scholarly journals Activity of the SNARE Protein SNAP29 at the Endoplasmic Reticulum and Golgi Apparatus

2021 ◽  
Vol 9 ◽  
Author(s):  
Elena Morelli ◽  
Elisa A. Speranza ◽  
Enrica Pellegrino ◽  
Galina V. Beznoussenko ◽  
Francesca Carminati ◽  
...  
Keyword(s):  
Stem Cells ◽  
Endoplasmic Reticulum ◽  
Cell Division ◽  
Golgi Apparatus ◽  
Regulatory Function ◽  
Snare Protein ◽  
Cellular Processes ◽  
Systemic Disorder ◽  
Membrane Compartments

Snap29 is a conserved regulator of membrane fusion essential to complete autophagy and to support other cellular processes, including cell division. In humans, inactivating SNAP29 mutations causes CEDNIK syndrome, a rare multi-systemic disorder characterized by congenital neuro-cutaneous alterations. The fibroblasts of CEDNIK patients show alterations of the Golgi apparatus (GA). However, whether and how Snap29 acts at the GA is unclear. Here we investigate SNAP29 function at the GA and endoplasmic reticulum (ER). As part of the elongated structures in proximity to these membrane compartments, a pool of SNAP29 forms a complex with Syntaxin18, or with Syntaxin5, which we find is required to engage SEC22B-loaded vesicles. Consistent with this, in HeLa cells, in neuroepithelial stem cells, and in vivo, decreased SNAP29 activity alters GA architecture and reduces ER to GA trafficking. Our data reveal a new regulatory function of Snap29 in promoting secretory trafficking.

An Ultra-Structural Study of Human Melanoma in Vivo and Vitro

1976 ◽  
Vol 34 ◽  
pp. 258-259
Author(s):  
James R. Gaylor ◽  
Fredda Schafer ◽  
Robert E. Nordquist
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Apparatus ◽  
Protein Aggregation ◽  
Structural Study ◽  
Human Melanoma ◽  
Protein Matrix ◽  
Early Form ◽  
Endoplasmic Reticulum Protein ◽  
Mitochondrial Origin

Several theories on the origin of the melanosome exist. These include the Golgi origin theory, in which a tyrosinase-rich protein is "packaged" by the Golgi apparatus, thus forming the early form of the melanosome. A second theory postulates a mitochondrial origin of melanosomes. Its author contends that the melanosome is a modified mitochondria which acquires melanin during its development. A third theory states that a pre-melanosome is formed in the smooth or rough endoplasmic reticulum. Protein aggregation is suggested by one author as a possible source of the melanosome. This fourth theory postulates that the melanosome originates when the protein products of several genetic loci aggregate in the cytoplasm of the melanocyte. It is this protein matrix on which the melanin is deposited. It was with these theories in mind that this project was undertaken.

Endothelial stroma programs hematopoietic stem cells to differentiate into regulatory dendritic cells through IL-10

Blood ◽  
2006 ◽  
Vol 108 (4) ◽  
pp. 1189-1197 ◽  
Author(s):  
Hua Tang ◽  
Zhenhong Guo ◽  
Minghui Zhang ◽  
Jianli Wang ◽  
Guoyou Chen ◽  
...  
Keyword(s):  
Stem Cells ◽  
Dendritic Cells ◽  
T Cell ◽  
Hematopoietic Stem Cells ◽  
Critical Role ◽  
Regulatory Function ◽  
Hematopoietic Stem ◽  
Regulatory Dendritic Cells

Abstract Regulatory dendritic cells (DCs) have been reported recently, but their origin is poorly understood. Our previous study demonstrated that splenic stroma can drive mature DCs to proliferate and differentiate into regulatory DCs, and their natural counterpart with similar regulatory function in normal spleens has been identified. Considering that the spleen microenvironment supports hematopoiesis and that hematopoietic stem cells (HSCs) are found in spleens of adult mice, we wondered whether splenic microenvironment could differentiate HSCs into regulatory DCs. In this report, we demonstrate that endothelial splenic stroma induce HSCs to differentiate into a distinct regulatory DC subset with high expression of CD11b but low expression of Ia. CD11bhiIalo DCs secreting high levels of TGF-β, IL-10, and NO can suppress T-cell proliferation both in vitro and in vivo. Furthermore, CD11bhiIalo DCs have the ability to potently suppress allo-DTH in vivo, indicating their preventive or therapeutic perspectives for some immunologic disorders. The inhibitory function of CD11bhiIalo DCs is mediated through NO but not through induction of regulatory T (Treg) cells or T-cell anergy. IL-10, which is secreted by endothelial splenic stroma, plays a critical role in the differentiation of the regulatory CD11bhiIalo DCs from HSCs. These results suggest that splenic microenvironment may physiologically induce regulatory DC differentiation in situ.

scholarly journals Subcellular distribution of selenium in deficient mouse liver

1989 ◽  
Vol 258 (2) ◽  
pp. 541-545 ◽  
Author(s):  
R Reiter ◽  
R Otter ◽  
A Wendel
Keyword(s):  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
Golgi Apparatus ◽  
Trace Element ◽  
Fold Increase ◽  
Subcellular Fractionation ◽  
Fast Response ◽  
Cell Compartment ◽  
Deficient Mice

Selenium (Se)-deficient mice were labelled in vivo with single pulses of [75Se]selenite, and the intrahepatic distribution of the trace element was studied by subcellular fractionation. At 1 h after intraperitoneal injection of 3.3 or 10 micrograms of Se/kg body weight, 15% of the respective doses were found in the liver. Accumulation in the subcellular fractions followed the order: Golgi vesicular much greater than lysosomal greater than cytosolic = microsomal greater than mitochondrial, peroxisomal, nuclear and plasma-membrane fraction. At a dose of 3.3 micrograms/kg, more than 90% of the hepatic Se was protein-bound. When cross-contamination was accounted for, the following specific Se contents of the subcellular compartments were extrapolated: Golgi apparatus, 7.50 pmol/mg; cytosol, 0.90 pmol/mg; endoplasmic reticulum, 0.80 pmol/mg; mitochondria, 0.49 pmol/mg; nuclei, lysosomes, peroxisomes and plasma membrane, less than 0.4 pmol/mg. At 10 micrograms/kg, a roughly 2-3-fold increase in Se content of all fractions was found without major changes in the intrahepatic distribution pattern. An extraordinary rise in the cytosolic fraction was due to an apparently non-protein-bound Se pool. At 24 h after dosing, total hepatic Se had decreased to 6% of the initial dose and had become predominantly protein-bound. The 60% decrease in hepatic Se was reflected in a similar fall in the subcellular levels of the trace element. The Golgi apparatus still had the highest specific Se content, although accumulation was 5 times less than that after 1 h. The cytosolic pool accounted for 50% of the hepatic Se at both labelling times. After 1 h the Golgi apparatus was, with 19%, the second largest intrahepatic pool, followed by the endoplasmic reticulum with 16%. The high affinity and fast response of the Golgi apparatus to Se supplementation of deficient mice is interpreted in terms of a predominant function of this cell compartment in the processing and the export of Se-proteins from the liver.

scholarly journals Hematopoietic stem cells differentiate into restricted myeloid progenitors before cell division

2018 ◽  
Author(s):  
Tatyana Grinenko ◽  
Anne Eugster ◽  
Lars Thielecke ◽  
Beata Ramazs ◽  
Anja Krueger ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Stem Cells ◽  
Cell Division ◽  
Hematopoietic Stem Cells ◽  
Embryonic Stem ◽  
Erythroid Progenitors ◽  
Multipotent Stem Cells ◽  
Hematopoietic Stem ◽  
Myeloid Progenitors

SummaryHematopoietic stem cells (HSCs) continuously replenish all blood cell types through a series of differentiation steps that involve the generation of lineage-committed progenitors as well as necessary expansion due to repeated cell divisions. However, whether cell division in HSCs precedes differentiation is unclear. To this end, we used an HSC cell tracing approach and Ki67RFP knock-in mice to assess simultaneously divisional history, cell cycle progression, and differentiation of adult HSCs in vivo. Our results reveal that HSCs are able to differentiate into restricted progenitors, especially common myeloid progenitors, restricted megakaryocyte-erythroid progenitors (PreMEs) and pre-megakaryocyte progenitors (PreMegs), without undergoing cell division and even before entering the S phase of the cell cycle. Additionally, the phenotype of the undivided but differentiated progenitors correlated with expression of lineage-specific genes that manifested as functional differences between HSCs and restricted progenitors. Thus, HSC fate decisions appear to be uncoupled from physical cell division. Our results facilitate a better understanding of the mechanisms that control fate decisions in hematopoietic cells. Our data, together with separate findings from embryonic stem cells, suggest that cell division and fate choice are independent processes in pluripotent and multipotent stem cells.

scholarly journals ZapA tetramerization is required for midcell localization and ZapB interaction in Escherichia coli

2019 ◽  
Author(s):  
Nils Y. Meiresonne ◽  
Tanneke den Blaauwen
Keyword(s):  
Cell Division ◽  
Chromosome Segregation ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Bacterial Cell Division ◽  
Cellular Processes ◽  
Interaction Partners ◽  
Associated Proteins

AbstractBacterial cell division is guided by FtsZ treadmilling precisely at midcell. FtsZ itself is regulated by FtsZ associated proteins (Zaps) that couple it to different cellular processes. ZapA is known to enhance FtsZ bundling but also forms the synchronizing link with chromosome segregation through ZapB and matS bound MatP. ZapA exists as dimers and tetramers in the cell. Using the ZapAI83E mutant that only forms dimers, this paper investigates the effects of ZapA multimerization state on its interaction partners and cell division. By employing (fluorescence) microscopy and Förster Resonance Energy Transfer in vivo it is shown that; dimeric ZapA is unable to complement a zapA deletion strain and localizes diffusely through the cell but still interacts with FtsZ that is not part of the cell division machinery. Dimeric ZapA is unable to recruit ZapB, which localizes in its presence unipolarly in the cell. Interestingly, the localization profiles of the chromosome and unipolar ZapB anticorrelate. The work presented here confirms previously reported in vitro effects of ZapA multimerization in vivo and further places it in a broader context by revealing the strong implications for ZapB localization and ter linkage.

scholarly journals PEROXIDASE ACTIVITY IN RAT LIVER MICROBODIES AFTER AMINO-TRIAZOLE INHIBITION

1970 ◽  
Vol 45 (3) ◽  
pp. 576-585 ◽  
Author(s):  
Richard L. Wood ◽  
Peter G. Legg
Keyword(s):  
Endoplasmic Reticulum ◽  
Fine Structure ◽  
Golgi Apparatus ◽  
Peroxidase Activity ◽  
Catalase Activity ◽  
Staining Technique ◽  
Male Rats ◽  
Hepatic Cells ◽  
In Vivo Effects

The in vivo effects of 3-amino-1,2,4-triazole (AT) on the fine structure of microbodies in hepatic cells of male rats has been studied by the peroxidase-staining technique. Within 1 hr of intraperitoneal injection AT abolishes microbody peroxidase-staining, and the return of staining coincides temporally with the known pattern of return of catalase activity following AT inhibition; this is further evidence that the peroxidase staining of microbodies is due to catalase activity. Peroxidase staining reappears in the microbody matrix without evidence of either massive degradation or rapid proliferation of the organelles. Furthermore, during the period of return of activity, ribosomal staining occurs adjacent to microbodies whose matrix shows little or no peroxidase staining. These observations are interpreted as evidence that (a) catalase is capable of entering preexisting microbodies without traversing the cisternae of the rough endoplasmic reticulum or the Golgi apparatus, and that (b) the ribosomal staining is probably not cytochemical diffusion artifact and may represent a localized site of synthesis or activation of catalase.

scholarly journals Ultrastructure of mononuclear phagocytes developing in liquid bone marrow cultures. A study on peroxidatic activity

1979 ◽  
Vol 149 (1) ◽  
pp. 17-26 ◽  
Author(s):  
JWM Van Der Meer ◽  
RHJ Beelen ◽  
DM Fluitsma ◽  
R Van Furth
Keyword(s):  
Bone Marrow ◽  
Endoplasmic Reticulum ◽  
Golgi Apparatus ◽  
Nuclear Envelope ◽  
Rough Endoplasmic Reticulum ◽  
Precursor Cells ◽  
Mononuclear Phagocytes ◽  
Peroxidatic Activity

Monoblasts, promonocytes, and macrophages in in vitro cultures of murine bone marrow were studied ultrastructurally, with special attention to peroxidatic activity. Monoblasts show peroxidatic activity in the rough endoplasmic reticulum and nuclear envelope as well as in the granules. The presence of peroxidatic activity in the Golgi apparatus could not be determined. Promonocytes have peroxidase-positive rough endoplasmic reticulum, Golgi apparatus, nuclear envelope, and granules, as previously reported. During culture, cells are formed with peroxidatic activity similar to that of monocytes or exudate macrophages (positive granules; negative Golgi apparatus, RER, and nuclear envelope); we call these cells early macrophages. In addition, transitional macrophages with both positive granules and positive RER, nuclear envelope, negative Golgi apparatus (as in exudate- resident macrophages in vivo), and mature macrophages with peroxidatic activity only in the RER and nuclear envelope (as in resident macrophages in vivo) were found. A considerable number of cells without detectable peroxidatic activity were also encountered. Our finding that macrophages with the peroxidatic pattern of monocytes (early macrophages), exudate-resident macrophages (transitional macrophages), and resident macrophages (mature macrophages), develop in vitro from proliferating precursor cells deriving from the bone marrow, demonstrates once again that resident macrophages in tissues originate from precursor cells in the bone marrow. Therefore, this conclusion can no longer be challenged on the basis of a cytochemical difference between monocytes and exudate macrophages on the one hand and resident macrophages on the other.

scholarly journals IN VIVO INCORPORATION OF 3H-GALACTOSE BY THYROID FOLLICULAR CELLS OF THE RAT, AS SHOWN BY ELECTRON MICROSCOPIC RADIOAUTOGRAPHY

1972 ◽  
Vol 20 (3) ◽  
pp. 220-224 ◽  
Author(s):  
A. HADDAD
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Apparatus ◽  
Rough Endoplasmic Reticulum ◽  
Side Chains ◽  
Follicular Cells ◽  
Electron Microscopic ◽  
Thyroid Follicular Cells ◽  
Apical Vesicles ◽  
Electron Microscopic Radioautography

Radioactive galactose was injected intravenously into rats and localized in thyroid follicular cells by electron microscopic radioautography at intervals ranging from 2.5 to 30 min after injection. The galactose label was mostly present in the Golgi apparatus at 2.5 min, with some of it in the adjacent rough endoplasmic reticulum. By 30 min, the label was found in apical vesicles and colloid. It was concluded that galactose is added to the carbohydrate side chains of incomplete thyroglobulin molecules during their travel through the cisternae of the endoplasmic reticulum into the Golgi apparatus; the uptake begins as this organelle is approached, but predominates within it. The thyroglobulin molecule which has thus been labeled is transported by the apical vesicles to the colloid.

scholarly journals EVIDENCE FOR THE PARTICIPATION OF THE GOLGI APPARATUS IN THE INTRACELLULAR TRANSPORT OF NASCENT ALBUMIN IN THE LIVER CELL

1970 ◽  
Vol 47 (3) ◽  
pp. 555-567 ◽  
Author(s):  
Hans Glaumann ◽  
Jan L. E. Ericsson
Keyword(s):  
Endoplasmic Reticulum ◽  
Golgi Apparatus ◽  
Liver Cell ◽  
Intracellular Transport ◽  
Low Density Lipoprotein ◽  
Density Lipoprotein ◽  
Parenchymal Liver Cell ◽  
Parenchymal Liver ◽  
Membrane Bound

A comparative biochemical and radioautographic in vivo study was performed to identify the site of synthesis and route of migration of albumin in the parenchymal liver cell after labeling with leucine-14C or leucine-3H via the portal vein. Free cytoplasmic ribosomes, membrane-bound ribosomes, rough- and smooth-surfaced microsomes, and Golgi membranes were isolated. The purity of the Golgi fraction was examined morphologically and biochemically. After administration of leucine-14C, labeled albumin was extracted, and the sequence of transport was followed from one fraction to the other. Approximately 2 min after the intravenous injection, bound ribosomes displayed a maximal rate of leucine-14C incorporation into albumin. 4 min later, a peak was reached for rough microsomes. Corresponding maximal activities for smooth microsomes were recorded at 15 min, and for the Golgi apparatus at ∼20 min. The relative amount of albumin, calculated on a membrane protein basis, was higher in the Golgi fraction than in the microsomes. By radioautography the silver grains were preferentially localized over the rough-surfaced endoplasmic reticulum at the 5 min interval. Apparent activity in the Golgi zone was noted 9 min after the injection; at 15 and 20 min, the majority of the grains were found in this location. Many of the grains associated with the Golgi apparatus were located over Golgi vacuoles containing 300–800 A electron-opaque bodies. It is concluded that albumin is synthesized on bound ribosomes, subsequently is transferred to the cavities of rough-surfaced endoplasmic reticulum, and then undergoes migration to the smooth-surfaced endoplasmic reticulum and the Golgi apparatus. In the latter organelle, albumin can be expected to be segregated together with very low density lipoprotein in vacuoles known to move toward the sinusoidal portion of the cell and release their content to the blood.

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