Effects of the polyamine spermine on binding of follicle-stimulating hormone to membrane-bound immature bovine testis receptors

OAZ1 knockdown enhances viability and inhibits ER and LHR transcriptions of granulosa cells in geese

An increasing number of studies suggest that ornithine decarboxylase antizyme 1 (OAZ1), which is regarded as a tumor suppressor gene, regulates follicular development, ovulation, and steroidogenesis. The granulosa cells in the ovary play a critical role in these ovarian functions. However, the action of OAZ1 mediating physiological functions of granulosa cells is obscure. OAZ1 knockdown in granulosa cells of geese was carried out in the current study. The effect of OAZ1 knockdown on polyamine metabolism, cell proliferation, apoptosis, and hormone receptor transcription of primary granulosa cells in geese was measured. The viability of granulosa cells transfected with the shRNA OAZ1 at 48 h was significantly higher than the control (p<0.05). The level of putrescine and spermidine in granulosa cells down-regulating OAZ1 was 7.04- and 2.11- fold higher compared with the control, respectively (p<0.05). The CCND1, SMAD1, and BCL-2 mRNA expression levels in granulosa cells down-regulating OAZ1 were each significantly higher than the control, respectively (p<0.05), whereas the PCNA and CASPASE 3 expression levels were significantly lower than the control (p<0.05). The estradiol concentration, ER and LHR mRNA expression levels were significantly lower in granulosa cells down-regulating OAZ1 compared with the control (p<0.05). Taken together, our results indicated that OAZ1 knockdown elevated the putrescine and spermidine contents and enhanced granulosa cell viability and inhibited ER and LHR transcriptions of granulosa cells in geese.

Modulation by polyamines of gamma-glutamyl transpeptidase activity and lactate production in cultured Sertoli cells from immature and adult regressed golden hamster

Polyamines are involved in cellular growth and differentiation. To analyze a possible role of polyamines on the regulation of Sertoli cell function, we studied the effect of putrescine, spermidine, and spermine on gamma-glutamyl transpeptidase (gamma-GTP) activity and lactate production on Sertoli cell cultures obtained from immature and adult-regressed golden hamsters. Sertoli cells were cultured for 7 days. The 72 hour conditioned media obtained on day 6 were used to evaluate lactate levels. Gamma glutamyl transpeptidase activity was determined in the cells harvested on day 7. Cultured Sertoli cells isolated from immature and adult-regressed golden hamsters exhibited a clear morphological response to follicle-stimulating hormone (FSH) and to spermine. Gamma glutamyl transpeptidase activity increased in response to FSH in a dose-dependent manner. Dose-dependent stimulation of lactate production by FSH was also observed. For each functional parameter, a similar ED50 value of FSH stimulation was observed in both groups of animals. Spermine increased basal and FSH-stimulated gamma-GTP activity in immature and adult-regressed Sertoli cell cultures. A stimulatory effect of spermidine and putrescine on gamma-GTP activity was exclusively observed in adult-regressed Sertoli cell cultures. In Sertoli cells obtained from immature hamsters, spermine exerted a stimulatory effect on basal and FSH-stimulated lactate production. These results suggest that, in addition to the known effects of hormones and paracrine factors, polyamines may influence the functionality of Sertoli cells.

Polyamines in the photosynthetic apparatus : Photosystem II highly resolved subcomplexes are enriched in spermine

The three main polyamines putrescine (Put), spermidine (Spd) and spermine (Spm) were characterized by HPLC in intact spinach leaf cells, intact chloroplasts, thylakoid membranes, Photosystem II membranes, the light-harvesting complex and the PS II complex. All contain the three polyamines in various ratios; the HPLC polyamine profiles of highly resolved PS II species (a Photosystem II core and the rection center) suggest an enrichment in the polyamine Spm.

Characterization of nuclear corticosteroid receptors in rat adipocytes. Regional variations and modulatory effects of hormones

The corticosteroid receptor was investigated in isolated rat adipocytes with a new technique which characterizes the corticosteroid receptors that can be activated and tightly bound to the nucleus. The binding reaction with [3H]triamcinolone was performed with intact isolated adipocytes and the radioactivity associated with nucleus was subsequently determined after cell lysis. Scatchard analysis revealed a homogeneous class of nuclear corticosteroid receptors in rat epididymal adipocytes with an apparent Kd of 4.93 +/- 1.5 nM and a Bmax of 21.8 +/- 6.6 fmol/10(6) cells corresponding to about 13,000 receptors per nucleus. The corticosteroid binding exhibited regional variations in isolated adipocytes. The highest receptor number was found in epididymal adipocytes (Bmax 25.8 +/- 3.9 fmol/10(6) cells) whereas there were significantly lower nuclear binding sites in perirenal adipocytes (16.5 +/- 5.5 fmol/10(6) cells) (P less than 0.05) and subcutaneous adipocytes (4.8 +/- 1.5 fmol/10(6) cells) (P less than 0.01). The apparent affinity in the three fat depots were similar with Kd values about 4 nM. The nuclear corticosteroid receptor in adipocytes was steroid specific, as neither unlabelled estradiol nor testosterone were able to displace the [3H]triamcinolone binding at concentrations up to 100 microM. However, unlabelled progesterone and promegestrone (R5020) were able to compete with triamcinolone-binding (by 50-80%). In order to investigate whether the nuclear corticosteroid binding in adipocytes were under influence of other hormones we examined the effects of lipolytic and antilipolytic compounds on the binding. Preincubation with isoproterenol and dibutryl-cAMP for 1 h was able to decrease the corticosteroid binding by 30-50%. However, the antilipolytic hormone insulin had no effect in preincubations performed for up to 2 h. In conclusion, high affinity nuclear corticosteroid receptors were found in rat adipocytes. These receptors exhibited regional variations and were modulated by lipolytic hormones.

Characterization of antilipolytic action of polyamines in isolated rat adipocytes

The interactions of polyamines with the lipolytic system were studied in isolated rat adipocytes. Spermine, spermidine and putrescine significantly inhibited adenosine deaminase-stimulated lipolysis. An antilipolytic effect of spermine was detectable at a concentration of 0.25 mM (P less than 0.05). At a concentration of 10 mM all three polyamines inhibited the stimulated lipolysis by 50-60% (P less than 0.001). In addition, spermine enhanced the antilipolytic sensitivity of insulin. Spermine (1 mM) decreased the half-maximal inhibitory concentration of insulin from 320 +/- 70 pM to 56 +/- 20 pM (P less than 0.01). The antilipolytic effects and the cyclic-AMP-lowering effects of the polyamines were almost completely prevented in the presence of different phosphodiesterase (PDE) inhibitors (3-isobutyl-1-methylxanthine and RO 20-1724) and, in addition, polyamines had no effect on lipolysis stimulated by dibutyryl cyclic AMP, indicating that polyamines may inhibit lipolysis by activating the PDE enzyme. This latter suggestion was confirmed by demonstrating that spermine (5 mM) significantly enhanced the low-Km PDE enzyme activity (P less than 0.01). Finally, the amounts of polyamines present in isolated adipocytes were measured, and the estimated cytoplasmic concentrations were 0.02 mM (putrescine), 0.86 mM (spermidine), and 1.0 mM (spermine). It is concluded that polyamines may possibly be involved in the physiological regulation of triacylglycerol mobilization in adipocytes.

Polyamines in rat adipocytes: their localization and their effects on the insulin receptor binding

Effects of polyamines on the insulin binding in isolated rat adipocytes were studied. In addition, the concentration of polyamines in adipose tissue was determined, and their localization revealed by fluorescence cytochemistry and immunocytochemistry. Spermine (0.1-10 mM) dose-dependently enhanced the insulin receptor binding; at a concentration of 5-10 mM spermine the insulin binding was enhanced by 100% above control values. Spermidine had a weaker effect than spermine whereas putrescine had no effect on insulin binding. Competition curves with unlabelled insulin indicated that spermine increased the insulin binding capacity without significantly affecting the binding affinity. Fluorescence and immunocytochemistry on adipose tissue localized the polyamines spermidine and/or spermine almost exclusively to the thin layer of adipocyte cytoplasm surrounding the lipid droplet. In addition, chemical analysis for polyamines in the adipocyte medium and in the cells indicated that a differential release of polyamines may have occurred from the cells. The possibility that polyamines may act as intracellular or intercellular (autocrine) regulators, modulating insulin binding, is discussed.