Differential Roles of C-terminal Eps15 Homology Domain Proteins as Vesiculators and Tubulators of Recycling Endosomes

Journal of Biological Chemistry

Naslavsky

Caplan

2014

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Background: Major histocompatibility complex class I (MHC I) trafficking is crucial for antigen presentation. Results: Diacylglycerol kinase ␣ (DGK␣) depletion interferes with tubular recycling endosome (TRE) biogenesis and delays MHC I recycling to the plasma membrane. Conclusion: DGK␣ mediates MHC I recycling by interacting with MICAL-L1 and generating phosphatidic acid. Significance: A novel role for DGK␣ in generating phosphatidic acid for TRE biogenesis and MHC I recycling.

Section: Discussionmentioning

confidence: 99%

Diacylglycerol Kinase α Regulates Tubular Recycling Endosome Biogenesis and Major Histocompatibility Complex Class I Recycling

Journal of Biological Chemistry

Naslavsky

Caplan

2014

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“…Quantification of MICAL-L1-containing Tubular Recycling Endosomes-Tubular recycling endosomes were quantified as described previously (11). Briefly, with NIH ImageJ software, the image background was reduced by adjusting the threshold.…”

Section: Methodsmentioning

confidence: 99%

“…Nonetheless, we have demonstrated that they have distinct mechanistic functions. EHD1 induces the vesiculation of TRE, whereas EHD3 supports the process of membrane tubulation (11).…”

mentioning

confidence: 99%

“…EHD3 is subsequently recruited to these membranes through the interaction of its EH domain with the NPF motifs of MICAL-L1 and/or Syndapin2. A recent model holds that EHD1 thereafter joins this complex on TRE, where it binds to both MICAL-L1 and Syndapin2, possibly replacing EHD3 within the complex to perform fission and give rise to newly formed vesicles (11).…”

mentioning

confidence: 99%

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EHD3 Protein Is Required for Tubular Recycling Endosome Stabilization, and an Asparagine-Glutamic Acid Residue Pair within Its Eps15 Homology (EH) Domain Dictates Its Selective Binding to NPF Peptides

Bahl

Journal of Biological Chemistry

Spagnol

et al. 2016

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An elaborate network of dynamic lipid membranes, termed tubular recycling endosomes (TRE), coordinates the process of endocytic recycling in mammalian cells. The C-terminal Eps15 homology domain (EHD)-containing proteins have been implicated in the bending and fission of TRE, thus regulating endocytic recycling. EHD proteins have an EH domain that interacts with proteins containing an NPF motif. We found that NPFcontaining EHD1 interaction partners such as molecules interacting with CasL-like1 (MICAL-L1) and Syndapin2 are essential for TRE biogenesis. Also crucial for TRE biogenesis is the generation of phosphatidic acid, an essential lipid component of TRE that serves as a docking point for MICAL-L1 and Syndapin2. EHD1 and EHD3 have 86% amino acid identity; they homo-and heterodimerize and partially co-localize to TRE. Despite their remarkable identity, they have distinct mechanistic functions. EHD1 induces membrane vesiculation, whereas EHD3 supports TRE biogenesis and/or stabilization by an unknown mechanism. While using phospholipase D inhibitors (which block the conversion of glycerophospholipids to phosphatidic acid) to deplete cellular TRE, we observed that, upon inhibitor washout, there was a rapid and dramatic regeneration of MICAL-L1-marked TRE. Using this "synchronized" TRE biogenesis system, we determined that EHD3 is involved in the stabilization of TRE rather than in their biogenesis. Moreover, we identify the residues Ala-519/Asp-520 of EHD1 and Asn-519/ Glu-520 of EHD3 as defining the selectivity of these two paralogs for NPF-containing binding partners, and we present a model to explain the atomic mechanism and provide new insight for their differential roles in vesiculation and tubulation, respectively.

“…However, a recent study has determined that the GTPase Dyn2 is also required for mitochondrial fission (Lee et al, 2016). Given the homology between EHD1 and dynamin (Daumke et al, 2007), and the role of EHD1 as an ATPase involved in endosomal fission (Cai et al, 2013(Cai et al, , 2014Jakobsson et al, 2011), we sought to explore the possibility that EHD1 may also act directly in mediating mitochondrial fission. To do so, we took advantage of a clever assay used by Lee et al to identify the role of Dyn2 in mitochondrial fission (Lee et al, 2016).…”

Section: Ehd1 Likely Functions Upstream Of the Known Mitochondrial Fimentioning

confidence: 99%

Control of mitochondrial homeostasis by endocytic regulatory proteins

Farmer

Reinecke

Journal of Cell Science

et al. 2017

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Mitochondria play essential roles in cellular energy processes, including ATP production, control of reactive oxygen species (ROS) and apoptosis. While mitochondrial function is regulated by the dynamics of fusion and fission, mitochondrial homeostasis remains incompletely understood. Recent studies implicate dynamin-2 and dynamin-related protein-1 (Drp1, also known as DNM1L), as GTPases involved in mitochondrial fission. Here, we identify the ATPase and endocytic protein EHD1 as a novel regulator of mitochondrial fission. EHD1 depletion induces a static and elongated network of mitochondria in the cell. However, unlike dynamin-2 and Drp1, whose depletion protects cells from staurosporine-induced mitochondrial fragmentation, EHD1-depleted cells remain sensitive to staurosporine, suggesting a different mechanism for EHD1 function. Recent studies have demonstrated that VPS35 and the retromer complex influence mitochondrial homeostasis either by Mul1-mediated ubiquitylation and degradation of the fusion protein Mfn2, or by removal of inactive Drp1 from the mitochondrial membrane. We demonstrate that EHD1 and its interaction partner rabankyrin-5 interact with the retromer complex to influence mitochondrial dynamics, likely by inducing VPS35-mediated removal of inactive Drp1 from mitochondrial membranes. Our study sheds light on mitochondrial dynamics, expanding a new paradigm of endocytic protein regulation of mitochondrial homeostasis.