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B Bhandari

Publications and source records attributed to B Bhandari.

At least 19 recordsLinked to original sources
PubMed1991

A functional promoter flanks an intronless glutamine synthetase gene.

We recently reported the 5'-flanking nucleotide sequence of a putative glutamine synthetase (GS) gene from 3T3-L1 cells (Bhandari, B., Beckwith, K. D. & Miller, R. E. (1988) Proc. Natl. Acad. Sci. U.S.A. 85, 5789-5793). We now find that this gene (GSr) has many, but not all, of the characteristics of a typical retroposon. It lacks introns, it contains a short poly(A) tract at its 3' end; it is flanked by 10-base pair (bp) direct repeats; and it corresponds closely at its 5' end to the transcription start site of the intron-containing GS gene (GSi) (Kuo, C. F. & Darnell, J. E., Jr. (1989) J. Mol. Biol. 208, 45-56). GSr includes a full-length, uninterrupted coding sequence that differs little (less than 5%) from that of the intron-containing gene. By contrast, the 5'-flanking sequence of GSr has no similarity with that of GSi. The first 1,029 bp of the GSr 5'-flanking sequence drives expression of a promoterless bacterial chloramphenical acetyltransferase (CAT) gene in transfected HeLa cells at a level comparable to that of the Rous sarcoma virus promoter. Analysis of variably deleted GSrCAT fusions genes in both HeLa and 3T3-L1 cells indicates that full promoter activity of the 1,029-bp sequence requires greater than 348 bp. Moreover, nuclear extract from 3T3-L1 adipocytes as well as murine liver protects four segments in the GSr 5'-flanking sequence from DNase I digestion. Nevertheless, reverse transcription of RNA from 3T3-L1 adipocytes, mouse adipocytes, or mouse liver followed by primer-directed enzymatic amplification of the reverse transcripts reveals the presence of GSi transcripts but the absence of GSr transcripts. Thus, the 5'-flanking sequence of GSr is an active promoter that drives transcription of GSrCAT fusion genes and includes binding domains for proteins that have the potential to regulate transcription. We conclude that the intronless murine GS gene isolated from 3T3-L1 cells arose as a retroposon that was inserted into the genome downstream of a potentially active promoter.

Autoradiography↗
PubMed1991

Glycerol 3-phosphate dehydrogenase gene expression in cultured 3T3-L1 adipocytes: regulation by insulin, dexamethasone and dibutyryl cAMP at the level of mRNA abundance, transcription and mRNA stability.

In fully differentiated 3T3-L1 adipocytes, glycerol 3-phosphate dehydrogenase (G3PDH:Sn-glycerol 3-phosphate:NAD+ 2-oxidoreductase, EC 1.1.1.8) is subject to regulation by hormones and dibutyryl cAMP. An increase by insulin (4-fold) and decrease by dexamethasone (by 50%) and dibutyryl cAMP (by 70%) was observed for G3PDH mRNA abundance as analyzed by Northern blot hybridization. In addition, incubation of adipocytes with dibutyryl cAMP resulted in 3-fold increase in G3PDH gene transcription as measured by nuclear transcript elongation assay. The effects of these modulators on the control of G3PDH mRNA stability were also investigated. The G3PDH mRNA has a half-life of about 125 min. Dibutyryl cAMP caused an increase in G3PDH mRNA degradation by greater than 2-fold (t1/2 = 55 min) whereas insulin had an opposite effect (t1/2 = 240 min) and dexamethasone was without any effect on G3PDH mRNA stability. Taken together, our results directly demonstrate that in fully differentiated 3T3-L1 adipocytes the regulation of G3PDH gene expression by dibutyryl cAMP and insulin is exerted by alterations in transcription as well as mRNA stability.

3T3 Cells↗
PubMed1990

Hormonal regulation of stability of glutamine synthetase mRNA in cultured 3T3-L1 adipocytes.

In 3T3-L1 adipocytes, glutamine synthetase (GS; EC 6.3.1.2) is subject to regulation by dexamethasone, insulin and dibutyryl cyclic AMP (Bt2cAMP). Dexamethasone increases GS-mRNA content and GS-gene transcription, whereas insulin and Bt2cAMP prevent these increases. The effects of these modulators on the control of GS-mRNA stability were investigated. We report here that GS mRNA has a half-life of about 110 min. Bt2cAMP increases GS-mRNA degradation by greater than 2-fold (half-life 50 min), whereas insulin or dexamethasone have little effect on GS-mRNA stability. Down-regulation of GS-gene expression by Bt2cAMP will involve a co-ordinate response at the level of gene transcription and mRNA stability. However, the molecular mechanisms by which insulin and dexamethasone regulate GS-gene expression in cultured adipocytes remains to be elucidated.

Adipose Tissue↗
PubMed1989

Evaluation of nutritional and immunization services in a tribal ICDS block of Rajasthan.

The evaluation of nutritional and immunization services was undertaken in the tribal ICDS block Kherwara (Rajasthan) by comparing the results of door to door surveys conducted on pretested schedules in six randomly selected Anganwadi Villages at the start (1983) and after completion of 4 years of the project (1987). A significant improvement (p less than 0.001) was found in nutritional status of children below 6 years of age. Except for BCG, the study revealed improved vaccination coverage. However, the achievements were far less than the targets laid under the National Health Policy. Concerted efforts are required to improve the services further for achieving the desired goals.

Child Health Services↗
PubMed1989

Under utilization of MCH services--the major factor for very high IMR in rural Rajasthan.

Infant mortality rate (IMR) and its relation to the utilization of health services was studied in twelve villages of ICDS block Rajsamand, Rajasthan from 1st April, 1985 to 31st March, 1986. The total number of births and infant deaths were 386 and 74, respectively during one year, computing 37.44 as birth rate and 191.70 as IMR. Neonatal deaths contributed 51.4%, the most common causes of which were septicemia (28.9%), birth asphyxia (23.6%), extreme prematurity (18.4%) and tetanus neonatorum (13.1%). The common causes of deaths in post-neonatal period were pneumonia (36.1%), diarrhea (25.0%), complications of measles (16.7%) and that of pertussis (8.3%). Extreme under utilization of preventive, promotive and curative MCH services was found to be one of the major factors for very high IMR prevailing in the region.

Child Health Services↗
PubMed1988

Cloning, nucleotide sequence, and potential regulatory elements of the glutamine synthetase gene from murine 3T3-L1 adipocytes.

Glutamine synthetase [L-glutamate:ammonia ligase (ADP-forming); EC 6.3.1.2] specific activity, cellular content, mRNA abundance, and gene transcription rate increase by greater than 100-fold during adipocyte differentiation of 3T3-L1 cells. In 3T3-L1 adipocytes dexamethasone increases, whereas insulin as well as N6,O2'-dibutyryladenosine 3',5'-cyclic monophosphate decrease, glutamine synthetase gene expression. We analyzed the nucleotide sequence of a 1.9-kilobase Sal I-EcoRI restriction fragment from a 3T3-L1 glutamine synthetase genomic clone. This genomic fragment is composed of 1851 base pairs (bp) and includes the first exon and 1029 bp of the 5' flanking sequence. The 600 bp at the 3' end of the 1.9-kb Sal I-EcoRI restriction fragment constitute an open reading frame. We identified the transcription start site at a location 222 bp upstream of the glutamine synthetase coding sequences. The 5' flanking region of the gene encompasses several potential regulatory elements including TATA and CAAT sequences and a 40-bp poly(dT-dG).poly(dC-dA) putative enhancer element. Potential hormone and fat-specific regulatory elements are also located upstream of the transcription start site; they include glucocorticoid and cAMP response elements and fat-specific elements. These potential regulatory elements could account for the differentiation-associated changes and hormone-mediated changes seen in glutamine synthetase gene transcription and mRNA abundance.

Adipose Tissue↗
PubMed1988

Robinow syndrome.

Explore the source record for details and available documents.

Abnormalities, Multiple↗
PubMed1987

Glutamine synthetase gene transcription in cultured 3T3-L1 adipocytes: regulation by dexamethasone, insulin and dibutyryl cyclic AMP.

We have investigated the regulation of glutamine synthetase (GS) mRNA synthesis in cultured 3T3-L1 adipocytes. Specific mRNA synthesis (transcription) was analyzed by measuring elongation of transcripts in isolated nuclei. Transcription rate was assayed by hybridization of newly synthesized [32P]RNA to a GS cDNA. GS transcription rate increased more than 100-fold during adipocyte differentiation and was inhibited more than 90% by alpha-amanitin. In 3T3-L1 adipocytes dexamethasone stimulated GS gene transcription while insulin and dibutyryl cAMP decreased GS gene transcription.

Adipose Tissue↗
PubMed1987

Insulin and dexamethasone stimulate transcription of an amplified glutamine synthetase gene in Chinese hamster ovary cells.

We have investigated the regulation of glutamine synthetase (GS) mRNA synthesis in Chinese hamster ovary cell mutants which overproduce GS and contain an amplified GS gene. Specific mRNA synthesis was analyzed by measuring elongation of transcripts in isolated nuclei. Transcription was assayed by hybridization of newly synthesized [32P]RNA to a genomic GS clone. Nuclear transcript elongation was inhibited more than 90% by alpha-amanitin. The relative rates of GS mRNA synthesis in nuclei from cells incubated for 2 days with no additions, insulin, dexamethasone, or (Bu)2cAMP are 186, 419, 375, and 227 ppm, respectively. The insulin- and dexamethasone-mediated increases in GS transcription rate (2-fold) were associated with 3.7- and 5.8-fold increases in GS mRNA abundance. By contrast, alpha-tubulin gene transcription was not altered by insulin or dexamethasone; however, it was decreased by (Bu)2cAMP.

Animals↗
PubMed1986

Selection of a rat glutamine synthetase cDNA clone.

We have selected a glutamine synthetase clone (pGSRK-1) from a rat kidney cDNA library. A partial restriction map has been constructed for the 1.65 kilobase pair (kbp) glutamine synthetase cDNA. Northern hybridization analysis indicates that 1) GS-specific RNA increases many-fold during adipocyte differentiation and 2) dexamethasone increases and insulin decreases GS-specific RNA in 3T3-L1 adipocytes.

Adipose Tissue↗
PubMed1986

Glutamine synthetase mRNA in cultured 3T3-L1 adipocytes. Complexity, content and hormonal regulation.

Glutamine synthetase (GS) activity increases more than 100-fold during adipocyte differentiation of cultured 3T3-L1 cells. We now find that Northern hybridization analysis of RNA from 3T3-L1 adipocytes with a rat GS cDNA clone (pGSRK-1) yields two hybridizable GS RNAs of length 3.2 and 1.6 kilobases (kb). Densitometric analyses of autoradiographs of the Northern blots probed with pGSRK-1 indicate that the 3.2 kb GS-specific RNA is at least 4- to 5-fold more abundant than the 1.6 kb GS RNA. Analyses of both total and poly(A+)RNA from 3T3-L1 adipocytes yielded similar results. (It is noteworthy that an mRNA of 1.2 kb would be sufficient to encode the 42 500 Da GS subunit.) Quantitative dot-blot hybridization analysis indicates that dexamethasone increases GS mRNA while both insulin and dibutyryl cAMP decrease GS mRNA and/or prevent the dexamethasone-mediated increase. Our data suggest that there are at least two GS mRNAs in 3T3-L1 adipocytes and that they are regulated in parallel by dexamethasone, insulin and dibutyryl cAMP.

Adipose Tissue↗
PubMed1986

Glyburide action in cultured 3T3-L1 adipocytes.

During adipocyte differentiation of 3T3-L1 cells, glyburide increased the specific activity (mU/mg protein) of glycerol-3-P dehydrogenase (by at least 14-fold) and glutamine synthetase (by 5-fold). The glyburide-mediated increases in enzyme activities were greater in the presence than in the absence of insulin. Our data indicate that glyburide either potentiates or mimics the actions of insulin to increase the activity of glycerol-3-P dehydrogenase during adipocyte differentiation of cultured 3T3-L1 cells.

Adipose Tissue↗
PubMed1986

Hormonal regulation of amino acid uptake by cultured 3T3-L1 adipocytes.

Incubation of the adipocytes for 20 hours with insulin or with Bt2cAMP plus the theophylline stimulated adipocyte uptake of AIB and MeAIB but did not stimulate the uptake of glutamine or cycloleucine. MeAIB uptake by both 3T3-L1 preadipocytes and 3T3-C2 cells was relatively unresponsive to insulin. However, MeAIB uptake by 3T3-C2 cells was stimulated by treatment with Bt2cAMP plus theophylline. Incubation of 3T3 adipocytes for 60 min with insulin yielded maximal stimulation of 2-deoxyglucose uptake but no stimulation of the uptake of AIB, MeAIB or glutamine. Responsiveness of transport to Bt2cAMP does not appear to require adipocyte differentiation. By contrast, adipocyte differentiation may be required for the development of the insulin-responsive transport systems.

Amino Acids↗