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Query: UMLS:C0038187 (starvation)
 24,951 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effect of 72 h fasting, nutritional therapy of fasted rats, and acute and chronic glucocorticoid treatment on the yield of histone H1 from rat hind limb muscles was determined. Fasting significantly enhanced the extractability of muscle H1. The effect of treating starved rats with glucose alone, or with glucose supplemented with branched-chain amino acids (BCAA), or with two commercial preparations of mixtures of essential and non-essential amino acids was evaluated. Treatment of starved rats with glucose alone significantly decreased H1 extractability from muscles, but isocaloric treatment with glucose supplemented with BCAA or two commercial preparations of amino acid mixtures was more effective. Glucocorticoid treatment for 5 days enhanced the yield of H1 from muscles less than starvation. The enhanced H1 extractability from muscles noted in starved rats is similar to that reported in rats with insulinopenic diabetes and may reflect changes in nuclear fragility.
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PMID:Effect of fasting, branched-chain amino acids, and glucocorticoids on histone H1 extractability from rat skeletal muscle. 129 63

The in vivo association of histone H1 with specific genes in Tetrahymena thermophila was studied by using a simplified cross-linking and immunoprecipitation technique. Four genes were analyzed whose activities vary in three different developmental states (logarithmic growth, starvation, and conjugation). Hybridization of the immunoprecipitated DNA to cloned probes showed an inverse correlation between the level of immunoprecipitation with H1 antiserum and transcriptional activity. This represents the first demonstration of an alteration in histone H1-DNA interaction associated with developmental changes in transcriptional activity.
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PMID:Formaldehyde cross-linking and immunoprecipitation demonstrate developmental changes in H1 association with transcriptionally active genes. 199 18

It has been known for several years that DNA replication and histone synthesis occur concomitantly in cultured mammalian cells. Normally all five classes of histones are synthesized coordinately. However, mouse myeloma cells, synchronized by starvation for isoleucine, synthesize increased amounts of histone H1 relative to the four nucleosomal core histones. This unscheduled synthesis of histone H1 is reduced within 1 h after refeeding isoleucine, and is not a normal component of G1. The synthesis of H1 increases coordinately again with other histones during the S phase. The DNA synthesis inhibitors, cytosine arabinoside and hydroxyurea, block all histone synthesis in S-phase cells. The levels of histone H1 mRNA, relative to the other histone mRNAs, is increased in isoleucine-starved cells and decreases rapidly after refeeding isoleucine. The increased incorporation of histone H1 is at least partially due to the low isoleucine content of histone H1. Starvation of cells for lysine resulted in a decrease in H1 synthesis relative to core histones. Again the ratio was altered on refeeding the amino acid. 3T3 cells starved for serum also incorporated only H1 histones into chromatin. The ratio of different H1 proteins also changed. The synthesis of the H1(0) protein was predominant in G0 cells, and reduced in S-phase cells. These data indicate the metabolism of H1 is independent of the other histones when cell growth is arrested.
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PMID:Uncoordinate synthesis of histone H1 in cells arrested in the G1 phase. 715 89

Although Dictyostelium differentiation occurs in the absence of external nutrients, two periods of mitosis occur, one during early development and one during the formation of the migrating pseudoplasmodium. We showed previously that cyclin B mRNA levels vary in a cell cycle dependent manner during vegetative cell growth. In the present study, we report that cyclin B mRNA levels change dramatically during development, reaching a maximum at the tipped aggregate stage. However, amounts of cyclin B protein vary only slightly, peaking during early development and decreasing during late aggregation and pseudoplasmodial formation. Cdc2 protein levels also remain relatively constant during development. Cdc2-histone H1 kinase activity was considerably higher in vegetative cell extracts of transformants that expressed large amounts of truncated cyclin B protein in comparison to extracts of the parental Ax-2 cells. These results suggest that Cdc2 kinase activity is dependent upon the level of cyclin B in vegetative cells. This result is consistent with the idea that variations in the level of cyclin B during growth regulate the cell cycle. When Cdc2 histone H1 kinase activity was determined during development, it was also found that activity correlated reasonably well with the amount of cyclin B protein. Thus, there was an increase in Cdc2 histone H1 kinase activity early in development, and then levels decreased as development progressed. The increase in Cdc2 histone H1 kinase activity that occurs early in development following starvation may be important in accelerating G2-phase cells through into mitosis. There was no increase in Cdc2 histone H1 kinase that accompanied the previously reported late developmental mitosis.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Cyclin B and Cdc2 expression and Cd2 kinase activity during Dictyostelium differentiation. 757 76

The activated c-Ha-rasVal12 oncogene is often involved in the genesis of human malignancies. We show here that in c-Ha-rasVal12 oncogene-transformed mouse NIH 3T3 fibroblasts the copy number and expression level of the mutant ras oncogene correlates with the degree of chromatin decondensation, as assessed by micrococcal nuclease (MNase) and DNase I digestion. MNase and DNase I analyses further revealed that the nucleosomal repeat lengths were different in the normal and ras oncogene-transformed cells, 162.3 bp and 178.1 bp, respectively. These chromatin changes were accompanied by alterations in the content of histone H1 zero. Furthermore, using DNase I as a probe, we discovered that serum stimulation of normal and transformed cells, synchronized by serum starvation, induces rapid reversible changes in the structure of bulk chromatin that may be linked to transcriptional activation. Our data thus indicate that cell transformation by ras is associated with specific changes in chromatin structure that make it more vulnerable, and prone to additional mutations characteristic of cancer development in vivo.
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PMID:Cell transformation by c-Ha-rasVal12 oncogene is accompanied by a decrease in histone H1 zero and an increase in nucleosomal repeat length. 772 50

Conditional overexpression of human cyclins B1, D1, and E was accomplished by using a synthetic cDNA expression system based on the Escherichia coli tetracycline repressor. After induction of these cyclins in asynchronous Rat-1 fibroblasts, a decrease in the length of the G1 interval was observed for cyclins D1 and E, consistent with an acceleration of the G1/S phase transition. We observed, in addition, a compensatory lengthening of S phase and G2 so that the mean cell cycle length in populations constitutively expressing these cyclins was unchanged relative to those of their uninduced counterparts. We found that expression of cyclin B1 had no effect on cell cycle dynamics, despite elevated levels of cyclin B-associated histone H1 kinase activity. Induction of cyclins D1 and E also accelerated entry into S phase for synchronized cultures emerging from quiescence. However, whereas cyclin E exerted a greater effect than cyclin D1 in asynchronous cycling cells, cyclin D1 conferred a greater effect upon stimulation from quiescence, suggesting a specific role for cyclin D1 in the G0-to-G1 transition. Overexpression of cyclins did not prevent cells from entering into quiescence upon serum starvation, although a slight delay in attainment of quiescence was observed for cells expressing either cyclin D1 or cyclin E. These results suggest that cyclins D1 and E are rate-limiting activators of the G1-to-S phase transition and that cyclin D1 might play a specialized role in facilitating emergence from quiescence.
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PMID:Acceleration of the G1/S phase transition by expression of cyclins D1 and E with an inducible system. 811 3

Cyclin D2 is a member of the family of D-type cyclins that is implicated in cell cycle regulation, differentiation, and oncogenic transformation. To better understand the role of this cyclin in the control of cell proliferation, cyclin D2 expression was monitored under various growth conditions in primary human and established murine fibroblasts. In different states of cellular growth arrest initiated by contact inhibition, serum starvation, or cellular senescence, marked increases (5- to 20-fold) were seen in the expression levels of cyclin D2 mRNA and protein. Indirect immunofluorescence studies showed that cyclin D2 protein localized to the nucleus in G0, suggesting a nuclear function for cyclin D2 in quiescent cells. Cyclin D2 was also found to be associated with the cyclin-dependent kinases CDK2 and CDK4 but not CDK6 during growth arrest. Cyclin D2-CDK2 complexes increased in amounts but were inactive as histone H1 kinases in quiescent cells. Transient transfection and needle microinjection of cyclin D2 expression constructs demonstrated that overexpression of cyclin D2 protein efficiently inhibited cell cycle progression and DNA synthesis. These data suggest that in addition to a role in promoting cell cycle progression through phosphorylation of retinoblastoma family proteins in some cell systems, cyclin D2 may contribute to the induction and/or maintenance of a nonproliferative state, possibly through sequestration of the CDK2 catalytic subunit.
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PMID:Increased expression of cyclin D2 during multiple states of growth arrest in primary and established cells. 958 57

Three polymorphic subtypes of erythrocyte histone H1 (H1.a, H1.b, and H1.z) were analyzed using a sodium dodecyl sulfate polyacrylamide gel in quail populations divergently selected for a high (line 1) or low (line 2) reduction in body mass following temporary food withdrawal. Both H1.b and H1.z histone alleles were found to be differently distributed in these populations during the selection period. The frequency of b1 in line 2 was approximately 1.9-2.8 times lower than in line 1 and approached the values in line 1 when the selection was suspended. Similarly, the frequency of allele z2 at locus H1.z increased significantly (about 1.6-2.3 times) in line 2 during selection and returned to the initial values when selection was stopped. On the other hand, allele a0 at locus H1.a was kept at relatively low levels (usually below 0.05) in both lines during selection. At that time its level was approximately three to four times lower than in a random mating control population. When selection was suspended, the frequency of a0 in line 1 increased significantly, approaching the values in the control line, and remained essentially unchanged in line 2. Thus, all three polymorphic histone H1 loci in quail responded through changes in allele frequencies to the breeding selection, which was directed at the amount of body weight loss upon transient starvation. It seems that either H1 histone locus could be linked to loci controlling the rate of body weight reduction following starvation or weight loss during fasting might be influenced by a panel of H1 histone alleles that can contribute to functional differences in avian chromatin.
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PMID:Distribution of allelic forms of erythrocyte H1 histones in Japanese quail populations divergently selected for amount of weight loss after transient starvation. 967 72

In Tetrahymena thermophila, highly phosphorylated histone H1 of growing cells becomes partially dephosphorylated when cells are starved in preparation for conjugation. To determine the effects of H1 phosphorylation on gene expression, PCR-based subtractive hybridization was used to clone cDNAs that were differentially expressed during starvation in two otherwise-isogenic strains differing only in their H1s. H1 in A5 mutant cells lacked phosphorylation, and H1 in E5 cells mimicked constitutive H1 phosphorylation. Sequences enriched in A5 cells included genes encoding proteases. Sequences enriched in E5 cells included genes encoding cdc2 kinase and a Ser/Thr kinase. These results indicate that H1 phosphorylation plays an important role in regulating the pattern of gene expression during the starvation response and that its role in transcription regulation can be either positive or negative. Treatment of starved cells with a phosphatase inhibitor caused CDC2 gene overexpression. Expression of the E5 version of H1 in starved cells containing endogenous, wild-type H1 caused the wild-type H1 to remain highly phosphorylated. These results argue that Cdc2p is the kinase that phosphorylates Tetrahymena H1, establish a positive feedback mechanism between H1 phosphorylation and CDC2 expression, and indicate that CDC2 gene expression is regulated by an H1 phosphatase.
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PMID:The H1 phosphorylation state regulates expression of CDC2 and other genes in response to starvation in Tetrahymena thermophila. 1587 Feb 66

Linker histone H1 is highly phosphorylated in normal growing Tetrahymena thermophila but becomes noticeably dephosphorylated in response to certain conditions such as prolonged starvation. Because phosphorylation of H1 has been associated with the regulation of gene expression, DNA repair, and other critical processes, we sought to use mass spectrometry-based approaches to obtain an in depth phosphorylation "signature" for this linker histone. Histone H1 from both growing and starved Tetrahymena was analyzed by nanoflow reversed-phase HPLC MS/MS following enzymatic digestions, propionic anhydride derivatization, and phosphopeptide enrichment via IMAC. We confirmed five phosphorylation sites identified previously and detected two novel sites of phosphorylation and two novel minor sites of acetylation. The sequential order of phosphorylation on H1 was deduced by using mass spectrometry to define the modified sites on phosphorylated H1 isoforms separated by cation-exchange chromatography. Relative levels of site-specific phosphorylation on H1 isolated from growing and starved Tetrahymena were obtained using a combination of stable isotopic labeling, IMAC, and tandem mass spectrometry.
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PMID:Comprehensive phosphoprotein analysis of linker histone H1 from Tetrahymena thermophila. 1683 17


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