Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0038187 (starvation)
 24,951 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Using a stable cell line 25-RA derived from wild-type Chinese hamster ovary (CHO) cells as the parental cell, this laboratory previously reported the isolation and characterization of CHO cell mutants (cholesterol-trafficking or CT) defective in transporting LDL-derived cholesterol out of the acidic compartment(s) (lysosomes/endosomes) to the endoplasmic reticulum (ER) for esterification. In this report, we show that the CT mutation can be complemented by fusion with human cells; however, attempts to complement the CT defect through DNA transfection have resulted in a collection of stable cell lines designated as ST cells. Under cholesterol starvation condition, the ST cells exhibit an elevated rate of cholesterol ester biosynthesis (by 3- to 5-fold) compared to both the parental CHO cells and the CT cells. The phenotypes of the ST cells are stable. ST cells are thus new cell lines arisen from the CT cells. When the plasma membranes of the parental, CT, and ST cells are labelled with [3H]cholesterol, ST cells show rates of [3H]cholesterol esterification much higher than that observed in CT cells but lower than that observed in the parental CHO cells. This result shows that translocation of plasma membrane cholesterol to the ER for esterification is defective in the CT cells. This result also suggests that ST cells acquire increased cholesterol trafficking activity between the lysosome and the ER without mixing the plasma membrane cholesterol pool. The characteristics of CT cells and ST cells reported here suggest that translocation of both lysosomal LDL-derived cholesterol and plasma membrane cholesterol to the ER for esterification may require common cellular factors involved in cholesterol egress from the acidic compartment(s) (lysosomes/endosomes).
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PMID:Translocation of both lysosomal LDL-derived cholesterol and plasma membrane cholesterol to the endoplasmic reticulum for esterification may require common cellular factors involved in cholesterol egress from the acidic compartments (lysosomes/endosomes). 785 68

Starvation of mouse hepatoma cells for essential amino acids or glucose results in the ADP-ribosylation of the molecular chaperone BiP/GRP78. Addition of the missing nutrient to the medium reverses the reaction. The signal mediating the response to environmental nutrients involves the translational efficiency. An inhibitor of proteins synthesis, cycloheximide, or reduced temperature, both of which reduce translational efficiency, stimulate the ADP-ribosylation of BiP/GRP78. Inhibition of N-linked glycosylation of proteins results in the overproduction of BiP/GRP78. The over produced protein is not ADP-ribosylated suggesting that this is the functional form of BiP/GRP78. The over produced BiP/GRP78 can, however, be ADP-ribosylated if the cells are starved for an essential amino acid. BiP/GRP78 resides in the lumen of the endoplasmic reticulum where it participates in the assembly of secretory and integral membrane proteins. ADP-ribosylation of BiP/GRP78 during starvation is probably part of a nutritional stress response which conserves limited nutrients by slowing flow through the secretory pathway.
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PMID:ADP-ribosylation of the molecular chaperone GRP78/BiP. 789 57

The ultrastructure of rat's pterygopalatine ganglionic neurocytes after starvation was investigated. The following changes of cell organelles were observed. The mitochondria display altered internal structures--lack of matrix, swellings, and myelin structures. Rough endoplasmic reticulum and free ribosomes were reduced. Strong plication of nuclear membrane, diminution of nucleoli, increased number of lysosomes and lipofuscin granules were also noticed. The extent of these changes is variable and depends on the time period of starvation. The smallest changes were observed in the groups starved for 24-48 hrs, the largest--in the groups starved 120-144 hrs.
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PMID:Electron microscopy of pterygopalatine ganglion in starved rats. 805 47

Anoxia, glucose starvation, calcium ionophore A23187, EDTA, glucosamine, and several other conditions that adversely affect the function of the endoplasmic reticulum (ER) induce the synthesis of the glucose-regulated class of stress proteins (GRPs). The primary GRPs induced by these stresses migrate at 78 and 94 kDa (GRP78 and GRP94). In addition, another protein of approximately 150-170 kDa (GRP170) has been previously observed and is coordinately induced with GRP78 and GRP94. To characterize this novel stress protein, we have prepared an antisera against purified GRP170. Immunofluorescence, Endoglycosidase H sensitivity, and protease resistance of this protein in microsomes indicates that GRP170 is an ER lumenal glycoprotein retained in a pre-Golgi compartment. Immunoprecipitation of GRP170 with our antibody coprecipitates the GRP78 (also referred to as the B cell immunoglobulin-binding protein) and GRP94 members of this stress protein family in Chinese hamster ovary cells under stress conditions. ATP depletion, by immunoprecipitation in the presence of apyrase, does not affect the interaction between GRP78 and GRP170 but results in the coprecipitation of an unidentified 60-kDa protein. In addition, GRP170 is found to be coprecipitated with immunoglobulin (Ig) in four different B cell hybridomas expressing surface IgM, cytoplasmic Ig light chain only, cytoplasmic Ig heavy chain only, or an antigen specific secreted IgG. In addition, in IgM surface expressing WEHI-231 B cells, anti-IgM coprecipitates GRP78, GRP94, as well as GRP170; antibodies against GRP170 and GRP94 reciprocally coprecipitate GRP94/GRP170 as well as GRP78. Results suggest that this 170-kDa GRP is a retained ER lumenal glycoprotein that is constitutively present and that may play a role in immunoglobulin folding and assembly in conjunction or consecutively with GRP78 and GRP94.
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PMID:The 170-kDa glucose-regulated stress protein is an endoplasmic reticulum protein that binds immunoglobulin. 830 33

Assembly of histocompatibility class I antigens (MHC) with beta 2-microglobulin (beta 2m) and peptide takes place in the rough endoplasmic reticulum (ER). At present, it is unclear why peptides generated in the cytosol or ER by proteolysis are not further degraded. Also, it is an open question whether assembly and/or peptide binding is self-instructive or is promoted by additional molecules, for example, chaperones. We previously demonstrated that the adenovirus glycoprotein E3/19K binds to human and some mouse MHC molecules in the ER, interfering with their transport to the cell surface. Here we show that immunoprecipitates from human cells that express transfected E3/19K and murine MHC Kd molecules not only contain MHC heavy chain, beta 2m and E3/19K but also two additional proteins with apparent molecular weights of 100 kDa and 110 kDa. Biochemical characterization of these proteins, designated p100 and p110, demonstrates that they are transmembrane glycoproteins with a similar if not identical protein backbone. Consistent with a role as chaperones, we find that glucose starvation induces complex formation between p100/110 and MHC-E3/19K. Most interestingly, p100 and p110 are displaced from the complex by addition of Kd-specific peptides. Therefore, p100 and p110 might be chaperones that promote correct folding of MHC antigens and/or peptide binding to MHC.
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PMID:Novel proteins associated with MHC class I antigens in cells expressing the adenovirus protein E3/19K. 834 54

In this study the ultrastructure of rat jejunal epithelial cells was examined, following a starvation period of 72 hours and an enteral refeeding period of 12 days, with either Nutrison, Pepti 2000, or Nutri 2000. Most changes occurred in the animals examined immediately after the 72-hour starvation period; these mainly included a significant decrease in microvilli population, occasional cell membrane disintegration, and a usual microvesicular appearance and degranulation of the rough endoplasmic reticulum. No alterations were found in the normally-fed animals (control group). This was also practically the same for the Pepti 2000 group. In the Nutrison group, a small amount of changes were found, while in the Nutri 2000 group many alterations were detected, which nevertheless were fewer than in the starved animals. The results demonstrate that the micromorphological alterations of the intestinal epithelium caused by starvation improve faster when an oligopeptidic formula is provided, which consequently results in faster and better absorption of the nutrients.
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PMID:Ultrastructural alterations of the rat intestinal epithelium fed with polymeric, oligopeptidic or elementary full diet, following starvation. 835 63

The phorbol ester TPA (phorbol 12-myristate 13-acetate) substitutes for CO2 as an agonist for transforming Trypanosoma cruzi epimastigotes to the metacyclic trypomastigote stage in a starvation medium consisting of phosphate buffered saline + 10 mM proline, 10 mM sodium acetate and 0.035% NaHCO3. Since TPA is thought to stimulate protein kinase C by mimicking the activity of the secondary messenger diacylglycerol, the above result suggested that T. cruzi metacyclogenesis could be activated by a Ca(2+)-dependent protein kinase C signal induction pathway. Accordingly, cytosolic calcium flux ([Ca2+]i) in epimastigotes, activated with 5% CO2 or TPA (10(-7) M), was measured with the Ca2+ molecular probe, fluo-3AM. In addition, [Ca2+]i was measured in cells incubated with putative metacyclogenic agonists (e.g. proline, glutamate, bioamines, ionophores and catecholamines). None of the compounds studies, except for EGTA, affected cytosolic Ca2+ levels. Control assays with 11 microM thapsigargin, which mobilizes noncytoplasmic Ca2+ stores by inhibiting endoplasmic reticulum Ca(2+)-ATPase, validated our fluorometric assay procedure. Although thapsigargin significantly increases cytoplasmic Ca2+ fluorescence, it has no effect on transformation. The protein kinase C inhibitors staurosporine, H-7 and HA 1004 were tested for their effect on T. cruzi metacyclogenesis. Low concentrations of staurosporine and HA 1004 significantly elevated Peru strain transformation while H-7 had no effect on Peru strain metacyclogenesis. Inhibitor H-7 did significantly depress CL transformation. The results indicate that induction of T. cruzi metacyclic trypomastigote formation by CO2 and TPA is not accompanied by changes in cytosolic Ca2+ and do not provide supporting evidence for participation of a protein kinase C-mediated phosphoinositide cascade in metacyclogenesis.
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PMID:Absence of transitory [Ca2+]i flux during early in vitro metacyclogenesis of Trypanosoma cruzi. 846 96

Inositol starvation of auxotrophic yeast interrupts glycolipid biosynthesis and prevents lipid modification of a normally glycosyl phosphatidylinositol (GPI)-linked protein, Gas1p. The unanchored Gas1p precursor undergoes progressive modification in the endoplasmic reticulum (ER), but is not modified by Golgi-specific glycosylation. Starvation-induced defects in anchor assembly and protein processing are rapid, and occur without altered maturation of other proteins. Cells remain competent to manufacture anchor components and to process Gas1p efficiently once inositol is restored. Newly synthesized Gas1p is packaged into vesicles formed in vitro from perforated yeast spheroplasts incubated with either yeast cytosol or the purified Sec proteins (COP II) required for vesicle budding from the ER. In vitro synthesized vesicles produced by inositol-starved membranes do not contain detectable Gas1p. These studies demonstrate that COP II components fulfill the soluble protein requirements for packaging a GPI-anchored protein into ER-derived transport vesicles. However, GPI anchor attachment is required for this packaging to occur.
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PMID:GPI anchor attachment is required for Gas1p transport from the endoplasmic reticulum in COP II vesicles. 859 1

Upon fractionation of a post mitochondrial supernatant from rat liver, phosphorylase kinase activity was largely recovered in the cytosol and the smooth endoplasmic reticulum (SER) fraction. The presence of phosphorylase kinase in SER vesicles was not due to an interaction of the enzyme with glycogen particles, since previous elimination of SER glycogen either by 48 h animal starvation or by treatment of the membrane fraction with alpha-amylase did not significantly alter phosphorylase kinase activity content. Washing of the initial pellet of SER fraction (crude SER) by dilution and recentrifugation, released in the supernatant an amount of phosphorylase kinase activity, which is dependent on: i) the degree of dilution, ii) the number of washes, iii) the ionic strength of the washing solution and iii) the presence or absence of Ca2+. Crude SER-associated phosphorylase kinase was marginally affected by increased concentrations of antibody against rabbit skeletal muscle holoenzyme which nevertheless drastically inhibited cytosolic enzyme activity, while it showed a higher resistance to partial proteolysis and a different Western blotting profile with anti-phosphorylase kinase when compared with the soluble kinase. A small but significant fraction of SER phosphorylase kinase was strongly associated with the microsomal fraction being partly extractable only in presence of detergents. This membrane-bound enzyme form exhibited an alkaline pH optimum, in contrast to the neutral pH optima of both soluble and weakly associated phosphorylase kinase.
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PMID:The association of phosphorylase kinase with membranes of rat liver smooth endoplasmic reticulum. 871 29

The Pseudomonas syringae cyclic lipodepsipeptide syringomycin inhibits the growth of Saccharomyces cerevisiae. A novel yeast gene, SYR2, was found to complement two syringomycin-resistant S. cerevisiae mutants. SYR2 was cloned, sequenced, and shown to encode a 349 amino acid protein located in the endoplasmic reticulum. SYR2 was identical to SUR2, which is involved in survival during nutritional starvation. Gene disruption or overexpression of SYR2 did not affect cell viability or ergosterol levels, but did influence cellular phospholipid levels. The findings suggest that phospholipids are important for the growth inhibitory action of syringomycin.
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PMID:SYR2, a gene necessary for syringomycin growth inhibition of Saccharomyces cerevisiae. 886 22


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