Beatriz Levy-Wilson
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Mice Expressing the Human CYP7A1 Gene in the Mouse CYP7A1 Knock-out Background Lack Induction of CYP7A1 Expression by Cholesterol Feeding and Have Increased Hypercholesterolemia When Fed a High Fat Diet Open
Cholesterol 7alpha-hydroxylase (CYP7A1) catalyzes the rate-limiting step in the pathway responsible for the formation of the majority of bile acids. Transcription of the gene is regulated by the size of the bile acid pool and dietary and h…
Identification and Characterization of a 315-Base Pair Enhancer, Located More than 55 Kilobases 5′ of the Apolipoprotein B Gene, That Confers Expression in the Intestine Open
We recently reported that an 8-kilobase (kb) region, spanning from -54 to -62 kb 5' of the human apolipoprotein B (apoB) gene, contains intestine-specific regulatory elements that control apoB expression in the intestines of transgenic mic…
The Nuclear Matrix Protein CDP Represses Hepatic Transcription of the Human Cholesterol-7α Hydroxylase Gene Open
To date, the molecular mechanisms that govern hepatic-specific transcription of the human cholesterol 7alpha-hydroxylase (CYP7A1) gene are poorly understood. We recently reported that the region extending from -1888 to +46, which includes …
Characterization of Hepatic-specific Regulatory Elements in the Promoter Region of the Human Cholesterol 7α-Hydroxylase Gene Open
Cholesterol 7alpha-hydroxylase is the rate-limiting enzyme in the degradation of cholesterol to bile salts and plays a central role in regulating cholesterol homeostasis. The mechanisms involved in the transcriptional control of the human …
Evaluation of the function of the human apolipoprotein B gene nuclear matrix association regions in transgenic mice Open
The human apolipoprotein B (apoB) gene resides in a 47.5 kb DNasel-sensitive chromosomal domain in hepatic and intestinal cells, flanked by the 5' distal matrix association region (MAR) and the 3' proximal MAR. A third MAR, the 5' proximal…
Members of the Caudal Family of Homeodomain Proteins Repress Transcription from the Human Apolipoprotein B Promoter in Intestinal Cells Open
Apolipoprotein B (apoB) is the major protein component of low density lipoproteins, and plays a central role in cholesterol transport and metabolism. The apoB gene is transcribed in the liver and in the intestine in humans. Although much i…
Sequences Containing the Second-Intron Enhancer Are Essential for Transcription of the Human Apolipoprotein B Gene in the Livers of Transgenic Mice Open
To identify DNA sequence elements from the human apolipoprotein B (apoB) gene required for high-level, correct tissue-specific expression in transgenic mice, we made several constructs that included one or more of the key regulatory elemen…
The Mechanism by Which the Human Apolipoprotein B Gene Reducer Operates Involves Blocking of Transcriptional Activation by Hepatocyte Nuclear Factor 3 Open
Previously, we showed that when a DNA fragment extending from -3067 to -2734 of the human apolipoprotein B (apo-B) gene is inserted immediately upstream of an apo-B promoter segment (-139 to +121), transcription from this promoter is reduc…
Nuclease-hypersensitive sites define a region with enhancer activity in the third intron of the human apolipoprotein B gene. Open
The positions of several DNase I-hypersensitive (DH) sites have been mapped in the second and third introns of the human apolipoprotein B gene. Two such DH sites, I and V, are present both in human hepatoma (HepG2) and colon carcinoma (CaC…
Similarities and differences in the function of regulatory elements at the 5' end of the human apolipoprotein B gene in cultured hepatoma (HepG2) and colon carcinoma (CaCo-2) cells. Open
The arrangement of regulatory elements along the apolipoprotein B promoter region (positions -898 to +1) has been examined in transient transfection experiments performed in HepG2 and Hep3B (hepatic) and CaCo-2 (intestinal) cell lines, all…
The mechanisms by which a human apolipoprotein B gene enhancer and reducer interact with the promoter are different in cultured cells of hepatic and intestinal origin. Open
In the preceding paper (Paulweber, B., Onasch, M. A., Nagy, B. P., and Levy-Wilson, B. (1991) J. Biol. Chem. 266, 24149-24160) we demonstrated that the segment of the apolipoprotein B promoter extending from -260 to -85 is functionally dif…
Identification of a negative regulatory region 5' of the human apolipoprotein B promoter. Open
We have identified a negative regulatory region between positions -1802 and -3211 of the human apolipoprotein B gene that reduces expression of the gene. This "reducer" effect was detected in transient transfection experiments performed wi…
Characterization of tissue-specific enhancer elements in the second intron of the human apolipoprotein B gene. Open
We report the identification and characterization of tissue-specific transcriptional enhancer elements that influence the expression of the human apolipoprotein B gene. A 704-base pair PstI fragment comprising sequences from the first and …
The limits of the DNase I-sensitive domain of the human apolipoprotein B gene coincide with the locations of chromosomal anchorage loops and define the 5′ and 3′ boundaries of the gene Open
In eukaryotic cells, chromatin is organized as domains or loops that are generated by periodic attachment of the chromatin fiber to protein components of a nuclear matrix, or scaffold. These chromosomal loops may have a function in gene re…
Tissue-specific undermethylation of DNA sequences at the 5′ end of the human apolipoprotein B gene Open
The methylation-sensitive restriction endonucleases HpaII and HhaI and the methylation-insensitive enzyme MspI were used to examine the methylation status of the 5' end of the human apolipoprotein B gene in cells in which the gene is trans…
Two copies of the human apolipoprotein C-I gene are linked closely to the apolipoprotein E gene. Open
The gene for human apolipoprotein (apo) C-I was selected from human genomic cosmid and lambda libraries. Restriction endonuclease analysis showed that the gene for apoC-I is located 5.5 kilobases downstream of the gene for apoE. A copy of …
DNase I- and micrococcal nuclease-hypersensitive sites in the human apolipoprotein B gene are tissue specific. Open
We have mapped the DNase I- and micrococcal nuclease-hypersensitive sites present in the 5' end of the human apolipoprotein B (apo-B) gene in nuclei from cells expressing or not expressing the gene. Four DNase I-hypersensitive sites were f…
Human apolipoprotein CI (apoC1) gene locus: DraI dimorphic site Open
DESCRIPTION 0.3kb human apolipoprotein CI cDNA fragment isolated from a human liver cDNA library and subcloned into the EcoRI site of pBR329 (1).POLYMORPHISM DraI (TTTAAA) (International Biotechnologies Inc.) detects two invariant bands at…
Kinetic changes in protein synthesis in response to a sublethal heat shock in starved Tetrahymena thermophila. Open
We have analyzed the alterations that occur in the patterns of protein synthesis of Tetrahymena thermophila cells when these cells are exposed to a sublethal heat treatment. At least 11 major polypeptides, ranging in size from 97,000 to 27…
Enhanced phosphorylation of high-mobility-group proteins in nuclease-sensitive mononucleosomes from butyrate-treated HeLa cells. Open
The protein composition of nucleosome fractions differing in their sensitivity to micrococcal nuclease and derived from butyrate-treated or untreated HeLa cells has been compared. Most of the high-mobility-group-14 (HMG-14) and HMG-17 cont…
Distribution of high mobility group proteins among domains of trout testis chromatin differing in their susceptibility to micrococcal nuclease. Open
Trout testis nuclei were treated with micrococcal nuclease, an enzyme which is known to digest preferentially the linker regions in transcriptionally competent portions of the chromatin. The digested nuclei were fractionated by two differe…
The release of high mobility group protein H6 and protamine gene sequences upon selective DNase I degradation of trout testis chromatin Open
Limited digestion of trout testis nuclei with DNase I selectively degrades the protamine genes. Concomitant with the degradation of transcribed DNA sequences a series of chromosomal proteins are released; among these, the major species cor…
Transcriptionally active mononucleosomes from trout testis are heterogeneous in composition. Open
Limited micrococcal nuclease action on trout testis nuclei yields two mononucleosome subsets, MN1 and MN2, enriched in transcribed DNA sequences. MN1 is soluble and MN2 insoluble in 0.1 M NaCl. Electrophoresis of intact MN1 and MN2 mononuc…
Evidence for the location of high mobility group protein T in the internucleosomal linker regions of trout testis chromatin. Open
Antibodies against the trout testis non"histone chromosomal protein, high mobility group protein T (HMG-T), have been elicited in goats. The antiserum was shown to be specific for HMG-T and did not cross-react with histone 1 or with the ot…
Limited action of micrococcal nuclease on trout testis nuclei generates two mononucleosome subsets enriched in transcribed DNA sequences. Open
Hybridization experiments show that DNA extracted from two distinct subsets of mononucleosomes (MNI and MN2) generated by a limited action of micrococcal nuclease on trout testis nuclei is enriched approximately 7-fold in sequences that ar…
Effects of nuclear disruption on the macromolecular composition of nucleosome subfractions Open
The macromolecular composition of nucleosomal subfractions obtained by limited action of micrococcal nuclease upon trout testis chromatin has been analyzed with the purpose of comparison with the properties of transcriptionally active nucl…
Multiacetylated forms of H4 are found in a putative transcriptionally competent chromatin fraction from trout testis Open
We have examined the distribution of acetylated histones derived from various trout testis chromatin fractions of different composition. Our results indicate that a chromatin fraction, preferentially solubilized by micrococcal nuclease, co…