Biomedical subjects

J Gorski

Publications and source records attributed to J Gorski.

At least 55 records · Page 3Linked to original sources

PubMed1997

Quantitative trait loci for estrogen-dependent pituitary tumor growth in the rat.

Growth control is of fundamental importance to biology in general and of critical importance to cancer research in particular. Tumors develop when control of the normal growth process is lost. The rat pituitary is a model system for control of estrogen-dependent growth. Chronic estrogen treatment induces uncontrolled growth in the pituitaries of Fischer 344 (F344) rats, but not of Brown Norway (BN) rats. We have identified five quantitative trait loci (QTL) for estrogen-dependent pituitary mass (Edpm) in an F2 intercross of F344 and BN. These QTL reside on rat Chromosomes (Chrs) 2, 3, 5, and 9 and explain a total of 55% of the genetic variance in the F2. We have also detected suggestive evidence for a QTL on rat Chr 14. For Edpm2-1, Edpm2-2, Edpm3, and Edpm5, the F344 allele corresponds with increased pituitary mass, as expected. Surprisingly, for Edpm9 and the suggested QTL on Chr 14, the BN allele corresponds with increased pituitary mass. We also find evidence for interaction (epistasis) between Edpm3 and Edpm9 and between Edpm5 and the suggested QTL on Chr 14.

Alleles↗

PubMed1997

Palmitate incorporation into lipids pools of contracting red and white muscles.

We compared the incorporation of the blood-borne [14C]-palmitate into selected lipid and phospholipid pools in rat muscles (soleus, red and white gastrocnemius), at rest and during contractions (15 and 60 tetani/min) in one leg (5 min) while the contralateral leg served as a control. [1-(14)C]-palmitate (20 microCi/rat) was administered into the carotid artery (t = 1 min). [14C]-palmitate deposition was greatest in soleus (100%) and lower in red (82%) and white gastrocnemius muscles (63%), respectively (p < 0.05). [14C] was deposited primarily into the tri-acylglycerol (approximately 50%) and phospholipid pools (approximately 30%) of soleus and red gastrocnemius muscles, and into the di-acylglycerol (approximately 30%), tri-acylglycerol (approximately 30%) and phospholipid pools (approximately 30%) in white gastrocnemius muscle. During contraction the concentrations of tri-acylglycerol were not changed. But, contraction increased [14C]-palmitate incorporation into soleus and red gastrocnemius muscles (600-700%) and into white gastrocnemius muscles (200%). Slightly more [14C] was directed from the phospholipids into the tri-acylglycerol pool during contraction. [14C]-palmitate deposition was also increased in the subclasses of phospholipids during contraction in red and white gastrocnemius. In conclusion, the deposition of [14C]palmitate into different lipid and phospholipid pools is quite rapid, and is dependent on contraction and the muscle fiber type.

Animals↗

PubMed1997

Polymorphism at beta 85 and not beta 86 of HLA-DR1 is predominantly responsible for restricting the nature of the anchor side chain: implication for concerted effects of class II MHC polymorphism.

The first hydrophobic pocket, P1, of class II MHC has been shown to be an important site of peptide anchoring. Two polymorphisms occur in this pocket in the human class II MHC beta chain at position 85 and 86. beta 85 is usually Val, occasionally Ala, whereas beta 86 can be Gly or Val. However, Ala85 is found only in conjunction with Val86. The independent effect of the polymorphism at these two positions on the binding of normal and substituted antigenic peptides has never been examined. To do so, three soluble HLA-DR1 variants that contain the naturally occurring combinations of these side chains at these two positions were generated and tested with a panel of influenza matrix peptides varying at anchor P1. DR1 alleles differing only at position 86 are very similar in the binding of a panel of antigenic peptide, indicating that beta 86 does not substantially influence the peptide binding of DR1. In contrast, DR1 varying only at position beta 85 differ in their binding of substituted peptides containing Ala, Tyr or Trp at the P1 anchor position. Thus, beta 85 shows the predominant effect on the P1 anchor side chain preference of the P1 pocket in DR1. This is in contrast to other HLA-DR alleles where beta 86 has been shown to control the nature of the P1 anchor. These previous data together with our own imply that the role of polymorphism in P1 may be influenced by the contextual framework of the remaining allelic polymorphism.

Alleles↗

PubMed1997

Clinical experience with Thera DR rate-drop response pacing algorithm in carotid sinus syndrome and vasovagal syncope. The International Rate-Drop Investigators Group.

This study examined the effectiveness of cardiac pacing using the Thera DR rate-drop response algorithm for prevention of recurrent symptoms in patients with carotid sinus syndrome (CSS) or vasovagal syncope. The algorithm comprises both diagnostic and treatment elements. The diagnostic element consists of a programmable "window" used to identify heart rate changes compatible with an evolving neurally mediated syncopal episode. The treatment arm consists of pacing at a selectable rate and for a programmable duration. Forty-three patients (mean age 53 +/- 20.4 years) with CSS alone (n = 8), CSS in conjunction with vasovagal syncope (n = 4), or vasovagal syncope alone (n = 31) were included. Thirty-nine had recurrent syncope, while the remaining four reported multiple presyncopal events. Prior to pacing, 40 +/- 152 syncopal episodes (range from 1 to approximately 1,000 syncopal events) over the preceding 56 +/- 84.5 months. Postpacing follow-up duration was 204 +/- 172 days. Three patients have been lost to follow-up and in one patient the algorithm was disabled. Among the remaining 39 individuals, 31 (80%) indicated absence or diminished frequency of symptoms, or less severe symptoms. Twenty-three patients (23/29, or 59%) were asymptomatic with respect to syncope or presyncope. Sixteen patients had symptom recurrences. Of these, seven experienced syncope (7/39, or 18%) and 9 (29%) had presyncope: the majority of patients with recurrences (6/7 syncope and 7/9 presyncope) were individuals with a history of vasovagal syncope. Consequently, although symptoms were observed during postpacing follow-up, they appeared to be of reduced frequency and severity. Thus, our findings suggest that a transient period of high rate pacing triggered by the Thera DR rate-drop response algorithm was beneficial in a large proportion of highly symptomatic patients with CSS or vasovagal syncope.

Adolescent↗

PubMed1997

Functional differences in lipid metabolism in resting skeletal muscle of various fiber types.

Intramuscular lipid pool turnover [triacylglycerols (TG), phospholipids (PL), mono- and diacylglycerols (MG, DG)] and the oxidation of endogenous and exogenous lipids were determined with pulse-chase studies in incubated muscles of varied oxidative potential [soleus strips (SOL)--> epitrochlearis --> flexor digitorum brevis]. Incorporation of palmitate into TG and PL pools and its oxidation were linearly related to time and exogenous palmitate concentration in all muscles. Total palmitate incorporation (deposition and oxidation) was greatest in SOL. However, palmitate incorporation into TG was similar in all muscles when expressed as a percentage of the total incorporation. In contrast, palmitate incorporation into PL was greatest in the least oxidative muscle. Palmitate oxidation, incorporation into TG, and citrate synthase activity were all strongly correlated with muscle cytosolic fatty acid-binding protein content (r = 0.96, 1.0, and 0.98, respectively). During the chase, reducing exogenous palmitate from 1.0 mM to 0.5 or 0 mM resulted in a significant (approximately 30%) loss of [(14)C]palmitate from the TG pool in SOL and a significant increase in (14)CO(2) production from endogenous stores. No significant loss of (14)C label from lipid pools occurred in the less oxidative muscles, suggesting a closely regulated interaction between energy provision from exogenous and endogenous lipid pools in oxidative muscle. Glucose oxidation increased significantly in all muscles in the absence of palmitate. The loss of (14)C label from TG in SOL during the chase without palmitate was not accompanied by a significant change in TG content. This suggests that, during rest, there is a small subpool of TG with a relatively rapid turnover.

Animals↗

PubMed1997

Estrogens and the genetic control of tumor growth.

Biochemical and genetic studies of the estrogen-induced pituitary tumors of the F344 rat provide a new model for understanding cancer biology. Because a genetic difference in tumor susceptibly already exists in this animal model it is possible to search for the underlying mechanisms. Interestingly, thus far marked changes in expression of known or unknown oncogenes do not appear to be involved in the formation of this tumor. Similarly, known angiogenic factors have not been implicated in this model's dramatic angiogenic response to estrogen. It will be very informative to dissect out the critical genes and the products that are involved in this system and then to determine whether similar genes are involved in human, estrogen-induced cancers.

Animals↗

PubMed1996

Estrogen-induced transcription of the progesterone receptor gene does not parallel estrogen receptor occupancy.

The activation of the silent endogenous progesterone receptor (PR) gene by 17-beta-estradiol (E2) in cells stably transfected with estrogen receptor (ER) was used as a model system to study the mechanism of E2-induced transcription. The time course of E2-induced PR transcription rate was determined by nuclear run-on assays. No marked effect on specific PR gene transcription rates was detected at 0 and 1 h of E2 treatment. After 3 h of E2 treatment, the PR mRNA synthesis rate increased 2.0- +/- 0.2-fold and continued to increase to 3.5- +/- 0.4-fold by 24 h as compared with 0 h. The transcription rate increase was followed by PR mRNA accumulation. No PR mRNA was detectable at 0, 1, and 3 h of E2 treatment. PR mRNA accumulation was detected at 6 h of E2 treatment and continued to accumulate until 18 h, the longest time point examined. Interestingly, this slow and gradual transcription rate increase of the endogenous PR gene did not parallel binding of E2 to ER, which was maximized within 30 min. Furthermore, the E2-ER level was down-regulated to 15% at 3 h as compared with 30 min of E2 treatment and remained low at 24 h of E2 exposure. These paradoxical observations indicate that E2-induced transcription activation is more complicated than just an association of the occupied ER with the transcription machinery.

Animals↗

PubMed1996

Molecular identification of T cells that respond in a primary bulk culture to a peptide derived from a platelet glycoprotein implicated in neonatal alloimmune thrombocytopenia.

Neonatal alloimmune thrombocytopenia induced by the human platelet alloantigen 1a (HPA1a) is characterized by generation of alloantibodies by a mother who is homozygous for the HPA1b alloantigen and almost always HLA-DRB3*0101. The disease is viewed as B cell mediated but the linkage with HLA is indicative of a role for T cells. The HPA1a and HPA1b allotypes are defined, respectively, by Leu and Pro at amino acid 33 of the beta-chain of the platelet integrin GPIIbIIIa (alpha(IIb)beta3). Under the assumption that the same polymorphism may control both the B cell epitope and constitute the MHC-bound peptide, we restimulated PBMC from a woman with an affected child with a synthetic peptide from this polymorphic region. Molecular analysis of the responding T cell repertoire identified two T cells which predominated in cultures stimulated with the alloantigen peptide and which were absent in cultures with the autoantigen peptide. In spite of the use of different V families, sequence of the CDR3 region of the T cell receptor (TCR) beta-chain revealed the presence of a shared motif, L-P-S/T. Oligonucleotide probes specific for the CDR3 sequence indicated that these T cells were present in the PBMC at the highest levels immediately after delivery of the affected infant and their frequency dropped at later times.

Antigens, Human Platelet↗

PubMed1996

Identification and characterization of an estrogen-responsive element binding protein repressed by estradiol.

Cytosolic proteins from uteri of 19-day-old rats were analyzed by an electrophoresis mobility shift assay (EMSA) using a 31 base pair DNA probe containing an estrogen-responsive element (ERE) from the vitellogenin A2 gene. EMSA identified three distinct cytosolic protein-DNA complexes that are separable by Q-Sepharose anion exchange chromatography into an estrogen receptor (ER)-containing fraction (150 mM NaCl eluate) and a non-ER-containing fraction (250 mM NaCl eluate). We thus refer to the non-ER fraction as the ERE binding protein (ERE-BP). The ERE-BP-containing fraction was repressed to 40-50% of its normal levels following a single injection of estradiol. In addition, ERE-BP levels were repressed to the same extent (greater than 50%) by day 20 of the rat's gestational period. Examination of the expression pattern of ERE-BP shows that this activity is differentially expressed in both estrogen-responsive and nonresponsive tissues, with the highest levels of expression occurring in the pituitary. We next examined the specificity of ERE-BP binding by competition analysis using DNA sequences corresponding to binding sites of several known transcription factors. ERE-BP was found to be specific for both the ER binding site (ERE) and TATA binding protein binding sites. Furthermore, saturation analysis demonstrated that ERE-BP binds to the ERE and TATA binding protein sequences with an apparent Kd of 1.2 and 0.12 nM, respectively. Partial purification of ERE-BP using three chromatography steps (Q-Sepharose, hydroxyapatite, and Sephacryl S300) followed by sodium dodecyl sulfate analysis indicated the presence of three major protein bands (p102, p81, and p48) as judged by Coomassie staining. UV cross-linking of the ERE-BP/DNA complex followed by sodium dodecyl sulfate analysis-polyacrylamide gel electrophoresis analysis indicates that the 48 kDa band seen in the final, partially purified fraction correlates with the ERE-BP activity. Thus, this study has identified a unique uterine cytosolic protein that binds to the ER binding site and may influence ER binding.

Animals↗

PubMed1996

Genetic separation of tumor growth and hemorrhagic phenotypes in an estrogen-induced tumor.

Chronic administration of estrogen to the Fischer 344 (F344) rat induces growth of large, hemorrhagic pituitary tumors. Ten weeks of diethylstilbestrol (DES) treatment caused female F344 rat pituitaries to grow to an average of 109.2 +/- 6.3 mg (mean +/- SE) versus 11.3 +/- 1.4 mg for untreated rats, and to become highly hemorrhagic. The same DES treatment produced no significant growth (8.9 +/- 0.5 mg for treated females versus 8.7 +/- 1.1 for untreated females) or morphological changes in Brown Norway (BN) rat pituitaries. An F1 hybrid of F344 and BN exhibited significant pituitary growth after 10 weeks of DES treatment with an average mass of 26.3 +/- 0.7 mg compared with 8.6 +/- 0.9 mg for untreated rats. Surprisingly, the F1 hybrid tumors were not hemorrhagic and had hemoglobin content and outward appearance identical to that of BN. Expression of both growth and morphological changes is due to multiple genes. However, while DES-induced pituitary growth exhibited quantitative, additive inheritance, the hemorrhagic phenotype exhibited recessive, epistatic inheritance. Only 5 of the 160 F2 pituitaries exhibited the hemorrhagic phenotype; 36 of the 160 F2 pituitaries were in the F344 range of mass, but 31 of these were not hemorrhagic, indicating that the hemorrhagic phenotype is not merely a consequence of extensive growth. The hemorrhagic F2 pituitaries were all among the most massive, indicating that some of the genes regulate both phenotypes.

Animals↗

PubMed1996

Molecular defects in TCRBV genes preclude thymic selection and limit the expressed TCR repertoire.

A prerequisite for the assembly of a functional TCR is the rearrangement of gene segments to result in in-frame transcripts that can vary in length across the CDR3 region. Selection for in-frame 3-bp spaced rearrangements is observed for functional TCRB genes in thymocyte DNA and mRNA transcripts from PBMC. Previous analyses of the expressed human TCRBV gene repertoire have suggested that BV10S1 and BV19S1 gene segments may be expressed at very low levels or not at all in some individuals. CDR3 size analysis for BV10 and BV19 transcripts and thymic DNA rearrangements revealed no such selection of in-frame 3-bp spaced rearrangements. Comparison of the BV19 leader intron sequence with consensus 5'-splice signal sequences suggested that the mature mRNA for this gene would contain the unspliced leader intron. Sequencing of BV19 transcripts from PBMC confirmed that the intron was not spliced, resulting in a predicted translation product that terminates prematurely. Both genomic DNA and mRNA were analyzed for the BV10 gene. The leader sequence contained a single extra base, which would result in a shift in the V region reading frame upon conventional mRNA splicing. This gene is predicted to be nonfunctional due to the presence of a stop codon in the V gene segment just after the splice signal. A splice variant that uses an alternative 3'-splice site further downstream in the V region was also detected. This variant is predicted to be nonfunctional due to the presence of an in-frame stop codon in the V region. These processing defects are sufficient to abrogate positive selection. Therefore, the conclusions drawn from previous studies of the expressed T cell repertoire in normal and disease states based on the presumed functional status of these two genes need to be reassessed.

Base Sequence↗

PubMed1996

T cell recognition of MHC class II-associated peptides is independent of peptide affinity for MHC and sodium dodecyl sulfate stability of the peptide/MHC complex. Effects of conservative amino acid substitutions at anchor position 1 of influenza matrix protein19-31.

T cells recognize peptide fragments of Ags bound to MHC-encoded molecules. Pockets in the MHC peptide-binding groove accommodate a limited set of amino acid side chains present at anchor positions in peptide; however, the functional significance of accommodation of different side chains at an anchor position in peptide is not clear. A panel of T cell clones was evaluated to test the effect of conservative amino acid substitution at a primary peptide anchor position. Results of T cell stimulation studies were correlated with two well studied characteristics of the peptide/MHC complex, which are the affinity of peptide binding to MHC and the stability of the resulting complex upon PAGE in the presence of SDS. We found that formation of a functional complex required neither high affinity peptide binding nor SDS stability. Furthermore, T cell clones differed in their ability to recognize individual peptide variants, suggesting that some structural aspect of the peptide/MHC complex is influenced by interactions between peptide anchor residues and MHC pockets.

Amino Acid Sequence↗

PubMed1996

Estrogen-induced changes in rRNA accumulation and RNA polymerase I activity in the rat pituitary: correlation with pituitary tumor susceptibility.

Chronic treatment with the synthetic estrogen diethylstilbestrol induces pituitary tumors in rats and the susceptibility to such tumors is highly strain dependent. The Fischer 344 (F344) strain, which is particularly susceptible, develops pituitary tumors after 30-55 days of estrogen treatment. In contrast, the Sprague-Dawley (SD) strain is relatively resistant to such tumors. DES implants (5 mg) were placed in 21-day-old male rats over a 10-day period and changes in their testes and pituitaries were monitored. Both F344 and SD strains responded similarly by exhibiting a measurable decrease in testes weight to one-third that of controls on day 10. In F344 rats, DNA synthesis in the pituitary increased to 228% as compared with controls after 3 days of DES treatment and remained high on days 7 and 10. In SD rats, DNA synthesis increased to only 150% of that exhibited by controls on day 3 and started to decline on day 7. Surprisingly, total RNA accumulation also responded to DES differentially between these two strains. In F344 rats, the RNA level was 250% as compared with that of controls after 3 days of DES treatment and continued to increase gradually on days 7 and 10. The RNA level in the SD strain increased only slightly from the same DES treatment. A nuclear run-on assay showed elevated pituitary transcription of ribosomal DNA in the F344 rats after 3 days of estrogen administration. The enzymatic activity of pituitary RNA polymerase I, the enzyme responsible for initiating rRNA synthesis, increased twofold in F344 rats when measured after 3 days of estrogen treatment whereas no increase was observed in the SD rats. These results suggest that estrogen-induced changes in the accumulation of rRNA occur at a very early stage in tumorigenesis, prior to any visible tumor growth in the rat pituitary.

Animals↗

PubMed1996

Decreased expression of carboxypeptidase E protein is correlated to estrogen-induction of rat pituitary tumors.

Following the cleavage of peptide precursors by endopeptidases such as the proprotein convertases PC2 and PC3, carboxypeptidase E (CPE) functions to remove basic amino adds from the C-terminus of various pituitary hormones. We investigated the role of CPE in the differential sensitivity between rat strains to estrogen-induced pituitary tumors. Pituitary CPE protein levels were unchanged by diethylstilbestrol (DES) in tumor-resistant Sprague-Dawley (SD) rats. However, in tumor-susceptible Fischer 344 (F344) rats, DES decreased CPE protein levels such that by 7 and 8 weeks of treatment, CPE was barely detectable. One week withdrawal of DES caused an increase in CPE protein levels at 8 weeks. After 2 and 4 weeks of DES treatment, CPE protein levels in F344 rats decreased to 18 and 2.3% of control values, respectively, but no strain difference was observed in the protein levels of proprotein convertase 2 (PC2) or PC3. Additionally, Brown Norway (BN), F344, and F1 hybrid (BN x F344) rats were treated with DES for 10 weeks. The level of pituitary CPE protein was not affected by DES in BN rats whereas F344 rats had only 8% of the level of CPE pituitary protein of BN rats. The pituitaries of F1 rats, which had an intermediate weight response to DES, had an intermediate level of CPE protein (31% that of BN rats). Levels of CPE mRNA were not affected by DES in SD rats while in F344 rats DES tended to decrease levels of CPE mRNA after both 2 and 4 weeks of treatment, although the response was variable. It thus appears that pituitary CPE protein is differentially regulated by DES between tumor-resistant rats and F344 rats primarily at the post-transcriptional level. Furthermore, in F344 rats, levels of CPE protein are inversely correlated to increases in pituitary weight caused by DES treatment.

Animals↗

PubMed1996

Immunolocalization of estrogen receptor protein in the mouse blastocyst during normal and delayed implantation.

We previously showed that estrogen receptor (ER) mRNA is present in preimplantation mouse embryos. The apparent synthesis of ER mRNA by the blastocyst at the time of implantation when estrogen is required was of special interest. A demonstration of the presence of ER protein would support the idea that estrogen can act directly on the embryo. The mouse embryo at the blastocyst stage is differentiated into two cell types, the trophectoderm and the inner cell mass. To determine whether ER mRNA is translated into ER protein and its cell-specific distribution, immunocytochemical analyses were performed in mouse blastocysts. ER protein was detected in all cell types of the normal, dormant, or activated blastocyst. To trace the fate of ER in these cell types, immunocytochemistry was performed in implanting blastocysts and early egg cylinder stage embryos developed in culture. Again, ER was detected in all cells of the implanting blastocyst. At the early egg cylinder stage, continued expression of ER was observed in cells derived from the inner cell mass or the trophoblast. In trophoblast giant cells, ER was concentrated in small regions of the nucleus, possibly the nucleoli, which was similar to that observed in dormant and activated blastocysts. The embryonic expression of ER at such early stages in a broad array of cells suggests that ER may have a general role during early development.

Animals↗

PubMed1996

Gip-2 codon 179 oncogene mutations: absent in adrenal cortical tumors.

The role of G protein mutations in the pathogenesis of adrenal cortex neoplasms is controversial. Two published studies disagree on the existence of a cysteine or histidine for arginine substitution at position 179 (R179C/H) of the GTP binding region of the alpha chain of an inhibitory G protein (Gi2alpha) in these tumors. Prior studies using detection by mutation-specific oligonucleotide hybridization showed either 3 of 11 or 0 of 56 tumors harbored mutations. To resolve this discrepancy and ascertain the importance of the R179C/H Gi2alpha mutation in the development of adrenal cortex tumors, we screened tumors from 29 patients (24 with adenoma, 5 with carcinoma) using a more sensitive assay employing polymerase chain reaction (PCR) and examination for restriction fragment length polymorphisms (RFLP). Detection of the potential R179C/H mutation by this technique was possible because the wild-type coding sequence includes the BSTU-1 restriction endonuclease recognition site CGCG, whereas the mutated gene does not. Results showed complete digestion of the amplified DNA samples from all 29 patients and the negative control DNA by BSTU-1, indicating that all tumor samples exhibited only the wild-type sequence. Direct sequencing of PCR product from four tumor samples confirmed the presence of only the wild-type sequence. The 0 of 29 rate of R179C/H mutations we found in Gi2alpha is different than the 3 of 11 positive rate (p < 0.05, Fishers' exact) previously reported but agrees with the report showing 0 of 56 mutations. We conclude a mutation at position 179 of Gi2alpha is not important in the pathogenesis of most adrenal cortical tumors.

Adenoma↗

PubMed1996

Effect of estrogen on the expression of galanin mRNA in pituitary tumor-sensitive and tumor-resistant rat strains.

The hypothesis that estrogen-induced pituitary tumors are mediated by the neuropeptide galanin was tested using tumor-resistant (Sprague-Dawley; SD) and tumor-sensitive (Fischer 344; F344) rat strains. Diethylstilbestrol (DES) increased expression of galamin mRNA in both strains after 1, 2, and 4 weeks of treatment and doubled pituitary weights in F344 rats while pituitary weights in SD rats were unchanged by DES treatment. In F344 rats, both the expression of galanin mRNA and pituitary weights increased linearly with the length of DES treatment. In SD rats however, despite increasing levels of galanin mRNA, pituitary weights did not increase. These data indicate that galanin gene expression, by itself, is not sufficient to account for increased pituitary growth. However, our data do not rule out the possibility that galanin has an indirect role in promoting pituitary growth.

Animals↗

PubMed1996

Differential expression of isomorphic HLA-DR beta genes is not a sole function of transcription.

Cells expressing HLA DR7 contain two functional DR beta genes, DRB1 and DRB4, whose mRNA is present at different levels. We examined whether the mRNA levels are due to differential transcriptional regulation or post-transcriptional regulation. As part of this analysis, a novel series of upstream elements was identified. Analysis of the proximal promoter activity, using a transient expression system, showed that the isomorphic promoter activities of B1 and B4 are about equal. RNase protection analysis of steady-state pre-mRNA and mRNA levels shows that the DR7 B1 pre-mRNA levels are 3 to 4 fold higher than B4 pre-mRNA levels. However, the B1 mRNA levels are increased seven fold relative to the B4 mRNA levels. The disproportionate increase of the mRNA levels relative to the corresponding pre-mRNA levels indicates that regulation also occurs at the post-transcriptional level.

Base Sequence↗