Biomedical subjects

E C Strauss

Publications and source records attributed to E C Strauss.

5 recordsLinked to original sources

PubMed1992

In vivo protein-DNA interactions at hypersensitive site 3 of the human beta-globin locus control region.

The expression of beta-globin genes in developing erythroid cells is dependent on distant, upstream regulatory sequences, known as the locus control region (LCR), which are marked in chromatin by DNase I hypersensitive sites (HS-1 to HS-4). Linkage of the beta-globin gene complex LCR or fragments surrounding core regions of 200-300 base pairs to the human beta-globin gene permits consistent, high-level expression of the transgene in mice. To define the array of nuclear factors interacting with beta-LCR HS-3, we have performed in vivo dimethyl sulfate footprinting of the active HS-3 core in erythroid cells by a modified procedure that permits assessment of protein-DNA contacts at adenine, as well as guanine, residues. In vivo protein occupancy differs considerably from that predicted from previous in vitro binding analyses. In vivo footprinting detects protein binding at four sites recognized by the erythroid transcription factor GATA-1, at two CACC/GT motifs, and at a single AP-1/NF-E2 site. The regulatory elements occupied in vivo in HS-3 appear similar to those described previously in globin gene promoters and 3' enhancers. These findings suggest that the distinctive properties of the HS-3 region may be attributable to the organization of these occupied motifs and the consequent protein interactions, rather than to the binding of unique LCR regulatory factors.

Animals↗

PubMed1992

In vivo footprinting of the human alpha-globin locus upstream regulatory element by guanine and adenine ligation-mediated polymerase chain reaction.

A major regulatory element required for expression of the human alpha-globin genes is located 40 kb upstream of the embryonic zeta-globin gene. To understand how this and other locus control region (LCR) elements contribute to high-level expression in erythroid cells, we have performed high-resolution, in vivo dimethyl sulfate footprinting. In addition, we have modified the dimethyl sulfate-based ligation-mediated polymerase chain reaction in vivo footprinting procedure to permit the assessment of interactions at guanine and adenine residues, rather than guanines alone. In vivo footprinting of the human alpha-LCR element carried on chromosome 16 in a mouse erythroleukemia cell environment revealed protein occupancy at GATA-1, AP-1/NF-E2, and CACC/GGTGG motifs, specific differences compared with in vitro protein binding, and distinct changes in one region upon dimethyl sulfoxide-induced cellular maturation. No protein contacts were detected in nonexpressing hepatoma cells. In addition, we have demonstrated that two AP-1 motifs in the alpha-LCR element which are occupied in vivo bind purified mouse NF-E2 protein in vitro. Our data suggest that three proteins, GATA-1, NF-E2, and unknown CACC/GGTGG factors, are minimally required as DNA-binding proteins for the function of LCR-like elements. The juxtaposition and interaction of these factors with each other, and with accessory proteins not directly in contact with DNA, are likely to account for the relative position independence of the upstream globin regulatory elements.

Adenine↗

PubMed1991

CCAAT displacement protein as a repressor of the myelomonocytic-specific gp91-phox gene promoter.

The cytochrome b heavy chain (gp91-phox) is expressed exclusively in terminally differentiating myelomonocytic cells. The human gp91-phox gene spans approximately 30 kilobases, and is divided into 13 exons. A ubiquitous factor that is indistinguishable from the CCAAT-binding factor CP1 interacts in vitro with the distal gp91-phox promoter CCAAT box motif. CP1 binding is prevented, however, by a CCAAT displacement protein (CDP) that binds to the region surrounding the CCAAT box. CDP DNA-binding activity is found in nuclear extracts prepared from cells in which the endogenous gp91-phox gene is transcriptionally inactive, but is absent or reduced in expressing cells, consistent with CDP functioning as a repressor of gp91-phox transcription. Introduction of gp91-phox promoter/reporter constructs into nonexpressing cells yields significantly less expression than that produced by the parental reporter vector alone. The reduction in expression is relieved when the CDP/CP1-binding site is removed from the gp91-phox promoter, confirming that it is a target for repression. No derepression is observed if the CP1-binding site is selectively mutated. Derepression of expression exhibited upon deletion of the CDP/CP1-binding site suggests that, in addition to blocking the interaction of the CCAAT-binding factor with the gp91-phox promoter, CDP may also repress transcription mediated through a distinct cis-element(s). We propose that down-regulation of CDP DNA-binding activity is a necessary step in the induction of myelomonocytic-specific expression of the gp91-phox gene.

Amino Acid Sequence↗

PubMed1986

Analysis of a human V beta gene subfamily.

We have isolated and sequenced five germline V beta gene segments that are homologous to the V region of the YT35 cDNA encoding the beta chain of the T cell antigen receptor from the tumor MOLT-3. One of these gene segments is identical to the YT35 V segment, and therefore is the corresponding germline V beta gene segment encoding the YT35 cDNA. The other four V beta members exhibit 77-98% homology to the YT35 V gene segment. Two of these V beta gene segments are pseudogenes. Analyses of the coding region sequences reveal that, although the V beta segments are very diverse, they are mutating at a rate comparable to that observed in most eukaryotic genes. Analyses of the genomic clones show that the spacing distance between germline V beta gene segments ranges from 3 kb to greater than 30 kb, and the entire V beta 8 subfamily appears to be linked by a total of no more than 110 kb of DNA.

Base Sequence↗

PubMed1986

Specific-primer-directed DNA sequencing.

A simple and rapid strategy for DNA sequence analysis based on the Sanger chain-termination method is described. This procedure utilizes full-sized inserts of 1 to 4 kb of DNA cloned into M13 bacteriophage vectors. After the sequence of the first 600-650 bp of the insert DNA has been determined with the commercially available universal vector primer, a specific oligonucleotide is synthesized utilizing the sequence data obtained from the 3' end of the sequence and used as a primer to extend the sequence analysis for another 600-650 nucleotides. Additional primers are synthesized in a similar manner until the nucleotide sequence of the entire insert DNA has been determined. General guidelines for the selection of oligonucleotide length and composition and the use of unpurified primers are discussed. The use of the specific-primer-directed approach to dideoxynucleotide sequence analysis, in association with highly purified single-stranded template DNA, reduces considerably the time required for the analysis of large segments of DNA.

Bacteriophages↗