Transcriptional activation of the human villin gene during enterocyte differentiation

Enterocyte differentiation occurs along the crypt-villus axis and is generally thought to involve the transcriptional activation of cell-specific genes, among which is the brush-border structural protein villin. We have examined the molecular mechanisms of villin induction using both in vivo and in vitro systems. Total RNA was purified from rat tissues or cultured cells by the guanidinium thiocyanate method and Northern blot analyses carried out using radiolabeled complementary DNA probes specific for villin or the actin control. Transient transfection (calcium/phosphate method) assays were performed using a luciferase reporter gene containing 2 kb of the human villin gene 5'-flanking region. We have found that the villin mRNA was expressed at high levels in the small intestine, to a lesser degree in the colon, and was not detected in the brain or liver. In HT-29 cells, villin mRNA levels increased 2.5-fold (P<0.001) after 24 hours of sodium butyrate treatment, consistent with the process of enterocyte differentiation. Similarly, villin gene expression was induced in Caco-2 cells during postconfluence differentiation. Transient transfection assays demonstrated marked reporter gene activation (fourfold, P<0.001) in response to sodium butyrate in HT-29 cells, but no activation in the liver cell line HepG2. The effects of sodium butyrate were dose dependent, reaching a maximum at a concentration of 5 mmol/L. We conclude that a 2 kb region of the human villin gene is able to mediate its transcriptional activation during HT-29 cell differentiation. This DNA regulatory region appears to function in a cell type-specific (gut) manner.

[Isolation of human herpes virus 6 from peripheral blood of renal transplant recipients]

One strain of the viruses was isolated from preipheral blood lymphocytes (PBL) of a renal transplant recipient. PBL isolated from blood samples were cocultured with the PHA actived cord blood lymphocytes (CBL). Two of twelve recipient's samples found cytopathic effect after 10 to 14 days. Examination of ultrathin-sections of the virus infected cells by electron microscope showed herpes-like virus particles. Detection of indirect immunofluorescences with McAbs against HHV-6 was positive in the infected cells.

[Clinical observation on juvenile-children type of Coats' disease]

OBJECTIVES

To observe the clinical features and the effects of management of juvenile-children type of Coats' disease and to approach the classification of the disease.

METHODS

Fundus was examined and fundus fluorescein angiography (FFA) was made. Laser photocoagulation and cryotherapy were used for treatment.

RESULTS

Compared to adult type of Coats' disease, this type was characterized by early onset, severe macular lesion, rapid progression and poor visual prognosis. The vision in 75.0% of eyes was unchanged, and in 19.2% of eyes was improved after treatment.

CONCLUSIONS

Visual damage is more severe in this type. Early examination and early treatment are the key points to decrease visual deterioration. The classification of the disease is helpful in understanding the disease.

[Determination of chrysophanol in semen Cassiae by HPLC]

A HPLC method for the determination of chrysophanol in Semen Cassiae was investigated. The result showed that this method was simple, specific and accurate. The recovery was 99.0% and relative standard deviation was 1.8%. The method is useful for the quality control of this medicinal meaterial.

Thyroid hormone and the gut: selective transcriptional activation of a villus-enterocyte marker

BACKGROUND

Thyroid hormone (T3) is an important regulator of gut mucosal growth, differentiation, and barrier function, but its mechanism of action in the gastrointestinal tract is largely unknown. The present studies were carried out to define the molecular mechanisms by which T3 alters gut gene expression.

METHODS

In vivo: Adult, male, Sprague-Dawley rats were given three daily injections (intraperitoneal) of either saline solution or 30 micrograms/kg triiodothyronine. Small intestinal tissues were harvested, and Northern blot analyses were performed by using specific radiolabeled cDNA probes. In vitro: HT-29 cells were transfected with reporter plasmids and treated with or without T3, and chloramphenicol acetyltransferase activity was measured.

RESULTS

The T3-induced changes in enterocyte gene expression occurred in villus enterocytes and not in crypt cells and were independent of food intake. Northern analyses with an intron-specific probe revealed that the T3 induction in intestinal alkaline phosphatase (IAP) expression occurs at the level of transcription. Transient transfection assays revealed no T3-induced changes under basal conditions but marked increases (sixfold, p < 0.001) when a T3-receptor (TR beta-1) plasmid was cotransfected. Furthermore, T3 was found to induce greater IAP reporter gene activity in differentiated (+ sodium butyrate) compared with undifferentiated HT-29 cells.

CONCLUSIONS

T3 induces IAP expression at the level of gene transcription. Both in vivo and in vitro, IAP transcriptional activation occurs to a greater extent in differentiated enterocytes than in undifferentiated crypt cells. Transactivation of the IAP gene by T3 is mediated via a DNA cis-element(s) located within the 2.4 kb segment present in the reporter gene.

Cellular growth state differentially regulates enterocyte gene expression in butyrate-treated HT-29 cells

Enterocyte differentiation occurs at the crypt-villus junction through the transcriptional activation of cell-specific genes, including the brush-border enzyme intestinal alkaline phosphatase (IAP) and the microvillar structural protein, villin. Based upon previous in vivo studies demonstrating that IAP and villin are differentially affected by alterations in epithelial growth state, we examined the regulation of these two genes in an in vitro model of enterocyte differentiation. HT-29 cells were maintained in DMEM + 10% FCS and treated with sodium butyrate to induce enterocyte differentiation. Cell count and [3H]thymidine measurements confirm that sodium butyrate causes a marked decrease in cellular growth state, consistent with the differentiation process. Northern blot analyses revealed time- and dose-dependent increases (P < 0.001) in steady-state IAP and villin mRNA levels. The increases in both IAP and villin expression were dependent upon the presence of one or more newly synthesized proteins. Post-confluence and serum starvation were used to cause cell cycle withdrawal prior to the differentiation process. As predicted from our previous in vivo data, villin expression was unaffected by changes in cellular growth state, whereas IAP expression was dramatically diminished under hypoproliferative conditions. We conclude that early withdrawal from the cell cycle alters the course of enterocyte differentiation, specifically decreasing IAP expression.

Small bowel adaptation: counterregulatory effects of epidermal growth factor and somatostatin on the program of early gene expression

BACKGROUND

Small intestinal crypt cell proliferation is essential to the normal renewal of the epithelium, as well as the adaptive responses that follow resection or injury. The present studies were designed to elucidate the molecular mechanisms by which epidermal growth factor (EGF) and somatostatin interact to regulate crypt cell proliferation.

METHODS

Rat crypt (IEC-6) cells were maintained in Dulbecco's modified Eagle's medium plus 10% fetal calf serum and treated with EGF (10 or 100 ng/ml) or somatostatin (0.5 microgram/ml). Cell counts were done to examine the effects on cellular growth, and Northern blot analyses were carried out by using complementary DNA probes corresponding to various protooncogenes.

RESULTS

EGF caused a 41% increase in cellular growth, an effect that was almost completely blocked by pretreatment (30 minutes) with somatostatin. EGF led to dramatic increases in c-fos (greater than 20-fold), c-jun (2-fold), and jun B (3-fold) gene expression at 30 minutes, consistent with the previously characterized immediate-early gene response in IEC-6 cells. Somatostatin alone had no effects on protooncogene levels, but pretreatment with somatostatin resulted in a marked inhibition (80%, p < 0.001 in all cases) of the EGF-induced increases in protooncogene expression.

CONCLUSIONS

Somatostatin inhibits the EGF-induced protooncogene expression in IEC-6 cells. The somatostatin inhibition of immediate-early gene expression lends support to its role as a negative growth regulator in intestinal epithelia and indicates that its effect occur at an upstream site in the cellular growth response.

Pattern of rat intestinal brush-border enzyme gene expression changes with epithelial growth state

Enterocyte growth and differentiation occur simultaneously within the epithelium, but little is known regarding any relationship between these two processes. Four rat models of small intestinal epithelial hypo- and hyperplasia (neonatal ontogeny, fasting/refeeding, hypo-/hyperthyroidism, and bombesin treatment) were used to study the regulation of enterocyte gene expression in relation to epithelial growth state. Mucosal scrapings, as well as crypt and villus cell populations, were subjected to Northern blot analyses using radiolabeled cDNA probes corresponding to lactase, intestinal alkaline phosphatase, villin, ornithine decarboxylase (ODC), and the actin control. In all four models, the hypoplastic (atrophic) condition is characterized by high levels of lactase and low levels of the 3.0-kb intestinal alkaline phosphatase mRNA, whereas under hyperplastic conditions this pattern is reversed. The changes in intestinal alkaline phosphatase and lactase are qualitatively similar along the longitudinal axis of the intestine and are proportional to the degree of hyperplasia, as verified by ODC mRNA levels. Furthermore, the crypt-villus axis of differentiation is maintained regardless of epithelial growth state. In conclusion, the pattern of brush-border enzyme gene expression changes as a function of epithelial growth state, indicating a previously unrecognized degree of plasticity to the state of enterocyte differentiation.

[A new method for qualitative determination of astragaloside]

A multi-function column has been devised for qualitative determination of astragaloside in Yuanheng-yitai Chutang Tablets. The result of experiment shows that the method is convenient fast and stable.

Differential cloning of novel intestine-specific genes whose expression is altered under conditions of villus atrophy

Atrophy of the small intestinal villi occurs in a variety of disease states and is associated with diarrhea, malabsorption, and impaired barrier function. We have previously demonstrated that villus atrophy is associated with an increase in lactase and a decrease in intestinal alkaline phosphatase gene expression. Given these changes in enterocyte phenotype with villus atrophy, we speculated that there may be other intestine-specific genes whose expression is altered as a function of epithelial growth state. We have employed two molecular techniques in order to identify and clone complementary DNAs (cDNA) which are differentially expressed in atrophic compared to normal small intestinal mucosa. In differential cDNA library (+/-) screening, duplicate filters of a normal jejunal cDNA library are hybridized with radiolabeled cDNA probes from either atrophic or control tissues. Comparisons of the intensities of hybridized clones allows for the identification of differentially expressed gene products. In the mRNA differential display system, RT-PCR is used to randomly amplify mRNA species. Similar to cDNA library screening, comparisons of radiolabeled bands on a polyacrylamide sequencing gel allow for the identification of differentially expressed genes. Using these methods, we have identified a novel cDNA, called D9, which appears to be expressed exclusively in the intestinal mucosa. Northern analyses have confirmed that the expression of the D9 mRNA is dramatically decreased under conditions of villus atrophy, suggesting an underlying relationship with epithelial growth state. DNA sequence analysis (GenBank) reveals no identity to previously cloned genes.(ABSTRACT TRUNCATED AT 250 WORDS)

[The diagnosis and treatment of insulinoma: an analysis on 20 cases]

From 1967 to 1994, a total of 20 pathologically proved benign insulinoma cases were treated in our hospital. Tumors were solitary in 19 cases, and multiple in 1, with diameter ranging from 0.5 to 3.0 cm. Diagnosis was made by autopsy in one and by laparotomy in 19. All 18 cases except for the one dying of pancreatic fistula postoperatively during the same hospitalization were followed up for 1 to 18 years without recurrence. The authors recommended calcium infusion test as the standard method of diagnosis, analysed the false diagnosis in one patient, and discussed operative experience on tumors deeply buried in the head of the pancreas.

Thyroid hormone responsiveness is developmentally regulated in the rat small intestine: a possible role for the alpha-2 receptor variant

Thyroid hormone (T3) alters gene expression through binding to a receptor protein located within the nucleus of target cells. Multiple forms of the T3 receptor (TR) have been identified and are encoded by the alpha and beta c-erbA genes. We have previously found that TR beta-1 is the major receptor form expressed in the adult rat small intestine, although there are also moderate levels of c-erbA alpha-2, a nonhormone-binding variant that is thought to inhibit T3 action. In developing rats, we studied the regulation of two small intestinal enterocyte genes previously shown to be T3 responsive, lactase and 3.0-kilobase intestinal alkaline phosphatase (IAP). Animals were treated with six daily ip injections of either saline (control) or 30 micrograms/100 g BW T3 (T3 group) and killed at 10 and 25 days of age. Northern analyses of RNA derived from intestinal tissues showed that the magnitude of the T3-induced changes in lactase and IAP gene expression increased with development. Jejunal 3.0-kilobase IAP messenger RNA (mRNA) levels were unaffected by T3 at 10 days, but increased by 15-fold at 25 days. Similarly, jejunal lactase mRNA levels were unchanged by T3 at 10 days, but decreased by 75% at 25 days. Qualitatively similar results were seen in the duodenum and ileum. Studies of TR expression revealed that TR beta-1 mRNA levels were unchanged during the developmental period, whereas the levels of c-erbA alpha-2 decreased by 90% between 5-25 days after birth. These results indicate that the rat small intestine becomes increasingly T3 responsive during postnatal development. These changes occur in parallel with a decline in c-erbA alpha-2 levels, suggesting that this T3 receptor variant may play a role in this hormonal responsiveness.

Bombesin maintains enterocyte phenotype in fasted rats

BACKGROUND

Previous studies have suggested a relationship between enterocyte phenotype and the growth state of the epithelium; under atrophic conditions, lactase gene expression is high, whereas intestinal alkaline phosphatase (IAP) expression is low, and vice versa. On the basis of this model, we hypothesized that the intestinal trophic factor bombesin would alter brush-border enzyme gene expression in a predictable way.

METHODS

Adult rats were fasted for 48 hours and treated (intraperitoneally) with either 10 micrograms/kg bombesin or the saline control every 8 hours. Small intestinal mucosal scrapings were taken, total RNA purified, and Northern blot analyses performed with radiolabeled cDNA probes corresponding to lactase, IAP, villin, and actin. Tissue samples were also taken for measurement of mucosal thickness.

RESULTS

Bombesin administration caused an increase in jejunal mucosal thickness, thereby confirming its trophic effects. Bombesin resulted in a decrease in lactase mRNA levels and an increase in IAP mRNA levels along the length of the small intestine. No changes occurred in the expression of either villin or actin. The pattern of enterocyte gene expression in the bombesin-treated animals was similar to that in control-fed rats.

CONCLUSIONS

Bombesin differentially regulates rat enterocyte gene expression, decreasing lactase and increasing IAP mRNA levels. These results lend further support to the hypothesis that a close relationship exists between enterocyte phenotype and epithelial growth state.

Immediate-early gene expression in EGF-stimulated intestinal epithelial cells

The mammalian small intestinal epithelium is a continuously renewable population of cells which arise from a proliferative zone of undifferentiated stem cells within the crypts. Epidermal growth factor (EGF) is thought to play a role in the maintenance and proliferative response of the intestinal epithelium. In order to investigate the early changes in intestinal gene expression which occur in response to a mitogenic stimulus, we performed studies in two different cell lines (IEC-6 and HT-29), both of which have characteristics of intestinal crypt cells. Cells were grown in DMEM + 10% FCS at 37 degrees C/5% CO2 and treated with either EGF (10 ng/ml) and/or cycloheximide (CHx) (10 micrograms/ml) for various times. Northern blot analyses were performed on total RNA using 32P-labeled cDNA probes corresponding to various protooncogenes. Our results showed that EGF treatment caused rapid increases in c-fos, c-jun, and junB expression (P < 0.001) in both cell lines. c-fos and c-jun followed similar time courses, peaking at 30 min, whereas junB levels plateaued at 1 hr. The magnitude and time course of protooncogene induction by EGF were similar in the two cell lines. A dose-response experiment indicated peak EGF effects at 10 ng/ml. CHx treatment resulted in greater and more prolonged increases in protooncogene expression when compared to EGF alone, indicating that protein synthesis is not required for protooncogene induction.(ABSTRACT TRUNCATED AT 250 WORDS)

Temporal pattern of rat small intestinal gene expression with refeeding

Studies were carried out to elucidate the molecular mechanisms underlying small intestinal epithelial growth. Adult rats were fasted for 4 days and then refed a chow diet for up to 48 h. Histological examination confirmed the sequential occurrence of mucosal atrophy and hyperplasia. Northern blot analyses of RNA derived from small intestinal mucosal scrapings revealed a striking pattern of alterations in the expression of two different categories of genes. There were very early increases in the expression of c-fos and c-jun, reflecting the mitogenic response to refeeding that occurs within the crypt compartment. Studies using the protein synthesis inhibitor cycloheximide suggest that c-fos and c-jun are part of the "immediate-early" response of the small intestine. At later time points after the refeeding stimulus, differential changes occurred in the expression of the brush-border enzymes, lactase, and intestinal alkaline phosphatase (IAP). Refeeding caused a decrease in lactase gene expression and an increase in the expression of the 3.0-kb IAP mRNA species, reflecting a return of the villus phenotype to the normal fed state. Thus we have demonstrated a complex and temporally related pattern of gene expression within the small intestinal epithelium upon refeeding. The results provide insight into the relationship between the processes of intestinal growth and differentiation.

[Experimental and epidemiological studies on the interrelationship of thiocyanate and thyroid function]

The testing of a SCN- dose (32 mg NaSCN/kg oral 21 d long) which is about 100 fold above the alimentary SCN(-)-uptake on guinea pig has shown neither histologic/morphometrical nor clinical clue to thyrostatic effect. In 6 regions of the GDR (1,349 persons) has not been secured epidemiologically any relationship between SCN- serum level as well as SCN- urine level and goiter. The partly in the tendency low increase of SCN- level by patients with bland goiter was always under the levels of smokers without goiter, exceeded indeed the threshold of significance in the area of Werdau. In the industrial agglomeration areas the I(-)-SCN(-)-quotient at the most unfavourable cases ran to 3.5 (Halle, smoker, struma), was consequently close to the critical level of the goiter risk.

[TSH receptor antibody determination using the TSH radioreceptor antibody assay in clinical practice]

We tested the clinical valency of the TSH-receptor antibody (TBIAb) determination (TRAK assay, Fa. Henning) for the differential diagnostics of various diseases of the thyroid gland (n = 259), particularly of the hyperthyroidism. In 110 out of 114 basedowians TBAIAb could be proved (sensitivity 96%). The specifity to healthy persons (n = 20) was 100%, to the disseminated autonomy (n = 61) 92%. In 43 bland strumas and 22 cases of primary hypothyroidisms no circulating TBIAb were found. Of 40 cases of Basedow's hyperthyroidism the TBIAb titres were pursued during a 12-month methimazol therapy. In these cases was shown that negative antibody titres at the end of the treatment were connected with an essentially lower rate of early relapses than positive ones. Moreover, a highly dosed application of methimazol revealed a more favourable tendency than a low dosed one. From this we conclude that the TBIAb measurement with a commercial kit is a sensitive, sufficiently specific and practicable method for the differential diagnostics of hyperthyroidism and that to a certain degree it allows conclusions on the course of Basedow's disease after thyrostatic long-term therapy.

N-acetylator phenotypes in hyperthyroidism

Acetylator phenotypes were determined with sulfamethazine in 114 healthy volunteers, 87 patients with immunogenic hyperthyroidism (Graves' disease) and 38 patients with disseminated thyroid autonomies. About 90% of the patients were females. No significant differences of acetylator phenotypes were observed between female volunteers and hyperthyreotic patients younger than 50 years. The proportion of slow acetylators was higher in older patients. Early and late relapses did not depend on acetylator status.

[Results of thyroid hormone therapy in bland struma]

2,191 patients with bland struma were treated with tri-iodothyronine and a mixed preparation (thyreotom) for at least 2 years. Several clinical criteria were used for judgement. A good result could be obtained in 78.3 to 51.2% depending on the size of the struma (I-III). While in diffuse strumata good results were obtained in 87.8 to 69.0%, in nodular goitres we were successful only in 52.0-32.9%. The therapy may be successful at every age. Since with growing age the nodular goitres prevail, the chances of success become smaller. For the same reason there is a close correlation between age of the goitre and the therapeutic effect. The rate of success continuously decreases with growing age of the goitre. From this results that the therapy in goitre must begin early, before nodular and regressive changes, respectively, render the treatment difficult or render an acceptable result difficult.

[Problems of treatment with thyroid hormones. Thyroxin monotherapy or a T3/T4 combination preparation?]

At the instance of T3- and T4-measurements of the daily profile in the serum after the application of triiodothyronine and the usual T3/T4-combination preparations is referred to the unphysiologically high T3-peaks 2 to 4 hours after the application depending on the proportion of triiodothyronine. The three distributed all over the day doses of e.g. thyreotom do not sufficiently smooth such undulations. The lacking triiodothyronine serum peaks after application of pure thyroxin as a bolus confirm the demand of a thyroxin monotherapy. Nevertheless, for answering the question of the "physiologic thyroid hormone therapy" some problems remain open which are discussed. Taking into consideration these facts (particularly conversation and extrathyroid influence of the thyroid hormone metabolism) a combination of T3 to T4 in the ratio 1:10 is recommended.