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

Autocrine motility factor (AMF)/phosphoglucose isomerase (PGI) is a ubiquitous cytosolic enzyme and is produced as a leaderless secretory protein, released from cells via a nonclassical pathway. AMF/PGI acts extracellularly as a potent mitogen/cytokine (CXXC, chemokine). Increased expression of AMF/PGI and its receptor/CXXC-R has been found in a wide spectrum of malignancies, and is associated with cancer progression and metastasis. To directly elucidate the functional role of AMF/PGI on cell motility and neoplastic transformation, we stably transfected AMF/PGI cDNA into NIH-3T3 cells. Ectopic overexpression of AMF/PGI results in its secretion and activation via a constitutive autocrine activation loop that renders the cells highly motile, acquiring a transformed phenotype in vitro and tumorigenicity in vivo. The transformed phenotype of AMF/PGI-transfected cells leads in part resistance to induction of apoptosis induced by serum starvation, through the activation of phosphatidylinositol 3'-kinase/Akt signaling pathway and down-regulation of caveolin-1 expression. Overexpression of this housekeeping gene induces resistance to apoptosis and neoplastic transformation, and, thus, AMF/PGI represents a novel class of oncogenic protein.
 ...
PMID:Overexpression of the autocrine motility factor/phosphoglucose isomerase induces transformation and survival of NIH-3T3 fibroblasts. 1251 4

We investigated the physiological role of Lactococcus lactis housekeeping surface protease HtrA. It is involved in surface properties under regular growth conditions, as the htrA mutant strain forms longer chains in liquid medium. It participates in cellular defence against environmental stress conditions: compared to the wild-type strain, the htrA mutant strain exhibited increased sensitivity to heat, ethanol, puromycin, and NaCl, but not to pH, H2O2, bile salts or to carbon or nitrogen starvation. htrA transcription in the wild-type strain showed a transient increase under stress conditions determined as requiring htrA, but not under overexpression of a secreted heterologous protein. Our results demonstrate that in L. lactis, htrA is a key factor in the response to specific stress conditions.
 ...
PMID:HtrA is a key factor in the response to specific stress conditions in Lactococcus lactis. 1285 67

The suf and isc operons of Escherichia coli have been implicated in Fe-S cluster assembly. However, it has been unclear why E. coli has two systems for Fe-S cluster biosynthesis. We have examined the regulatory characteristics and mutant phenotypes of both operons to discern if the two operons have redundant functions or if their cellular roles are divergent. Both operons are similarly induced by hydrogen peroxide and the iron chelator 2,2'-dipyridyl, although by different mechanisms. Regulation of the isc operon is mediated by IscR, whereas the suf operon requires OxyR and IHF for the response to oxidative stress and Fur for induction by iron starvation. Simultaneous deletion of iscS and most suf genes is synthetically lethal. However, although the suf and isc operons have overlapping functions, they act as distinct complexes because the SufS desulphurase alone cannot substitute for the IscS enzyme. In addition, suf deletion mutants are more sensitive to iron starvation than isc mutants, and the activity of the Fe-S enzyme gluconate dehydratase is diminished in the suf mutant during iron starvation. These findings are consistent with the model that the isc operon encodes the housekeeping Fe-S cluster assembly system in E. coli, whereas the suf operon is specifically adapted to synthesize Fe-S clusters when iron or sulphur metabolism is disrupted by iron starvation or oxidative stress.
 ...
PMID:A suf operon requirement for Fe-S cluster assembly during iron starvation in Escherichia coli. 1510 90

As an actively dividing organism, the intracellular parasite Toxoplasma gondii must adjust the size and composition of its membranes in order to accommodate changes due to housekeeping activities, to commit division and in fine to produce new viable progenies. Lipid inventory of T. gondii reveals that the biological membranes of this parasite are composed of a complex mixture of neutral and polar lipids. After examination of the origin of T. gondii membrane lipids, three categories of lipids can be described: (i) lipids scavenged by T. gondii from the host cell; (ii) lipids synthesized in large amounts by the parasite, independently from its host cell; and (iii) lipids produced de novo by the parasite, but whose synthesis does not come close to satisfying the entire parasite's needs. These latter must be adeptly acquired from the host environment. To this end, T. gondii diverts a large variety of lipid precursors from host cytoplasm and efficiently manufacture them into complex lipids. This rather remarkable reliance on host lipid resources for parasite survival opens new avenues to restrict parasite growth. Indeed, parasite starvation can be induced upon deprivation from essential host lipids. Lipid analogues with anti-proliferative properties are voraciously taken up by the parasites, which results in parasite membrane defects, and ultimately death.
 ...
PMID:Contribution of host lipids to Toxoplasma pathogenesis. 1636 61

Although Campylobacter jejuni is the leading cause of bacterial diarrhoeal disease in humans worldwide, its potential to adapt to the stressful conditions and survive in extra-intestinal environment is still poorly understood. We tested the effect of heat shock (55 degrees C, 3 min) and oxidative stress (3 mM H2O2 for 10 min or prolonged incubation at atmosphere oxygen concentration) on non-starved and starved cells of Campylobacter jejuni from different growth phases. Viability as assessed with the Bacterial Viability Kit LIVE/DEAD BacLighttrade mark dying before fluorescent microscopy and culturability of the cells (CFU ml(-1)) from both growth phases showed that starvation increased heat but not oxidative resistance. High temperature and oxidative stress invoked quick transformation from culturable spiral shaped to nonculturable spiral and coccoid cells. Despite physiological changes of the cells we were not able to document clear differences in the expression of heat shock and starvation genes (dnaK, htpG, groEL), oxidative (ahpC, sodB), virulence (flaA) and housekeeping genes (16S rRNA, rpoD) after heat treatment (55 degrees C, 3 min) or oxidative stresses applied. When starving, no induction of expression of any of these genes was noticed, chloramphenicol had no influence on their gene expression. Quantitative real-time PCR analyses showed that at least 10-20 min of heat shock was necessary to evidently increase the amount of groEL and rpoD transcripts.
 ...
PMID:Survival and stress induced expression of groEL and rpoD of Campylobacter jejuni from different growth phases. 1678 21

The yeast orthologue of mammalian TCTP is here proposed to be named Mmi1p (microtubule and mitochondria interacting protein). This protein displays about 50% amino acid sequence identity with its most distantly related orthologs in higher organisms and therefore probably belongs to a small class of yeast proteins which have housekeeping but so far incompletely known functions needed for every eukaryotic cell. Previous investigations of the protein in both higher cells and yeast revealed that it is highly expressed during active growth, but transcriptionally down-regulated in several kinds of stress situations including starvation stress. In human cells, TCTP presumably has anti-apoptotic functions as it binds to Bcl-XL in vivo. TCTP of higher cells was also shown to interact with the translational machinery. It has acquired an additional function in the mammalian immune system, as it is identical with the histamine releasing factor. Here, we show that in S. cerevisiae induction of apoptosis by mild oxidative stress, replicative ageing or mutation of cdc48 leads to translocation of Mmi1p from the cytoplasm to the mitochondria. Mmi1p is stably but reversibly attached to the outer surface of the mitochondria and can be removed by digestion with proteinase K. Glutathionylation of Mmi1p, which is also induced by oxidants, is not a prerequisite or signal for translocation as shown by replacing the only cysteine of Mmi1p by serine. Mmi1p probably interacts with yeast microtubules as deletion of the gene confers sensitivity to benomyl. Conversely, the deletion mutant displays resistance to hydrogen peroxide stress and shows a small but significant elongation of the mother cell-specific lifespan. Our results so far indicate that Mmi1p is one of the few proteins establishing a functional link between microtubules and mitochondria which may be needed for correct localization of mitochondria during cell division.
 ...
PMID:MMI1 (YKL056c, TMA19), the yeast orthologue of the translationally controlled tumor protein (TCTP) has apoptotic functions and interacts with both microtubules and mitochondria. 1680 52

The Lon ATP-dependent protease plays a major role in protein quality control. An increasing number of regulatory proteins, however, are being identified as Lon substrates, thus indicating that in addition to its housekeeping function, Lon plays an important role in regulating many biological processes in bacteria. This review presents and discusses the involvement of Lon in different aspects of bacterial physiology, including cell differentiation, sporulation, pathogenicity and survival under starvation conditions.
 ...
PMID:Biological roles of the Lon ATP-dependent protease. 1685 68

The chemolithotrophic ammonia-oxidizing bacterium Nitrosomonas europaea is known to be highly resistant to starvation conditions. The transcriptional response of N. europaea to ammonia addition following short- and long-term starvation was examined by primer extension and S1 nuclease protection analyses of genes encoding enzymes for ammonia oxidation (amoCAB operons) and CO(2) fixation (cbbLS), a third, lone copy of amoC (amoC(3)), and two representative housekeeping genes (glyA and rpsJ). Primer extension analysis of RNA isolated from growing, starved, and recovering cells revealed two differentially regulated promoters upstream of the two amoCAB operons. The distal sigma(70) type amoCAB promoter was constitutively active in the presence of ammonia, but the proximal promoter was only active when cells were recovering from ammonia starvation. The lone, divergent copy of amoC (amoC(3)) was expressed only during recovery. Both the proximal amoC(1,2) promoter and the amoC(3) promoter are similar to gram-negative sigma(E) promoters, thus implicating sigma(E) in the regulation of the recovery response. Although modeling of subunit interactions suggested that a nonconservative proline substitution in AmoC(3) may modify the activity of the holoenzyme, characterization of a DeltaamoC(3) strain showed no significant difference in starvation recovery under conditions evaluated. In contrast to the amo transcripts, a delayed appearance of transcripts for a gene required for CO(2) fixation (cbbL) suggested that its transcription is retarded until sufficient energy is available. Overall, these data revealed a programmed exit from starvation likely involving regulation by sigma(E) and the coordinated regulation of catabolic and anabolic genes.
 ...
PMID:Transcription of all amoC copies is associated with recovery of Nitrosomonas europaea from ammonia starvation. 1738 96

Akt activation assists tumor cell survival and promotes resistance to chemotherapy. Here we show that constitutively active Akt (CA-Akt) cells are highly sensitized to cell death induced by nutrient and growth factor deprivation, whereas dominant-negative Akt (DN-Akt) cells have a high rate of survival. The content of autophagosomes in starved CA-Akt cells was high, while DN-Akt cells expressed autophagic vacuoles constitutively, independently of nutrition conditions. Thus Akt down-regulation and downstream events can induce autophagosomes which were not directly determinants of cell death. Biochemical analysis in Akt-mutated cells show that (i) Akt and mTOR proteins were degraded more rapidly than the housekeeping proteins, (ii) mTOR phosphorylation at position Thr(2446) was relatively high in DN-Akt and low in CA-Akt cells, induced by starvation in mock cells only, which suggests reduced autoregulation of these pathways in Akt-mutated cells, (iii) both protein synthesis and protein degradation were significantly higher in starved CA-Akt cells than in starved DN-Akt cells or mock cells. In conclusion, constitutively active Akt, unable to control synthesis and wasting of proteins, accelerates the death of starved cells.
 ...
PMID:Cell survival under nutrient stress is dependent on metabolic conditions regulated by Akt and not by autophagic vacuoles. 1764 59

Autophagy is a conserved mechanism for the degradation of cellular contents in order to recycle nutrients or break down damaged or toxic material. This occurs by the uptake of cytoplasmic constituents into the vacuole, where they are degraded by vacuolar hydrolases. In plants, autophagy has been known for some time to be important for nutrient remobilization during sugar and nitrogen starvation and leaf senescence, but recent research has uncovered additional crucial roles for plant autophagy. These roles include the degradation of oxidized proteins during oxidative stress, disposal of protein aggregates, and possibly even removal of damaged proteins and organelles during normal growth conditions as a housekeeping function. A surprising regulatory function for autophagy in programmed cell death during the hypersensitive response to pathogen infection has also been identified.
 ...
PMID:Plant autophagy--more than a starvation response. 1770 43


<< Previous 1 2 3 4 5 6 Next >>