Genetic analysis of familial isolated growth hormone deficiency type I

Nuclear DNA from individuals belonging to nine different families in which two sibs were affected with isolated growth hormone deficiency type I were studied by restriction endonuclease analysis. By using 32P-labeled human growth hormone or the homologous human chorionic somatomammotropin complementary DNA (cDNA) sequences as a probe, the growth hormone genes of affected individuals from all families yielded normal restriction patterns. Polymorphic restriction endonuclease sites (HincII and MspI), which are closely linked to the structural gene for growth hormone on chromosome 17, were used as markers in linkage analysis of DNA of family members. Of the nine affected sib pairs two were concordant, three were possibly concordant, and four were discordant for both linked markers. Since only concordant sib pairs would have inherited the same growth hormone alleles, further studies to identify mutations of the growth hormone genes should be limited to this subgroup. It is unlikely that the discordance observed in four of the sib pairs is due to recombination, because the polymorphic HincII site is only 116 base-pairs from the -26 codon of the growth hormone gene. Thus, in at least four of the nine families, the mutation responsible for isolated growth hormone deficiency is not within or near the structural gene for growth hormone on chromosome 17.

Relative levels of methylation in human growth hormone and chorionic somatomammotropin genes in expressing and non-expressing tissues

It has been shown that the extent of methylation of cytosine in vertebrate DNA is inversely correlated with gene expression. We studied cytosine methylation in and around the homologous human growth hormone (GH) and chorionic somatomammotropin (CS) genes to determine if these genes are undermethylated in DNA from tissues in which they are expressed (pituitary and placenta, respectively) compared to other tissues. Hpa II and Hha I (which cleave only unmethylated 5' CCGG 3' and 5' GCGC 3' respectively) and Msp I (which cleaves CCGG and CmeCGG) were used to digest DNA samples followed by gel electrophoresis, Southern transfer and hybridization with a GH cDNA probe. The extent of methylation of Hpa II and Hha I sites in the GH and CS genes was leukocyte much greater than pituitary greater than placenta = hydatidiform mole. Taken as a whole, our data support the hypothesis that undermethylation is a necessary but not sufficient condition for gene expression since placental and pituitary DNAs are less methylated than leukocyte DNA in this region. However, the correlation between gene expression and undermethylation is imperfect since (1) hydatiform mole DNA has a very similar methylation pattern compared to placental DNA even though moles make little or no CS and (2) the level of methylation of the GH gene compared to the CS gene does not vary in a tissue-specific manner.

Regulated expression of human growth hormone genes in mouse cells

We have asked whether there are sequences around the human growth hormone gene that render this gene responsive to induction by glucocorticoid hormones. Recombinant clones encoding human growth hormone were introduced into the chromosome of murine fibroblasts by cotransformation. Exposure of cotransformants to glucocorticoids results in a three to five fold induction of human growth hormone mRNA and a similar induction in secreted human growth hormone protein. The DNA sequences required for induction reside within 500 nucleotides of 5'-flanking DNA. Fusion of this segment of 5'-flanking DNA to the structural gene sequences of a hormone-insensitive gene, such as thymidine kinase, now renders this gene responsive to glucocorticoid induction.

Primary structure of the human Met- and Leu-enkephalin precursor and its mRNA

The nucleotide sequence of a complete cDNA copy of enkephalin precursor mRNA from human phaeochromocytoma is reported. The corresponding amino acid sequence shows that the precursor is 267 amino acids long and contains six interspersed Met-enkephalin sequences and one Leu-enkephalin sequence. Five of the seven enkephalins are flanked on both sides by pairs of basic amino acid residues. The precursors does not contain the sequences of the opioid peptides, dynorphin, alpha-neo-endorphin or beta-endorphin.

The human growth hormone gene family: nucleotide sequences show recent divergence and predict a new polypeptide hormone

The nucleotide sequences of three nonallelic human genomic DNA fragments which each contain one member of the growth hormone gene family are presented. These genes code for the known polypeptide hormones, growth hormone (hGH), chorionic somatomammotropin (hCS), and a yet unknown protein which differs from hGH in 13 positions. Each gene is structured into five exons, the four introns occurring at identical positions. Reflecting recent gene divergence, 90-95% sequence homology is seen in exons, introns, 5', and immediate 3' nontranscribed regions. The regions downstream of the polyadenylation sites in the genes for hGH and its variant, but not for hCS, contain members of an Alu family repeat sequence.

The human pro-opiomelanocortin gene: organization, sequence, and interspersion with repetitive DNA

The human pro-opiomelanocortin (POMC) gene has been characterized by molecular cloning and DNA sequence analysis. Although this gene codes for several different polypeptide hormones, only a single intron interrupts the protein coding region. The DNA in this intron, and in a second intron found in the region of the gene homologous to the mRNA 5'-untranslated sequence, contains repetitive DNA sequences. At least some of these sequences belong to the Alu family of transcribed middle repetitive DNA. The determination of the complete nucleotide sequence of the coding regions of the gene demonstrates that the pattern of homologous and variable regions seen in the POMC protein between different species is reflected at the DNA level. DNA sequences encoding the highly conserved regions of POMC are 90-95% homologous between species while the coding sequences for the variable regions of the protein are approximately 70% homologous. The very high degree of homology in the amino terminal portion of POMC is consistent with an important physiological role for this peptide.

The sequence of human serum albumin cDNA and its expression in E. coli

A recombinant plasmid has been constructed which contains the mature protein coding region of the human serum albumin (HSA) gene. Bacteria containing this plasmid synthesize HSA protein under control of the E. coli trp promoter-operator. The DNA sequence and predicted protein sequence of HSA were determined from the cDNA plasmid and are compared to existing data obtained from direct protein sequencing. The DNA sequence predicts a mature protein of 585 amino acids preceded by a 24 amino acid "prepro" peptide.

Molecular basis for familial isolated growth hormone deficiency

Nuclear DNA from four individuals with familial isolated growth hormone (somatotropin) deficiency (IGHD) type A was studied by restriction endonuclease analysis. By using 32P-labeled human growth hormone (hGH) cDNA sequences as a probe, patterns seen after various digestions indicated that these individuals were homozygous for a deletion of at least 7.5 kilobases (kb) of DNA. This deletion includes the gene that encodes the normal growth hormone but does not include the variant growth hormone gene. Restriction patterns of DNAs from all family members agreed with an autosomal recessive mode of inheritance of the deletion that correlates with the clinical phenotype. Furthermore, independent assortment of the two types of hGH genes suggests that these genes are nonallelic. These findings indicate that, in these families, IGHD type A is caused by deletion of the normal hGH genes and that this disorder can occur in the presence of variant hGH genes.

Detection and partial characterization of proenkephalin mRNA

We have used an oligodeoxynucleotide of defined sequence to detect and quantitate proenkephalin mRNA in the poly(A)-containing fraction of RNA from bovine adrenal medullas. The decahexamer 5'-d(G-G-T-A-G-T-C-C-A-T-C-C-A-C-C-A)-3' was synthesized to be complementary to the codons specifying the amino acid sequence NH2-Trp-Trp-Met-Asp-Tyr-Gln-COOH. This stretch of amino acids occurs in peptide I, one of the intermediates in the biosynthetic pathway of the enkephalins in bovine adrenal medulla. This pathway starts with a precursor (proenkephalin) of about 45 kilodaltons [Stern, A. S., Jones, B. N., Shively, J. E., Stein, S. & Udenfriend, S. (1981) Proc. Natl. Acad. Sci. USA 78, 1962-1966]. The decahexamer hybridized to adrenal poly(A)+RNA and was extended into cDNA with reverse transcriptase (RNA-dependent DNA nucleotidyltransferase). Five main discrete products ranging in size from 115 to 168 nucleotides were observed. The sequences of these extensions were found to be identical over the approximately 70 nucleotides sequenced from their 5' termini and corresponded exactly to the sequence expected from the amino acid sequence of peptide I. These cDNAs and the decahexamer itself hybridized to an adrenal medullary poly(A)+RNA species of about 1500 nucleotides, sufficient in size to code for the proposed proenkephalin. At saturation, approximately 2 fmol of the decahexamer were bound per microgram of mRNA; thus, the proenkephalin mRNA represents about 0.1% of the total poly(A)+RNA population in the tissue.

The proopiocortin (adrenocorticotropin/beta-lipoprotein) gene is located on chromosome 2 in humans

The proopiocortin gene is located on chromosome 2 in humans. A 13-kb DNA fragment containing proopiocortin gene sequences was identified in human cells while proopiocortin-related genes sequences of 9.8 and 6.2 kb were present in mouse cells. In human-mouse cell hybrids which contained reduced numbers of human chromosomes and a complete set of mouse chromosomes, the 9.8- and 6.2-kb fragments were always present while the 13-kb fragment segregated with human chromosome 2 and the chromosome 2 enzyme markers acid phosphatase-1 (ACP1), malate dehydrogenase-1 (MDHI), and isocitrate dehydrogenase-1 (IDH1). Analysis of a single cell hybrid with a broken chromosome 2 indicates that the proopiocortin and ACP1 genes are closely linked and in the distal region of the short arm of chromosome 2.

The genes for growth hormone and chorionic somatomammotropin are on the long arm of human chromosome 17 in region q21 to qter

We used a cloned cDNA probe for human growth hormone and Southern blotting techniques to analyze DNA from a series of rodent x human somatic cell hybrids for the presence of growth hormone-related sequences. Our results provide evidence for the assignment of the genes for growth hormone and chorionic somatomammotropin as well as a growth hormone-like gene to human chromosome 17. Analysis of mouse x human hybrid cells containing only part of the long arm of chromosome 17 enabled us to localize these genes to region 17q21 to 17qter.

The structure of eight distinct cloned human leukocyte interferon cDNAs

Eight classes of human leukocyte interferon (LeIFN) cDNA clones have been identified in a cDNA library prepared from a myeloblastoid cell line. The nucleotide sequences demonstrate that the multiple human LeIFN genes code for a family of homologous, yet distinct proteins. One of the cDNA clones may have been derived from the transcription of a LeIFN pseudogene.

A system for shotgun DNA sequencing

A multipurpose cloning site has been introduced into the gene for beta-galactosidase (beta-D-galactosidegalactohydrolase, EC 3.21.23) on the single-stranded DNA phage M13mp2 (Gronenborn, B. and Messing, J., (1978) Nature 272, 375-377) with the use of synthetic DNA. The site contributes 14 additional codons and does not affect the ability of the lac gene product to undergo intracistronic complementation. Two restriction endonuclease cleavage sites in the viral gene II were removed by single base-pair mutations. Using the new phage M13mp7, DNA fragments generated by cleavage with a variety of different restriction endonucleases can be cloned directly. The nucleotide sequences of the cloned DNAs can be determined rapidly by DNA synthesis using chain terminators and a synthetic oligonucleotide primer complementary to 15 bases preceeding the new array of restriction sites.

Human leukocyte interferon produced by E. coli is biologically active

A human leukocyte interferon cDNA was enzymatically synthesized, inserted into the vector pBR322, and cloned in Escherichia coli. The DNA sequence codes for a 23-amino acid signal peptide followed by an interferon polypeptide of 165 amino acids. An expression plasmid was constructed which permits the synthesis in E. coli of 2.5 x 10(8) units of interferon per litre of culture. This LeIF protected squirrel monkeys from lethal encephalomyocarditis virus infection.

Direct expression in Escherichia coli of a DNA sequence coding for human growth hormone

DNA coding for human growth hormone was constructed by using chemically synthesised DNA in conjunction with enzymatically prepared cDNA. This 'hybrid' gene was expressed in Escherichia coli under the control of the lac promoter. A polypeptide was produced having the size and immunological properties characteristic of mature human growth hormone.

Structure of genes for human growth hormone and chorionic somatomammotropin

A 2.6-kilobase (kb) EcoRI restriction endonuclease fragment containing human growth hormone (hGH; somatotropin) gene sequences and a 2.8-kb EcoRI fragment containing human chorionic somatomammotropin (hCS; choriomammotropin) gene sequences have been identified by hybridization to cloned cDNA. Human DNA was cleaved with EcoRI and fractionated by preparative agarose gel electrophoresis; DNA in the size range 2--3 kb was ligated to lambda gt WES.lambda B DNA and viable recombinant bacteriophage were recovered by in vitro packaging. After infection of Escherichia coli and screening of phage plaques, single isolates of hGH and hCS gene sequences were obtained. Restriction endonuclease mapping showed that the hGH gene contains three intervening sequences interrupting the coding sequence. Partial DNA sequence analysis of the hGH gene, obtained by the chain termination method, confirmed the location of the intervening sequences and the identity of the fragment.

Corticotropin and beta-endorphin: construction and analysis of recombinant DNA complementary to mRNA for the common precursor

A cDNA fragment synthesized from mouse mRNA (ACTH/LPH mRNA) that codes for the precursor polypeptide containing corticotropin (ACTH), beta-lipotropin (LPH), and several other peptides has been cloned in bacteria. The mRNA was enriched for ACTH/LPH mRNA translational activity (to about 75%) prior to cDNA synthesis. It appears to contain about 1200 bases, of which approximately 450 bases are not translated. The cloned DNA fragment is complementary to the region of the mRNA coding for the protein fragment beta-LPH-(44--90); this contains all of the amino acids of [Met]-enkephalin (residues 61--65 of beta-LPH), most of the amino acids of beta-melanocyte-stimulating hormone, and all but the carboxy-terminal amino acid of beta-endorphin. Based on assignment of the amino acid sequence of mouse beta-LPH from the nucelic acid sequence, it appears that there is extensive homology of mouse beta-LPH with human and porcine beta-LPH. The data also establish the linkage between beta-melanocyte-stimulating hormone and beta-endorphin as a Lys-Arg sequence. It is hoped that this cloned DNA can be used as a probe to study the expression and structure of the ACTH/LPH gene.

Regulation of growth hormone messenger RNA

In cultured rat pituitary cells, glucocorticoids regulate growth hormone production by modulating the number of growth hormone messenger RNA molecules. The effect is quite specific, since only a few other mRNAs are affected by the hormones. This response is demonstrated by assays involving cell-free mRNA translation and cDNA-RNA hybridization. Furthermore, the inducibility by the glucocorticoids is regulated by at least one other class of hormones, thyroid hormone. Thus, this system serves as a model for studying not only the glucocorticoid regulation of specific mRNA, but also the control of this regulation by other factors in the target tissue.

Synthesis of growth hormone by bacteria

A hybrid gene was constructed between the beta-lactamase gene of plasmid pBR322 and the cloned coding sequence for rat growth hormone. This gene is expressed in bacteria and growth hormone sequences are detectable by immunological methods.

Construction and analysis of recombinant DNA for human chorionic somatomammotropin

DNA complementary to mRNA coding for the human polypeptide hormone, chorionic somatomammotropin, has been purified by specific restriction endonuclease digestion and religation before cloning into bacterial plasmids. The primary structure of a major portion of this mRNA species is deduced from the nucleotide sequence of the recombinant DNA.

Nucleotide sequence and amplification in bacteria of structural gene for rat growth hormone

The primary structure of DNA containing the sequence for rat pituitary growth hormone mRNA has been determined. DNA was obtained by reverse transcription of polyadenylated RNA from cultured pituitary cells and from recombinant bacterial plasmids. The amino acid sequences for rat growth hormone and its precursor form have been deduced from the determined nucleotide sequences.

Regulation of growth hormone gene expression: synergistic effects of thyroid and glucocorticoid hormones

Cultured rat pituitary cells (GC) respond to thyroid and glucocorticoid hormones by increases in growth hormone production and growth hormone mRNA. When these cells are transferred from medium containing normal animal serum (with 1.8 mug of thyroxine per dl) to a medium containing serum from a thyroidectomized calf, "hypothyroid medium" (with no detectable thyroid hormone), growth hormone production decreases markedly. In cells maintained for 5 days in hypothyroid medium, triiodothyronine induces within 50 hr a 17-fold increase in growth hormone production whereas glucocorticoids, during the same time, produce a negligible (3-fold or less) stimulation. In combination, the two hormones promote a 45-fold stimulation. In all instances the changes in growth hormone production are paralleled by changes in the levels of growth hormone mRNA as measured by cell-free translation. The transfer to hypothyroid medium and the hormonal induction do not affect the relative activities of other mRNAs whose products are detectable on polyacrylamide gels. These studies indicate that thyroid hormone can be an activator of the expression of the growth hormone gene. The results also show that triiodothyronine controls the magnitude of the effect of glucocorticoids on growth hormone mRNA, and provide a model for "permissive" triiodothyronine action. The synergistic effect of these two classes of hormone suggests that they increase levels of growth hormone mRNA by different mechanisms.

Regulation of growth hormone messenger RNA by thyroid and glucocorticoid hormones

Thyroid and glucocorticoid hormones stimulate growth hormone synthesis in cultured rat pituitary cells (GC). We have compared changes in growth hormone production and mRNA in these cells. Triiodothyronine (10 nM) and dexamethasone (1 micron) stimulated increases in growth hormone production by 2.5- and 3.8-fold, respectively. There were corresponding increases in the capacity of RNA from hormone-treated cells to direct synthesis of pregrowth hormone in a wheat germ cell-free translation system, suggesting hormone-regulated increases in growth hormone mRNA. Hormone-induced changes in mRNA were also demonstrated by determining the kinetics of hybridization of a cDNA probe prepared from RNA enriched (about 70%) for growth hormone translational activity with RNA from control and hormone-treated cells. These results suggest that thyroid and glucocorticoid hormones can regulate growth hormone production by influencing the levels of its mRNA.

Interaction of RNA polymerase with promoters from bacteriophage fd

Replicative form DNA of bacteriophage fd, which had been fragmented with the restriction endonuclease II from Hemophilus parainfluenzae (endo R- HpaII), was reacted with Escherichia coli RNA polymerase; the resulting stable preinitiation complexes were analysed using the filter binding assay followed by gel electrophoresis. At 120mM KCL the first-order rate constants for complex decay were determined to be 10(-2)-10(-6)s-1. The second-order rate constants for complex formation were found to be about 10(6) -10(7) M-1 s-1. From these values association constants for the individual promoters were calculated to be 2 x 10(-8) -2 x 10(-11) M-1. The rate of formation and the stability of promoter complexes was enhanced in superhelical DNA. No evidence was found for stable promoter-specific closed complexes consisting of enzyme and helical DNA. This and the kinetic data suggest that the unwinding of base pairs is already important early in promoter selection, and not only for the formation of the final open complex. The initiation of RNA synthesis form the preinitiation complex was faster than complex dissociation and complex formation for all promoters. Consequently, the initiation efficiency of a promoter is determined by the rate of complex formation, and not by its 'affinity' for the enzyme. No correlation was found between the relative order of the fd promoters for the binding and the dissociation reaction. This is explained by different structural determinants, for the two reactions, which are located in different parts of the promoter DNA.