Limited action of micrococcal nuclease on trout testis nuclei generates two mononucleosome subsets enriched in transcribed DNA sequences.

Levy-Wilson, Beatriz; Dixon, Gordon H.

doi:10.1073/pnas.76.4.1682

Cited by 70 publications

(8 citation statements)

References 13 publications

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“…Our findings have important implications relating to the function of the HMG proteins. These proteins are associated preferentially with transcriptionally competent chromatin (2)(3)(4)(5) and are thought to modify the basic structure of chromatin in such a way as to allow transcription to occur (9). Earlier estimates, however, suggested that the quantities of HMG proteins in the cell were not sufficient to saturate the highaffinity binding sites on each transcriptionally competent nucleosome (9) .…”

Section: Discussionmentioning

confidence: 99%

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Concentrations of high-mobility-group proteins in the nucleus and cytoplasm of several rat tissues.

Kuehl¹,

Salmond²,

Tran³

1984

The Journal of Cell Biology

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Nuclear and cytoplasmic fractions were isolated from various tissues of the rat by a nonaqueous technique . The high-mobility-group (HMG) proteins were extracted from these fractions with acid and separated by one-and two-dimensional PAGE . The concentrations of high-mobility-group proteins HMG1, HMG2, and HMG17 in the nucleus and cytoplasm were then estimated from the staining intensities of the electrophoretic bands . The cytoplasmic concentrations of these proteins were very low-usually less than '/3o of those present in the corresponding nuclear fractions . For the tissues studied (liver, kidney, heart, and lung), the concentrations of HMG proteins in the nucleus did not differ significantly from one tissue to another. Averaged over the four tissues investigated, there were 0.28 molecule of HMG1, 0 .18 molecule of HMG2, and 0.46 molecule of HMG17 per nucleosome . These values are considerably higher than those that have been reported previously .The high-mobility-group (HMG)' proteins are a family of well-characterized proteins which are present in relatively large amounts in the chromatin of all higher organisms (reviewed in reference 1) . The cells of higher eucaryotes contain four major HMG proteins : HMG1, HMG2, HMG14, and HMG17. These four proteins constitute two groups : one containing HMG1 and HMG2, and the other, HMG 14 and HMG17. The two proteins belonging to each group are of similar size, show considerable sequence homology, and may bind to similar or identical sites on the chromatin. Two major HMG proteins in trout testis, HMG-T and H6, have been extensively investigated. HMG-T is homologous to HMG 1 and HMG2, and H6, to HMG14 and HMG17.Considerable interest in the HMG proteins has been generated by reports that they are preferentially associated with transcriptionally competent portions of the genome (2-5), and a great deal of effort is currently being expended to define the role which these proteins play in transcription. Not all investigators have found such a relationship . Recently, Seale et al . (6) reported that there is little correlation between HMG protein content and transcriptional activity in HeLa cell chromatin, and Gabrielli et al . (7) have reported that, in mouse P815 cell chromatin, transcriptional activity is correlated with the presence of HMG 14, but not of HMG1 and HMG2 or of HMG 17 .' Ahbreviation used in this paper: HMG, high-mobility-group (protein) . 648Hypotheses concerning the function and metabolism of the HMG proteins frequently involve assumptions concerning their intracellular concentrations and subcellular distributions. Definitive information on these points, however, is unavailable. It has been suggested that there are -10' molecules of each of the major HMG proteins in a typical mammalian cell (8, 9), corresponding to about one molecule each of HMG1, HMG2, and HMG17 for every 30 nucleosomes. This value is apparently based on the yields of the HMG proteins which have been obtained from calf thymus using standard isolation techniques . Because yields were...

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Section: Discussionmentioning

confidence: 99%

“…Considerable interest in the HMG proteins has been generated by reports that they are preferentially associated with transcriptionally competent portions of the genome (2)(3)(4)(5), and a great deal of effort is currently being expended to define the role which these proteins play in transcription. Not all investigators have found such a relationship .…”

mentioning

confidence: 99%

Concentrations of high-mobility-group proteins in the nucleus and cytoplasm of several rat tissues.

Kuehl¹,

Salmond²,

Tran³

1984

The Journal of Cell Biology

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“…In addition to the histones, considerable attention has been focused on another group of chromosomal proteins, the high mobility group (HMG) proteins originally isolated from calf thymus nuclei . Although some of the HMG proteins appear clustered in the transcriptionally active regions of chromatin (Levy-Wilson et al, 1979;Weisbord et al, 1979), the precise function of these non-histone chromo-0006-2960/85/0424-1806S01.50/0 © 1985 American Chemical Society somal proteins still remains to be determined. Nevertheless, since the early studies on calf, proteins resembling HMGs have been isolated and characterized from a wide variety of eucaryotic cell types [for a review, see Mayes (1982)], including two lower eucaryotes: Tetrahymena (Hamana et al, 1979) and yeast (Petersen & Sheridan, 1978;Spiker et al, 1978;Weber & Isenberg, 1980).…”

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confidence: 99%

High mobility group like chromosomal proteins from amebas of the acellular slime mold Physarum polycephalum

Côté¹,

Neelin²,

Pallotta³

1985

Biochemistry

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“…The elucidation of the structure of the chro-has been discovered that transcription of a spematin and the specific interactions between cific chromatin region is accompanied by a dis-DNA and chromatin proteins is a prerequisite ruption of some of the organizational features of for understanding the control ofgene expression. the chromatin, resulting in an increased DNase The concept that structural changes occurring sensitivity of actively transcribed genes (6, 16-within the chromatin complex are responsible 19,27,28,34,35).…”

mentioning

confidence: 99%

Chromatin Conformation of Integrated Moloney Leukemia Virus DNA Sequences in Tissues of BALB/Mo Mice and in Virus-Infected Cell Lines

Breindl

Bacheler

Fan

et al. 1980

J Virol

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The technique of preferential DNase I digestion of transcriptionally active chromatin regions was used to study the structural organization of integrated Moloney murine leukemia virus (M-MuLV) proviral sequences in various cells carrying integrated viral genomes. BALB/Mo mice, which carry M-MuLV as an endogenous virus at a single Mendelian locus, were used to examine the genetically transmitted viral genome copy and additional M-MuLV sequences acquired somatically during leukemogenesis. It has been shown previously that M-MuLV genome expression in these mice is restricted to lymphatic target tissues. In young homozygous BALB/Mo mice carrying one M-MuLV genome copy per haploid mouse genome in all cells we found that the genetically transmitted viral genome copy was in a preferentially DNase I-sensitive conformation in lymphatic target tissues, whereas in nontarget tissues the same sequence was not preferentially DNase I sensitive. This suggests that the chromatin conformation and the transcriptional activity of the integrated proviral genome are related to and probably determined by the state of cellular differentiation. In target tissues from BALB/Mo mice examined at different ages and in different stages of leukemogenesis the majority of the new somatically acquired M-MuLV sequences were preferentially DNase I digestible. A very similar pattern of DNase I digestibility was observed in target tissues from BALB/c mice exogenously infected with M-MuLV. This shows that in these tissues somatically acquired proviral sequences integrate preferentially or exclusively at sites of the host genome in which they are in a transcriptionally active chromatin conformation. Alternatively, the chromatin structure of the respective host genome region may be changed after the integration of viral DNA. In nontarget tissues from BALB/Mo mice the M-MuLV-specific sequences remained DNase I resistant throughout the lives of the animals. A different pattern of DNase I digestibility was observed in virus-infected cell lines which had been produced by low-multiplicity infection, cloned, and selected for virus production. When cell lines harboring different numbers of M-MuLV proviral copies were examined, it was found that a minority of the proviral sequences (on the average only one M-MuLV genome copy per haploid mouse genome) were preferentially digestible by DNase I, independent of the total number of proviral genome copies present. This suggests that the chromatin conformation of newly acquired proviral sequences is influenced by the state of differentiation of the infected cell or the way infected cells are selected or both.

show abstract

Limited action of micrococcal nuclease on trout testis nuclei generates two mononucleosome subsets enriched in transcribed DNA sequences.

Cited by 70 publications

References 13 publications

Concentrations of high-mobility-group proteins in the nucleus and cytoplasm of several rat tissues.

Concentrations of high-mobility-group proteins in the nucleus and cytoplasm of several rat tissues.

High mobility group like chromosomal proteins from amebas of the acellular slime mold Physarum polycephalum

Chromatin Conformation of Integrated Moloney Leukemia Virus DNA Sequences in Tissues of BALB/Mo Mice and in Virus-Infected Cell Lines

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