scholarly journals Organelle relationships in cultured 3T3-L1 preadipocytes.

1980 ◽  
Vol 87 (1) ◽  
pp. 180-196 ◽  
Author(s):  
A B Novikoff ◽  
P M Novikoff ◽  
O M Rosen ◽  
C S Rubin
Keyword(s):  
Spatial Relationship ◽  
Morphological Differentiation ◽  
Coated Vesicles ◽  
Coated Pits ◽  
Exogenous Lipid ◽  
Acetate Esterase ◽  
Alpha Naphthyl Acetate Esterase ◽  
High Level ◽  
Relationship Of

In differentiating 3T3-L1 cells, lipid spheres, the endoplasmic reticulum (ER), microperoxisomes, and mitochondria form "constellations" that may reflect the interplay of lipid metabolizing enzymes in these organelles. ER cisternae are also situated very close to "rosettes,"plasmalemmal specializations found in mature adipocytes in vivo. As in hepatocytes and absorptive cells of the intestine, this spatial relationship of ER and plasmalemma suggests a role for rosettes in the uptake of exogenous lipid precursors. The morphological differentiation of 3T3-L1 preadipocytes includes the loss of "stress fibers" and the appearance of microfilament like structures that encase, in a complex manner, the cytosolic lipid spheres that appear during differentiation. Other features described for the first time in 3T3-L1 preadipocytes include: (a) the presence of an extensive acid phosphatase (AcPase) positive GERL from which coated vesicles apparently arise (these coated vesicles display AcPase activity and are much smaller and far more numerous than the coated vesicles that seem to arise from the plasmalemmal coated pits); (b) the abundance of AcPase-positive autophagic vacuoles; and (c) a high level of alpha-naphthyl-acetate-esterase activity which, by light microscopy cytochemistry, appears to be localized in the cytosol.

scholarly journals Studies on Analogues of L-Cysteine and L-Cystine

Blood ◽  
1956 ◽  
Vol 11 (1) ◽  
pp. 1-10 ◽  
Author(s):  
AUSTIN S. WEISBERGER ◽  
LEIF G. SUHRLAND ◽  
JOSEPH SEIFTER
Keyword(s):  
Amino Acids ◽  
Spatial Configuration ◽  
Spatial Relationship ◽  
Inhibitory Effect ◽  
Selenium Compounds ◽  
Low Concentrations ◽  
Relationship Of ◽  
Normal Cellular Function

Abstract The amino acids L-cysteine and L-cystine appear to have an important role in the metabolism of leukocytes. Decreased availability of these amino acids may therefore have important effects on leukocytes. The possibility of decreasing the influx of radioactive L-cystine into leukemic leukocytes was investigated by exposing the leukocytes to various analogues of cysteine (cystine) prior to incubation with S35 L-cystine. It was found that a highly specific structural and spatial configuration is required to decrease the influx of S35 L-cystine. Thus unlabeled L-cysteine is effective in decreasing the incorporation of radioactive L-cystine. However, analogues of cystine in which there is modification or substitution of the sulfhydryl, amino or carboxyl group do not decrease the influx of S35 L-cystine. Furthermore, any alteration in the spatial relationship of the sulfhydryl and amino groups of L-cysteine also results in a loss of the ability of an analogue to decrease the incorporation of S35 L-cystine. Of the compounds studied and in the concentrations employed, only unlabeled L-cysteine, selenium cystine and phenyl selenium cysteine were effective. Selenium cystine is identical with cystine except that selenium replaces the sulfur in the molecule. Phenyl selenium cysteine is also closely related structurally to cysteine. The mechanism of action of selenium cystine and phenyl selenium cysteine in decreasing the influx of S35 L-cystine is not known. Other selenium compounds tested were ineffective. These compounds may exert their inhibitory effect by (a) competitive combination with specific intracellular receptors for L-cysteine (L-cystine), (b) inactivation of enzymes or compounds essential for normal cellular function, (c) alteration in membrane permeability or (d) a toxic effect of selenium. Since selenium cystine and phenyl selenium cystine are inhibitory in low concentrations in vitro, these compounds may have important effects on leukemic leukocytes in vivo.

scholarly journals Phosphorylation of the cation-independent mannose 6-phosphate receptor is closely associated with its exit from the trans-Golgi network.

1993 ◽  
Vol 120 (1) ◽  
pp. 67-75 ◽  
Author(s):  
S Méresse ◽  
B Hoflack
Keyword(s):  
Cell Surface ◽  
Specific Inhibitor ◽  
Cytoplasmic Domain ◽  
Single Step ◽  
Coated Vesicles ◽  
Coated Pits ◽  
Trans Golgi Network ◽  
Mannose 6 Phosphate ◽  
Golgi Network

We have previously shown that two serine residues present in two conserved regions of the bovine cation-independent mannose 6-phosphate receptor (CI-MPR) cytoplasmic domain are phosphorylated in vivo (residues 2421 and 2492 of the full length bovine CI-MPR precursor). In this study, we have used CHO cells to investigate the phosphorylation state of these two serines along the different steps of the CI-MPR exocytic and endocytic recycling pathways. Transport and phosphorylation of the CI-MPR in the biosynthetic pathway were examined using deoxymannojirimycin (dMM), a specific inhibitor of the cis-Golgi processing enzyme alpha-mannosidase I which leads to the accumulation of N-linked high mannose oligosaccharides on glycoproteins. Upon removal of dMM, normal processing to complex-type oligosaccharides (galactosylation and then sialylation) occurs on the newly synthesized glycoproteins, including the CI-MPR which could then be purified and analyzed on lectin affinity columns. Phosphorylation of the newly synthesized CI-MPR was concomitant with the sialylation of its oligosaccharides and appeared as a major albeit transient modification. Phosphorylation of the cell surface CI-MPR was examined during its endocytosis as well as its return to the Golgi using antibody tagging and exogalactosylation. The cell surface CI-MPR was not phosphorylated when it entered clathrin-coated pits or when it moved to the early and late endosomes. In contrast, the surface CI-MPR was phosphorylated when it had been resialylated upon its return to the trans-Golgi network. Subcellular fractionation experiments showed that the phosphorylated CI-MPR and the corresponding kinase were found in clathrin-coated vesicles. Collectively, these results indicate that phosphorylation of the two serines in the CI-MPR cytoplasmic domain is associated with a single step of transport of its recycling pathways and occurs when this receptor is in the trans-Golgi network and/or has left this compartment via clathrin-coated vesicles.

Preliminary studies on haemoglobin and other proteins of the Pogonophora

1966 ◽  
Vol 46 (1) ◽  
pp. 115-124 ◽  
Author(s):  
Clyde Manwell ◽  
E. C. Southward ◽  
A. J. Southward
Keyword(s):  
Benthic Fauna ◽  
Starch Gel Electrophoresis ◽  
Low Oxygen ◽  
Partial Pressures ◽  
Starch Gel ◽  
Acetate Esterase ◽  
Dorsal Nerve ◽  
The Subject ◽  
High Level ◽  
Relationship Of

Starch gel electrophoresis of extracts of Siboglinum atlanticum showed that all five individuals tested have two acidic haemoglobin components and a strong α-naphthyl acetate esterase. There was individual variation in the position of the esterase. Low levels of amylase activity were found in the extracts but no trace of dehydrogenases for such important substrates as glucose-6-phosphate, lactate, malate, and glutamate could be revealed by standard histochemical methods as applied to zone electrophoresis. The high level of haemoglobin and the protein peculiarities of the Pogonophora are discussed in relation to experiments on respiration. It is concluded that Siboglinum haemoglobin functions at very low oxygen partial pressures and that the high level of haemoglobin dissolved in the blood plasma of pogonophores does not reflect a high level of oxygen consumption or activity. The meagre biochemical data at present available on the Pogonophora do not favour relationship of this phylum to the echinodtrm-chordate line any more than to the annelids or other invertebrate phyla.INTRODUCTIONLargely as a result of studies by A. V. Ivanov, the phylum Pogonophora has become recognized by zoologists in the past decade (reviewed by Hyman, 1959, esp. pp. 208–27; Ivanov, 1963; E. C. Southward, 1963). Pogonophores are small, extremely vermiform animals, living in tubes partly im-bedded in mud or muddy sand; while in some areas they are sufficiently abundant to dominate the benthic fauna, their occurrence at great depths has made living pogonophores very difficult to obtain.Two especially interesting problems associated with this newly recognized phylum are:(a) Pogonophora are the only group of free-living Metazoa without a gut at any stage in their development, and thus, the method of feeding and type of metabolism has been the subject of considerable speculation; (b) Pogonophora possess a few characteristics—e.g. a ventral heart and dorsal nerve cord—suggestive of the echinoderm-chordate line of evolution.

scholarly journals Trimeric binding of the 70-kD uncoating ATPase to the vertices of clathrin triskelia: a candidate intermediate in the vesicle uncoating reaction.

1989 ◽  
Vol 109 (4) ◽  
pp. 1457-1466 ◽  
Author(s):  
J Heuser ◽  
C J Steer
Keyword(s):  
Atp Hydrolysis ◽  
Bovine Brain ◽  
Coated Vesicles ◽  
Coated Pits ◽  
Experimental Conditions ◽  
Molecular Conformations ◽  
Product Release ◽  
Protein Polymer

Clathrin-coated vesicles were uncoated with the 70-kD "uncoating ATPase" from bovine brain, and the molecular products were visualized by freeze-etch electron microscopy. This yielded images of released clathrin triskelia with up to three 70-kD uncoating ATPase molecules bound to their vertices. Likewise, incubation of soluble clathrin triskelia with purified uncoating ATPase also led to trimeric binding of the ATPase to the vertices of clathrin triskelia. However, this occurred only when either EDTA or nonhydrolyzable analogues of ATP were present, in which case the ATPase also appeared to self-associate. When ATP was present instead, no 70-kD ATPases could be found on clathrin triskelia and all ATPases remained monomeric. These observations support the notion that ATP controls an allosteric conversion of the 70-kD uncoating ATPase between two different molecular conformations, an ATP-charged state in which the molecule has relatively low affinity for itself as well as low affinity for clathrin, and an ATP-discharged state in which both of these affinities are high. We presume that in vivo, the latter condition is brought about by ATP hydrolysis and product release, at which point the ATPase will bind tightly to clathrin and/or self-associate. We further propose that these reactions, when occurring in concert within a clathrin lattice, will tend to destabilize it by a mechanism we call "protein polymer competition". We stress the analogies between such a mechanism of uncoating and the ATP-driven events in muscle contraction. Finally, we show that under experimental conditions in which the uncoating ATPase fully removes the coats from brain coated vesicles, identical aliquots of the enzyme do not affect plasmalemmal coated pits in situ. This remarkable selectivity, the mechanism of which remains a complete mystery, is at least consistent with the idea that the 70-kD ATPase indeed plays a role in uncoating coated vesicles after they have formed in vivo.

scholarly journals Characterization of rrdA, a TetR Family Protein Gene Involved in the Regulation of Secondary Metabolism in Streptomyces coelicolor

2009 ◽  
Vol 75 (7) ◽  
pp. 2158-2165 ◽  
Author(s):  
Xijun Ou ◽  
Bo Zhang ◽  
Lin Zhang ◽  
Guoping Zhao ◽  
Xiaoming Ding
Keyword(s):  
Streptomyces Coelicolor ◽  
Morphological Differentiation ◽  
Transcript Level ◽  
Biosynthetic Gene Cluster ◽  
Pcr Analysis ◽  
Reverse Transcription Pcr ◽  
Family Protein ◽  
Severe Reduction ◽  
High Level

ABSTRACT Streptomyces not only exhibits complex morphological differentiation but also produces a plethora of secondary metabolites, particularly antibiotics. To improve our general understanding of the complex network of undecylprodigiosin (Red) biosynthesis regulation, we used an in vivo transposition system to identify novel regulators that influence Red production in Streptomyces coelicolor M145. Using this screening system, we obtained 25 Red-deficient mutants. Twenty-four of these mutants had a transposon inserted in the previously described Red biosynthetic gene cluster and produced different amounts of another secondary metabolite, actinorhodin (Act). One mutant was shown to have an insertion in a different region of the chromosome upstream of the previously uncharacterized gene rrdA (regulator of redD, sco1104), which encodes a putative TetR family transcription factor. Compared with wild-type strain M145, the rrdA null mutant exhibited increased Red production and decreased Act production. A high level of rrdA expression resulted in a severe reduction in Red production and Act overproduction. Reverse transcription-PCR analysis showed that RrdA negatively regulated Red production by controlling redD mRNA abundance, while no change was observed at the transcript level of the Act-specific activator gene, actII-orf4. The effects on Act biosynthesis might arise from competition for precursors that are common to both pathways.

Sinusoidal Cells in Bone Marrow Take Up BSA-Au Conjugates in the Presence of an Artificial Blood Substitute

1985 ◽  
Vol 43 ◽  
pp. 700-701
Author(s):  
J.S. Geoffroy ◽  
R.P. Becker
Keyword(s):  
Bone Marrow ◽  
Los Angeles ◽  
Iliac Artery ◽  
Blood Substitute ◽  
Sprague Dawley ◽  
Coated Pits ◽  
Sinusoidal Cells ◽  
Artificial Blood ◽  
Left Common Iliac Artery

The pattern of BSA-Au uptake in vivo by endothelial cells of the venous sinuses (sinusoidal cells) of rat bone marrow has been described previously. BSA-Au conjugates are taken up exclusively in coated pits and vesicles, enter and pass through an “endosomal” compartment comprised of smooth-membraned tubules and vacuoles and cup-like bodies, and subsequently reside in multivesicular and dense bodies. The process is very rapid, with BSA-Au reaching secondary lysosmes one minute after presentation. (Figure 1)In further investigations of this process an isolated limb perfusion method using an artificial blood substitute, Oxypherol-ET (O-ET; Alpha Therapeutics, Los Angeles, CA) was developed. Under nembutal anesthesia, male Sprague-Dawley rats were laparotomized. The left common iliac artery and vein were ligated and the right iliac artery was cannulated via the aorta with a small vein catheter. Pump tubing, preprimed with oxygenated 0-ET at 37°C, was connected to the cannula.

Ultrastructural evidence for mast cell-macrophage interrelationships in the dura mater of the rat: Infrequent mast cell-nerve associations

1990 ◽  
Vol 48 (3) ◽  
pp. 352-353
Author(s):  
Ruth V.W. Dimlich
Keyword(s):  
Mast Cell ◽  
Mast Cells ◽  
Dura Mater ◽  
Spatial Relationship ◽  
Potassium Phosphate ◽  
Plasma Extravasation ◽  
Close Spatial Relationship ◽  
Male Wistar Rats ◽  
Headache Pain ◽  
Relationship Of

Mast cells in the dura mater of the rat may play a role in cerebral pathologies including neurogenic inflammation (vasodilation; plasma extravasation) and headache pain . As has been suggested for other tissues, dural mast cells may exhibit a close spatial relationship to nerves. There has been no detailed ultrastructural description of mast cells in this tissue; therefore, the goals of this study were to provide this analysis and to determine the spatial relationship of mast cells to nerves and other components of the dura mater in the rat.Four adult anesthetized male Wistar rats (290-400 g) were fixed by perfusion through the heart with 2% glutaraldehyde and 2.8% paraformaldehyde in a potassium phosphate buffer (pH 7.4) for 30 min. The head of each rat was removed and stored in fixative for a minimum of 24 h at which time the dural coverings were removed and dissected into samples that included the middle meningeal vasculature. Samples were routinely processed and flat embedded in LX 112. Thick (1 um) sections from a minimum of 3 blocks per rat were stained with toluidine blue (0.5% aqueous).

scholarly journals Aberrantly high activation of a FoxM1–STMN1 axis contributes to progression and tumorigenesis in FoxM1-driven cancers

2021 ◽  
Vol 6 (1) ◽  
Author(s):  
Jun Liu ◽  
Jipeng Li ◽  
Ke Wang ◽  
Haiming Liu ◽  
Jianyong Sun ◽  
...  
Keyword(s):  
Cell Proliferation ◽  
Poor Prognosis ◽  
Soft Agar ◽  
Transcriptional Level ◽  
Regulation Mechanism ◽  
Strong Positive Correlation ◽  
Cell Viability Assay ◽  
High Level

AbstractFork-head box protein M1 (FoxM1) is a transcriptional factor which plays critical roles in cancer development and progression. However, the general regulatory mechanism of FoxM1 is still limited. STMN1 is a microtubule-binding protein which can inhibit the assembly of microtubule dimer or promote depolymerization of microtubules. It was reported as a major responsive factor of paclitaxel resistance for clinical chemotherapy of tumor patients. But the function of abnormally high level of STMN1 and its regulation mechanism in cancer cells remain unclear. In this study, we used public database and tissue microarrays to analyze the expression pattern of FoxM1 and STMN1 and found a strong positive correlation between FoxM1 and STMN1 in multiple types of cancer. Lentivirus-mediated FoxM1/STMN1-knockdown cell lines were established to study the function of FoxM1/STMN1 by performing cell viability assay, plate clone formation assay, soft agar assay in vitro and xenograft mouse model in vivo. Our results showed that FoxM1 promotes cell proliferation by upregulating STMN1. Further ChIP assay showed that FoxM1 upregulates STMN1 in a transcriptional level. Prognostic analysis showed that a high level of FoxM1 and STMN1 is related to poor prognosis in solid tumors. Moreover, a high co-expression of FoxM1 and STMN1 has a more significant correlation with poor prognosis. Our findings suggest that a general FoxM1-STMN1 axis contributes to cell proliferation and tumorigenesis in hepatocellular carcinoma, gastric cancer and colorectal cancer. The combination of FoxM1 and STMN1 can be a more precise biomarker for prognostic prediction.

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