Beta-adrenergic stimulation of c-fos gene expression in the mouse submandibular gland

Expression and induction by beta-adrenergic agonists of the cystatin S gene in submandibular glands of developing rats

Repeated administration of the beta-adrenergic agonist isoprenaline (isoproterenol, IPR), which produces hypertrophic/hyperplastic enlargements of rat submandibular and parotid glands, induces synthesis of a secretory protein shown to be a cysteine proteinase inhibitor, rat cystatin S. In the current study, Northern blot and hybridizations in situ were carried out to establish the developmental and beta-adrenergic regulation of the expression of the cystatin S gene. Cystatin S mRNA was not detected in submandibular glands of 20-day-old fetuses, nor in the glands of newborn or 10-day-old rats. However, steady-state levels of cystatin S mRNA increased between 21 and 28 days, reaching a conspicuously high concentration at 28 days; cystatin S mRNA then declined rapidly to a barely detectable level in glands of 32-day-old rats. IPR administration for 4 days induced high levels of cystatin S mRNA in submandibular glands of developing and adult rats. In both prepubertal and mature animals, induction of cystatin S mRNA in submandibular glands was more pronounced in female than in male animals. Hybridizations in situ revealed cystatin S mRNA only in acinar but not in duct cells of the submandibular gland. Developmentally, expression of the cystatin S gene coincided with acinar cell differentiation. These data suggest a complex neural, hormonal and developmental regulation of salivary cystatin genes.

Light and electron microscopic evidences of the presence of c-fos-like immunoreactivity in the rat adrenal cortex

The presence and localization of c-fos-like immunoreactivity in the rat adrenal cortex has been demonstrated by immunocytochemical methods at both light and electron microscopic level. C-fos-like immunoreactivity was detected in the zona fasciculata and the zona reticulata, but not in the zona glomerulosa. Ultrastructurally, all products of c-fos-like immunoreaction were localized exclusively in the regions associated with the euchromatin in the nucleus of the immunoreactive cells. Moreover, a higher density of the immunoreactive cells in the adrenal cortex of pregnant rats was found with quantitative immunocytochemistry as compared to the non-pregnant. The characteristic zonation of c-fos-like immunoreactivity in the adrenal cortex suggest that the c-fos protein is involved in the normal function of the glucocorticoid-producing cells of mammalian adrenals. The numerical increase in the immunoreactive cells in pregnant rats implies that basal expression of the c-fos-like protein may vary with the functional state of the cortical cells.

Regulation of nerve growth factor biosynthesis by beta-adrenergic receptor activation in astrocytoma cells: a potential role of c-Fos protein

The chain of events that results in increased production of nerve growth factor (NGF) following beta-adrenergic receptor (BAR) stimulation has been investigated in the C6-2B rat astrocytoma cell line. Exposure of these cells to the BAR agonist isoproterenol elicits the following cascade of events: (i) increase of cAMP content; (ii) increase of c-Fos mRNA content; (iii) accumulation of c-Fos protein immunoreactivity in the nucleus; (iv) increase of NGF mRNA content. The increase in c-Fos mRNA and its translation product are early events (15 and 40 min, respectively) and precede the accumulation of NGF mRNA, which peaks at 3 hr. The increase in the two mRNAs appears interrelated because cycloheximide inhibits the accumulation of c-Fos protein and NGF mRNA elicited by isoproterenol. Moreover, the accumulation of nuclear c-Fos protein and NGF mRNA induced by BAR stimulation is reduced by 2-aminopurine, an inhibitor of c-Fos mRNA induction. These data suggest that, in C6-2B astrocytoma cells, the nuclear accumulation of c-Fos protein is required for the induction of NGF mRNA expression by BAR stimulation.

A burst of c-fos gene expression in the mouse occurs at birth

Expression of the c-fos gene during murine perinatal development was studied. Before birth, all eight of the prenatal organs tested expressed undetectable or low levels of c-fos mRNA. On the day of birth, there occurred a 10- to 100-fold increase in the level of c-fos message in all of these organs. The expression was transient, in that 1 day after birth, the level of c-fos mRNA precipitously dropped. The c-fos gene expression at birth is unrelated to the expression of the c-myc gene and major histocompatibility complex class I genes, which display distinct kinetics during the perinatal development. The c-fos gene was also expressed locally and transiently in the gravid uterus 1 to 2 days prior to delivery. These results indicate that an event associated with birth induced c-fos gene expression in the mother and newborn.

A burst of c-fos gene expression in the mouse occurs at birth

Expression of the c-fos gene during murine perinatal development was studied. Before birth, all eight of the prenatal organs tested expressed undetectable or low levels of c-fos mRNA. On the day of birth, there occurred a 10- to 100-fold increase in the level of c-fos message in all of these organs. The expression was transient, in that 1 day after birth, the level of c-fos mRNA precipitously dropped. The c-fos gene expression at birth is unrelated to the expression of the c-myc gene and major histocompatibility complex class I genes, which display distinct kinetics during the perinatal development. The c-fos gene was also expressed locally and transiently in the gravid uterus 1 to 2 days prior to delivery. These results indicate that an event associated with birth induced c-fos gene expression in the mother and newborn.