Intranuclear Concentration of Lysosomal Hydrolases in Steroid Target Cells

Abstract

The present investigation was designed to determine whether the rapid intracellular redistribution of lysosomes to a perinuclear position in reproductive target cells after administration of specific gonadal hormones in vivo was accompanied by evidence of penetration of the nucleoplasm by lysosomal marker enzymes. Nuclei were prepared by conventional isolation and purification procedures from preputial glands or uteri that were excised from gonadectornized rats within 2-15 min after intravenous injection of physiological doses of estradiol-17/3, testosterone or saline control solutions. Control and experimental preparations were essentially "pure", as judged by routine phasecontrast microscopic criteria in general use. However, nuclei from target cells of animals given hormone contained substantial activities of representative lysosomal hydrolases, including acid phosphatase, /3-glucuronidase and acid ribonuclease 11. In contrast, the samples originating from the target tissue of saline-treated controls or from non-target tissues contained minimal concentrations of these enzyme activities. After further purification of the nuclei by removal of the outer nuclear membrane through brief exposure to very low concentrations of Triton X-100 in the cold, the resultant 'ultrapurified' nuclei retained significant concentrations of structurally latent lysosomal marker enzymes after hormonal pretreatment without evidence of appreciable contamination by enzymes of mitochondria1 origin. Similar results were obtained with nuclei isolated by non-aqueous procedures. These combined observations appear to exclude adsorption artifacts. The total activities of lysosomal enzymes in the unfractionated homogenates and the MgZ+-dependent ribonuclease activity indigenous to the nuclear compartment were unaffected by prior hormone treatment. These results are consistent with the hypothesis that invasion of the nucleoplasm of specific target cells by lysosomal products may serve as a mechanism for triggering genic derepression in steroid hormone-induced growth.

Immunocytochemical Localization of Bovine Serum Albumin (BSA) in the Liver and Testis of Rats injected with Testosterone-BSA, Hydrocortisone-BSA or Corticosterone-BSA.

“…In the rat liver cell membrane, corticosterone exhibits higher binding affinity than hydrocortisone in competition experiments (Suyemitsu and Terayama, 1975;Truebe et al, 1991). The administration of estrogen to rats results in the intranuclear accumulation of lysosomal enzymes in steroid target cells such as cells of the preputial gland (Szego et al, 1974). Markers of BSA such as gold seem to be more stable during intracellular digestion than BSA.…”

Steroid-Protein Binding: from Circulating Blood to Target Cell Nucleus

“…14, 15 in ref. 92; These phenomena are now believed attributable to concurrent invasion of the nucleus by lysosomal components as a result of action of endogenous [84,85] or administered [80,83,92,95,96] tropic hormone. The entry of lysosomal marker enzymes into the nuclear compartment, even when the nuclei have been rendered devoid of all morphologic evidence of ad herent cytoplasmic elements by removal of the outer nuclear membrane ('ultrapurified'), is illustrated in figure 6 and more extensively elsewhere [S3, 96], Such penetration of the nucleus by lysosomal components, a rapid by product of site-specific lysosome activation by tropic hormone, is not con fined to the steroids.…”

“…Incubation was conducted in duplicate for 3 h in a shaking bath at 37 °C in an atmo sphere of 0 2. The samples were then rapidly chilled, and the decanted incubation media were centrifuged at 105,000 g for 1 h. The resultant particle-free supernatant fractions were analyzed in triplicate for acid phosphatase activity with the precision described earlier [94,96].…”

“…5 min later, the paired adrenal glands from 20, each, experimental and control animals, respectively, were excised, pooled, and processed for isolation of 'ultrapurified' nuclei, stripped of outer membrane as described in Sxrcio cl al. [96]. The nuclei were analyzed for the two lysosomal marker enzymes indicated, as outlined in figure 6.…”

Lysosomal Membrane Stabilization and Antiestrogen Action in Specific Hormonal Target Cells (With colour plate I)

“…Long guided by recognition of the significance of the cytoarchitecture in the integrated response [1,2], and emphasizing ultrarapid, often highly transitory, correlates of hormonal interaction with these elements [3], our laboratories have recently identified lysosomal participation in the triggering of the chain of metabolic events leading to the induction of the normal growth process by certain steroid hormones in their cellular targets [4][5][6][7][8][9][10][11][12][13]. The data, to be summarized below, have permitted the formulation of a new and comprehensive model of hormonal control of growth, for the support of which there has been a surge of experimental evidence.…”