Biomedical subjects

D Patterton

Publications and source records attributed to D Patterton.

6 recordsLinked to original sources

PubMed1998

Distinct requirements for chromatin assembly in transcriptional repression by thyroid hormone receptor and histone deacetylase.

Histone deacetylase and chromatin assembly contribute to the control of transcription of the Xenopus TRbetaA gene promoter by the heterodimer of Xenopus thyroid hormone receptor and 9-cis retinoic acid receptor (TR-RXR). Addition of the histone deacetylase inhibitor Trichostatin A (TSA) relieves repression of transcription due to chromatin assembly following microinjection of templates into Xenopus oocyte nuclei, and eliminates regulation of transcription by TR-RXR. Expression of Xenopus RPD3p, the catalytic subunit of histone deacetylase, represses the TRbetaA promoter, but only after efficient assembly of the template into nucleosomes. In contrast, the unliganded TR-RXR represses templates only partially assembled into nucleosomes; addition of TSA also relieves this transcriptional repression. This result indicates the distinct requirements for chromatin assembly in mediating transcriptional repression by the deacetylase alone, compared with those needed in the presence of unliganded TR-RXR. In addition, whereas hormone-bound TR-RXR targets chromatin disruption as assayed through changes in minichromosome topology and loss of a regular nucleosomal ladder on micrococcal nuclease digestion, addition of TSA relieves transcriptional repression but does not disrupt chromatin. Thus, TR-RXR can facilitate transcriptional repression in the absence of hormone through mechanisms in addition to recruitment of deacetylase, and disrupts chromatin structure through mechanisms in addition to the inhibition or release of deacetylase.

Amino Acid Sequence↗

PubMed1996

Developmental roles for chromatin and chromosomal structure.

Chromosomal architecture is emerging as a key controlling influence in the developmental regulation of gene expression. Recent genetic experiments using Caenorhabditis elegans, Drosophila melanogaster, and the mouse have provided clear evidence for the functional differentiation of chromosomal structures during development. Chromosomes are visualized as highly specialized entities, within which the activity of particular domains is largely determined by defined structural proteins. At a more local level, the mechanisms regulating gene transcription during early embryogenesis in Xenopus and the mouse have been found to be dependent on the biochemical composition of individual nucleosomes. Thus, variation in the type and modification of chromosomal and chromatin structural proteins provides a dominant means of controlling the transcriptional activity of individual genes, individual chromosomal domains, and of entire chromosomes.

Animals↗

PubMed1995

Transcriptional activation of the matrix metalloproteinase gene stromelysin-3 coincides with thyroid hormone-induced cell death during frog metamorphosis.

A full-length cDNA was isolated for a thyroid hormone response gene in the metamorphosing frog intestine and shown by sequence analysis to be the frog homolog of the mammalian extracellular matrix metalloproteinase stromelysin-3 (ST3). Northern hybridization indicated that ST3 gene expression is differentially activated in tadpole tissues during metamorphosis. In the small intestine, in situ hybridization localized high levels of ST3 mRNA to fibroblast-like cells during thyroid hormone-induced metamorphosis. ST3mRNA was undetectable in the intestine prior to metamorphosis, while high levels were present at the metamorphic climax. At this time, primary intestinal epithelial cells are known to undergo cell death and replacement by secondary epithelial cells, arguing that ST3 is involved in the modification of the extracellular matrix during apoptosis. ST3mRNA was also expressed at high levels during tadpole tail resorption, but not in premetamorphic tail or developing hindlimb, further supporting a role for ST3 when tissue remodeling is accompanied by large-scale cell death. Premetamorphic tadpoles treated with thyroid hormone showed a similar but compressed time course of ST3 gene regulation, suggesting that thyroid hormone controls ST3 gene expression during metamorphosis. In contrast, during embryogenesis, ST3 was expressed before endogenous thyroid hormone is detectable, indicating that ST3 can also be regulated independently of thyroid hormone. These findings implicate that ST3 participates in the modification of the extracellular matrix during matamorphic apoptosis, but Northern analyses using heterologous probes raise the possibility that additional matrix metalloproteinases may also be involved.

Amino Acid Sequence↗

PubMed1994

Thyroid hormone-dependent differential regulation of multiple arginase genes during amphibian metamorphosis.

We have cloned three nonhepatic arginase genes in Xenopus laevis. The deduced amino acid sequences of the three arginases are almost identical and share about 60% identity with mammalian as well as Xenopus liver arginase. Both the liver and nonhepatic arginase genes are activated early during embryogenesis. The liver arginase gene is strongly expressed in tadpole liver, but weakly in other tissues. In contrast, the nonhepatic arginase genes have the strongest expression in the tadpole tail. During metamorphosis, the liver and nonhepatic arginase genes show distinct regulation patterns. In the intestine, both types of arginase genes are activated during the remodeling period. In the tail, the liver arginase gene is activated during tail resorption, whereas the nonhepatic ones are highly expressed throughout all stages examined. Finally, in the hindlimb, the liver arginase is up-regulated slightly during development, whereas the nonhepatic ones have low levels of expression until the end of metamorphosis. During 3,5,3'-L-triiodothyronine (T3)-induced metamorphosis, the nonhepatic arginase genes are activated very quickly, whereas the liver arginase gene is a late T3 response gene. These differential regulation patterns during normal and T3-induced metamorphosis suggest potential functions for the arginases during tissue remodeling.

Amino Acid Sequence↗

PubMed1994

Purification of an oligo(dG).oligo(dC)-binding sea urchin nuclear protein, suGF1: a family of G-string factors involved in gene regulation during development.

Contiguous deoxyguanosine residues (G strings) have been implicated in regulation of gene expression in several organisms via the binding of G-string factors. Regulation of expression of the chicken adult beta-globin gene may involve the interplay between binding of an erythrocyte-specific G-string factor, BGP1, and the stability of a positioned nucleosome (C. D. Lewis, S. P. Clark, G. Felsenfeld, and H. Gould, Genes Dev. 2:863-873, 1988). We have purified a 59.5-kDa nuclear protein (suGF1) from sea urchin embryos by DNA affinity chromatography. suGF1 has high binding affinity and specificity for oligo(dG).oligo(dC). The identity of the purified protein was confirmed by renaturation of sequence-specific DNA-binding activity from a sodium dodecyl sulfate-polyacrylamide gel slice and by Southwestern (DNA-protein) blotting. suGF1 binds in vitro to a G11 string present in the H1-H4 intergenic region of a sea urchin early histone gene battery. This suGF1 DNA recognition site occurs within a homopurine-homopyrimidine stretch previously shown to be incorporated into a positioned nucleosome core in vitro. DNase I footprinting shows that suGF1 protects the same base pairs on the promoter of the chicken beta A-globin gene as does BGP1. We show that a G-string cis-regulatory element of a sea urchin cell lineage-specific gene LpS1 (M. Xiang, S.-Y. Lu, M. Musso, G. Karsenty, and W. H. Klein, Development 113:1345-1355, 1991) also represents a high-affinity recognition site for suGF1. suGF1 may be a member of a family of G-string factors involved in the regulation of expression of unrelated genes during development of a number of different organisms.

Animals↗

PubMed1994

suGF1 binds in the major groove of its oligo(dG).oligo(dC) recognition sequence and is excluded by a positioned nucleosome core.

We have elsewhere reported the purification of a poly(dG).poly(dC)-binding nuclear protein (suGF1) from sea urchin embryos (J. Hapgood and D. Patterton, Mol. Cell. Biol. 14:this issue, 1994). We proposed that suGF1 may be a member of a family of G-string factors involved in developmental gene regulation, possibly via alterations in chromatin structure. In this article, we characterize the binding of purified suGF1 to 11 contiguous Gs in the H1-H4 intergenic region of a sea urchin early histone gene battery in vitro. It is shown that suGF1-DNA binding is dependent on ionic strength and requires divalent cations. Purified suGF1 forms discrete protein-DNA multimers, consistent with suGF1-suGF1 interactions. In a model for the suGF1-DNA complex derived from our footprinting and methylation interference data, suGF1 contacts the Gs in the major groove as well as one of the bordering phosphate backbones. The data are consistent with the direction of curvature of the DNA in the suGF1-DNA complex being the same as that preferred by the free DNA and exhibited by the DNA when bent around a positioned nucleosome core in vitro. However, on the basis of steric considerations, the binding of suGF1 and that of the histone octamer are predicted to be mutually exclusive. We show that suGF1 is indeed unable to bind to the G string when occupied by a histone octamer located in the major in vitro positioning frame in the H1-H4 intergenic region.

Animals↗