Wyniki wyszukiwania - Biblioteka Nauki

1

Effect of nuclear matrix attachment regions on transgene expression in tobacco plants.

100%

Nowak W. , Magdalena Gawłowska0 , Jarmołowski A. , Augustyniak J.

Acta Biochimica Polonica

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2001

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tom 48

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nr 3

637-646

EN

Matrix attachment regions (MARs) are thought to participate in the organization and segregation of independent chromosomal loop domains. Although there are several reports on the action of natural MARs in the context of heterologous genes in transgenic plants, in our study we tested a synthetic MAR (sMAR) with the special property of unpairing when under superhelical strain, for its effect on reporter gene expression in tobacco plants. The synthetic MAR was a multimer of a short sequence from the MAR 3' end of the immunoglobulin heavy chain (IgH) enhancer. This sMAR sequence was used to flank the β-glucuronidase (GUS) reporter gene within the T-DNA of the binary vector pBI121. Vectors with or without the sMARs were then used to transform tobacco plants by Agrobacterium tumefaciens. Transgenic plants containing the sMAR sequences flanking the GUS gene exhibited higher levels of transgene expression compared with transgenic plants which lacked the sMARs. This effect was observed independently of the position of the sMAR at the 5' side of the reporter gene. However, variation of the detected transgene expression was significant in all transformed plant populations, irrespective of the construct used. Most genes whose expression has been studied in transgenic plants are generally expressed in appropriate patterns. However, transgene expression can vary within an extremely wide range, often showing only a very low level [1, 2]. Variation in transgene expression is frequently attributed to corresponding variation in the transcription potential of different chromosomal insertion sites. DNA sequences called scaffold/matrix attachment regions (S/MARs) are involved in the structural and functional organization of all eukaryotic genomes. Evolutionarily, the structures of these sequences seem to be conserved. Typically, S/MARs are located every 5 to 200 kb of sequence and are known to bind specifically to components of the nuclear scaffold, therefore suggesting that they are responsible for loop domain base formation [3, 4].Of the MAR elements reported, many do not display extensive sequence homology. It is therefore reasonable to assume that the scaffold probably recognizes some structural features of the MAR DNA rather than a specific sequence [5].MARs appear to be functionally conserved, since animal MARs can bind to plant nuclear scaffolds and vice versa [6, 7].Most MARs have been generally characterized as AT-rich sequences. However, AT-richness per se is not a sufficient criterion for specific sequence recognition of MARs by specific binding proteins [7]. Their capacity to bind to the nuclear matrix is determined by the specific structure of DNA. A prominent structural characteristic of different MARs is their strong potential for extensive unpairing when subjected to superhelical strain [8, 9]. The ability to assume a stably unpaired conformation has been described for several MARs. For example, within the MAR 3' end of immunoglobulin heavy chain (IgH) enhancer there is an AATATATTT motif that is a nucleation site for DNA unwinding [10]. Concatamerized oligonucleotides containing seven repeats of this sequence exhibited a strong affinity for the nuclear scaffold and increased SV40 promoter activity in stably transformed mouse cells [11].In this paper we present results of our studies that concern the effect of a synthetic MAR on transgene expression in tobacco plants. The synthetic MAR sequences were used to flank the β-glucuronidase (GUS) gene whose transcription was under control of the 35S CaMV promoter in the binary vector pBI121. This construct was introduced into tobacco plants and the GUS reporter gene expression was monitored in stably transformed plants.

2

In-silico prediction and observations of nuclear matrix attachment

100%

Platts A. E. , Quayle A. K. , Krawetz S. A.

Cellular and Molecular Biology Letters

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2006

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tom 11

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nr 2

EN

The nuclear matrix is a functionally adaptive structural framework interior to the nuclear envelope. The nature and function of this nuclear organizer remains the subject of widespread discussion in the epigenetic literature. To draw this discussion together with a view to suggest a way forward we summarize the biochemical evidence for the modalities of DNA-matrix binding alongside the in-silico predictions. Concordance is exhibited at various, but not all levels. On the one hand, both the reiteration and sequence similarity of some elements of Matrix Attachment Regions suggest conservation. On the other hand, in-silico predictions suggest additional unique components. In bringing together biological and sequence evidence we conclude that binding may be hierarchical in nature, reflective of a biological role in replicating, transcribing and potentiating chromatin. Nuclear matrix binding may well be more complex than the widely accepted simple loop model.

3

Functions of the chicken lysosyme 5' MAR and MAR binding proteins

75%

Stratling W. H. , Weitzel J. M. , Buhrmester H. , Phi-Van L.

Cellular and Molecular Biology Letters

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1997

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tom 02

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nr 2

4

Sequences flanking rat hsp70.1 gene contain motifs specific for matrix attached regions and form complexes with nuclear matrix proteins in vitro

75%

Widlak P. , Rogolinski J. , Rzeszowska-Wolny J.

Cellular and Molecular Biology Letters

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1997

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tom 02

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nr 2

5

Interactions of matrix attachment region of DNA with the matrix proteins from the copper preincubated liver nuclei

63%

Widlak P. , Rogolinski J. , Rzeszowska-Wolny J.

Acta Biochimica Polonica

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1995

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tom 42

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nr 2

EN

Preincubation of rat liver nuclei with copper ions influenced the stability and protein composition of the nuclear matrices isolated by a "high salt" method. Also the specific interaction between matrix proteins and the kappa Ig matrix attachment region of DNA was affected.

6

Effect of nuclear matrix attachment regions on transgene expression in tobacco plants

63%

Nowak W. , Gawlowska M. , Jarmolowski A. , Augustyniak J.

Acta Biochimica Polonica

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2001

|

tom 48

|

nr 3

EN

Matrix attachment regions (MARs) are thought to participate in the organization and segregation of independent chromosomal loop domains. Although there are several reports on the action of natural MARs in the context of heterologous genes in transgenic plants, in our study we tested a synthetic MAR (sMAR) with the special property of unpairing when under superhelical strain, for its effect on reporter gene expression in tobacco plants. The synthetic MAR was a multimer of a short sequence from the MAR 3 end of the immunoglobulin heavy chain (IgH) enhancer. This sMAR sequence was used to flank the β-glucuronidase (GUS) reporter gene within the T-DNA of the binary vector pBI121. Vectors with or without the sMARs were then used to transform tobacco plants by Agrobacterium tumefaciens. Transgenic plants containing the sMAR sequences flanking the GUS gene exhibited higher levels of transgene expression compared with transgenic plants which lacked the sMARs. This effect was observed independently of the position of the sMAR at the 5 side of the reporter gene. However, variation of the detected transgene expression was significant in all transformed plant populations, irrespective of the construct used.