scholarly journals Obtaining a higherVoc in HIT cells

2005 ◽  
Vol 13 (6) ◽  
pp. 481-488 ◽  
Author(s):  
Mikio Taguchi ◽  
Akira Terakawa ◽  
Eiji Maruyama ◽  
Makoto Tanaka
Keyword(s):  
Hit Cells

Insulin biosynthesis in HIT cells. Effects of glucose, forskolin, IBMX, and dexamethasone

Diabetes ◽  
1988 ◽  
Vol 37 (2) ◽  
pp. 160-165 ◽  
Author(s):  
G. Gold ◽  
R. L. Qian ◽  
G. M. Grodsky
Keyword(s):  
Insulin Biosynthesis ◽  
Hit Cells

alpha-Glycerophosphate shuttle in a clonal beta-cell line

1989 ◽  
Vol 256 (1) ◽  
pp. E173-E178 ◽  
Author(s):  
M. D. Meglasson ◽  
K. M. Smith ◽  
D. Nelson ◽  
M. Erecinska
Keyword(s):  
Insulin Secretion ◽  
Cell Line ◽  
Electron Transport Chain ◽  
Direct Evidence ◽  
Mitochondrial Fraction ◽  
Secreting Cell ◽  
Transport Chain ◽  
Beta Cell Line ◽  
Atp Generation ◽  
Hit Cells

It has been proposed that the alpha-glycerophosphate (alpha-GOP) shuttle plays a crucial role in regulation of glycolysis in beta-cells by linking reoxidation of cytosolic NADH to formation of ATP in the electron transport chain (J. Biol. Chem. 265: 8287, 1981). Direct evidence for this suggestion is still lacking, however. In this work the operation of the alpha-GOP shuttle was investigated in the insulin-secreting cell line HIT-T15. The constituent enzymes of the pathway were found to be present in HIT cells. Flavin-linked alpha-GOP dehydrogenase was associated with the mitochondrial fraction, whereas NAD+-dependent alpha-GOP dehydrogenase was localized in the cytosol. In the presence of amobarbital (used to preserve the function of the alpha-GOP shuttle under conditions where oxidation of NADH by the respiratory chain was blocked), glucose increased insulin secretion, O2 consumption, and the cell [ATP]/[ADP] when compared with amobarbital alone. These results indicate that the alpha-GOP shuttle contributes to ATP generation in HIT cells and that its activation may be necessary for the initiation of insulin secretion by glucose.

scholarly journals Clonal Expansion of Second-Hit Cells with Somatic Recombinations or C>T Transitions Form Porokeratosis in MVD or MVK Mutant Heterozygotes

2019 ◽  
Vol 139 (12) ◽  
pp. 2458-2466.e9 ◽  
Author(s):  
Akiharu Kubo ◽  
Takashi Sasaki ◽  
Hisato Suzuki ◽  
Aiko Shiohama ◽  
Satomi Aoki ◽  
...  
Keyword(s):  
Clonal Expansion ◽  
Second Hit ◽  
Hit Cells

IGF-II, IGF-binding proteins and IGF receptors in pancreatic β-cell lines

1997 ◽  
Vol 152 (3) ◽  
pp. 455-464 ◽  
Author(s):  
L E L Katz ◽  
A Bhala ◽  
E Camron ◽  
S E Nunn ◽  
R L Hintz ◽  
...  
Keyword(s):  
Cell Lines ◽  
Binding Proteins ◽  
Conditioned Media ◽  
Pancreatic Β Cell ◽  
Β Cell ◽  
Igf Binding Proteins ◽  
Igf Receptors ◽  
Igf I ◽  
Igf Binding ◽  
Hit Cells

The IGFs are mitogenic agents which are closely linked to regulatory processes in carbohydrate metabolism. Because limited information is available on the occurrence of the IGF system in the pancreatic β-cell milieu, we evaluated the presence of IGFs, IGF receptors, and IGF-binding proteins (IGFBPs) in the β-cell lines βTC3 and HIT T-15. Serum-free conditioned media (SFCM) from βTC3 cells contained IGF-II at concentrations greater than 100 ng/ml. High (15 kDa) and low (7·5 kDa) molecular weight IGF-II were detected both by column chromatography followed by RIA and by immunoblotting. GH (10–1000 ng/ml) conditioning of βTC3 cells stimulated IGF-II secretion in a dose-dependent manner. IGF-II mRNA was detected in βTC3 cells using Northern blots, and also showed a GH-dependent relationship. IGF-II peptide was detected in SFCM from HIT cells, albeit at lower concentrations. To evaluate the presence of IGF receptors in β-cell lines, affinity cross-linking studies were performed on βTC3 cells, demonstrating type I IGF receptors which bound iodinated IGF-II with high affinity, iodinated IGF-I with lesser affinity, and had minimal appreciable binding to iodinated insulin. Type II IGF receptors were not detected. SFCM from βTC3 and HIT cells was subjected to Western ligand blotting, which disclosed the presence of two major IGFBPs of 29 kDa and 24 kDa, characteristic of IGFBP-2 and IGFBP-4. The identity of the specific IGFBPs was confirmed by immunoprecipitation and Northern blotting. Varying the glucose concentration had no significant effect on the levels of IGFBPs, nor did preconditioning with GH, IGF-I, IGF-II, insulin, or glucagon. Levels of both IGFBPs in βTC3 cell-conditioned media increased in the presence of dexamethasone at concentrations of 10−6 m or greater. In summary, we present evidence that β-cell lines comprise an environment for GH and IGF action. We speculate that IGFs, their receptors and binding proteins function as a complex interactive system which regulates β-cell growth and function. Journal of Endocrinology (1997) 152, 455–464

scholarly journals Analysis of the 5'-upstream region of mouse P/Q-type Ca2+ channel alpha1A subunit gene for expression in pancreatic islet beta cells using transgenic mice and HIT-T15 cells

2000 ◽  
Vol 24 (2) ◽  
pp. 225-232 ◽  
Author(s):  
E Takahashi ◽  
N Miyamoto ◽  
T Nagasu
Keyword(s):  
Gene Expression ◽  
Transgenic Mice ◽  
Beta Cell ◽  
Reporter Gene ◽  
Promoter Activity ◽  
Upstream Region ◽  
Subunit Gene ◽  
Reporter Expression ◽  
Hit Cells ◽  
Cell Expression

The omega-agatoxin-IVA-sensitive P/Q-type Ca(2+) channel plays a role in insulin release from the pancreatic islets of beta cells. To dissect the molecular mechanisms underlying beta cell expression of the P/Q-type channel, we characterized the 5'-upstream region of the mouse alpha(1A) subunit gene using transgenic mice and HIT insulinoma cells. The E. coli lacZ reporter gene was expressed in pancreatic acini and islets in transgenic mice carrying the 6.3 kb or 3.0 kb of the 5'-upstream region, although those with 1.5 kb or 0. 5 kb of the 5'-upstream region failed to show reporter expression on histological examination. As the expression of alpha(1A)subunit gene could not be detected in acini using RT-PCR analysis, the reporter expression in acini might have been ectopic expression. When linked to the placental alkaline phosphatase reporter gene to examine promoter activity for beta cell expression, the 6.3 kb and 3.0 kb fragment of the 5'-upstream region, but not the smaller 1.5 kb fragment, were able to drive reporter gene expression in HIT cells. The sequence between 3.0 and 1.5 kb upstream of the start codon enhanced thymidine kinase promoter activity in HIT cells, but not in fibroblast NIH3T3 cells. These results suggested that the beta cell-specific elements of the alpha(1A) subunit gene are likely to be located in the distal upstream region (-3021 to-1563) of the 5'-upstream sequence and that the 6.3 kb fragment of the 5'-upstream region alone might be a lack of a negative cis-regulatory element(s) to suppress the alpha(1A) subunit gene expression in acini.

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