Faculty Opinions recommendation of A nodule-specific protein secretory pathway required for nitrogen-fixing symbiosis.

Essential hypertension is a complex polygenic trait. To understand the genetics of Blood pressure (BP) control, loci are mapped using populations derived by crossing several rat strains with the genetically hypertensive rat model, the Dahl SS rat (SS) and validated as BP quantitative trait loci (QTL). Genes located within the mapped BP QTLs are candidates as inherited loci controlling BP, but require further proof. One such mapped locus is on rat chromosome 9, wherein the proof for one of the candidate genes Regulated Endocrine Specific Protein-18 ( Resp18 ), as a BP QTL, is currently inadequate. To ascertain the status of Resp18 as a BP QTL, a custom targeted gene disruption model of Resp18 was developed on the SS background. As a result of this ZFN mediated disruption, a 7 bp deletion occurred within exon 3 of the Resp18 locus, resulting in a truncated protein with 111aa compared to the full length protein consisting of 175aa. Under a high salt dietary regimen, both systolic and diastolic BP of Resp18 mutant rats were significantly increased compared to SS rats (151±3 vs.170±6mmHg; 116±2vs.129±4mmHg n=10-12, p <0.05). Resp18 mutant rats demonstrated higher proteinuria compared to SS rats (221±14vs.268±14mg of protein/kg body weight/24hr; n=14-25, p <0.05). In vascular reactivity experiment, Resp18 mutant rat mesenteric arteries demonstrated significantly reduced relaxation as compared to SS rats (n=4, p <0.05). An associated decrease in sodium excretion and an increase in glucose excretion were also observed in urine samples of Resp18 mutant rats compared to SS rats (51±7.3vs.27±2.7meq/L/24hr; 10±0.3 vs. 14±1.4mg/dl/24hr,n=5-8, p <0.05).Renal histology examination revealed that Resp18 mutant rat kidneys showed increased fibrosis compared to SS rats. The median survival of Resp18 mutant rats was 259 days, which was significantly lower than the median survival of 309 days for the SS (n=8-16, p <0.05). In conclusion, the data suggest that Resp18 is a gene associated with the development of hypertension, renal disease and increased mortality in the SS rats. Resp18 is a molecule involved in the secretory pathway and thereby, future studies will be conducted to examine the mechanistic links between Resp18 , its function in the secretory pathway and BP regulation.

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Recovery of protein secretion after brefeldin A treatment of rat lacrimal glands: effect of cAMP

AJP Cell Physiology ◽

10.1152/ajpcell.1996.271.3.c783 ◽

1996 ◽

Vol 271 (3) ◽

pp. C783-C793 ◽

Cited By ~ 6

Author(s):

P. Robin ◽

B. Rossignol ◽

M. N. Raymond

Keyword(s):

Golgi Apparatus ◽

Protein Secretion ◽

Secretory Pathway ◽

Brefeldin A ◽

Specific Protein ◽

Dependent Manner ◽

Lacrimal Glands ◽

Extracellular Stimuli ◽

Few Data

In exocrine cells, the discharge of secretory granule contents in response to extracellular stimuli has been widely documented. However, few data are available concerning the effect of these stimuli on the steps of the secretory pathway preceding protein exocytosis. To obtain more data on this subject, we used brefeldin A (BFA) to perturb intracellular protein transit. When, after exposure of the lacrimal gland lobules to 10 microM BFA, which led to a complete dismantling of the Golgi apparatus and fully inhibited the secretion of newly synthesized proteins, the drug concentration was lowered to 100 nM, a restoration of protein secretion was observed in a secretagogue-dependent manner. Secretagogues increasing the adenosine 3',5'-cyclic monophosphate (cAMP) level facilitated the recovery of protein secretion and Golgi apparatus restructuring, whereas other secretagogues, involving the calcium pathway, did not. Furthermore, the cAMP effect was prevented by H-89, a specific protein kinase A inhibitor. These effects of cAMP are due to neither BFA degradation nor BFA excretion from the cells. We conclude from these results that in rat lacrimal glands the recovery from the dramatic damage caused by BFA is promoted by a cAMP-dependent mechanism and further suggest a role of cAMP in the regulation of the Golgi structure and/or function.

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Compartmental organization of Golgi-specific protein modification and vacuolar protein sorting events defined in a yeast sec18 (NSF) mutant.

The Journal of Cell Biology ◽

10.1083/jcb.114.2.207 ◽

1991 ◽

Vol 114 (2) ◽

pp. 207-218 ◽

Cited By ~ 248

Author(s):

T R Graham ◽

S D Emr

Keyword(s):

Golgi Complex ◽

Protein Modification ◽

Secretory Pathway ◽

Protein Transport ◽

Temperature Shift ◽

Specific Protein ◽

Carboxypeptidase Y ◽

Protein Functions ◽

Dependent Transport ◽

Vacuolar Protein

The sec18 and sec23 secretory mutants of Saccharomyces cerevisiae have previously been shown to exhibit temperature-conditional defects in protein transport from the ER to the Golgi complex (Novick, P., S. Ferro, and R. Schekman, 1981. Cell. 25:461-469). We have found that the Sec18 and Sec23 protein functions are rapidly inactivated upon shifting mutant cells to the nonpermissive temperature (less than 1 min). This has permitted an analysis of the potential role these SEC gene products play in transport events distal to the ER. The sec-dependent transport of alpha-factor (alpha f) and carboxypeptidase Y (CPY) biosynthetic intermediates present throughout the secretory pathway was monitored in temperature shift experiments. We found that Sec18p/NSF function was required sequentially for protein transport from the ER to the Golgi complex, through multiple Golgi compartments and from the Golgi complex to the cell surface. In contrast, Sec23p function was required in the Golgi complex, but only for transport of alpha f out of an early compartment. Together, these studies define at least three functionally distinct Golgi compartments in yeast. From cis to trans these compartments contain: (a) An alpha 1----6 mannosyltransferase; (b) an alpha 1----3 mannosyltransferase; and (c) the Kex2 endopeptidase. Surprisingly, we also found that a pool of Golgi-modified CPY (p2 CPY) located in a compartment distal to the alpha 1----3 mannosyltransferase does not require Sec18p function for final delivery to the vacuole. This compartment appears to be equivalent to the Kex2 compartment as we show that a novel vacuolar CPY-alpha f-invertase fusion protein undergoes efficient Kex2-dependent cleavage resulting in the secretion of invertase. We propose that this Kex2 compartment is the site in which vacuolar proteins are sorted from proteins destined to be secreted.

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Integrated analysis of zone-specific protein and metabolite profiles within nitrogen-fixing Medicago truncatula-Sinorhizobium medicae nodules

PLoS ONE ◽

10.1371/journal.pone.0180894 ◽

2017 ◽

Vol 12 (7) ◽

pp. e0180894 ◽

Cited By ~ 6

Author(s):

Aaron J. Ogden ◽

Mahmoud Gargouri ◽

JeongJin Park ◽

David R. Gang ◽

Michael L. Kahn

Keyword(s):

Medicago Truncatula ◽

Specific Protein ◽

Integrated Analysis ◽

Nitrogen Fixing ◽

Sinorhizobium Medicae ◽

Metabolite Profiles

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The small GTPase Rab11F represents a molecular marker within the secretory pathway required for the nitrogen-fixing symbiosis

10.1101/661835 ◽

2019 ◽

Author(s):

Prachumporn Nounurai ◽

Holger Densow ◽

Hanna Bednarz ◽

Karsten Niehaus

Keyword(s):

Secretory Pathway ◽

Root Nodule ◽

Root Nodules ◽

Turgor Pressure ◽

Brefeldin A ◽

Small Gtpase ◽

Rab Gtpase ◽

Nitrogen Fixing ◽

Symbiotic Interaction ◽

Host Membrane

AbstractThe nitrogen-fixing root nodule is generally derived through a successful symbiotic interaction between legume plants and bacteria of the genusRhizobium. A root nodule shelter hundreds ofRhizobia, which are thought to invade into the plant cells through an endocytosis-like process despite the existence of turgor pressure. Each invadingRhizobiumis surrounded by the peribacteroid membrane to form the symbiosome, which results in the higher acquisition of host membrane materials. In this study, we show the localization of Rab11F, a RabA6b homolog with the large Rab-GTPase family, which was highly expressed in root nodules ofMedicago sativaandM. truncatula. Rab11F-labeled organelles accumulated the membrane specific dye FM4-64 and were sensitive to Brefeldin A by forming aggregates after treatment with this drug. By co-localization with the cis-Golgi marker, GmMan1-mCherry, Rab11F-organelles formed tri-colored organelles, whereby Rab11F was located to the opposite side of GmMan1-mCherry indicating that Rab11F-labeled structures were localized within the trans-Golgi network (TGN). In root nodules, Rab11F was localized transiently at the infection thread-covering membrane on the side of infection droplets and the peribacteroid membranes. The symbiosome acquires Rab11F during the entry process and differentiation. However, the symbiosome did not recruit Rab11F after cessation of division. In conclusion, thelegumeplant seemed to use a specialized secretion pathway from the TGN, which was marked by Rab11F, to proliferate the symbiosome membrane.

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Immunocytochemical Localization of the Prohormone Convertases PC1 and PC2 in Rat Prolactin Cells

Journal of Histochemistry & Cytochemistry ◽

10.1177/002215549804600113 ◽

1998 ◽

Vol 46 (1) ◽

pp. 101-108 ◽

Cited By ~ 6

Author(s):

Laurent Muller ◽

Renée Picart ◽

Alain Barret ◽

Nabil G. Seidah ◽

Claude Tougard

Keyword(s):

Anterior Pituitary ◽

Biochemical Analysis ◽

Secretory Pathway ◽

Secretory Granules ◽

Specific Protein ◽

Cell Type ◽

Prolactin Cells ◽

Prohormone Convertases ◽

New Information ◽

Peptide Precursor

The prohormone convertases PC1 and PC2 are subtilisin-related endopepti-dases that process prohormone and neuropeptide precursors. Using different ultrastructural immunocytochemical approaches, we have investigated their intracellular distribution in a neuroendocrine cell type that has not been examined thus far, the rat anterior pituitary lactotrope. These cells secrete mainly prolactin and also express the neuroendocrine-specific protein secretogranin II, which is considered a peptide precursor. Our study provides evidence for the expression of PC1 and PC2 in rat lactotropes and provides new information on their subcellular localization. Apart from their presence in the secretory granules, PC1 and PC2 displayed different major localization along the secretory pathway. PC1 immunoreactivity was concentrated in the Golgi apparatus, whereas PC2 immunoreactivity was prominent in the rough endoplasmic reticulum (RER). These observations provide morphological support for previous biochemical analysis of proPC1 and proPC2 post-translational processing, which has demonstrated that PC1 exits very rapidly from the RER, whereas PC2 is retained much longer in this compartment.

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ICA512 RESP18 homology domain is a protein condensing factor and insulin fibrillation inhibitor

10.1101/521351 ◽

2019 ◽

Author(s):

Pamela L Toledo ◽

Juha M Torkko ◽

Andreas Müller ◽

Carolin Wegbrod ◽

Anke Sönmez ◽

...

Keyword(s):

Secretory Pathway ◽

Secretory Granules ◽

Tyrosine Phosphatase ◽

Specific Protein ◽

Terminal Segment ◽

Extracellular Milieu ◽

Intrinsically Disordered ◽

Early Secretory Pathway ◽

Ph Range

Type 1 diabetes islet cell autoantigen 512 (ICA512) is a tyrosine phosphatase-like intrinsic membrane protein involved in the biogenesis and turnover of insulin secretory granules (SGs) in pancreatic islet β-cells. Whereas its membrane proximal and cytoplasmic domains have been functionally and structurally characterized, the role of ICA512 N-terminal segment named regulated endocrine-specific protein 18 homology domain (RESP18HD), which encompasses residues 35-131, remains largely unknown. Here we show that ICA512 RESP18HD residues 91-131 encode for an intrinsically disordered region (IDR), which in vitro acts as a condensing factor for the reversible aggregation of insulin and other β-cell proteins in a pH and Zn2+ regulated fashion. At variance with what has been shown for other granule cargoes with aggregating properties, the condensing activity of ICA512 RESP18HD is displayed at pH close to neutral, i.e. in the pH range found in the early secretory pathway, while it is resolved at acidic pH and Zn2+ concentrations resembling those present in mature SGs. Moreover, we show that ICA512 RESP18HD residues 35-90, preceding the IDR, inhibit insulin fibrillation in vitro. Finally, we found that glucose-stimulated secretion of RESP18HD upon exocytosis of SGs from insulinoma INS-1 cells is associated with cleavage of its IDR, conceivably to prevent its aggregation upon exposure to neutral pH in the extracellular milieu. Taken together, these findings point to ICA512 RESP18HD being a condensing factor for protein sorting and granulogenesis early in the secretory pathway, and for prevention of amyloidogenesis.

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