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B Chatterjee

Publications and source records attributed to B Chatterjee.

At least 37 records · Page 2Linked to original sources
PubMed1988

Changes in transcriptional activity and matrix association of alpha 2u-globulin gene family in the rat liver during maturation and aging.

Hepatic synthesis of alpha 2u-globulin in the male rat begins at puberty (about 40 days), reaches a peak level at about 80 days, and ceases at about 750-800 days of age. The age-dependent changes in alpha 2u-globulin synthesis are correlated with both the steady-state level of the hepatic mRNA for this protein and the rate of transcription of the alpha 2u-globulin gene family. Transcriptional activation of the alpha 2u-globulin gene family at puberty and cessation of transcription at senescence correlate with the association and dissociation of this gene domain with the nuclear matrix. Unlike the alpha 2u-globulin gene, the albumin gene in the liver shows preferential association with the nuclear matrix throughout the life. From these results we conclude that the age-dependent changes in alpha 2u-globulin synthesis are due to the alteration in the rate of transcription of the alpha 2u-globulin gene, and that the association of this gene domain to the nuclear matrix is a prerequisite to its transcriptional activation.

Aging↗
PubMed1988

Acute elevation of blood carboxyhemoglobin to 6% impairs exercise performance and aggravates symptoms in patients with ischemic heart disease.

Acute exposure to carbon monoxide has the potential to impair exercise capacity in patients with ischemic heart disease. The effect of sufficient inhalation of this compound to gradually produce a level of 6% carboxyhemoglobin was studied in 30 nonsmoking patients with obstructive coronary artery disease and evidence of exercise-induced ischemia. After an initial training session, subjects were exposed to air or carbon monoxide on successive days in a randomized double-blind crossover fashion. Cardiac function and exercise capacity were assessed during symptom-limited supine radionuclide ventriculography. On the carbon monoxide day, mean postexposure carboxyhemoglobin was 5.9 +/- 0.1% compared with 1.6 +/- 0.1% (p less than 0.01) after air exposure. The mean duration of exercise was significantly longer after air compared with carbon monoxide exposure (626 +/- 50 s for air versus 585 +/- 49 s for carbon monoxide, p less than 0.05). Actuarial methods suggested that subjects were likely to experience angina earlier during exercise on the day of carbon monoxide exposure (p less than 0.05). Both the level (62 +/- 2.4 versus 60 +/- 2.4%, p = 0.05) and change in left ventricular ejection fraction at submaximal exercise (1.6 +/- 1.6 versus -1.2 +/- 1.6%, p = 0.05) were greater on the air exposure day compared with the carbon monoxide day. The peak exercise left ventricular ejection fraction was not different for the two exposures (57 +/- 2.5% for both). These results demonstrate earlier onset of ventricular dysfunction, angina and poorer exercise performance in patients with ischemic heart disease after acute carbon monoxide exposure sufficient to increase blood carboxyhemoglobin to 6%.

Aged↗
PubMed1987

Cloning and expression of the rat liver cDNA for peroxisomal enoyl-CoA hydratase, 3-hydroxyacyl-CoA dehydrogenase in lambda GT11. Transcriptional regulation of enzyme activity by Wy-14643 in primary cultures of rat hepatocytes.

Proliferation of rat liver peroxisomes by the hypolipidemic drug Wy-14643 is associated with a concomitant induction of peroxisomal enzymes involved in the beta-oxidation of fatty acids. In order to explore the molecular mechanism of this induction process we have cloned the cDNA for the peroxisomal bifunctional enzyme enoyl-CoA hydratase, 3-hydroxyacyl-CoA dehydrogenase (ECH) in the lambda gt11 expression vector. The library was screened with the monospecific rabbit antiserum to ECH. Hybrid-selected-mRNA translation established that the immunoreactive clones contain the cDNA sequences of the ECH bifunctional enzyme. The cloned cDNA was used to define the early events associated with enzyme induction in primary cultures of rat hepatocytes. Dot-blot hybridization of the total hepatocyte RNA with the ECH cDNA probe showed that the ECH mRNA begins to rise at about 10-15 h following incubation with Wy-14643. At 24 h and 48 h of incubation the stimulation of the ECH mRNA over the vehicle-treated control reached 26-fold and 47-fold respectively. Run-off experiments in the isolated nuclei of hepatocytes showed no increase in the transcription rate of the ECH gene at 5 h after drug treatment and a 2-fold and 11-fold increase at 10 h and 20 h of drug treatment. From these results we conclude that the increase in ECH activity by Wy-14643 is due to an enhancement of the rate of transcription of the ECH gene. However, the relatively long lag period of about 10-15 h after exposure of hepatocytes to Wy-14643 suggests that the induction of the ECH mRNA may involve an indirect effect of the drug on the transcription of this gene.

3-Hydroxyacyl CoA Dehydrogenases↗
PubMed1987

Molecular cloning and characterization of cDNA for androgen-repressible rat liver protein, SMP-2.

SMP-2 is a rat liver protein whose synthesis is influenced by both androgens and aging. The steady-state level of its mRNA is repressed by the androgen. Compared to the adult male, SMP-2 mRNA is found in higher amounts in the prepubertal and senescent male rat livers which show relative androgen insensitivity. A cDNA library in the plasmid pBR322 was constructed from the female rat liver which contains a high level of SMP-2 mRNAs. Recombinant plasmids were screened by differential colony hybridization to 32P-labeled single-stranded cDNAs from adult female and adult male hepatic poly(A)+ RNAs. From a total of 3500 recombinant clones, 11 highly female specific clones were identified. From these female specific colonies the SMP-2 cDNA-containing plasmid (pSP11) was identified by its ability to select an mRNA species whose translation product is immunochemically and electrophoretically indistinguishable from SMP-2. This insert represents a 571-base pair portion of the SMP-2 cDNA. Rescreening of the library at a high colony density using the 32P-labeled cDNA insert of pSP11 identified several positive clones with larger inserts. Hybrid-selected mRNA translation again confirmed these clones to carry SMP-2 cDNA sequences. The plasmid pSP4a containing a 1040-base pair cDNA insert of SMP-2 was characterized by DNA sequence analysis. The size of the cDNA insert of pSP4a is close to the estimated size of the SMP-2 mRNA. The cDNA sequence provides an open reading frame of 282 amino acid residues. A comparison of the translated amino acid sequence with the protein sequences of NBRF-PIR, PSQNEW, and LOSALA data bases did not establish any sequence homology with known proteins. Northern blot analysis using the 32P-labeled cDNA insert of pSP4a confirms the androgenic repression of the SMP-2 mRNA.

Amino Acid Sequence↗
PubMed1987

Androgenic regulation of hepatic gene expression.

Androgen-dependent synthesis of alpha 2u globulin in the rat liver has been used in our laboratory as a model for studying the effect of sex hormones on hepatic gene expression. alpha 2u Globulin is a group of low molecular weight (Mr approximately 18,000) male specific urinary proteins synthesized and secreted by hepatocytes. In the male rat hepatic synthesis of alpha 2u globulin begins at puberty (approximately 40 days), reaches a peak level (approximately 20 mg/day) at about 75 days and declines during old age. Androgens can induce alpha 2u globulin in ovariectomized female rats in vivo and in the liver perfusion system in vitro. However, both prepubertal and senescent (greater than 800 days) male rats not only do not produce alpha 2u globulin but are also refractory to androgen administration. alpha 2u Globulin is coded by a multigene family comprising about 20-30 gene copies per haploid genome. All of these gene copies seem to express translationally active mRNAs giving rise to individual isoforms of alpha 2u globulin. Appearance and disappearance of the cytoplasmic androgen-binding protein (CAB) correlates with the androgen responsiveness of hepatocytes. Photoaffinity labeling of the hepatic cytosol shows that the biologically active binding protein, found in the cytosol of the mature male rat liver, has a molecular weight of 31 kDa. A molecular transition of the 31-kDa CAB to a biologically inactive 29-kDa form may be the basis of hepatic androgen insensitivity during prepuberty and senescence.

Alpha-Globulins↗
PubMed1986

Partial reversal of alpha 2u globulin gene expression by thyroxine in the liver of diabetic rats.

Synthesis of alpha 2u globulin and its mRNA has been used as an index to monitor the effect of thyroxine on specific gene expression in the liver of hypoinsulinemic male rats. Administration of a physiological dose of thyroxine can partially reverse (to approximately 30% of the normal control) the marked reduction (more than 90%) in the hepatic levels of alpha 2u globulin and its mRNA during streptozotocin-induced diabetes. Estimation of newly synthesized alpha 2u globulin RNA transcripts from the native chromatin of isolated liver nuclei by "nuclear runoff experiments" showed that thyroxine can elevate the rate of transcription of alpha 2u globulin gene in the diabetic rat. Hypoinsulinemic diabetes is also found to be associated with an approximately 35% reduction in the thyroid hormone receptor level as compared to the normal control. The stimulatory effect of thyroxine on the synthesis of alpha 2u globulin and its mRNA was also evident in spontaneous diabetic Wistar "BB" rats. From these studies it can be concluded that severe hypoinsulinemia can cause a decrease in thyroid hormone action at the level of specific gene expression.

Alpha-Globulins↗
PubMed1986

Effect of anterior hypothalamic deafferentation and continuous growth hormone infusion on the hepatic synthesis of alpha 2u-globulin in the male rat.

Anterior hypothalamic deafferentation and infusion of human GH (hGH) in the normal male rat caused a marked reduction in the hepatic concentration of alpha 2u-globulin, an androgen-dependent protein. Although s.c. injections of hGH (twice-daily) resulted in more than a 50% reduction in the hepatic level of alpha 2u-globulin, the same dose of hGH when administered continuously through osmotic minipumps caused a threefold greater inhibition. The decreased hepatic concentration of alpha 2u-globulin after hGH administration was associated with corresponding changes in the hepatic level of translatable alpha 2u-globulin messenger RNA. Continuous infusion of hGH through osmotic minipumps and removal of the anterior hypothalamic influence on GH secretion by deafferentation also caused a marked reduction in the cytoplasmic androgen-binding activity of the rat liver. These results suggest that alterations in the level and pattern of GH secretion may influence hepatic androgen-binding activity and alpha 2u-globulin synthesis.

Afferent Pathways↗
PubMed1984

Monoclonal antibodies to alpha 2u-globulin and immunocytofluorometric analysis of alpha 2u-globulin-synthesizing hepatocytes during androgenic induction and aging.

Stable hybridomas generated by fusion of spleen cells from hyperimmunized mice and mouse myeloma cells were cloned to prepare monoclonal antibodies to alpha 2u-globulin, an androgen-dependent urinary protein of hepatic origin. One of these monoclonal antibodies was used as a probe for immunocytofluorometric analysis of alpha 2u-globulin producing hepatocytes during androgenic induction and aging through fluorescence-activated cell sorting (FACS). FACS patterns of hepatocytes from mature male rats that produce high levels of alpha 2u-globulin showed tow distinct peaks, arbitrarily designated as peak I (weakly fluorescent) and peak II (brightly fluorescent). In the mature male rat, peak II represented about 40% of the total hepatocytes, and the fluorescence intensity of this subpopulation decreased in direct correspondence with the gradual decline of alpha 2u-globulin synthesis during aging. Similarly the androgenic induction of this protein in ovariectomized female rats was associated with an increase in the fluorescence intensity of the hepatocyte subpopulation under peak II rather than an increase in the relative number of these cells. From these results we conclude that the androgen-dependent synthesis of alpha 2u-globulin and its alteration during aging are confined to a specific subpopulation of hepatocytes within the liver.

Aging↗
PubMed1983

Reversible alteration of hepatic messenger RNA species for peroxisomal and non-peroxisomal proteins induced by the hypolipidaemic drug Wy-14,643.

Extensive peroxisomal proliferation in the hepatic parenchymal cells was observed when male rats were given a diet containing 0.1% Wy-14,643 [( 4-chloro-6-(2,3-xylidino)-2-pyrimidinylthio]acetic acid), a potent lipid-decreasing drug. This drug also caused a marked increase in the concentrations of the mRNA species coding for four proteins with Mr 77000, 61000, 43000 and 31000, and a similar decrease in the concentrations of three mRNA species coding for proteins of Mr 25000, 24000 and 19000. Specific immunoprecipitation studies identified the proteins of Mr 19000, 43000 and 77000 as alpha 2u-globulin, 3-ketoacyl-CoA thiolase (EC 2.3.1.16) and enoyl-CoA hydratase (EC 4.2.1.17) respectively. Comparisons of the Mr values suggest that the 61000- and 31000-Mr proteins may be equivalent to two additional peroxisomal enzymes, namely catalase (Mr 61000) and uricase (Mr 31000). The identity of the mRNA species coding for the 25000- and 24000-Mr proteins is at present unknown.

Animals↗
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↗