Biomedical subjects

J B Yoon

Publications and source records attributed to J B Yoon.

25 records · Page 2Linked to original sources

PubMed1992

Oct-1 and Oct-2 potentiate functional interactions of a transcription factor with the proximal sequence element of small nuclear RNA genes.

The promoters of both RNA polymerase II- and RNA polymerase III-transcribed small nuclear RNA (snRNA) genes contain an essential and highly conserved proximal sequence element (PSE) approximately 55 bp upstream from the transcription start site. In addition, the upstream enhancers of all snRNA genes contain binding sites for octamer-binding transcription factors (Octs), and functional studies have indicated that the PSE and octamer elements work cooperatively. The present study has identified and characterized a novel transcription factor (designated PTF) which specifically binds to the PSE sequence of both RNA polymerase II- and RNA polymerase III-transcribed snRNA genes. PTF binding is markedly potentiated by Oct binding to an adjacent octamer site. This potentiation is effected by Oct-1, Oct-2, or the conserved POU domain of these factors. In agreement with these results and despite the independent binding of Octs to the promoter, PTF and Oct-1 enhance transcription from the 7SK promoter in an interdependent manner. Moreover, the POU domain of Oct-1 is sufficient for significant in vitro activity in the presence of PTF. These results suggest that essential activation domains reside in PTF and that the potentiation of PTF binding by Octs plays a key role in the function of octamer-containing snRNA gene enhancers.

Base Sequence↗

PubMed1992

Discoordinate hormonal and ontogenetic regulation of four rat serpin genes.

To understand the roles of four highly homologous rat hepatic serine protease inhibitor genes (Spi 2.1, Spi 2.2, Spi 2.3, and alpha 1-antitrypsin), we measured the hepatic content of their specific mRNAs under several physiological conditions. Spi 2.1 and 2.3 mRNAs, which are regulated by growth hormone, paralleled serum growth hormone levels developmentally. Only Spi 2.1 mRNA decreased with starvation, while Spi 2.2, 2.3, and alpha 1-antitrypsin mRNAs did not change. Despite the close homology of the Spi genes to mouse contrapsin, which is regulated by testosterone, none of the serine protease inhibitor mRNAs examined here was dependent on androgens for expression. Spi 2.2 mRNA displayed a unique ontogenetic regulation, with a rise in hepatic content at day 19 to levels five times that of any other age group. These studies confirm the importance of growth hormone in the regulation of Spi 2.1 and 2.3 mRNAs and suggest that Spi 2.2 mRNA may be regulated by metabolic alterations occurring in the weaning period.

Aging↗

PubMed1992

Incidence estimation of genitourinary cancer in Korea.

A nation-wide study was performed to estimate the incidence of bladder, kidney, renal pelvis and ureter, prostate, testicular and other genitourinary cancer among Koreans in Korea using medical records of the inpatients of the beneficiaries of the Korea Medical Insurance Corporation (KMIC) from Jan. 1, 1989 to Dec. 31, 1989. The crude incidence rate of bladder cancer (ICD-9 188) is estimated to be 4.43 and 0.98 per 100,000 in males and females, respectively. Around 1,093 new cases of bladder cancer (895 male and 198 female) are estimated to occur in a year. The adjusted rate for the world population is 7.76 in males and 1.19 in females which is similar to that of Japanese in Osaka and Chinese in Shanghai, but lower than in American whites and blacks. The crude incidence of kidney, renal pelvis and ureteral cancer (ICD-9 189) is estimated to be 1.61 and 0.87 in males and females, respectively. Around 507 new cases of kidney, renal pelvis and ureteral cancer (332 male and 175 female) are estimated to occur in a year. The adjusted rate for the world population is 2.69 in males and 1.04 in females. In the prostate (ICD-9 185), the crude incidence rate of cancer is estimated to be 1.36. Around 274 new cases of prostate cancer are occurring in a year. The adjusted rate for the world population is 2.98 which is similar to the Chinese rate. The incidence of genitourinary cancer continuously increases with age.

Adult↗

PubMed1990

An inducible nuclear factor binds to a growth hormone-regulated gene.

Transcription of the serine protease inhibitor (Spi) 2.1 gene, a member of the serine protease inhibitor family, is induced by growth hormone (GH) in rat liver. To further study the mechanism involved in this process, we have isolated and characterized the Spi 2.1 gene from a rat genomic library. Examination of the 5'-flanking region of the Spi 2.1 gene from normal animals revealed the presence of a DNase I hypersensitive site within 500 base pairs of the transcriptional initiation site, which was not detectable in hypophysectomized animals. Portions of the 5'-flanking region of the Spi 2.1 gene were fused to a heterologous promoter and reporter gene and introduced into primary rat hepatocytes by lipofection. Spi 2.1 sequences from -275 to -54 gave a 2-3-fold induction of reporter gene activity in cells grown in the presence of GH, similar to the level of induction of the endogenous Spi 2.1 mRNA in isolated hepatocytes. Further definition of the essential sequences revealed that a segment from -147 to -102 could confer GH responsiveness when linked in tandem copies in front of a heterologous promoter. Using the gel shift assay, a nuclear factor(s) from normal rat liver was identified which could interact with this minimal response fragment. The importance of this activity to GH regulation was suggested by the fact that it was absent in hypophysectomized animals but reappeared by 1 h after treatment of such animals with GH. The appearance of this activity was not blocked by pretreatment of animals with an inhibitor of protein synthesis, suggesting a preexisting factor is modified by GH to yield an activity which interacts with the Spi 2.1 gene.

Animals↗

PubMed1989

Homologous rat hepatic protease inhibitor genes show divergent functional responses to inflammation.

The genes encoding three distinct serine protease inhibitors (Spi) have been cloned from rat liver. These inhibitors are highly homologous with each other and are similar to alpha 1-antitrypsin at the nucleic and amino acid sequence level. Although previous investigators have examined the regulation of the Spi 2 locus by inflammation, the use of various techniques and the complexity of this genetic locus have led to incomplete and somewhat confusing results. Oligonucleotide probes specific for Spi 2.1, Spi 2.2, Spi 2.3, and a 3' mouse cDNA probe for alpha 1-antitrypsin mRNA were used to measure these mRNA after induction of inflammation with subcutaneous turpentine in Fischer rats. alpha 1-Antitrypsin mRNA increased 1.8-fold, and Spi 2.2 increased 7-fold. In contrast, Spi 2.1 and 2.3 mRNA sequences decreased fourfold. The maximal changes occurred between 24 and 48 h after inflammation, with a gradual return toward normal over the next 4 days. Since Spi 2.1, Spi 2.3, and alpha 1-antitrypsin mRNA sequences are responsive to growth hormone, two other growth hormone-responsive mRNA sequences, alpha 2u-globulin and insulin-like growth factor I, were measured, and they also decreased after induction of inflammation. The results of this study show that, despite a marked similarity of nucleotide sequence, Spi 2.1 and 2.3 genes respond very differently from Spi 2.2 and alpha 1-antitrypsin to both growth hormone and inflammation. We speculate that the functions of Spi 2.1 and 2.3 products are different from those of Spi 2.2 and alpha 1-antitrypsin and may involve the regulation of growth.

Animals↗

PubMed1989

A survey of externally recognizable genitourinary anomalies in Korean newborns. Korean Urological Association.

To estimate the incidence of externally recognizable genitourinary anomalies and associated anomalies in the newborns in Korea, retrospective and prospective studies have been performed. Thirty eight of 48 urology training hospitals participated in this nationwide survey. In this study we have included minor defects or variations in the anomaly to evaluate the incidence of the recognizable genitourinary conditions in the newborns. The incidence of genitourinary anomaly in 1,000 newborn delivery in a year was 11.0 in the prospective study and this figure is about three times higher than the retrospective study and is considered to be close to the true incidence. The incidence of genitourinary anomaly in 1,000 male newborn was 20.4. Hydrocele, cryptorchidism and hypospadias were most commonly observed. The incidence of hydrocele in 1,000 male newborn was 9.89 and the incidence of cryptorchidism was 7.26 and the incidence of hypospadias was 2.13. The incidence of associated anomaly in 100 genitourinary anomaly was 7.9. Congenital heart diseases and anorectal anomalies were commonly associated anomalies. In the newborns with genitourinary anomalies, premature infants account larger portion than is usually reported in total delivery.

Birth Weight↗

PubMed1987

Growth hormone induces two mRNA species of the serine protease inhibitor gene family in rat liver.

In order to study the molecular actions of growth hormone on gene expression, we have cloned and characterized two unique, but related, cDNA sequences from rat liver, lambda Spi-1 and lambda Spi-2. These two cDNA sequences are complementary to rat hepatic mRNA species previously designated as Spots 3 and 20 when assayed by in vitro translation and two-dimensional gel electrophoresis. By Northern blot, the two mRNAs are both 1900 bases in length and growth hormone administered to hypophysectomized rats increases the levels of both of these mRNAs. In contrast, the combined administration of thyroxine, corticosterone, and dihydrotestosterone to hypophysectomized rats did not augment these mRNAs. The simultaneous administration of all four hormones resulted in a level greater than that observed for animals treated with growth hormone alone. Analysis of genomic DNA suggests the presence of two similar, but not identical, genes. DNA sequencing of lambda Spi-1 and lambda Spi-2 revealed that they were 90% homologous at the nucleotide level and 87% homologous at the amino acid sequence level. lambda Spi-2 has 78% homology with mouse contrapsin, 60% with human alpha 1-antichymotrypsin, and 51-55% with alpha 1-antitrypsins, all members of the serine protease inhibitor gene family. The nucleotide and deduced amino acid sequences of lambda Spi-1 and lambda Spi-2 which align with the reactive centers of known members of this family differ substantially from each other and from other members of the family. The difference in the reactive center suggests that the specificity or function of these proteins may differ from other members of serine protease inhibitor gene family.

Amino Acid Sequence↗