SAF-B protein couples transcription and pre-mRNA splicing to SAR/MAR elements.
Interphase chromatin is arranged into topologically separated domains comprising gene expression and replication units through genomic sequence elements, so-called MAR or SAR regions (for matrix- or scaffold-associating regions). S/MAR regions are located near the boundaries of actively transcribed genes and were shown to influence their activity. We show that scaffold attachment factor B (SAF-B), which specifically binds to S/MAR regions, interacts with RNA polymerase II (RNA pol II) and a subset of serine-/arginine-rich RNA processing factors (SR proteins). SAF-B localized to the nucleus in a speckled pattern that coincided with the distribution of the SR protein SC35. Furthermore, we show that overexpressed SAF-B induced an increase of the 10S splice product using an E1A reporter gene and repressed the activity of an S/MAR flanked CAT reporter gene construct in vivo . This indicates an association of SAF-B with SR proteins and components of the transcription machinery. Our results describe the coupling of a chromatin organizing S/MAR element with transcription and pre-mRNA processing components and we propose that SAF-B serves as a molecular base to assemble a 'transcriptosome complex' in the vicinity of actively transcribed genes.
Nayler
O
O
Max-Planck Institute of Neurobiology and Max-Planck Institute of Biochemistry, Am Klopferspitz 18a,D-82152 Martinsried, Germany.
Strätling
W
W
Bourquin
J P
JP
Stagljar
I
I
Lindemann
L
L
Jasper
H
H
Hartmann
A M
AM
Fackelmayer
F O
FO
Ullrich
A
A
Stamm
S
S
D016475:3T3 Cells; D000818:Animals; D001665:Binding Sites; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D015500:Chloramphenicol O-Acetyltransferase / Q000235:genetics; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D017930:Genes, Reporter; D006801:Humans; D036961:Matrix Attachment Region Binding Proteins; D051379:Mice; D034521:Nuclear Matrix-Associated Proteins; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D009693:Nucleic Acid Hybridization; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D012319:RNA Polymerase II / Q000378:metabolism; D012322:RNA Precursors; D012326:RNA Splicing; D016601:RNA-Binding Proteins; D051381:Rats; D011960:Receptors, Estrogen; D012441:Saccharomyces cerevisiae; D000068103:Serine-Arginine Splicing Factors; D014158:Transcription, Genetic
D004268:DNA-Binding Proteins; D036961:Matrix Attachment Region Binding Proteins; D034521:Nuclear Matrix-Associated Proteins; D009687:Nuclear Proteins; D010750:Phosphoproteins; D012322:RNA Precursors; D016601:RNA-Binding Proteins; D011960:Receptors, Estrogen; C109132:SAFB protein, human; C486371:Safb protein, rat; D000068103:Serine-Arginine Splicing Factors; D015500:Chloramphenicol O-Acetyltransferase; D012319:RNA Polymerase II