scholarly journals Synthetic Genetic Array Analysis of the PtdIns 4-kinase Pik1p Identifies Components in a Golgi-specific Ypt31/rab-GTPase Signaling Pathway

2005 ◽  
Vol 16 (2) ◽  
pp. 776-793 ◽  
Author(s):  
Vicki A. Sciorra ◽  
Anjon Audhya ◽  
Ainslie B. Parsons ◽  
Nava Segev ◽  
Charles Boone ◽  
...  
Keyword(s):  
Signaling Pathway ◽  
Protein Trafficking ◽  
Secretory Pathway ◽  
Rab Gtpase ◽  
Secretory Function ◽  
Synthetic Genetic Array ◽  
Array Analysis ◽  
Biologically Relevant ◽  
Specific Subset ◽  
Associated Proteins

Phosphorylated derivatives of phosphatidylinositol are essential regulators of both endocytic and exocytic trafficking in eukaryotic cells. In Saccharomyces cerevisiae, the phosphatidylinositol 4-kinase, Pik1p generates a distinct pool of PtdIns(4)P that is required for normal Golgi structure and secretory function. Here, we utilize a synthetic genetic array analysis of a conditional pik1 mutant to identify candidate components of the Pik1p/PtdIns(4)P signaling pathway at the Golgi. Our data suggest a mechanistic involvement for Pik1p with a specific subset of Golgi-associated proteins, including the Ypt31p rab-GTPase and the TRAPPII protein complex, to regulate protein trafficking through the secretory pathway. We further demonstrate that TRAPPII specifically functions in a Ypt31p-dependent pathway and identify Gyp2p as the first biologically relevant GTPase activating protein for Ypt31p. We propose that multiple stage-specific signals, which may include Pik1p/PtdIns(4)P, TRAPPII and Gyp2p, impinge upon Ypt31 signaling to regulate Golgi secretory function.

scholarly journals Commonly used trafficking blocks disrupt ARF1 activation and the localization and function of specific Golgi proteins

2018 ◽  
Vol 29 (8) ◽  
pp. 937-947 ◽  
Author(s):  
Catherine E. Gilbert ◽  
Elizabeth Sztul ◽  
Carolyn E. Machamer
Keyword(s):  
Protein Trafficking ◽  
Secretory Pathway ◽  
Brefeldin A ◽  
Small Gtpase ◽  
Cold Temperature ◽  
Nucleotide Exchange ◽  
Specific Subset ◽  
Nucleotide Exchange Factor ◽  
Cargo Proteins ◽  
And Function

ADP-ribosylation factor (ARF) proteins are key regulators of the secretory pathway. ARF1, through interacting with its effectors, regulates protein trafficking by facilitating numerous events at the Golgi. One unique ARF1 effector is golgin-160, which promotes the trafficking of only a specific subset of cargo proteins through the Golgi. While studying this role of golgin-160, we discovered that commonly used cold temperature blocks utilized to synchronize cargo trafficking (20 and 16°C) caused golgin-160 dispersal from Golgi membranes. Here, we show that the loss of golgin-160 localization correlates with a decrease in the levels of activated ARF1, and that golgin-160 dispersal can be prevented by expression of a GTP-locked ARF1 mutant. Overexpression of the ARF1 activator Golgi brefeldin A–resistant guanine nucleotide exchange factor 1 (GBF1) did not prevent golgin-160 dispersal, suggesting that GBF1 may be nonfunctional at lower temperatures. We further discovered that several other Golgi resident proteins had altered localization at lower temperatures, including proteins recruited by ARF-like GTPase 1 (ARL1), a small GTPase that also became dispersed in the cold. Although cold temperature blocks are useful for synchronizing cargo trafficking through the Golgi, our data indicate that caution must be taken when interpreting results from these assays.

Secretory pathway genes assessed by high-throughput microscopy and synthetic genetic array analysis

2011 ◽  
Vol 7 (9) ◽  
pp. 2589 ◽  
Author(s):  
Peter W. Bircham ◽  
David R. Maass ◽  
Christina A. Roberts ◽  
Poh Y. Kiew ◽  
Yee S. Low ◽  
...  
Keyword(s):  
High Throughput ◽  
Secretory Pathway ◽  
Synthetic Genetic Array ◽  
Array Analysis

HSP20 Exerts a Protective Effect on Preeclampsia by Regulating Function of Trophoblast Cells Via Akt Pathways

2018 ◽  
Vol 26 (7) ◽  
pp. 961-971 ◽  
Author(s):  
Fanfan Li ◽  
Yin Xie ◽  
Yuanyuan Wu ◽  
Mengzhou He ◽  
Meitao Yang ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Signaling Pathway ◽  
Akt Signaling ◽  
Extravillous Trophoblast ◽  
Akt Signaling Pathway ◽  
Trophoblast Cells ◽  
Heat Shock Protein 20 ◽  
Apoptosis Index ◽  
Proliferation And Apoptosis ◽  
Associated Proteins

Preeclampsia (PE) remains the leading cause of maternal and fetal morbidity and mortality. Excessive apoptosis of the placenta and poor remodeling of spiral arteries caused by insufficient invasion of trophoblast cells into uterus have been implicated in the pathogenesis of PE. Accumulating evidence showed that heat shock protein 20 (HSP20) is closely associated with the proliferation, apoptosis, and metastasis of tumor cells. However, little is known about whether HSP20 plays a role in the development of PE. In this study, we detected the apoptosis index and the expressions of HSP20 and apoptosis-associated proteins in the placentas from PE and normal pregnancies. We found that HSP20 was reversely related to the apoptosis rate and the levels of proapoptotic proteins. Moreover, we identified that HSP20 could suppress the proliferation and apoptosis of trophoblast cells, turning them into a more invasive phenotype. Additionally, H2O2-induced oxidative stress was significantly alleviated, and several key proteins on the Akt signaling pathway were upregulated in HSP20-overexpressing trophoblast cells. These findings strongly suggested that HSP20 might play a role in the remodeling of spiral arteries through affecting the invasiveness of extravillous trophoblast cells via Akt signaling pathway, and the dysregulation of it might contribute to the pathophysiology of PE.

scholarly journals Ykt6 membrane-to-cytosol cycling regulates exosomal Wnt secretion

2018 ◽  
Author(s):  
Karen Linnemannstöns ◽  
Pradhipa Karuna M ◽  
Leonie Witte ◽  
Jeanette Clarissa Kittel ◽  
Adi Danieli ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Wnt Signaling ◽  
Signaling Pathways ◽  
Long Range ◽  
Protein Trafficking ◽  
Secretory Pathway ◽  
Multivesicular Bodies ◽  
Phosphorylation Sites ◽  
Wnt Proteins ◽  
C Terminus

Protein trafficking in the secretory pathway, for example the secretion of Wnt proteins, requires tight regulation. These ligands activate Wnt signaling pathways and are crucially involved in development and disease. Wnt is transported to the plasma membrane by its cargo receptor Evi, where Wnt/Evi complexes are endocytosed and sorted onto exosomes for long-range secretion. However, the trafficking steps within the endosomal compartment are not fully understood. The promiscuous SNARE Ykt6 folds into an auto-inhibiting conformation in the cytosol, but a portion associates with membranes by its farnesylated and palmitoylated C-terminus. Here, we demonstrate that membrane detachment of Ykt6 is essential for exosomal Wnt secretion. We identified conserved phosphorylation sites within the SNARE domain of Ykt6, which block Ykt6 cycling from the membrane to the cytosol. In Drosophila, Ykt6-RNAi mediated block of Wg secretion is rescued by wildtype but not phosphomimicking Ykt6. The latter accumulates at membranes, while wildtype Ykt6 regulates Wnt trafficking between the plasma membrane and multivesicular bodies. Taken together, we show that a regulatory switch in Ykt6 fine-tunes sorting of Wnts in endosomes.

scholarly journals Coupling of terminal differentiation deficit with neurodegenerative pathology in Vps35-deficient pyramidal neurons

2020 ◽  
Vol 27 (7) ◽  
pp. 2099-2116 ◽  
Author(s):  
Fu-Lei Tang ◽  
Lu Zhao ◽  
Yang Zhao ◽  
Dong Sun ◽  
Xiao-Juan Zhu ◽  
...  
Keyword(s):  
Protein Trafficking ◽  
Pyramidal Neurons ◽  
Transmembrane Protein ◽  
Terminal Differentiation ◽  
Physiological Role ◽  
Neurodegenerative Pathology ◽  
Associated Proteins ◽  
Developing Neurons ◽  
Vacuolar Protein ◽  
Embryonic Neurons

AbstractVps35 (vacuolar protein sorting 35) is a key component of retromer that regulates transmembrane protein trafficking. Dysfunctional Vps35 is a risk factor for neurodegenerative diseases, including Parkinson’s and Alzheimer’s diseases. Vps35 is highly expressed in developing pyramidal neurons, and its physiological role in developing neurons remains to be explored. Here, we provide evidence that Vps35 in embryonic neurons is necessary for axonal and dendritic terminal differentiation. Loss of Vps35 in embryonic neurons results in not only terminal differentiation deficits, but also neurodegenerative pathology, such as cortical brain atrophy and reactive glial responses. The atrophy of neocortex appears to be in association with increases in neuronal death, autophagosome proteins (LC3-II and P62), and neurodegeneration associated proteins (TDP43 and ubiquitin-conjugated proteins). Further studies reveal an increase of retromer cargo protein, sortilin1 (Sort1), in lysosomes of Vps35-KO neurons, and lysosomal dysfunction. Suppression of Sort1 diminishes Vps35-KO-induced dendritic defects. Expression of lysosomal Sort1 recapitulates Vps35-KO-induced phenotypes. Together, these results demonstrate embryonic neuronal Vps35’s function in terminal axonal and dendritic differentiation, reveal an association of terminal differentiation deficit with neurodegenerative pathology, and uncover an important lysosomal contribution to both events.

scholarly journals Regular Aerobic Exercise-Alleviated Dysregulation of CAMKIIα Carbonylation to Mitigate Parkinsonism via Homeostasis of Apoptosis With Autophagy

2019 ◽  
Vol 79 (1) ◽  
pp. 46-61
Author(s):  
Wenfeng Liu ◽  
Rang Fu ◽  
Zhiyuan Wang ◽  
Shaopeng Liu ◽  
Changfa Tang ◽  
...  
Keyword(s):  
Aerobic Exercise ◽  
Signaling Pathway ◽  
Oxidative Modification ◽  
Substantia Nigra Pars Compacta ◽  
Rat Striatum ◽  
Long Term Effects ◽  
Neurodegenerative Process ◽  
Age Related ◽  
Potential Biomarker ◽  
Associated Proteins

Abstract This study investigated carbonylation of proteins with oxidative modification profiling in the striatum of aging and Parkinson disease (PD) rats, as well as the long-term effects of regular aerobic exercise on the carbonylation process and the damaging effects of PD vs habitual sedentary behavior. Regular aerobic exercise improved the PD rats’ rotational behavior, increased tyrosine hydroxylase expression in both the striatum and substantia nigra pars compacta, and decreased α-synuclein expression significantly. Interestingly, apoptotic nuclei and autophagosomes were increased in the aerobic exercise PD rat striatum. Carbonylated protein Ca2+/calmodulin-dependent protein kinase alpha (CAMKIIα) was present in the middle-aged and aged groups but only in the sedentary, not the exercise, PD rat striatum. Notably, CAMKIIα was characterized by a 4-hydroxynonenal adduct. Regular aerobic exercise upregulated CAMKIIα expression level, activated the CAMK signaling pathway, and promoted the expression of autophagy markers Beclin1 and microtubule-associated proteins 1 A/1B light chain 3II. Aberrant carbonylation of CAMKII initiated age-related changes and might be useful as a potential biomarker of PD. Regular aerobic exercise alleviated protein carbonylation modification of CAMKIIα and regulated the CAMK signaling pathway, thereby affecting and regulating the homeostasis of apoptosis and autophagy in the striatum to alleviate the neurodegenerative process of PD lesions.

scholarly journals Epstein-Barr Virus Exploits the Secretory Pathway to Release Virions

2020 ◽  
Vol 8 (5) ◽  
pp. 729
Author(s):  
Asuka Nanbo
Keyword(s):  
Epstein Barr Virus ◽  
Secretory Pathway ◽  
Lytic Cycle ◽  
Rab Gtpase ◽  
Rab Gtpases ◽  
Extracellular Milieu ◽  
Barr Virus ◽  
Intracellular Compartments ◽  
Epstein Barr

Herpesvirus egress mechanisms are strongly associated with intracellular compartment remodeling processes. Previously, we and other groups have described that intracellular compartments derived from the Golgi apparatus are the maturation sites of Epstein-Barr virus (EBV) virions. However, the mechanism by which these virions are released from the host cell to the extracellular milieu is poorly understood. Here, I adapted two independent induction systems of the EBV lytic cycle in vitro, in the context of Rab GTPase silencing, to characterize the EBV release pathway. Immunofluorescence staining revealed that p350/220, the major EBV glycoprotein, partially co-localized with three Rab GTPases: Rab8a, Rab10, and Rab11a. Furthermore, the knockdown of these Rab GTPases promoted the intracellular accumulation of viral structural proteins by inhibiting its distribution to the plasma membrane. Finally, the knockdown of the Rab8a, Rab10, and Rab11a proteins suppressed the release of EBV infectious virions. Taken together, these findings support the hypothesis that mature EBV virions are released from infected cells to the extracellular milieu via the secretory pathway, as well as providing new insights into the EBV life cycle.

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