Hormone-Induced Activation of Target-Specific Lysosomes: Acute Translocation to the Nucleus After Administration of Gonadal Hormones in Vivo

Abstract

Recent evidence from these laboratories has implicated the primary lysosomal population of specific target cells in the selective reception of steroid hormones at the cell periphery. This phenomenon was shown to be associated with covert labilization of the lysosomal bounding membrane. It has now been demonstrated that this interaction with trophic hormones results in rapid migration of lysosomes to a perinuclear position. Suspensions of nuclei were isolated from preputial glands of ovariectomized rats within short intervals after administration of gonadal hormone in vivo. Identification of cellular organelles by ultraviolet fluorescence microscopy was carried out on preparations subjected to intravital staining in vitro with acridine orange. Lysosomes were present in high concentrations in nuclear fractions of preputial glands from animals pretreated with oestradiol-17\g=b\, diethylstilboestrol, or testosterone, and essentially absent in preparations obtained from animals injected with oestradiol-17\g=a\or control solution. The response could be detected within 1 min of hormone administration, was obtained with as little as 0\m=.\1\g=m\ghormone/100 g body wt, and was not observed in preparations from lung tissue. In the early stages of hormonal activation, lysosomes in preputial gland preparations formed adherent perinuclear clusters and appeared relatively intact. However, lysosome fragmentation and dissolution rapidly ensued and was accompanied by the appearance of polynuclear\p=m-\multilysosomalaggregates. Concomitantly, isolated lysosome preparations subjected to enzymatic analyses revealed increased release from the particle-bound form of hydrolytic enzymes characteristic of these organelles. Progressive nuclear metachromasy was also observed after administration of the active hormones, suggesting the breakdown of macromolecules which yield products with enhanced capacity for binding acridine orange. These results suggested that modification of the nuclear surface and of intranuclear constituents, leading to altered adhesive-* Some of the present data were presented in preliminary form at the Third International Congress on Hormonal Steroids,

Intranuclear Concentration of Lysosomal Hydrolases in Steroid Target Cells

“…Moreover, hormonally-induced lysosomal enzyme concentration in the nucleoplasm of responsive target cells appeared to have a slightly later onset in these experiments. This was probably a reflection of the prompt arrest of lysosomal translocation as a result of immersion of the tissues in liquid nitrogen immediately on excision, rather than by pooling in beakers submerged in crushed ice until cellular disruption in aqueous media (see also [4,6]). Acid ribonuclease has also been found in liver nuclei prepared by the nonaqueous technique [38], whereas this activity was minimal in hepatic nuclei isolated by conventional aqueous methods [39].…”

“…As noted above in the case of estrogen influence, these findings were not attributable to generalized enhancement of enzymatic activities or to de novo synthesis, for they took place without concomitant change in the unfractionated homogenate (data not shown). In contrast, translocation of lysosoma1 hydrolases to the nucleoplasm failed to occur in response to androgen pretreatment in nuclei isolated from uterus of ovariectomized animals ( Table 2; see also [6]). Likewise, experiments with lysosome-enriched, or 'ultrapurified' nuclear, preparations from the adrenal glands of ovariectomized rats pretreated for short periods with physiological concentrations of estradiol-17D revealed no biochemical or morphological evidence of altered lysosomal function (not illustrated).…”

“…Intense and selective accumulation of tritiated hormonal steroids occurs in lysosome fractions of reproductive and sex accessory organs within seconds of exposure to the steroid in vivo or in vitro [4,5]. Subsequently, translocation of activated lysosomes to the nuclear region [6,7], followed by invasion of the nucleoplasm by lysosomal constituents [7,8], can be demonstrated with the use of cytochemical methods. Concomitantly, labilization of the lysosomal surface membrane occurs, as evidenced by escape of latent hydrolases and acidic matricular protein.…”

“…[6]). However, when the animals had been exposed in vivo to active steroid hormone in physiological concentration for even very brief periods, the nuclear surfaces retained rosettes of adherent lysosomes despite centrifugation through heavy sucrose.…”

“…Likewise, experiments with lysosome-enriched, or 'ultrapurified' nuclear, preparations from the adrenal glands of ovariectomized rats pretreated for short periods with physiological concentrations of estradiol-17D revealed no biochemical or morphological evidence of altered lysosomal function (not illustrated). Lysosomes from lung were similarly inert to estrogen administration in vivo by biochemical [9] and morphological [6] criteria. Thus, there is preferential localization of enzymes of lysosomal origin in the 'ultrapurified' nuclei of selective target cells induced by specific hormone.…”