A novel role for Gβγ in mitotic Golgi fragmentation

In mammalian cells, the Golgi reassembly stacking protein of 65 kDa (GRASP65) has been implicated in both Golgi stacking and ribbon linking by forming trans-oligomers. To better understand its function and regulation, we used biochemical methods to identify the DnaJ homolog subfamily A member 1 (DjA1) as a novel GRASP65-binding protein. In cells, depletion of DjA1 resulted in Golgi fragmentation, short and improperly aligned cisternae, and delayed Golgi reassembly after nocodazole washout. In vitro, immunodepletion of DjA1 from interphase cytosol reduced its activity to enhance GRASP65 oligomerization and Golgi membrane fusion, while adding purified DjA1 enhanced GRASP65 oligomerization. DjA1 is a cochaperone of Heat shock cognate 71-kDa protein (Hsc70), but the activity of DjA1 in Golgi structure formation is independent of its cochaperone activity or Hsc70, rather, through DjA1-GRASP65 interaction to promote GRASP65 oligomerization. Thus, DjA1 interacts with GRASP65 to enhance Golgi structure formation through the promotion of GRASP65 trans-oligomerization.

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Cell-matrix adhesion controls Golgi organization and function by regulating Arf1 activation in anchorage dependent cells

10.1101/261842 ◽

2018 ◽

Author(s):

Vibha Singh ◽

Chaitanya Erady ◽

Nagaraj Balasubramanian

Keyword(s):

Membrane Trafficking ◽

Microtubule Network ◽

Matrix Adhesion ◽

Cell Matrix ◽

Summary Statement ◽

Golgi Fragmentation ◽

And Function ◽

Golgi Organization ◽

Cell Matrix Adhesion ◽

Constitutively Active

AbstractCell-matrix adhesion regulates membrane trafficking to control anchorage-dependent signaling. While a dynamic Golgi complex can contribute to this pathway, its control by adhesion remains untested. We find the loss of adhesion rapidly disorganizes the Golgi in mouse and human fibroblast cells, its integrity restored rapidly on re-adhesion to fibronectin (but not poly-l-lysine coated beads) along the microtubule network. Adhesion regulates the trans-Golgi more prominently than the cis /cis-medial Golgi, though they show no fallback into the ER making this reorganization distinct from known Golgi fragmentation. This is controlled by an adhesion-dependent drop and recovery of Arf1 activation, mediated through the Arf1 GEF BIG1/2 over GBF1. Constitutively active Arf1 disrupts this regulation and prevents Golgi disorganization in non-adherent cells. Adhesion regulates active Arf1 binding to the microtubule minus-end motor protein dynein to control Golgi reorganization, which ciliobrevin blocks. This regulation by adhesion controls Golgi function, promoting cell surface glycosylation on the loss of adhesion that constitutively active Arf1 blocks. This study hence identifies cell-matrix adhesion to be a novel regulator of Arf1 activation, controlling Golgi organization and function in anchorage-dependent cells.Summary StatementThis study identifies a role for cell-matrix adhesion in regulating organelle (Golgi) architecture and function which could have implications for multiple cellular pathways and function.

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Golgi Fragmentation in Human Patients with Chronic Atrial Fibrillation: A New Aspect of Remodeling

The Thoracic and Cardiovascular Surgeon ◽

10.1055/s-0038-1635079 ◽

2018 ◽

Vol 67 (02) ◽

pp. 098-106 ◽

Cited By ~ 3

Author(s):

Luisa Jungk ◽

Heike Franke ◽

Aida Salameh ◽

Stefan Dhein

Keyword(s):

Atrial Fibrillation ◽

Golgi Apparatus ◽

Fragment Size ◽

Chronic Atrial Fibrillation ◽

Ionic Channels ◽

Longitudinal Axis ◽

Cyclin Dependent Kinase ◽

Microtubule Depolymerization ◽

Tissue Samples ◽

Golgi Fragmentation

Background Atrial fibrillation (AF) is the most common chronic arrhythmia in elderly people and is accompanied by remodeling processes. While much is known about changes in ionic channels and in extracellular matrix, less is known about possible changes of intracellular structures. Objective We wanted to investigate, whether AF may also affect the structure of the Golgi apparatus and the microtubular network. Methods One-hundred fifty-three cardiac surgery patients were investigated [n = 24 in sinus rhythm (SR) and n = 129 with chronic AF of >1 year duration]. Tissue samples of the left atrial free wall were examined immunohistochemically. Golgi apparatus was detected by GM130 and its phosphorylated isoform. Furthermore, we investigated the length of the microtubules by α-tubulin staining. We also measured stathmin (phospho-S37), which is known to induce microtubule depolymerization. In addition, we investigated the cyclin-dependent kinase cdk5-activation, a typical stimulus for Golgi fragmentation, by measuring membrane-associated cdk5. Results We found significant fragmentation of the Golgi apparatus in AF together with a reduced fragment size. Significant more fragments of the Golgi were found lateral to the nucleus in AF, while the Golgi in SR was located more to the polar side of the nucleus, that is, in the longitudinal axis of the cell. This was accompanied by a significant reduction of the number of tubulin strands longer than 10 µm. These changes did not go along with an activation of stathmin, but with an increase in membrane association of cdk5. Conclusions The present data may show that AF associated remodeling also involves intracellular remodeling of the Golgi-microtubular apparatus.

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Truncated Adenomatous Polyposis Coli Mutation Induces Asef-Activated Golgi Fragmentation

Molecular and Cellular Biology ◽

10.1128/mcb.00135-18 ◽

2018 ◽

Vol 38 (17) ◽

Cited By ~ 5

Author(s):

Sang Bum Kim ◽

Lu Zhang ◽

Jimok Yoon ◽

Jeon Lee ◽

Jaewon Min ◽

...

Keyword(s):

Cell Migration ◽

Cell Polarity ◽

Adenomatous Polyposis Coli ◽

Full Length ◽

Cholesterol Homeostasis ◽

Dependent Manner ◽

Adenomatous Polyposis ◽

Polyposis Coli ◽

Golgi Fragmentation ◽

Cell Cell

ABSTRACT Adenomatous polyposis coli (APC) is a key molecule to maintain cellular homeostasis in colonic epithelium by regulating cell-cell adhesion, cell polarity, and cell migration through activating the APC-stimulated guanine nucleotide-exchange factor (Asef). The APC-activated Asef stimulates the small GTPase, which leads to decreased cell-cell adherence and cell polarity, and enhanced cell migration. In colorectal cancers, while truncated APC constitutively activates Asef and promotes cancer initiation and progression, regulation of Asef by full-length APC is still unclear. Here, we report the autoinhibition mechanism of full-length APC. We found that the armadillo repeats in full-length APC interact with the APC residues 1362 to 1540 (APC-2,3 repeats), and this interaction competes off and inhibits Asef. Deletion of APC-2,3 repeats permits Asef interactions leading to downstream signaling events, including the induction of Golgi fragmentation through the activation of the Asef-ROCK-MLC2. Truncated APC also disrupts protein trafficking and cholesterol homeostasis by inhibition of SREBP2 activity in a Golgi fragmentation-dependent manner. Our study thus uncovers the autoinhibition mechanism of full-length APC and a novel gain of function of truncated APC in regulating Golgi structure, as well as cholesterol homeostasis, which provides a potential target for pharmaceutical intervention against colon cancers.

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Golgi Fragmentation in Neurodegenerative Diseases: Is There a Common Cause?

Cells ◽

10.3390/cells8070748 ◽

2019 ◽

Vol 8 (7) ◽

pp. 748 ◽

Cited By ~ 7

Author(s):

José Ángel Martínez-Menárguez ◽

Mónica Tomás ◽

Narcisa Martínez-Martínez ◽

Emma Martínez-Alonso

Keyword(s):

Neurodegenerative Diseases ◽

Mammalian Cells ◽

Early Event ◽

Specific Group ◽

Common Cause ◽

Intracellular Traffic ◽

Common Causes ◽

Golgi Fragmentation ◽

Complex Forms ◽

Lateral Sclerosis

In most mammalian cells, the Golgi complex forms a continuous ribbon. In neurodegenerative diseases, the Golgi ribbon of a specific group of neurons is typically broken into isolated elements, a very early event which happens before clinical and other pathological symptoms become evident. It is not known whether this phenomenon is caused by mechanisms associated with cell death or if, conversely, it triggers apoptosis. When the phenomenon was studied in diseases such as Parkinson’s and Alzheimer’s or amyotrophic lateral sclerosis, it was attributed to a variety of causes, including the presence of cytoplasmatic protein aggregates, malfunctioning of intracellular traffic and/or alterations in the cytoskeleton. In the present review, we summarize the current findings related to these and other neurodegenerative diseases and try to search for clues on putative common causes.

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