scholarly journals Degradation of dendritic cargos requires Rab7-dependent transport to somatic lysosomes

2018 ◽  
Vol 217 (9) ◽  
pp. 3141-3159 ◽  
Author(s):  
Chan Choo Yap ◽  
Laura Digilio ◽  
Lloyd P. McMahon ◽  
A. Denise R. Garcia ◽  
Bettina Winckler
Keyword(s):  
Membrane Proteins ◽  
Spatial Heterogeneity ◽  
Protein Turnover ◽  
Cellular Stress ◽  
Proximal Segment ◽  
Late Endosomes ◽  
Dendritic Membrane ◽  
Dependent Transport

Neurons are large and long lived, creating high needs for regulating protein turnover. Disturbances in proteostasis lead to aggregates and cellular stress. We characterized the behavior of the short-lived dendritic membrane proteins Nsg1 and Nsg2 to determine whether these proteins are degraded locally in dendrites or centrally in the soma. We discovered a spatial heterogeneity of endolysosomal compartments in dendrites. Early EEA1-positive and late Rab7-positive endosomes are found throughout dendrites, whereas the density of degradative LAMP1- and cathepsin (Cat) B/D–positive lysosomes decreases steeply past the proximal segment. Unlike in fibroblasts, we found that the majority of dendritic Rab7 late endosomes (LEs) do not contain LAMP1 and that a large proportion of LAMP1 compartments do not contain CatB/D. Second, Rab7 activity is required to mobilize distal predegradative LEs for transport to the soma and terminal degradation. We conclude that the majority of dendritic LAMP1 endosomes are not degradative lysosomes and that terminal degradation of dendritic cargos such as Nsg1, Nsg2, and DNER requires Rab7-dependent transport in LEs to somatic lysosomes.

scholarly journals Bulk degradation of dendritic cargos requires Rab7-dependent transport in Rab7-positive/LAMP1-negative endosomes to somatic lysosomes

2017 ◽  
Author(s):  
C.C. Yap ◽  
L. Digilio ◽  
L.P. McMahon ◽  
A.D.R. Garcia ◽  
B. Winckler
Keyword(s):  
Membrane Proteins ◽  
Protein Turnover ◽  
Cellular Stress ◽  
Distal Portion ◽  
Proximal Portion ◽  
Spatial Gradient ◽  
Protein Homeostasis ◽  
Late Endosomes ◽  
Dendritic Membrane ◽  
Dependent Transport

AbstractRegulation of protein homeostasis (“proteostasis”) is necessary for maintaining healthy cells. Disturbances in proteostasis lead to aggregates, cellular stress and can result in toxicity. There is thus great interest in when and where proteins are degraded in cells. Neurons are very large as well as very long-lived, creating unusually high needs for effective regulation of protein turnover in time and space. We previously discovered that the dendritic membrane proteins Nsg1 and Nsg2 are short-lived with half-lives of less than two hours. Their short half-lives enabled us to ask whether these proteins are degraded by local degradative pathways in dendrites. We discovered a striking spatial gradient of late endosomes/lysosomes in dendrites, with late endosomes (Rab7-positive/LAMP1-negative/cathepsinB-negative) found in distal portion of dendrites, and degradative lysosomes (LAMP1-positive/cathepsinB-positive) being overwhelmingly found in the soma and in the proximal portion of dendrites. Surprisingly, the majority of dendritic Rab7-positive late endosomes do not contain LAMP1, unlike Rab7-positive late endosomes in fibroblasts. Secondly, Rab7 activity is required to mobilize these distal pre-degradative dendritic late endosomes for transport to the soma and degradation. We conclude that the vast majority of dendritic LAMP1-positive endosomes are not degradative lysosomes and that bulk degradation of dendritic cargos, such as Nsg1, Nsg2, and DNER, requires Rab7-dependent transport in late endosomes to somatic lysosomes.

scholarly journals Sphingosine kinases and their metabolites modulate endolysosomal trafficking in photoreceptors

2011 ◽  
Vol 192 (4) ◽  
pp. 557-567 ◽  
Author(s):  
Ikuko Yonamine ◽  
Takeshi Bamba ◽  
Niraj K. Nirala ◽  
Nahid Jesmin ◽  
Teresa Kosakowska-Cholody ◽  
...  
Keyword(s):  
Membrane Proteins ◽  
Transient Receptor Potential ◽  
Receptor Potential ◽  
Endosomal Trafficking ◽  
Loss Of Function ◽  
Late Endosomes ◽  
Sphingosine 1 Phosphate ◽  
Sphingosine Kinases ◽  
Transient Receptor ◽  
G Protein Coupled

Internalized membrane proteins are either transported to late endosomes and lysosomes for degradation or recycled to the plasma membrane. Although proteins involved in trafficking and sorting have been well studied, far less is known about the lipid molecules that regulate the intracellular trafficking of membrane proteins. We studied the function of sphingosine kinases and their metabolites in endosomal trafficking using Drosophila melanogaster photoreceptors as a model system. Gain- and loss-of-function analyses show that sphingosine kinases affect trafficking of the G protein–coupled receptor Rhodopsin and the light-sensitive transient receptor potential (TRP) channel by modulating the levels of dihydrosphingosine 1 phosphate (DHS1P) and sphingosine 1 phosphate (S1P). An increase in DHS1P levels relative to S1P leads to the enhanced lysosomal degradation of Rhodopsin and TRP and retinal degeneration in wild-type photoreceptors. Our results suggest that sphingosine kinases and their metabolites modulate photoreceptor homeostasis by influencing endolysosomal trafficking of Rhodopsin and TRP.

scholarly journals Protein Kinase D Regulates Trafficking of Dendritic Membrane Proteins in Developing Neurons

2008 ◽  
Vol 28 (37) ◽  
pp. 9297-9308 ◽  
Author(s):  
M. Bisbal ◽  
C. Conde ◽  
M. Donoso ◽  
F. Bollati ◽  
J. Sesma ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Membrane Proteins ◽  
Protein Kinase D ◽  
Dendritic Membrane ◽  
Developing Neurons

scholarly journals The Rab8 GTPase selectively regulates AP-1B–dependent basolateral transport in polarized Madin-Darby canine kidney cells

2003 ◽  
Vol 163 (2) ◽  
pp. 339-350 ◽  
Author(s):  
Agnes Lee Ang ◽  
Heike Fölsch ◽  
Ulla-Maija Koivisto ◽  
Marc Pypaert ◽  
Ira Mellman
Keyword(s):  
Membrane Proteins ◽  
Intracellular Transport ◽  
Rho Gtpase ◽  
Dominant Negative ◽  
Recycling Endosome ◽  
Gtp Hydrolysis ◽  
Clathrin Adaptor ◽  
Dominant Negative Allele ◽  
Dependent Transport ◽  
Darby Canine Kidney

The AP-1B clathrin adaptor complex plays a key role in the recognition and intracellular transport of many membrane proteins destined for the basolateral surface of epithelial cells. However, little is known about other components that act in conjunction with AP-1B. We found that the Rab8 GTPase is one such component. Expression of a constitutively activated GTP hydrolysis mutant selectively inhibited basolateral (but not apical) transport of newly synthesized membrane proteins. Moreover, the effects were limited to AP-1B–dependent basolateral cargo; basolateral transport of proteins containing dileucine targeting motifs that do not interact with AP-1B were targeted normally despite overexpression of mutant Rab8. Similar results were obtained for a dominant-negative allele of the Rho GTPase Cdc42, previously implicated in basolateral transport but now shown to be selective for the AP-1B pathway. Rab8-GFP was localized to membranes in the TGN-recycling endosome, together with AP-1B complexes and the closely related but ubiquitously expressed AP-1A complex. However, expression of active Rab8 caused a selective dissociation of AP-1B complexes, reflecting the specificity of Rab8 for AP-1B–dependent transport.

scholarly journals Chimeric Forms of Furin and Tgn38 Are Transported from the Plasma Membrane to the Trans-Golgi Network via Distinct Endosomal Pathways

1999 ◽  
Vol 146 (2) ◽  
pp. 345-360 ◽  
Author(s):  
William G. Mallet ◽  
Frederick R. Maxfield
Keyword(s):  
Plasma Membrane ◽  
Membrane Proteins ◽  
Chimeric Proteins ◽  
Endocytic Recycling ◽  
Single Pass ◽  
Trans Golgi Network ◽  
Late Endosomes ◽  
Recycling Pathway ◽  
Endosomal Transport ◽  
Golgi Network

Furin and TGN38 are membrane proteins that cycle between the plasma membrane and the trans-Golgi network (TGN), each maintaining a predominant distribution in the TGN. We have used chimeric proteins with an extracellular Tac domain and the cytoplasmic domain of TGN38 or furin to study the trafficking of these proteins in endosomes. Previously, we demonstrated that the postendocytic trafficking of Tac-TGN38 to the TGN is via the endocytic recycling pathway (Ghosh, R.N., W.G. Mallet, T.T. Soe, T.E. McGraw, and F.R. Maxfield. 1998. J. Cell Biol. 142:923–936). Here we show that internalized Tac-furin is delivered to the TGN through late endosomes, bypassing the endocytic recycling compartment. The transport of Tac-furin from late endosomes to the TGN appears to proceed via an efficient, single-pass mechanism. Delivery of Tac-furin but not Tac-TGN38 to the TGN is blocked by nocodazole, and the two pathways are also differentially affected by wortmannin. These studies demonstrate the existence of two independent pathways for endosomal transport of proteins to the TGN from the plasma membrane.

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