Globin gene regulation and switching: circa 1990. 1990

S H Orkin
Department of Pediatrics, Howard Hughes Medical Institute, Harvard Medical School, Boston, Massachusetts 02115.

Suggestions that the field of hemoglobin regulation and erythroid cell molecular biology was undergoing a tortuous and slow death, awash in the scientific community several years ago, were dispelled by the findings presented at the Seventh Conference on Hemoglobin Switching. After a phase in which neither the cis-elements nor trans-factors important for globin and erythroid gene expression were evident, recent progress has been rapid. Once again, studies in this area are providing fundamental insights into eukaryotic biology. The long-distance influence of LCR elements on chromatin structure and gene expression is remarkable and likely to be encountered in the analysis of other developmentally regulated, multigene loci. How LCR elements influence chromatin structure and maintain an open configuration is a problem at the core of gene regulation. We can be optimistic that further dissection of LCRs will delineate DNA sequences critical for these effects and associated proteins. The interaction of LCRs with individual genes must depend on specific protein-protein interactions, most likely involving a small, but elite, group of regulators. At least one critical transcriptional regulator of erythroid-expressed genes, GATA-1, is firmly established. Others are being pursued. The mechanisms by which they collaborate with each other should provide the missing pieces to the puzzle of cell-specific gene expression in the erythroid lineage. As the phenomenology of Hb switching is mimicked in transgenic mice, the elements mediating competitive and non-competitive (or autonomous) modes of regulation will be systematically delineated. Whether knowledge of the cis- and trans- components involved in switching will lead to the development of therapeutic approaches aimed at altering their complex interactions is uncertain. Fortunately, recent progress in hematopoietic stem cell biology once again raises hopes that gene transfer strategies for management of hemoglobin disorders may be more than a distant, impractical goal.

UI MeSH Term Description Entries
D005786 Gene Expression Regulation Any of the processes by which nuclear, cytoplasmic, or intercellular factors influence the differential control (induction or repression) of gene action at the level of transcription or translation. Gene Action Regulation,Regulation of Gene Expression,Expression Regulation, Gene,Regulation, Gene Action,Regulation, Gene Expression
D005810 Multigene Family A set of genes descended by duplication and variation from some ancestral gene. Such genes may be clustered together on the same chromosome or dispersed on different chromosomes. Examples of multigene families include those that encode the hemoglobins, immunoglobulins, histocompatibility antigens, actins, tubulins, keratins, collagens, heat shock proteins, salivary glue proteins, chorion proteins, cuticle proteins, yolk proteins, and phaseolins, as well as histones, ribosomal RNA, and transfer RNA genes. The latter three are examples of reiterated genes, where hundreds of identical genes are present in a tandem array. (King & Stanfield, A Dictionary of Genetics, 4th ed) Gene Clusters,Genes, Reiterated,Cluster, Gene,Clusters, Gene,Families, Multigene,Family, Multigene,Gene Cluster,Gene, Reiterated,Multigene Families,Reiterated Gene,Reiterated Genes
D005914 Globins A superfamily of proteins containing the globin fold which is composed of 6-8 alpha helices arranged in a characterstic HEME enclosing structure. Globin
D006801 Humans Members of the species Homo sapiens. Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia
D014158 Transcription, Genetic The biosynthesis of RNA carried out on a template of DNA. The biosynthesis of DNA from an RNA template is called REVERSE TRANSCRIPTION. Genetic Transcription
D014162 Transfection The uptake of naked or purified DNA by CELLS, usually meaning the process as it occurs in eukaryotic cells. It is analogous to bacterial transformation (TRANSFORMATION, BACTERIAL) and both are routinely employed in GENE TRANSFER TECHNIQUES. Transfections
D014714 Vertebrates Animals having a vertebral column, members of the phylum Chordata, subphylum Craniata comprising mammals, birds, reptiles, amphibians, and fishes. Vertebrate

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