Follistatins: more than follicle-stimulating hormone suppressing proteins.
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Amino Acid Sequence↗
Biomedical subjects
U Michel
Publications and source records attributed to U Michel.
Expression of follistatin messenger ribonucleic acid in Sertoli cell-enriched cultures: regulation by epidermal growth factor and protein kinase C-dependent pathway but not by follicle-stimulating hormone and protein kinase A-dependent pathway.
In this study the localization and regulation of steady-state follistatin messenger ribonucleic acid (mRNA) levels in testicular cell cultures were examined with a solution-hybridization assay using a specific 32P-labelled cytosolic RNA antisense probe for follistatin and a 35S-labelled cytosolic RNA antisense probe for cyclophilin as internal standard. Testes from immature rats were dispersed with collagenase and fractionated in Sertoli and Leydig cell-enriched cultures. Follistatin mRNA was mainly localized to the Sertoli cell-enriched fraction and the expression of follistatin mRNA could be stimulated in vitro with fetal calf serum, epidermal growth factor or phorbol-12-myristate-13-acetate (an activator of protein kinase C), whereas follicle-stimulating hormone and forskolin (an activator of protein kinase A) had no effect. Neither prostaglandin E2, the synthetic glucocorticoid RU 28362 or all-trans-retinoic acid, which all regulate follistatin mRNA levels in non-testicular cell types, nor extracellular adenosine triphosphate (a purinergic receptor agonist) or testosterone had any obvious influence on follistatin mRNA levels in Sertoli cell-enriched cultures. From this study it is concluded that Sertoli cells are likely to be the source of follistatin expression in the rat testis, that follistatin mRNA levels in Sertoli cell-enriched cultures are subjected to regulation by epidermal growth factor and the protein kinase C-dependent pathway but are not regulated by extracellular adenosine triphosphate, follicle-stimulating hormone, all-trans-retinoic acid, prostaglandin E2, forskolin, testosterone or the glucocorticoid RU 28362 and that the regulation of follistatin mRNA is sex- and tissue-specific.
Animals↗
Cardiovascular risk factors in schoolchildren.
A total of 1470 students in Berlin, Germany, aged 7-22 years, were screened for cardiovascular risk factors such as hypercholesterolemia, hypertension, obesity, smoking habits, and a positive family history. Only 56% had no modifiable risk factor, but 16% showed total cholesterol (TC) levels greater than 200 mg/dl. One percent had severe and 11% had borderline hypertension. Also, 21% were overweight, and 27% of the adolescents greater than or equal to 15 years admitted to smoking regularly. In this paper we concentrate on cholesterol findings of this study, i.e., the dependence of TC on sex, age, weight, and the use of oral contraceptives. There was an age dependency in both sexes. In boys the lowest TC levels were found in the 12-17-year-olds, whereas the group under 10 had the highest ones. In the age group over 17, TC was higher than in the younger groups. The age dependency of the TC levels in girls was similar, but less pronounced. The minimum level was reached earlier, namely in the group 14-15 years old, rather than in the group 16-17. TC levels of girls compared to boys were significantly higher in the 12-13 and 16-17 age groups. Girls who use oral contraceptives had significantly higher TC levels. Obesity had no influence on TC. Our results support the demand for screening for cardiovascular risk factors in children.
Adolescent↗
Follistatin steady state messenger ribonucleic acid levels in confluent cultures of a rat renal mesangial cell line are regulated by multiple factors.
The regulation of steady state levels of follistatin (FS) messenger RNA (mRNA) was examined in a rat renal mesangial cell line in tissue culture. A specific 32P-radiolabeled antisense probe was used which corresponds to the 3' end of exon 5 together with the 5' end of exon 6 of the rat FS gene, and which distinguishes between the two different forms of FS mRNA. In addition, a specific 35S-radiolabeled probe for the ubiquitous protein cyclophilin was developed and used as an internal standard. Total RNA was harvested from confluent cell cultures to yield four independent samples per treatment/time point, and equal amounts of RNA from every sample in a given experiment were subjected to S1-nuclease analysis for the estimation of specific mRNA levels. Treatment of the cultured cells with epidermal growth factor (10 nM) caused an 8- to 9-fold increase in the FS mRNA level after 4 h, but no consistent change was observed after treatment with basic fibroblast growth factor (0.28 or 0.56 nM), somatostatin (3.7-73 nM), angiotensin II (0.1-2500 nM), or FS itself (0.29 nM) for between 4 and 48 h. Neither activin (0.5 or 1.2 nM) nor inhibin (0.64 nM) changed the FS mRNA level in the mesangial cell line during a 24-h treatment. FS mRNA levels in the cells also were not affected by a 48-h treatment with the steroids dihydrotestosterone (1-1000 nM), estradiol (1 and 100 nM), and the antiprogesterone RU 486 (1000 nM), whereas 100 nM RU 28362 (a synthetic glucocorticoid) caused a 5- to 6-fold increase and 1000 nM progesterone increased the FS mRNA level up to 3.5-fold above control. Retinoic acid, a vitamin A derivative, significantly increased the FS steady state mRNA level at 3 nM, and at 1000 nM stimulated FS mRNA up to 5-fold within 4 h, whereas incubation of the cells with 30 microM prostaglandin E2 for 4 h caused a 10-fold increase. The FS mRNA level increased 3- and 4-fold within 4 h during incubation of the cells with 100 nM phorbol 12-myristate, 13-acetate, and 25 microM forskolin, respectively, whereas the calcium ionophore A23187 (1-100 microM) caused no change within this timespan. None of the tested hormones had an obvious effect on the ratio of the two different forms of FS mRNA (FS 344:FS 317).(ABSTRACT TRUNCATED AT 400 WORDS)
Activins↗
Expression of mRNA for follicle-stimulating hormone suppressing protein in ovarian tissues of cows.
The expression of bovine follicle-stimulating hormone (FSH)-suppressing protein (FSP) mRNA was investigated in different ovarian tissues of cows. Northern blot analysis, using a cDNA probe to bovine FSP, demonstrated that the FSP gene in the bovine ovary is highly expressed in a pool of isolated granulosa cells. Two bands (2.8 and 1.8 kb) were observed in all tissues expressing the mRNA. FSP mRNA was low in small antral follicles and increased in growing follicles to reach a maximum in preovulatory follicles. Low amounts of mRNA of steady state FSP were observed in all stages of the corpus luteum as well as in the corpus luteum of pregnant cows, in the corpus albicans and theca tissue, whereas this mRNA could not be detected in the liver. These results are consistent with the hypothesis that, in cows, FSP functions as an autocrine regulator in developing follicles to facilitate luteinization of granulosa cells.
Animals↗
Regulation of steady-state follistatin mRNA levels in rat granulosa cells in vitro.
The regulation of steady-state follistatin mRNA levels by different pituitary hormones and peptide factors was examined in granulosa cell cultures derived from diethylstilboestrol-treated immature rats. Cytosolic RNA from cell cultures was prepared by lysis and equal amounts of RNA from all samples were analysed with a solution-hybridization assay using a 32P-labelled antisense probe corresponding to a part of exon 5 together with a part of the 5' end of exon 6 of the rat follistatin gene. In addition, a specific 35S-labelled probe for cyclophilin was used as an internal standard. The results show that 5 micrograms FSH/l for 24 to 72 h stimulated steady-state follistatin mRNA levels, reaching levels 18.5-fold higher than controls. LH (0.2-100 micrograms/l) had only minor effects on follistatin mRNA levels in FSH-primed granulosa cells and prolactin, GH and IGF-I did not show any significant effects. Activin raised basal as well as FSH-stimulated steady-state follistatin mRNA levels up to ten- and twofold above controls respectively, whereas epidermal growth factor was found to inhibit FSH-stimulated follistatin mRNA levels in a dose-dependent manner. It is concluded that follistatin mRNA levels in granulosa cells are regulated by FSH rather than LH, and that the stimulation by FSH can be inhibited by epidermal growth factor but enhanced by activin. Activin alone was also capable of stimulating follistatin mRNA.
Activins↗
Rat follistatin: ontogeny of steady-state mRNA levels in different tissues predicts organ-specific functions.
Follistatin (FS), a monomeric glycoprotein which specifically binds activin, is expressed in many tissues. This study investigated 1) the ontogeny of the steady-state FS mRNA levels in different extragonadal tissues and 2) whether the ratio of the differential splicing products, FS 344 or its carboxy-truncated form FS 317, is changed during postnatal development. Whereas the levels of FS mRNA 344 in the kidney showed a profound increase from the day of birth to adulthood, the levels in the muscle peaked during the infantile period and then declined. Brain cortex, heart and thymus also showed tissue specific expression in the steady-state mRNA level of FS during postnatal development. None of the tissues showed a measurable change in the ratio of the mRNA for FS 344 and FS 317. The FS mRNA 344 levels in male and female kidney were not different. It is concluded that the ontogeny of steady state FS mRNA varies in a tissue specific manner during postnatal development of the rat and may be involved in modulating the outcome of activin.
Animals↗
Effects of growth factors and hormones on basal and FSH-stimulated inhibin production by porcine granulosa cells in vitro.
The effect of several growth factors, protein and steroid hormones on follicle stimulating hormone (FSH)-stimulated and basal inhibin secretion by mature porcine granulosa cells (g-cells) in culture was examined in order to elucidate the putative role of growth factors and hormones in the regulation of inhibin secretion by porcine g-cells in vitro. Cells were incubated with the respective hormones over a timespan of 0-144 h and immunoreactive inhibin was measured with a radioimmunoassay against porcine inhibin. Epidermal growth factor (EGF) and human transforming growth factor type beta (TGF-beta) decreased basal and gonadotrophin-stimulated inhibin and progesterone in a dose-dependent manner. In the absence of insulin, insulin-like growth factor type I (IGF-I) caused a 4-fold enhancement of basal inhibin secretion, but inhibin secretion was elevated only to 20% above control in the presence of 500 nM insulin. Porcine platelet-derived growth factor (PDGF) had no significant effect on basal or FSH-induced inhibin secretion by g-cells. In addition, neither gonadotrophin-releasing hormone (GnRH) nor prolactin (PRL), arginine vasopressin (AVP) and oxytocin affected basal or FSH-stimulated inhibin release by porcine g-cells. Oestradiol caused a slight but significant (P less than 0.01) rise of basal inhibin production (158% of control) in the last 2 days of culture (96-144 h) and the effect of androstenedione on basal (158% of control) and FSH-stimulated (140% of control) inhibin release (P less than 0.01) was also only visible on Days 4-6 of culture. In contrast to androstenedione and oestradiol, progesterone did not show any effect during 6 days of culture in a dose range of 10(-5) to 10(-9) M. Like steroids, prostaglandin E2 (PGE2) had a stimulatory effect on basal inhibin production (250% of control) by porcine g-cells, visible on Days 3-6 of culture, but an inhibitory effect on FSH-stimulated release (less than 40% of control). Over all the experiments with different hormones and growth factors, tested in varying doses and over a time span of 0-144 h, there was a strong correlation between progesterone and inhibin secretion by g-cells (0-48 h = 0.78; 48-96 h = 0.92; 96-144 h = 0.92). These results suggest that EGF, TGF-beta, IGF-I, oestradiol and androstendione as well as PGE2 have para- and/or autocrine modulatory effects on basal and FSH-stimulated inhibin secretion by mature porcine g-cells in vitro and further demonstrate that the secretion of the proteohormone inhibin and the steroid progesterone are closely related.
Androstenedione↗
The biphasic modulation of inhibin mRNA levels and secretion by PMSG in rat granulosa cells in vitro.
Granulosa cell cultures derived from diethylstilboestrol-treated immature rats were used to study the in vitro effect of pregnant mare serum gonadotrophin (PMSG) on steady state mRNA levels for the inhibin alpha and beta A subunits and the secretion of immunoreactive inhibin and progesterone. After 48 h treatment the dose-response curve of PMSG revealed a maximum stimulation (2.5-3.5 fold) of cytosolic alpha and beta A mRNAs over the range of 1 to 10 mU PMSG mL-1, with corresponding stimulation of inhibin secretion. A high dose of PMSG (160-500 mU mL-1) clearly suppressed inhibin alpha mRNA levels as well as inhibin secretion, whereas progesterone (P) was maximally stimulated (up to 600 fold). Although the level of cytosolic inhibin beta A subunit mRNA was also down-regulated by a high concentration of PMSG in the culture medium, the doses required to suppress its mRNA level to less than those of the control varied. These data demonstrate that low doses of follicle stimulating hormone/luteinizing hormone (FSH/LH)-like (PMSG) activity enhances and high doses decrease the steady-state mRNA levels of inhibin in rat granulosa cells in vitro; this biphasic regulation in vitro reflects the differential regulation of inhibin secretion observed during the rat oestrous cycle.
Animals↗
[Blood pressure with physical stress (ergometry) of 105 normotensive, borderline hypertensive and hypertensive children and adolescents].
Hypertension is one of the principal risk factors for cardiovascular diseases; its roots go back to childhood. A load study such as ergometry can help to recognise which persons are at risk. Ergometric measurements were performed by us on 105 children and adolescents, 72 of whom had borderline hypertensive or hypertensive blood pressure levels. Of these, the blood pressure rose during stress in 14%, the proportionate share being independent of the physical activity of the subjects. However, among those whose hypertension was on a borderline level, there was a disproportionately large percentage of obese subjects. These showed in addition an increase in blood pressure with increasing load and a reduced physical performance range. Obesity and lack of physical mobility had an unfavourable influence on blood pressure. Unfortunately there are no standardised rules for assessing the blood pressure during stress in children and adolescents. This would be all the more desirable since this easy examination is of prognostic value for an early discovery of manifest hypertension.
Adolescent↗
Rat follistatin: gonadal and extragonadal expression and evidence for alternative splicing.
Follistatin (FS) or FSH-suppressing protein is a polypeptide which exists in multiple forms and has inhibin-like activity. We investigated the distribution of tissues expressing FS mRNA. A segment of the rat FS mRNA corresponding to the last 157 nucleotides of exon 5 and the first 71 nucleotides of exon 6 was prepared by PCR and subcloned in plasmid GEM4Z (pGEM4Z) to produce a radiolabeled RNA probe. S1-Nuclease analysis of RNA extracted from rat tissues indicated alternative splicing of the rat FS gene and gonadal as well as extragonadal expression. In addition to the ovary and testis, the FS mRNA was detected in cerebral cortex, pituitary, adrenal, thymus, pancreas, gut, kidney, heart, uterus, skeletal muscle and lung. Treatment of female rats with combined Pregnant Mare Serum Gonadotropin (PMSG) and human Chorionic Gonadotropin (hCG) increased expression of FS mRNA in the ovary. Our results show that the mRNA for the precursor of the larger known form of FS (FS 344) is much more abundant than the mRNA for the smaller molecule (less than 5%) and that stimulation of FS transcription by PMSG and hCG in the ovary does not change this relationship.
Animals↗
Significance of the in vivo deuterated phenylalanine load for long-term phenylalanine tolerance and psycho-intellectual outcome in patients with PKU.
In 20 patients with PAH deficiency, in vivo RA was determined by an intravenous deuterated Phe load. Sixteen patients had RAs of less than 0.4% of normal, 3 a clearly detectable activity between 0.8 and 1.4% of normal. Long-term Phe tolerance as measured by the distribution of plasma Phe levels in categories (0-3.9, 4.0-9.9, 10-15.9 and over 16 mg/dl) was much improved in patients with RAs greater than 0.8%. There was a negative correlation between RA and number of plasma Phe levels greater than 16 mg/dl. Relationship between full scale IQ at the age of 9 years and dietary control showed a positive correlation between IQ and the number of Phe levels between 0-10 mg/dl (k = .50 p less than 0.05). Highest (negative) correlation (k = -0.67 p less than 0.007) was found between full scale IQ and the number of Phe values greater than 16 mg/dl as measured over 9 years. On the one hand detectable RA of PAH reduces the risk of high Phe levels and thus may also reduce the risk of brain damage in untreated or suboptimally treated patients with PAH. On the other hand enzyme measurement of PAH is no predictive parameter for Phe tolerance in an individual patient since RA may be very similar in phenylketonuric/hyperphenylalaninaemic patients. For practical purposes the oral protein loading test at the age of 6 months will give the most reliable results for differential diagnosis of PAH deficiency.
Aging↗
Results of psychological testing of patients aged 3-6 years.
Cognitive development of early treated PKU children (132) was investigated by intelligence tests, tests for visual perception, motor and language development. Deviations from test norms occurred at 5 years of age concerning performance IQ, mathematical thinking, and visual perception. With the exception of mathematical thinking, "normal" results were obtained at the age of 6 years. Correlation with levels of plasma Phe revealed a relation between quality of dietary control and performance IQ. Results are discussed in light of methodological aspects and with respect to treatment consequence.
Child, Preschool↗
Preliminary neuropsychological test results.
A series of information processing tasks was administered to 22 PKU children aged 8.5 years who had been under dietary treatment since birth as well as to 20 controls of the same age. This contribution presents the results of two tasks from this series: a continuous performance task and a calculation task. The continuous performance task revealed a sustained attention deficit in the PKU group. In the calculation task the PKU children were slower than the controls and this difference increased with task difficulty. When the PKU sample was divided in two groups (above and below the median value of the concurrent plasma Phe level), the high Phe level group performed much worse in comparison to the low Phe level group. The latter group actually matched performance level of the controls. This could be observed for both tasks. The serum Phe level, assessed since birth over 6 month periods, correlated highly with task performance. As regards sustained attention, the Phe level measured during the 2 years preceeding test administration appeared to be an even better predictor for task performance than the concurrent Phe level, a finding which seems to underline the chronic effect of Phe on basic attention mechanisms. The results so far seem to stress the value of well-controlled dietary restrictions.
Child↗
Inhibin production by porcine granulosa and luteal cells: development and biological validation of a RIA.
We describe the development and biological validation of a radioimmunoassay for immuno- and bioactive porcine inhibin. A synthetic 1-32 porcine inhibin peptide was used to raise an antiserum and Tyr-1-32 peptide as tracer. As standard we employed porcine follicular fluid calibrated with the 1-32 alpha-inhibin. Medium obtained from serum-free cultured porcine granulosa cells was chromatographed on Superose S-12 and Mono-Q. Resulting fractions were analysed for inhibin bio- and immunoreactivity. It is shown that granulosa cells produce at least two types of bioactive inhibins, one being also immunoactive in our RIA. We studied secretion of immunoreactive inhibin from porcine ovarian cells under various conditions: Inhibin secretion from mature and immature granulosa cells can be stimulated by FSH, whereas hCG enhances inhibin secretion only from mature granulosa cells. During extended time of culture, the capability of granulosa cells to secrete inhibin is reduced. In contrast, progesterone secretion from these cells increases; this is due to spontaneous functional luteinization. This assumption is supported by the low inhibin secretion of luteal cells in comparison to granulosa cells. Intracellular inhibin content in luteal cells is below detection limit of the RIA, whereas granulosa cells contain readily detectable amounts of this hormone.
Animals↗
[Pathophysiology of hyperprolactinemia in breast cancer].
To characterize the prolactin secretion in human breast cancer, plasma prolactin levels were measured in 514 patients with breast cancer in long term follow-up studies. In hyperprolactinemic patients suppression and stimulation tests were performed and the 24-h secretion profile was recorded. Tissue extracts and sera of hyperprolactinemic breast cancer patients were incubated with cultured pituitary cells in vitro to detect a prolactin releasing activity in these specimens. 44% of breast cancer patients developed hyperprolactinemia in the course of the disease. In 35% of measurements hyperprolactinemia was induced by non tumor related causes, e.g. prolactin-stimulating drugs, surgery, uremia, prolactinoma. Excluding such influences on the prolactin level, hyperprolactinemia over 1,000 mU/l was almost only found in patients with progressive metastatic disease. In these patients hyperprolactinemia was associated with tumor load, but not correlated to BSR, CEA or prognostic factors. Hyperprolactinemia in breast cancer was not of paraneoplastic origin. No prolactin-releasing activity was detected in tumor tissue and sera of hyperprolactinemic breast cancer patients.
Breast↗
Continuation vs discontinuation of low-phenylalanine diet in PKU adolescents.
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Adolescent↗
[Ophthalmologic prevention in premature infants].
Forty-four of the 262 pupils at the school for blind and visually handicapped children in Nuremberg, i.e., 17%, suffer from sequelae of retinopathy of prematurity (ROP); this condition is currently top of the list of causes of blindness. The risk factors involved were identified by analyzing 294 histories of premature children born between 1981 und 1984. In the case of 16 children, ophthalmoscopic criteria were taken from the 1984 international classification. The data of the children with ROP, at birth and at the time when ROP developed, were recorded on a prognosis card, in each case between the child's absolute age (abscissa) and birthweight in g (ordinate). In this way it was possible to read off the critical phase of retinal development for each newly examined child. This card facilitates monitoring, the provision of forensic evidence, the timing of ophthalmoscopy during critical phases of retinal development, and may also enable further relationships to be detected.
Birth Weight↗