scholarly journals Delivery of endocytosed proteins to the cell–division plane requires change of pathway from recycling to secretion

eLife ◽  
2014 ◽  
Vol 3 ◽  
Author(s):  
Sandra Richter ◽  
Marika Kientz ◽  
Sabine Brumm ◽  
Mads Eggert Nielsen ◽  
Misoon Park ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Cell Division ◽  
Membrane Trafficking ◽  
Nucleotide Exchange ◽  
Division Plane ◽  
Plant Cytokinesis ◽  
Guanine Nucleotide Exchange ◽  
Cargo Delivery ◽  
Golgi Network ◽  
Cell Division Plane

Membrane trafficking is essential to fundamental processes in eukaryotic life, including cell growth and division. In plant cytokinesis, post-Golgi trafficking mediates a massive flow of vesicles that form the partitioning membrane but its regulation remains poorly understood. Here, we identify functionally redundant Arabidopsis ARF guanine-nucleotide exchange factors (ARF-GEFs) BIG1–BIG4 as regulators of post-Golgi trafficking, mediating late secretion from the trans-Golgi network but not recycling of endocytosed proteins to the plasma membrane, although the TGN also functions as an early endosome in plants. In contrast, BIG1-4 are absolutely required for trafficking of both endocytosed and newly synthesized proteins to the cell–division plane during cytokinesis, counteracting recycling to the plasma membrane. This change from recycling to secretory trafficking pathway mediated by ARF-GEFs confers specificity of cargo delivery to the division plane and might thus ensure that the partitioning membrane is completed on time in the absence of a cytokinesis-interphase checkpoint.

scholarly journals Activation of Rab8 guanine nucleotide exchange factor Rabin8 by ERK1/2 in response to EGF signaling

2014 ◽  
Vol 112 (1) ◽  
pp. 148-153 ◽  
Author(s):  
Juanfei Wang ◽  
Jinqi Ren ◽  
Bin Wu ◽  
Shanshan Feng ◽  
Guoping Cai ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Membrane Trafficking ◽  
Guanine Nucleotide Exchange Factor ◽  
Small Gtpases ◽  
Guanine Nucleotide ◽  
Nucleotide Exchange ◽  
Exchange Factor ◽  
Guanine Nucleotide Exchange ◽  
Nucleotide Exchange Factor ◽  
Egf Signaling

Exocytosis is tightly regulated in many cellular processes, from neurite expansion to tumor proliferation. Rab8, a member of the Rab family of small GTPases, plays an important role in membrane trafficking from the trans-Golgi network and recycling endosomes to the plasma membrane. Rabin8 is a guanine nucleotide exchange factor (GEF) and major activator of Rab8. Investigating how Rabin8 is activated in cells is thus pivotal to the understanding of the regulation of exocytosis. Here we show that phosphorylation serves as an important mechanism for Rabin8 activation. We identified Rabin8 as a direct phospho-substrate of ERK1/2 in response to EGF signaling. At the molecular level, ERK phosphorylation relieves the autoinhibition of Rabin8, thus promoting its GEF activity. We further demonstrate that blocking ERK1/2-mediated phosphorylation of Rabin8 inhibits transferrin recycling to the plasma membrane. Together, our results suggest that ERK1/2 activate Rabin8 to regulate vesicular trafficking to the plasma membrane in response to extracellular signaling.

Localization and function of Arf family GTPases

2005 ◽  
Vol 33 (4) ◽  
pp. 639-642 ◽  
Author(s):  
J.G. Donaldson ◽  
A. Honda
Keyword(s):  
Plasma Membrane ◽  
Membrane Trafficking ◽  
In Vitro Assays ◽  
Nucleotide Exchange ◽  
Guanine Nucleotide Exchange ◽  
Nucleotide Exchange Factors ◽  
Multiple Regions ◽  
Sites Of Action ◽  
And Function

Arfs are a family of Ras-related GTP-binding proteins that function in the regulation of membrane trafficking and structure. The six mammalian Arf proteins are expressed ubiquitously and so it is anticipated that each will have a distinct localization and function within the cell. It has been assumed that much of this specificity will be defined by determining which regulators of Arfs, the GEFs (guanine nucleotide-exchange factors) and GAPs (GTPase-activating proteins) function with which Arf proteins. Although in vitro assays may indicate Arf preferences for the numerous Arf GEFs and GAPs that have been identified, in the cell the different Arfs, GEFs and GAPs are targeted to specific compartments where they carry out their functions. We have embarked on studies to define regions of the Arf1 and Arf6 proteins that determine their sites of action and specific activities at the Golgi and plasma membrane respectively. Chimaeras were made between Arf1 and Arf6 in order to identify regions of the protein that contributed to targeting and function. Whereas Arf6 is targeted to the plasma membrane through multiple regions along the protein, we have found a Golgi-targeting region in Arf1 that is sufficient to target Arf6 to the Golgi complex.

scholarly journals Promiscuity of the catalytic Sec7 domain within the guanine nucleotide exchange factor GBF1 in ARF activation, Golgi homeostasis, and effector recruitment

2019 ◽  
Vol 30 (12) ◽  
pp. 1523-1535 ◽  
Author(s):  
Jay M. Bhatt ◽  
William Hancock ◽  
Justyna M. Meissner ◽  
Aneta Kaczmarczyk ◽  
Eunjoo Lee ◽  
...  
Keyword(s):  
Brefeldin A ◽  
Guanine Nucleotide ◽  
Nucleotide Exchange ◽  
Guanine Nucleotide Exchange ◽  
Nucleotide Exchange Factors ◽  
Downstream Effector ◽  
Nucleotide Exchange Factor ◽  
Sec7 Domain ◽  
Golgi Network ◽  
The Impact

The integrity of the Golgi and trans-Golgi network (TGN) is disrupted by brefeldin A (BFA), which inhibits the Golgi-localized BFA-sensitive factor (GBF1) and brefeldin A–inhibited guanine nucleotide-exchange factors (BIG1 and BIG2). Using a cellular replacement assay to assess GBF1 functionality without interference from the BIGs, we show that GBF1 alone maintains Golgi architecture; facilitates secretion; activates ADP-ribosylation factor (ARF)1, 3, 4, and 5; and recruits ARF effectors to Golgi membranes. Unexpectedly, GBF1 also supports TGN integrity and recruits numerous TGN-localized ARF effectors. The impact of the catalytic Sec7 domain (Sec7d) on GBF1 functionality was assessed by swapping it with the Sec7d from ARF nucleotide-binding site opener (ARNO)/cytohesin-2, a plasma membrane GEF reported to activate all ARFs. The resulting chimera (GBF1-ARNO-GBF1 [GARG]) targets like GBF1, supports Golgi/TGN architecture, and facilitates secretion. However, unlike GBF1, GARG activates all ARFs (including ARF6) at the Golgi/TGN and recruits additional ARF effectors to the Golgi/TGN. Our results have general implications: 1) GEF’s targeting is independent of Sec7d, but Sec7d influence the GEF substrate specificity and downstream effector events; 2) all ARFs have access to all membranes, but are restricted in their distribution by the localization of their activating GEFs; and 3) effector association with membranes requires the coincidental presence of activated ARFs and specific membrane identifiers.

scholarly journals AGS3-dependent trans-Golgi network membrane trafficking is essential for compaction in mouse embryos

2020 ◽  
Vol 133 (23) ◽  
pp. jcs243238
Author(s):  
Zheng-Wen Nie ◽  
Ying-Jie Niu ◽  
Wenjun Zhou ◽  
Dong-Jie Zhou ◽  
Ju-Yeon Kim ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Membrane Trafficking ◽  
Fluorescent Protein ◽  
Mouse Embryos ◽  
Cell Contact ◽  
Protein Signaling ◽  
Cell Stage ◽  
Trans Golgi Network ◽  
Early Mouse ◽  
Golgi Network

ABSTRACTActivator of G-protein signaling 3 (AGS3, also known as GPSM1) regulates the trans-Golgi network. The AGS3 GoLoco motif binds to Gαi and thereby regulates the transport of proteins to the plasma membrane. Compaction of early embryos is based on the accumulation of E-cadherin (Cdh1) at cell-contacted membranes. However, how AGS3 regulates the transport of Cdh1 to the plasma membrane remains undetermined. To investigate this, AGS3 was knocked out using the Cas9-sgRNA system. Both trans-Golgi network protein 46 (TGN46, also known as TGOLN2) and transmembrane p24-trafficking protein 7 (TMED7) were tracked in early mouse embryos by tagging these proteins with a fluorescent protein label. We observed that the majority of the AGS3-edited embryos were developmentally arrested and were fragmented after the four-cell stage, exhibiting decreased accumulation of Cdh1 at the membrane. The trans-Golgi network and TMED7-positive vesicles were also dispersed and were not polarized near the membrane. Additionally, increased Gαi1 (encoded by GNAI1) expression could rescue AGS3-overexpressed embryos. In conclusion, AGS3 reinforces the dynamics of the trans-Golgi network and the transport of TMED7-positive cargo containing Cdh1 to the cell-contact surface during early mouse embryo development.

scholarly journals Intersectin-1 interacts with the golgin GCC88 to couple the actin network and Golgi architecture

2019 ◽  
Vol 30 (3) ◽  
pp. 370-386 ◽  
Author(s):  
Christian Makhoul ◽  
Prajakta Gosavi ◽  
Regina Duffield ◽  
Bronwen Delbridge ◽  
Nicholas A. Williamson ◽  
...  
Keyword(s):  
Dynamic Balance ◽  
Nucleotide Exchange ◽  
Actin Networks ◽  
Guanine Nucleotide Exchange ◽  
Membrane Flux ◽  
Nucleotide Exchange Factor ◽  
Golgi Ribbon ◽  
Microtubule Networks ◽  
Golgi Network ◽  
Membrane Tether

The maintenance of the Golgi ribbon relies on a dynamic balance between the actin and microtubule networks; however, the pathways controlling actin networks remain poorly defined. Previously, we showed that the trans-Golgi network (TGN) membrane tether/golgin, GCC88, modulates the Golgi ribbon architecture. Here, we show that dispersal of the Golgi ribbon by GCC88 is dependent on actin and the involvement of nonmuscle myosin IIA. We have identified the long isoform of intersectin-1 (ITSN-1), a guanine nucleotide exchange factor for Cdc42, as a novel Golgi component and an interaction partner of GCC88 responsible for mediating the actin-dependent dispersal of the Golgi ribbon. We show that perturbation of Golgi morphology by changes in membrane flux, mediated by silencing the retromer subunit Vps26, or in a model of neurodegeneration, induced by Tau overexpression, are also dependent on the ITSN-1-GCC88 interaction. Overall, our study reveals a role for a TGN golgin and ITSN-1 in linking to the actin cytoskeleton and regulating the balance between a compact Golgi ribbon and a dispersed Golgi, a pathway with relevance to pathophysiological conditions.

scholarly journals Asymmetric cell division: Plane but not simple

2001 ◽  
Vol 11 (6) ◽  
pp. R233-R236 ◽  
Author(s):  
Paul N. Adler ◽  
Job Taylor
Keyword(s):  
Cell Division ◽  
Asymmetric Cell Division ◽  
Division Plane ◽  
Cell Division Plane
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