifs; D003598:Cytoskeletal Proteins / Q000737:chemistry / Q000378:metabolism*; D004705:Endocytosis; D011992:Endosomes / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D019012:Integrin beta1 / Q000378:metabolism; D007425:Intracellular Membranes / Q000378:metabolism; D047908:Intracellular Signaling Peptides and Proteins / Q000737:chemistry / Q000378:metabolism*; D060588:LIM Domain Proteins; D008840:Microfilament Proteins; D006899:Mixed Function Oxygenases; D008954:Models, Biological; D011485:Protein Binding; D021381:Protein Transport; D011990:Receptors, Transferrin / Q000378:metabolism*; D033921:Vesicular Transport Proteins / Q000378:metabolism*; D020691:rab GTP-Binding Proteins / Q000378:metabolism; D000096985:Calponins
D048868:Adaptor Proteins, Signal Transducing; D003598:Cytoskeletal Proteins; D019012:Integrin beta1; D047908:Intracellular Signaling Peptides and Proteins; D060588:LIM Domain Proteins; D008840:Microfilament Proteins; D006899:Mixed Function Oxygenases; D011990:Receptors, Transferrin; D033921:Vesicular Transport Proteins; D020691:rab GTP-Binding Proteins; C120700:EHD1 protein, human; C455272:MICAL1 protein, human; D000096985:Calponins; C082377:RAB8A protein, human