Prolactin regulatory element binding protein as a potential transcriptional factor for the insulin gene in response to glucose stimulation

Ohtsuka, Shouji; Murao, Koji; Imachi, Hitomi; Cao, Wen; Yu, Xiao; Li, J.; Iwama, Hisakazu; Wong, Norman C.W.; Bancroft, Carter; Ishida, Toshihiko

doi:10.1007/s00125-006-0255-y

Cited by 24 publications

(34 citation statements)

References 31 publications

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“…The INS-1 cells originated from a rat insulinoma cell line developed and propagated at the Division of Biochimie Cliniqe (courtesy of C. B. Wollheim) and were cultured as described previously [8]. For protein extraction, mRNA isolation, and cholesterol measurement, after 6 h of starvation, the cells were treated with varying doses of IGF-1 (R & D Systems) for 24 h or for different time (0 h, 8 h, 12 h, and 24 h) before harvesting as described previously [8]. We isolated pancreatic islets from adult Wistar rats and maintained as described previously [8].…”

Section: Cell Culturementioning

confidence: 99%

“…For protein extraction, mRNA isolation, and cholesterol measurement, after 6 h of starvation, the cells were treated with varying doses of IGF-1 (R & D Systems) for 24 h or for different time (0 h, 8 h, 12 h, and 24 h) before harvesting as described previously [8]. We isolated pancreatic islets from adult Wistar rats and maintained as described previously [8]. All cells were incubated in humidified 5 % CO 2 at 37 °C.…”

Section: Cell Culturementioning

confidence: 99%

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Insulin-like Growth Factor 1 Regulates the Expression of ATP-Binding Cassette Transporter A1 in Pancreatic Beta Cells

et al. 2016

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ATP-binding cassette transporter A1 (ABCA1) in pancreatic beta cells influences insulin secretion and cholesterol homeostasis. The present study investigates whether insulin-like growth factor 1 (IGF-1), which mediates stimulation of ABCA1 gene expression, could also interfere with the phosphatidylinositol 3-kinase (PI3-K) cascade.ABCA1 expression was examined by real-time polymerase chain reaction (PCR), Western blot analysis, and a reporter gene assay in rat insulin-secreting INS-1 cells incubated with IGF-1. The binding of forkhead box O1 (FoxO1) protein to the ABCA1 promoter was assessed by a chromatin immunoprecipitation (ChIP) assay. ABCA1 protein levels increased in response to rising concentrations of IGF-1. Real-time PCR analysis showed a significant increase in ABCA1 mRNA expression. However, both effects were suppressed after silencing the IGF-1 receptor. In parallel with its effect on endogenous ABCA1 mRNA levels, IGF-1 induced the activity of a reporter construct containing the ABCA1 promoter, while it was abrogated by LY294002, a specific inhibitor of PI3-K. Constitutively active Akt stimulated activity of the ABCA1 promoter, and a dominant-negative mutant of Akt or mutagenesis of the FoxO1 response element in the ABCA1 promoter abolished the ability of IGF-1 to stimulate promoter activity. A ChIP assay showed that FoxO1 mediated its transcriptional activity by directly binding to the ABCA1 promoter region. The knockdown of FoxO1 disrupted the effect of IGF-1 on ABCA1 expression. Furthermore, IGF-1 promoted cholesterol efflux and reduced the pancreatic lipotoxicity. These results demonstrate that the PI3-K/Akt/FoxO1 pathway contributes to the regulation of ABCA1 expression in response to IGF-1 stimulation.

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Section: Cell Culturementioning

confidence: 99%

Section: Cell Culturementioning

confidence: 99%

Insulin-like Growth Factor 1 Regulates the Expression of ATP-Binding Cassette Transporter A1 in Pancreatic Beta Cells

et al. 2016

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“…PREB mRNA transcripts were present not only in the pituitary, but also in the pancreas and the adrenal gland. In a recent study, we reported that PREB might participate in the regulation of insulin gene transcription in response to glucose stimulation and in steroidogenesis [12][13][14]. In this report, we examined the effect of TRH on PREB expression in GH3 cells.…”

Section: Discussionmentioning

confidence: 89%

“…The PREB expression vector was transfected into the cultured INS-1 cells by the conventional cationic liposome transfection method as described previously [14]. The transfected cells were selected by adding G418 to the media, and clones showing high PREB production were identified using western blot analysis.…”

Section: Stable Transfectionmentioning

confidence: 99%

The transcription factor prolactin regulatory element-binding protein mediates prolactin transcription induced by thyrotropin-releasing hormone in GH3 cells

Murao

Imachi

et al. 2010

Endocr

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The prolactin regulatory element-binding protein (PREB) is a transcription factor that regulates prolactin (PRL) promoter activity in the rat anterior pituitary. PRL gene expression and secretion are regulated by various hormones and growth factors, including dopamine, epidermal growth factor, and thyrotropin-releasing hormone (TRH). We examined the effect of TRH on PREB expression in pituitary cells. Western blots probed with a PREB-specific antiserum showed that the relative abundance of PREB in GH3 cells increased on treatment with TRH in a dose-dependent manner. The relative abundance of PREB mRNA also increased in a dose-dependent manner after treatment with TRH. TRH induced the expression of the luciferase reporter protein under the PREB promoter control. We used inhibitors of certain signal transduction pathways to show that TRH-induced PREB induction is sensitive to the protein kinase A (PKA) inhibitor. TRH stimulated the activity of the wild-type PRL promoter, whereas mutation of the PREB core-binding element on the PRL promoter reduced this ability. In summary, we have shown that TRH stimulated PREB expression in GH3 cells via the PKA pathway. PREB can function as a transcriptional regulator of PRL promoter activity and might be involved in TRH-induced PRL gene transcription.

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“…In mammals, PREB is highly expressed in extrapituitary tissues such as the pancreas, where it acts in INS and glucokinase regulation (Ohtsuka et al, 2006;Muraoka et al, 2009). However, no studies have been performed in avian species.…”

Section: Discussionmentioning

confidence: 99%

Characterization and Expression of Turkey Prolactin Regulatory Element Binding in the Anterior Pituitary Gland and Pancreas During Embryogenesis

et al. 2015

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The PRL regulatory element-binding (PREB) protein is a transcription factor that was originally cloned from the rat anterior pituitary gland and characterized as a regulator of the PRL promoter. It is also strongly expressed in several extrapituitary tissues; however, its functional role is not well understood to date. In this study, we aimed to clone and characterize the turkey PREB gene and investigate its mRNA expression in the anterior pituitary gland and pancreas during embryogenesis. Based on the conserved sequence of chicken and mammalian PREB cDNAs, a turkey PREB cDNA fragment was obtained, and after sequencing of the fragment, the 5′ -and 3′ -ends of mRNA were amplified and determined. To identify the PREB gene structure, polymerase chain reaction (PCR) amplification was performed. The turkey PREB gene consists of 9 exons and 8 introns, and it encodes a 411-amino-acid protein. The expression of PREB mRNA in the anterior pituitary gland was measured during embryogenesis. Levels of PREB mRNA significantly increased at embryonic day 22, with maximum levels being detected on day 25 of ontogeny, which correlated with similar changes in levels of PRL mRNA. The highest level of PREB mRNA was detected on day 19 in the pancreas. However, the highest level of insulin mRNA was detected at embryonic day 25. These results indicate that PREB may be involved in the expression of PRL mRNA in the anterior pituitary gland, whereas insulin mRNA may be expressed independently of the expression of PREB mRNA in the pancreas during embryogenesis.

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Prolactin regulatory element binding protein as a potential transcriptional factor for the insulin gene in response to glucose stimulation

Cited by 24 publications

References 31 publications

Insulin-like Growth Factor 1 Regulates the Expression of ATP-Binding Cassette Transporter A1 in Pancreatic Beta Cells

Insulin-like Growth Factor 1 Regulates the Expression of ATP-Binding Cassette Transporter A1 in Pancreatic Beta Cells

The transcription factor prolactin regulatory element-binding protein mediates prolactin transcription induced by thyrotropin-releasing hormone in GH3 cells

Characterization and Expression of Turkey Prolactin Regulatory Element Binding in the Anterior Pituitary Gland and Pancreas During Embryogenesis

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