Estrogen and progesterone receptor structure and action in breast cancer cells.
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Animals↗
Biomedical subjects
S Bettuzzi
Publications and source records attributed to S Bettuzzi.
Regional and cellular distribution within the rat prostate of two mRNA species undergoing opposite regulation by androgens.
We have investigated, by in-situ hybridization histochemistry, the distribution within the rat ventral prostate of the mRNAs for sulphated glycoprotein-2 (SGP-2) and ornithine decarboxylase (ODC; EC 4.1.1.17), two proteins that appear to be inversely regulated by androgens in this organ, in that the level of SGP-2 mRNA is lowered, while the activity of ODC is enhanced by the latter hormones. Low-magnification autoradiograms of whole ventral prostate sections showed that, in intact animals, the SGP-2 transcript was only detectable in restricted areas and not diffused evenly throughout the section. Reciprocally, the ODC transcript was not detectable in areas where the SGP-2 transcript was detected, but appeared distributed uniformly in the remaining parts of the section. The effect of castration on the levels of the two mRNAs was evaluated by a semiquantitative analysis of autoradiograms from whole ventral prostate sections using an autoimmune image analyser. Four days after castration, SGP-2 mRNA increased by about 11-fold, while ODC mRNA decreased by fivefold. The distribution of the two mRNAs among the different cell types, studied by treating the slides with photographic emulsion and counterstaining, showed that both were expressed exclusively in the epithelial luminal cells of the ducts. Furthermore, each of the two mRNAs preferentially accumulated in a cell population which was morphologically distinct while accumulation of the other was negligible. SGP-2 mRNA was mostly found in cuboidal epithelial cells and ODC mRNA in columnar epithelial cells. Castration caused a dramatic accumulation of SGP-2 and a decrease in ODC mRNAs in the cells of the columnar epithelium 4 days later.(ABSTRACT TRUNCATED AT 250 WORDS)
Androgens↗
Studies on the relationship between cell proliferation and cell death: opposite patterns of SGP-2 and ornithine decarboxylase mRNA accumulation in PHA-stimulated human lymphocytes.
To assess the relationship between cell proliferation and cell death, the mRNA accumulation of ornithine decarboxylase (ODC) and sulfated glycoprotein 2 (SGP-2) were measured in human peripheral blood lymphocytes (HPBL) 2-6 hours after stimulation with phytohemagglutinin (PHA). ODC is the rate limiting enzyme of polyamines biosynthesis and its early induction in mitogen-stimulated lymphocytes has been reported. On the other hand, SGP-2, a glycoprotein present in most mammalian tissues, is induced in classical models of apoptosis, such as dexamethasone-treated thymocytes. Indeed, a consistent amount of SGP-2 mRNA in quiescent HPBL, an early and progressive decrease of SGP-2 mRNA and a parallel increase of ODC mRNA accumulation, were observed, in PHA-stimulated HPBL, suggesting that concomitant repression of SGP-2 and induction of ODC genes contribute for the cell entering the cell cycle.
Blotting, Northern↗
In vivo accumulation of sulfated glycoprotein 2 mRNA in rat thymocytes upon dexamethasone-induced cell death.
Two hours after a single intraperitoneal injection of dexamethasone (20 micrograms/Kg b.w.) into adult male rats, a typical ladder of DNA fragments was detectable upon separation on agarose gels of DNA from thymocytes. This became maximally evident at 4 hours. Accumulation of sulfated glycoprotein-2 (SGP-2) mRNA, whose rate of expression has been associated to the processes of programmed cell death, preceded the appearance of DNA degradation, starting to increase as early as 30 min after steroid injection, and maintained higher than controls until 8 hrs; a different time course was shown by changes in the levels of beta-actin mRNA. In the spleen, under the same conditions, the SGP-2 message also increased at 30 min, prior to DNA fragmentation, but decreased thereafter below the control value.
Animals↗
The gene for SP-40,40, human homolog of rat sulfated glycoprotein 2, rat clusterin, and rat testosterone-repressed prostate message 2, maps to chromosome 8.
Sulfated glycoprotein 2 (SGP-2) is a rat glycoprotein that is particularly abundant in seminal fluid, where it is found associated with the acrosome and the tail of mature spermatozoa; for this reason it has been suggested that it has an important role in spermatogenesis. On the basis of nucleotide sequence homology, it has been proposed that the orthologous human gene is that coding for serum protein-40,40 (SP-40,40), a serum protein also called complement lysis inhibitor (CLI), SP-40,40 has been shown to act as a control mechanism of the complement cascade: in fact, it prevents the binding of a C5b-C7 complex to the membrane of the target cell and in this way inhibits complement-mediated cytolysis. SGP-2 and SP-40,40 seem then to be part of different biological systems. Furthermore it has been shown that another protein, testosterone-repressed prostate message 2 (TRPM-2), shares sequence homology with SGP-2 and SP-40,40. TRPM-2 is expressed at high levels and in a temporally precisely defined manner in dying cells, an observation that would suggest its involvement in the cascade of events leading to cell death. We have used a large panel of 24 mouse/human hybrid cell lines and a cDNA for SGP-2, which is also highly homologous to that for rat clusterin, to map the chromosomal location of the orthologous human gene. The mapping data and the Southern analysis presented in this paper, in addition to the data available from the literature, strongly suggest that in the human genome there is a single locus homologous to the probe used and that it codes for the protein which has been called, in different species, SP-40,40, SGP-2, clusterin, and TRPM-2. The chromosomal mapping of the locus for this multiname protein should facilitate its cloning and a better understanding of the apparently many biological functions of its product.
Animals↗
Identification of an androgen-repressed mRNA in rat ventral prostate as coding for sulphated glycoprotein 2 by cDNA cloning and sequence analysis.
The concentrations of a small number of mRNAs in the rat ventral prostate increase after castration and then decrease upon androgen treatment. Since the repression of specific gene expression may be important in the regulation of organ growth, we have cloned a cDNA for an androgen-repressed mRNA, the concentration of which increased 17-fold 4 days after castration, and this increase was reversed rapidly by androgen treatment. By sequence analysis the androgen-repressed mRNA was identified as that coding for sulphated glycoprotein 2.
Androgens↗
Increased levels of clusterin mRNA in the ventral prostate of the aging rat are associated to increases in cuboidal (atrophic) cell population and not to changes in apoptotic activity.
In the ventral prostate of the intact rat, clusterin mRNA is expressed in a small population of cuboidal epithelial cells undergoing apoptosis, but not in the columnar cells comprising the vast majority of the glandular epithelium. Upon castration, clusterin mRNA expression and apoptotic activity are turned off in the cuboidal cells and turned on in the columnar ones. We show here that the progressive enhancements in the abundance of clusterin mRNA, occurring in the rat ventral prostate upon aging, are based on increases of the cuboidal cells at the expense of the columnar ones. DNA fragmentation, a typical sign of apoptosis, assayed both by agarose gel electrophoresis and in situ staining, was undetectable in 3-month-old rats but was evident among the cuboidal cells of 24-month-old animals and columnar cells of 1-day castrates. The DNA content of the ventral prostate did not change significatively between young and old rats, indicating that no increase in the rate of cell death occurs within the age interval examined. It is concluded that the enhancement in cuboidal cell population, the consequent augmented accumulation of clusterin mRNA, and the increased frequency of DNA fragmentation that we have detected in the aging rat ventral prostate are not directly related to the rate of apoptosis.
Aging↗