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B Chatterjee

Publications and source records attributed to B Chatterjee.

At least 55 records · Page 3Linked to original sources
PubMed1983

Age-dependent regulation of the polymorphic forms of alpha 2u-globulin.

Hepatic synthesis of alpha 2u-globulin in the male rat shows a gradual decline and ultimate loss during aging and senescence. Northern blot analysis with a cloned cDNA probe showed that the decrease in alpha 2u-globulin synthesis during aging is associated with a corresponding decrease in the concentration of its hepatic mRNA. By means of two-dimensional gel electrophoresis, alpha 2u-globulin is resolved into a family of proteins. A monoclonal mouse antibody can identify at least five major isoelectric variants of alpha 2u-globulin within the total protein synthesized by rat hepatocytes. These isoelectric variants are also present in the in vitro translation products of hepatic mRNA. An examination of the hepatic synthesis of the isoelectric variants of alpha 2u-globulin during aging showed a differential regulation of the variant forms of this protein. Variant 2 (pI 6.1, the most prominent form) is the first to appear at puberty (40 days). The weakest member of the five major isoelectric forms (variant 4, pI 4.1) is the last to disappear at senescence. Although the overall decline in alpha 2u-globulin synthesis during aging seems to be due to an age-dependent decrease in the androgen responsiveness of hepatocytes, it is postulated that the differential regulation of the isoelectric variants may represent changes at the level of the genes coding for this protein.

Aging↗
PubMed1983

Interacting role of thyroxine and growth hormone in the hepatic synthesis of alpha 2u-globulin and its messenger RNA.

Hypophysectomy completely abolishes and thyroidectomy results in a 90% reduction in the hepatic content of alpha 2u-globulin and its mRNA in the male rat. Thyroid hormone is also known to be required for the synthesis and secretion of pituitary growth hormone. In the hypothyroid rat either thyroxine or growth hormone was found to increase the activity and number of sequences of the mRNA for alpha 2u-globulin (measured by translational assay and hybridizational analysis with a cloned cDNA probe) to the euthyroid level. Treatment of hypophysectomized rats with a hormone combination containing growth hormone but not thyroxine increased the hepatic level of the mRNA for alpha 2u-globulin to that of normal animals. From these results we conclude that thyroxine indirectly influences the hepatic concentration of the mRNA for alpha 2u-globulin through its effect on pituitary growth hormone. Although administration of growth hormone to hypothyroid animals raised the hepatic concentration of alpha 2u-globulin mRNA to the euthyroid level, synthesis of alpha 2u-globulin remained low (50% of the normal). Complete recovery of alpha 2u-globulin synthesis required thyroxine. Therefore, in addition to an indirect effect on the hepatic level of alpha 2u-globulin mRNA, thyroxine also directly influences the synthesis of this protein. This direct effect of thyroxine on alpha 2u-globulin synthesis seems to be exerted at a step distal to the formation of mature mRNA.

Alpha-Globulins↗
PubMed1983

Sexual dimorphism in the liver.

That the liver in oviparous females supplies the major part of the egg yolk proteins requires a marked degree of sexual dimorphism of this organ. In addition to vitellogenin, several minor components (e.g. vitamin binding proteins) are supplied by the liver to the oocyte in oviparous animals and to the developing embryo in viviparous females. Other metabolic adjustments to maintain reproductive competency of the female (e.g. increased lipid synthesis, detoxification of the waste products of the developing embryo, and reproductively sensible steroid metabolism) are some of the physiological bases for the differences between the female and male liver. Sex-differences in several other hepatic proteins, enzymes, and hormone receptors have also been established. alpha 2mu Globulin, Bond's protein, and carbonic anhydrase are clear examples of the sex specificity of rat liver. Differential expression of the genes for the male- and female-specific proteins in the liver is brought about by the androgenic and estrogenic hormones. The hepatic receptors for these hormones also show a marked degree of sexual dimorphism. During development and aging, these receptors seem to appear when the need for these hormones is most critical. The timely appearance of the hepatic estrogen and androgen receptor and the facilitated action of these hormones are mediated through "pre- and neonatal imprinting" by the sex hormones, especially androgen. Exploration of the physiological and molecular basis of this "imprinting" mechanism remains an exciting area of contemporary endocrinology.

Alpha-Globulins↗
PubMed1982

Synthesis and processing of the dimorphic forms of rat alpha 2u-globulin.

alpha 2u-Globulin the androgen-dependent male rat urinary protein, can be resolved into two distinct molecular forms by SDS-polyacrylamide slab gel electrophoresis. These two forms designated as alpha 2u-A (M, 18,800) and alpha 2u (Mr 18,100) are found both in urine and in the liver cells. Translation of rat liver mRNA in the rabbit reticulocyte lysate produced two preprotein forms of alpha 2u-globulin, designated as alpha 2uA' (Mr 20,300) and alpha 2uB' (Mr 19,600). Cell-free translation of rat liver mRNA in the presence of dog pancreas microsomal membrane or in Xenopus oocytes produced the two processed forms of alpha 2u-globulin (alpha 2uA and alpha 2uB). Quantitation of alpha 2uA and alpha 2uB within the in vitro translation products of the hepatic mRNA from albino rats of Yale, Sprague-Dawley and Fischer strains showed genetic differences in the proportion of translatable mRNA for alpha 2uA and alpha 2uB. The ratio of alpha 2uA: alpha 2uB in the translation products of liver mRNA from Yale rats was found to be 1:2.5 while in the case of both Sprague-Dawley and Fischer rats, the ratio was 1:4. A small portion of the alpha 2uA and alpha 2uB synthesized in the cultured hepatocytes, in the Xenopus oocytes or in the membrane-supplemented cell-free system appeared as two additional forms, designated as alpha 2uA" (Mr 21,200) and alpha 2uB" (Mr 20,600). Unlike alpha 2uA and alpha 2uB both alpha 2uA" and alpha 2uB" were found to bind to Con A-Sepharose, suggesting their glycoprotein nature.

Alpha-Globulins↗
PubMed1982

Pretranslational regulation of alpha 2u-globulin in rat liver by growth hormone.

Hypophysectomy is known to cause complete suppression of the hepatic synthesis alpha 2u-globulin. The effect of hypophysectomy on the synthesis of alpha 2u-globulin can be reversed by multiple hormone treatment. The role of pituitary growth hormone in the multihormonal regulation of alpha 2u-globulin in rat liver was examined in the hypophysectomized male rats with and without growth hormone supplementation. Daily treatment of hypophysectomized rats with 5 alpha-dihydrotestosterone, corticosterone, thyroxine, and growth hormone for 8 days caused about 80% recovery in the hepatic content of alpha 2u-globulin and its corresponding mRNA as determined by radioimmunoassay, in vitro translation, and liquid hybridization with a cloned cDNA probe. However, omission of growth hormone from the treatment regimen failed to raise hepatic alpha 2u-globulin and its mRNA to more than 5% of the normal control. The possible effect of growth hormone on the translation of the mRNA for alpha 2u-globulin was examined with cultured hepatocytes derived from growth hormone-deficient rats. Culture of these cells in the presence of growth hormone for 24 h did not turn on the synthesis of alpha 2u-globulin. These results indicate that growth hormone regulates the synthesis of alpha 2u-globulin by acting at a step antecedent to mRNA translation.

Alpha-Globulins↗
PubMed1981

Differential regulation of the messenger RNA for three major senescence marker proteins in male rat liver.

Changes in the mRNAs coding for specific hepatic proteins in male rats during aging were examined by in vitro translation of the liver mRNA in the rabbit reticulocyte lysate. Characterization of the [35S]methionine-labeled translation products by sodium dodecyl sulfate-polyacrylamide slab gel electrophoresis followed by autoradiography showed major age-dependent changes in the hepatic concentrations of three mRNA species. The translation products of these three mRNAs were found to have Mr = 28,500, 26,300, and 19,500 and are called senescence marker proteins (SMP) 1, 2, 3, respectively. On the basis of its immunochemical reactivity, SMP-3 (Mr = 19,500) is identified as alpha 2u-globulin while the mRNAs for SMP-1 (Mr = 28,500) and SMP-2 (Mr = 26,300) code for two yet uncharacterized proteins. The liver of the prepubertal male rats was found to contain the mRNA for SMP-2 and showed almost complete absence of the mRNAs for SMP-1 and SMP-3. However, the mRNAs for both SMP-1 and SMP-3 were present in the postpubertal young adults while the mRNA for SMP-2 was absent. Finally, when the animals reached senescence, the mRNAs for SMP-1 and SMP-3 disappeared from the liver with the reappearance of the SMP-2 mRNA. Age-dependent regulation of the mRNAs for these three senescence marker proteins can serve as an important model for the study of differential gene expression during aging.

Aging↗
PubMed1980

Messenger RNA for alpha 2u-globulin of rat liver. Purification, partial characterization of the mRNA, and synthesis of a Hae III restriction fragment as its cDNA probe.

The mRNA for the androgen-dependent hepatic protein, alpha 2u-globulin is normally present in the liver of mature male rats to the extent of about 1% of the total mRNA population. alpha 2u mRNA which was found to migrate as a 14 S band was purified about 18-fold through preparative urea-agarose gel electrophoresis. 32P-Labeled cDNA synthesized with this partially purified alpha 2u mRNA was used as substrate for two restriction endonucleases Hha I and Hae III. Digestion of the cDNA with Hha I failed to reduce its electrophoretic heterogeneity. However, Hae III digestion of the cDNA preparation greatly reduced the molecular complexity and produced several distinct cDNA bands. One of these Hae III fragments (Band A) containing 410 nucleotide residues was extracted from polyacrylamide gel and found to be complementary to alpha 2u mRNA. The identity of this cDNA fragment was established by its ability to inhibit selectively the translation of alpha 2u mRNA in the rabbit reticulocyte cell-free system and by its hybridization kinetics with poly(A)+ hepatic RNA from animals with different rates of alpha 2u synthesis. The relative R0t 1/2 values showed a direct correlation between mRNA sequences complementary to the cDNA fragment (A) and to both translatable alpha 2u mRNA and hepatic level of alpha 2u-globulin in adult male, female, and maturing male rats. Thus, the cDNA fragment containing 410 nucleotide residues generated by the restriction cleavage with Hae III can be used as a convenient probe for identification and quantitation of alpha 2u mRNA under different physiological and experimental conditions.

Alpha-Globulins↗
PubMed1979

Superinduction of alpha 2u globulin by actinomycin D: evidence for drug-mediated increase in alpha 2u mRNA.

Actinomycin D, an inhibitor of DNA-dependent RNA synthesis, increased the hepatic concentration of alpha 2u globulin, an androgen-inducible protein in the rat. Spayed female rats with a marginally induced state of alpha 2u synthesis showed an approximately 5-fold increase in hepatic alpha 2u globulin within 3-6 hr after treatment with actinomycin D. Initial treatment of these animals with 5 alpha-dihydrotestosterone, followed by actinomycin D, resulted within 2-3 hr in a more than 2-fold increase in hepatic alpha 2u globulin compared to animals treated with the androgen alone. In spite of inhibition of hepatic synthesis of poly(A)-containing RNA to less than 25% of control, superinduction with actinomycin D resulted in a parallel increase in the translatable mRNA for alpha 2u globulin. These results showing increase in both alpha 2u globulin and its translatable mRNA after superinduction with actinomycin D support the concept of post-transcriptional repression of alpha2u synthesis.

Alpha-Globulins↗