A 39-kD DNA-binding protein from mouse brain stimulates transcription of myelin basic protein gene in oligodendrocytic cells.

Abstract

Abstract. The MB1 regulatory sequence of the myelin basic protein (MBP) gene spanning between nucleotides -14 to -50 with respect to the transcription start site is critical for cell type-specific transcription of the MBP gene, which encodes the major protein component of myelin sheath in cells derived from the central nervous system (CNS). This regulatory sequence has the ability to interact with a developmentally controlled DNA-binding protein from mouse brain that stimulates transcription of MBP promoter in an in vitro system (Haas, S., J. Gordon, and K. Khalili. 1993. Mol. Cell. Biol. 13:3103-3112). Here, we report the purification of a 39-kD protein from mouse brain tissue at the peak of myelination and MBP production that binds to the MB1 regulatory motif. Following partial amino acid sequence analysis, we have identified a complementary DNA encoding a 39-kD DNA-binding protein called pur a. Expression ofpur a cDNA in the prokaryotic and eukaryotic cells resulted in the synthesis of a protein with characteristics similar to the purified brainderived 39-kD protein in band shift competition assays. Cotransfection of the recombinant pur ~ expressor plasmid with MBP promoter construct indicated that Pur t~ stimulates transcription of the MBP promoter in oligodendrocytic cells, and that the nucleotide sequence required for binding of the 39-kD Pur c~ to DNA within the MB1 region is crucial for this activity. Moreover, transient expression of Pur a caused elevation in the level of endogenous MBP RNA in oligodendrocytic cells. Thus, Pur or, a sequence-specific DNAbinding protein upon binding to MB 1 regulatory region may play a significant role in determining the cell typespecific expression of MBP in brain.M YELIN basic protein (MBP) 1 is a major component of the myelin sheath composing greater than 30% of the total myelin protein in the central nervous system (CNS) (6, for review see 5). This protein has several isoforms, all of which are encoded by alternative splicing of a single major transcript from a single gene on mouse chromosome 18 (7,23,33,35,36,43). MBP is expressed in a cell type-specific manner. In the CNS, myelin formation and MBP gene expression occur in oligodendrocytes, whereas in the peripheral nervous system This work represents equal contributions of the first two authors.

Deletions of PURA, at 5q31, and PURB, at 7p13, in myelodysplastic syndrome and progression to acute myelogenous leukemia

“…21 Expression of the PURA gene has been observed in all tissues analyzed, and the protein is highly conserved across several species. [22][23][24] Pur␣ has been implicated in control of DNA replication, 22,25,26 and it has been reported to be a transcriptional activator of both viral 27 and mammalian 23,28,29 promoters.…”

Cell cycle arrest and morphological alterations following microinjection of NIH3T3 cells with Puraα

“…In human cells both p107 (Devoto et al, 1992) and p130 (Hannon et al, 1993) may be found in complexes with Cyclin A and CDK2, proteins now believed to associated with Pura (Itoh et al, 1998). In addition to its e ects on DNA replication, several recent reports have now established Pura as a transcription factor (Chepenik et al, 1998;Du et al, 1997;Haas et al, 1995;Herault et al, 1992Herault et al, , 1993Kelm et al, 1997;Krachmarov et al, 1996;Zambrano et al, 1997). It is quite conceivable that changes in gene expression could result from changes in Pura levels during the cell cycle.…”

Association of Purα and E2F-1 suppresses transcriptional activity of E2F-1

“…Pura is a 322 amino acid sequence-speci®c singlestranded DNA-binding protein implicated in the control of both DNA replication and gene transcription Du et al, 1997;Haas et al, 1995;Kelm et al, 1997;Zambrano et al, 1997). Structurally, the central region of Pura is composed of three 23 amino acid class I repeats interspersed with two 26 amino acid class II repeats .…”