scholarly journals Chronic Exposure to High Glucose Concentrations Increases Proglucagon Messenger Ribonucleic Acid Levels and Glucagon Release from InR1G9 Cells1

Endocrinology ◽  
1999 ◽  
Vol 140 (10) ◽  
pp. 4644-4650 ◽  
Author(s):  
Eric Dumonteil ◽  
Beate Ritz-Laser ◽  
Chistophe Magnan ◽  
Iléana Grigorescu ◽  
Alain Ktorza ◽  
...  
Keyword(s):  
Gene Expression ◽  
High Glucose ◽  
Messenger Rna ◽  
Cell Function ◽  
High Plasma ◽  
Glucagon Release ◽  
Cell Content ◽  
Messenger Ribonucleic Acid ◽  
Elevated Glucose ◽  
Rna Levels

Abstract α cell function is impaired in diabetes. In diabetics, plasma levels of glucagon are high despite persistently elevated glucose levels and may even rise paradoxically in response to a glucose load; high plasma glucagon levels are accompanied by increased proglucagon gene expression. We have investigated the effects of high glucose concentrations on InR1G9 cells, a glucagon-producing cell line. We show here that chronically elevated glucose concentrations increase glucagon release by 2.5- to 4-fold, glucagon cell content by 2.5- to 3-fold, and proglucagon messenger RNA levels by 4- to 8-fold, whereas changes for 24 h have no effect on proglucagon messenger RNA levels. Persistently elevated glucose affects proglucagon gene expression at the level of transcription and insulin is capable of preventing this effect. We conclude that chronically elevated glucose may be an important factor in the α cell dysfunction that occurs in diabetes and thus that glucose may not only affect the β cell but also the α cell.

scholarly journals Differential Effects of Gonadotropin-Releasing Hormone (GnRH) Pulse Frequency on Gonadotropin Subunit and GnRH Receptor Messenger Ribonucleic Acid Levels in Vitro*

Endocrinology ◽  
1997 ◽  
Vol 138 (3) ◽  
pp. 1224-1231 ◽  
Author(s):  
Ursula B. Kaiser ◽  
Andrzej Jakubowiak ◽  
Anna Steinberger ◽  
William W. Chin
Keyword(s):  
Gene Expression ◽  
Messenger Rna ◽  
Pulse Frequency ◽  
Gnrh Receptor ◽  
Pituitary Cells ◽  
Mrna Levels ◽  
Subunit Gene ◽  
Differential Effects ◽  
Messenger Ribonucleic Acid

Abstract The hypothalamic hormone, GnRH, is released and transported to the anterior pituitary in a pulsatile manner, where it binds to specific high-affinity receptors and regulates gonadotropin biosynthesis and secretion. The frequency of GnRH pulses changes under various physiological conditions, and varying GnRH pulse frequencies have been shown to regulate differentially the secretion of LH and FSH and the expression of the gonadotropin α, LHβ, and FSHβ subunit genes in vivo. We demonstrate differential effects of varying GnRH pulse frequency in vitro in superfused primary monolayer cultures of rat pituitary cells. Cells were treated with 10 nm GnRH pulses for 24 h at a frequency of every 0.5, 1, 2, or 4 h. α, LHβ, and FSHβ messenger RNA (mRNA) levels were increased by GnRH at all pulse frequencies. α and LHβ mRNA levels and LH secretion were stimulated to the greatest extent at a GnRH pulse frequency of every 30 min, whereas FSHβ mRNA levels and FSH secretion were stimulated maximally at a lower GnRH pulse frequency, every 2 h. GnRH receptor (GnRHR) mRNA levels also were increased by GnRH at all pulse frequencies and were stimulated maximally at a GnRH pulse frequency of every 30 min. Similar results were obtained when the dose of each pulse of GnRH was adjusted to maintain a constant total cumulative dose of GnRH over 24 h. These data show that gonadotropin subunit gene expression is regulated differentially by varying GnRH pulse frequencies in vitro, suggesting that the differential effects of varying GnRH pulse frequencies on gonadotropin subunit gene expression occur directly at the level of the pituitary. The pattern of regulation of GnRHR mRNA levels correlated with that of α and LHβ but was different from that of FSHβ. This suggests that α and LHβ mRNA levels are maximally stimulated when GnRHR levels are relatively high, whereas FSHβ mRNA levels are maximally stimulated at lower levels of GnRHR expression, and that the mechanism for differential regulation of the gonadotropins by varying pulse frequencies of GnRH may involve levels of GnRHR. Furthermore, these data suggest that the mechanisms whereby varying GnRH pulse frequencies stimulate α, LHβ, and GnRHR gene expression are similar, whereas the stimulation of FSHβ mRNA levels may be different.

scholarly journals Regulation of tropomyosin gene expression during myogenesis.

1981 ◽  
Vol 1 (3) ◽  
pp. 289-301 ◽  
Author(s):  
M Moss ◽  
R Schwartz
Keyword(s):  
Gene Expression ◽  
Nucleic Acid ◽  
Messenger Rna ◽  
Deoxyribonucleic Acid ◽  
Critical Role ◽  
Fold Increase ◽  
Nucleic Acid Content ◽  
Total Nucleic Acid ◽  
Synthetic Capacity ◽  
Rna Levels

In skeletal muscle, tropomyosin has a critical role in transduction of calcium-induced contraction. Presently, little is known about the regulation of tropomyosin gene expression during myogenesis. In the present study, qualitative and quantitative changes in the nucleic acid populations of differentiating chicken embryo muscle cells in culture have been examined. Total nucleic acid content per nucleus increased about fivefold in fully developed myotubes as compared to mononucleated myoblasts. The contribution of deoxyribonucleic acid to the total nucleic acid population decreased from 24% in myoblasts to 5% of total nucleic acid in myotubes. Concomitant with the decrement in deoxyribonucleic acid contribution to total nucleic acid was an increase in polyadenylated ribonucleic acid (RNA) content per cell which reached levels in myotubes that were 17-fold higher than those of myoblasts. Specific changes in the RNA population during myogenesis were further investigated by quantitation of the synthetic capacity (messenger RNA levels) per cell for alpha- and beta-tropomyosin. Cell-free translation and immunoprecipitation demonstrated an approximately 40-fold increase in messenger RNA levels per nucleus for alpha- and beta-tropomyosin after fusion in the terminally differentiated myotubes. Indirect immunofluorescence with affinity-purified tropomyosin antibodies demonstrated the presence of tropomyosin-containing filaments in cells throughout myogenesis. Thus, the tropomyosin genes are constitutively expressed during muscle differentiation through the production of tropomyosin messenger RNA and translation into tropomyosin protein.

Regulation of tropomyosin gene expression during myogenesis

1981 ◽  
Vol 1 (3) ◽  
pp. 289-301
Author(s):  
M Moss ◽  
R Schwartz
Keyword(s):  
Gene Expression ◽  
Nucleic Acid ◽  
Messenger Rna ◽  
Deoxyribonucleic Acid ◽  
Critical Role ◽  
Fold Increase ◽  
Nucleic Acid Content ◽  
Total Nucleic Acid ◽  
Synthetic Capacity ◽  
Rna Levels

In skeletal muscle, tropomyosin has a critical role in transduction of calcium-induced contraction. Presently, little is known about the regulation of tropomyosin gene expression during myogenesis. In the present study, qualitative and quantitative changes in the nucleic acid populations of differentiating chicken embryo muscle cells in culture have been examined. Total nucleic acid content per nucleus increased about fivefold in fully developed myotubes as compared to mononucleated myoblasts. The contribution of deoxyribonucleic acid to the total nucleic acid population decreased from 24% in myoblasts to 5% of total nucleic acid in myotubes. Concomitant with the decrement in deoxyribonucleic acid contribution to total nucleic acid was an increase in polyadenylated ribonucleic acid (RNA) content per cell which reached levels in myotubes that were 17-fold higher than those of myoblasts. Specific changes in the RNA population during myogenesis were further investigated by quantitation of the synthetic capacity (messenger RNA levels) per cell for alpha- and beta-tropomyosin. Cell-free translation and immunoprecipitation demonstrated an approximately 40-fold increase in messenger RNA levels per nucleus for alpha- and beta-tropomyosin after fusion in the terminally differentiated myotubes. Indirect immunofluorescence with affinity-purified tropomyosin antibodies demonstrated the presence of tropomyosin-containing filaments in cells throughout myogenesis. Thus, the tropomyosin genes are constitutively expressed during muscle differentiation through the production of tropomyosin messenger RNA and translation into tropomyosin protein.

Hydroxyindole-O-methyltransferase gene expression in the pineal gland of chicken embryo: development of messenger RNA levels and regulation by serum

1995 ◽  
Vol 88 (2) ◽  
pp. 204-211 ◽  
Author(s):  
Aline Grechez-Cassiau ◽  
Pierre Grève ◽  
Jérôme Guerlotté ◽  
Jean-Pierre Collin ◽  
Pierre Voisin
Keyword(s):  
Gene Expression ◽  
Pineal Gland ◽  
Embryo Development ◽  
Chicken Embryo ◽  
Messenger Rna ◽  
Methyltransferase Gene ◽  
Rna Levels

534. CO-ORDINATED GENE EXPRESSION IN BOVINE GRANULOSA CELLS PRECEDES FOLLICULAR DOMINANCE

2009 ◽  
Vol 21 (9) ◽  
pp. 132
Author(s):  
N. Matti ◽  
H. F. Irving-Rodgers ◽  
W. M. Bonner ◽  
N. Hatzirodos ◽  
T. R. Sullivan ◽  
...  
Keyword(s):  
Gene Expression ◽  
Granulosa Cells ◽  
Follicular Fluid ◽  
Messenger Rna ◽  
Equal Size ◽  
Dominant Follicle ◽  
Rt Pcr ◽  
Steroidogenic Enzymes ◽  
Rna Levels

During growth of bovine follicles, one emerges as the largest and dominant follicle. What regulates dominance remains unknown, but candidates include oestradiol, TGFB1, and recently CYP11A1 and focal intra-epithelial matrix (focimatrix). The two to four largest follicles were dissected from pairs of bovine ovaries and follicular fluid collected. A portion of the follicle wall was histologically classified for follicle health or atretia, and granulosa cells harvested for quantitative RT-PCR. Messenger RNA levels of focimatrix (COL4A1, LAMB2, HSPG2), steroidogenic enzymes (CYP11A1, CYP19A1) and TGFB1 genes were measured. Follicular fluid progesterone and oestradiol concentrations were measured by RIA. Follicles were identified as pre-deviated (before size-deviation) if the largest two or more healthy follicles were of equal size (6.7±0.1 mm, n = 14 animals, 35 follicles), and as post-deviated (after size-deviation) if they differed in size by 0.5–1.0 mm (7.2±0.2 mm; n = 11 animals, 26 follicles). For analyses, pre-deviated follicles were grouped into either the highest (oestradiol, CYP11A1) or lowest (TGFB1) expression (n = 14) and compared to the remaining follicles (n = 21). Deviated follicles were classified into dominant (n = 12) and subordinate (n = 14) based on diameter. Dominant follicles did not differ from subordinate follicles in any parameters measured, but were significantly larger than subordinate or pre-deviated follicles (P<0.01). For pre-deviated follicles grouped on oestradiol no parameters differed significantly, and when grouped on TGFB1, LAMB2 (P<0.05), HSPG (P<0.05), CYP19A1 (P<0.05) and TGFB1 (P<0.01) differed but levels were lower, not higher as expected. When grouped on CYP11A1, COL4A1 (P<0.05), LAMB2 (P<0.01), HSPG2 (P<0.01) and CYP19A1 (P<0.001) were significantly elevated in the high CYP11A1 group. This suggests that CYP11A1 and focimatrix might be important in follicle dominance.

scholarly journals Aminoguanidine Exerts a β-Cell Function-preserving Effect in High Glucose-cultured β-Cells (INS-1)

2000 ◽  
Vol 1 (2) ◽  
pp. 111-119 ◽  
Author(s):  
Yuji Tajiri ◽  
Valdemar Grill
Keyword(s):  
Insulin Release ◽  
High Glucose ◽  
Cell Function ◽  
Cultured Cells ◽  
Culture Media ◽  
Insulin Content ◽  
Beneficial Effects ◽  
Cell Functions ◽  
Elevated Glucose ◽  
Β Cell Function

We investigated the effects of aminoguanidine (AG) onβ-cell functions in an insulin secreting cell line (INS-1). Culture with 27 mM glucose for one week markedly decreased both insulin release and insulin content compared to culture in 0.8 mM or 3.3 mM glucose. Relative to culture at 27 mM glucose alone, the co-exposure to 1 mM AG almost doubled basal as well as glucose or 25 mM KCl-stimulated insulin release and increased insulin content by 42%. AG failed to affect release and content in cells cultured at 0.8 or 3.3 mM glucose. Preproinsulin mRNA content in 27 mM glucose-cultured cells was 52% suppressed compared to 0.8 mM glucose-cultured cells, and AG treatment partially counteracted this decline. Advanced glycosylation end product (AGE)-associated fluorescence (370 nm excitation and 440 nm emission) of cells′ extracts did not differ between 27 mM and 0.8 mM glucose-cultured cells after 1 week of culture and fluorescence was unaffected by AG. Accumulation of nitrite into culture media was markedly increased from 27 mM glucose-cultured cells, and this accumulation was 33% suppressed by AG. In conclusion, AG partially protects against glucotoxic effects in INS-1 cells. These beneficial effects may involve a decrease in early glycation products and/or nitric oxide synthase (NOS) activity. The effects which were obtained after one week of high glucose exposure may supplement AGE-associated effects seen after chronically elevated glucose.

scholarly journals Differential Expression of Rat Insulin I and II Messenger Ribonucleic Acid after Prolonged Exposure of Islet β-Cells to Elevated Glucose Levels*

Endocrinology ◽  
1998 ◽  
Vol 139 (2) ◽  
pp. 491-495 ◽  
Author(s):  
Zhidong Ling ◽  
Harry Heimberg ◽  
André Foriers ◽  
Frans Schuit ◽  
Daniel Pipeleers
Keyword(s):  
Ribonucleic Acid ◽  
Messenger Rna ◽  
Prolonged Exposure ◽  
Pancreatic Tissue ◽  
Β Cells ◽  
Messenger Ribonucleic Acid ◽  
Glucose Levels ◽  
Fold Reduction ◽  
Elevated Glucose ◽  
Cells Cultured

Abstract Prolonged exposure of rat islet β-cells to 10 mmol/liter glucose has been previously shown to activate more cells into a glucose-responsive state (&gt;90%) than has exposure to 6 mmol/liter glucose (50%). The present study demonstrates that this recruitment of more activated cells results in 4- to 6-fold higher levels of proinsulin I and proinsulin II messenger RNA (mRNA). However, only the rate of proinsulin I synthesis is increased. Failure to increase the rate of proinsulin II synthesis in the glucose-activated cells results in cellular depletion of the insulin II isoform, which can be responsible for degranulation of β-cells cultured at 10 mmol/liter glucose. Higher glucose levels (20 mmol/liter) during culture did not correct this dissociation between the stimulated insulin I formation and the nonstimulated insulin II formation. On the contrary, the rise from 10 to 20 mmol/liter glucose resulted in a 2-fold reduction in the levels of proinsulin II mRNA, but not of proinsulin I mRNA; this process further increased the ratio of insulin I over insulin II to 5-fold higher values than those in freshly isolated β-cells. The present data suggest that an elevated insulin I over insulin II ratio in pancreatic tissue is a marker for a prolonged exposure to elevated glucose levels. The increased ratio in this condition results from a transcriptional and/or a posttranscriptional failure in elevating insulin II formation while insulin I production is stimulated in the glucose-activated β-cells.

scholarly journals Procollagen production and procollagen messenger RNA levels and activity in human lung fibroblasts during periods of rapid and stationary growth.

1981 ◽  
Vol 256 (6) ◽  
pp. 3135-3140
Author(s):  
P. Tolstoshev ◽  
R.A. Berg ◽  
S.I. Rennard ◽  
K.H. Bradley ◽  
B.C. Trapnell ◽  
...  
Keyword(s):  
Messenger Rna ◽  
Human Lung ◽  
Lung Fibroblasts ◽  
Stationary Growth ◽  
Human Lung Fibroblasts ◽  
Rna Levels
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