• Molecules and Cells
• /
• v.41 no.10
• /
• pp.909-916
• /
• 2018

In pancreatic ${\beta}$ cells, glucose stimulates the biosynthesis of insulin at transcriptional and post-transcriptional levels. The RNA-binding protein, polypyrimidine tract-binding protein 1 (PTBP1), also named hnRNP I, acts as a critical mediator of insulin biosynthesis through binding to the pyrimidine-rich region in the 3'-untranslated region (UTR) of insulin mRNA. However, the underlying mechanism that regulates its expression in ${\beta}$ cells is unclear. Here, we report that glucose induces the expression of PTBP1 via the insulin receptor (IR) signaling pathway in ${\beta}$ cells. PTBP1 is present in ${\beta}$ cells of both mouse and monkey, where its levels are increased by glucose and insulin, but not by insulin-like growth factor 1. PTBP1 levels in immortalized ${\beta}$ cells established from wild-type (${\beta}IRWT$) mice are higher than levels in ${\beta}$ cells established from IR-null (${\beta}IRKO$) mice, and ectopic re-expression of IR-WT in ${\beta}IRKO$ cells restored PTBP1 levels. However, PTBP1 levels were not altered in ${\beta}IRKO$ cells transfected with IR-3YA, in which the Tyr1158/1162/1163 residues are substituted with Ala. Consistently, treatment with glucose or insulin elevated PTBP1 levels in ${\beta}IRWT$ cells, but not in ${\beta}IRKO$ cells. In addition, silencing Akt significantly lowered PTBP1 levels. Thus, our results identify insulin as a pivotal mediator of glucose-induced PTBP1 expression in pancreatic ${\beta}$ cells.

• Archives of Pharmacal Research
• /
• v.22 no.5
• /
• pp.437-447
• /
• 1999

Type I diabetes, also known as insulin-dependent diabetes mellitus (IDDM) results from the destruction of insulin-producing pancreatic $\beta$ cells by a progressive $\beta$ cell-specific autoimmune process. The pathogenesis of autoimmune IDDM has been extensively studied for the past two decades using animal models such as the non-obese diabetic (NOD) mouse and the Bio-Breeding (BB) rat. However, the initial events that trigger the immune responses leading to the selective destruction of the $\beta$ cells are poorly understood. It is thought that $\beta$ cell auto-antigens are involved in the triggering of $\beta$ cell-specific autoimmunity. Among a dozen putative $\beta$ cell autoantigens, glutamic acid decarboxylase (GAD) has bee proposed as perhaps the strongest candidate in both humans and the NOD mouse. In the NOD mouse, GAD, as compared with other $\beta$ cell autoantigens, provokes the earliest T cell proliferative response. The suppression of GAD expression in the $\beta$ cells results in the prevention of autoimmune diabetes in NOD mice. In addition, the major populations of cells infiltrating the iselts during the early stage of insulitis in BB rats and NOD mice are macrophages and dendritic cells. The inactivation of macrophages in NOD mice results in the prevention of T cell mediated autoimmune diabetes. Macrophages are primary contributors to the creation of the immune environment conducive to the development and activation of $\beta$cell-specific Th1-type CD4+ T cells and CD8+ cytotoxic T cells that cause autoimmune diabetes in NOD mice. CD4+ and CD8+ T cells are both believed to be important for the destruction of $\beta$ cells. These cells, as final effectors, can kill the insulin-producing $\beta$ cells by the induction of apoptosis. In addition, CD8+ cytotoxic T cells release granzyme and cytolysin (perforin), which are also toxic to $\beta$ cells. In this way, macrophages, CD4+ T cells and CD8+ T cells act synergistically to kill the $\beta$ cells in conjunction with $\beta$ cell autoantigens and MHC class I and II antigens, resulting in the onset of autoimmune type I diabetes.

• Proceedings of the Plant Resources Society of Korea Conference
• /
• 2019.10a
• /
• pp.68-68
• /
• 2019

In this study, we evaluated the effect of Rodgersia podophylla leave extracts (RPL) on ${\beta}$-catenin level in human cancer cells. RPL dose-dependently inhibited cell proliferation in SW480, A549, MDA-MB-231, PC-3 and AsPC-1 cells. RPL dramatically decreased ${\beta}$-catenin protein level in all cancer cells. However, decreased level of ${\beta}$-catenin mRNA expression was observed in A549 and AsPC-1 cells. In addition, RPL dramatically attenuated cyclin D1 mRNA expression in all cancer cells. MG132 decreased the downregulation of ${\beta}$-catenin protein level induced by RPL in all cancer cells, while RPL-induced downregulation of ${\beta}$-catenin was inhibited by the inhibition of $GSK-3{\beta}$ by LiCl in MDA-MB-231 cells. RPL phosphorylated ${\beta}$-catenin and $GSK-3{\beta}$. In addition, the inhibition of $GSK-3{\beta}$ by LiCl attenuated RPL-induced ${\beta}$-catenin phosphorylation. Based on these findings, RPL may be a potential candidate for the development of chemopreventive or therapeutic agents for human cancer.

• Journal of Periodontal and Implant Science
• /
• v.29 no.3
• /
• pp.645-654
• /
• 1999

Interleukin-6(IL-6) stimulate osteoclast differentiation. $17{\beta}$-estradiol, 1,25-dihydroxyvitamin $D_3$(1,25-$(OH)_2D_3$) and interleukin-$1{\beta}$ inhibit or stimulate osteoclast differentiation by decreasing or increasing the synthesis of interleukin-6(IL-6) from stromal/osteoblastic cells, respectively. Periodontal ligament(PDL) cells reside between the alveolar bone and the cementum and have osteoblastic characteristics. To estimate the effect of $17{\beta}$-estradiol and 1,25$(OH)_2D_3$ on IL-6 production of PDL cells, PDL cells were treated with $17{\beta}$-estradiol or 1,25-$(OH)_2D_3$ in the absence or the presence of IL-$1{\beta}$. The concentration of IL-6 produced form PDL cells was determined by enzym linked immunosorbent assay(ELISA). In unstimulated PDL cells, we detected constitutive production of IL-6 at 1st and 2nd day. IL-$1{\beta}$ increased IL-6 synthesis at 1st day and 2nd day. $17{\beta}$-estradiol had no significant effect on the secretion of this cytokine, either constitutively or after stimulation with IL- $1{\beta}$(0.05 ng/ml). 1,25-$(OH)_2D_3$($10^{-8}M$) decreased not only constitutive IL-6 production but also IL-$1{\beta}$-induced IL-6 production at 2nd day. These results suggest that 1,25-$(OH)_2D_3$ may control IL-$1{\beta}$-induced osteoclast differentiation by decreasing IL-$1{\beta}$-induced IL-6 secretion of PDL cells.

• Molecules and Cells
• /
• v.19 no.3
• /
• pp.375-381
• /
• 2005

Phospholipase C-${\beta}$ (PLC-${\beta}$) hydrolyses phosphatidylinositol 4,5-bisphosphate and generates inositol 1,4,5-trisphosphate in response to activation of various G protein-coupled receptors (GPCRs). Using glial cells from knock-out mice lacking either PLC-${\beta}1$ [PLC-${\beta}1$ (-/-)] or PLC-${\beta}3$ [PLC-${\beta}3$ (-/-)], we examined which isotype of PLC-${\beta}$ participated in the cellular signaling events triggered by thrombin. Generation of inositol phosphates (IPs) was enhanced by thrombin in PLC-${\beta}1$ (-/-) cells, but was negligible in PLC-${\beta}3$ (-/-) cells. Expression of PLC-${\beta}3$ in PLC-${\beta}3$ (-/-) cells resulted in an increase in pertussis toxin (PTx)-sensitive IPs in response to thrombin as well as to PAR1-specific peptide, while expression of PLC-${\beta}1$ in PLC-${\beta}1$ (-/-) cells did not have any effect on IP generation. The thrombin-induced $[Ca^{2+}]_i$ increase was delayed and attenuated in PLC-${\beta}3$ (-/-) cells, but normal in PLC-${\beta}1$ (-/-) cells. Pertussis toxin evoked a delayed $[Ca^{2+}]_i$ increase in PLC-${\beta}3$ (-/-) cells as well as in PLC-${\beta}1$ (-/-) cells. These results suggest that activation of PLC-${\beta}3$ by pertussis toxin-sensitive G proteins is responsible for the transient $[Ca^{2+}]_i$ increase in response to thrombin, whereas the delayed $[Ca^{2+}]_i$ increase may be due to activation of some other PLC, such as PLC-${\beta}4$, acting via PTx-insensitive G proteins.

• The Korean Journal of Zoology
• /
• v.32 no.3
• /
• pp.290-303
• /
• 1989

The activities of $\beta$-glucosidase, $\beta$-glucuronidase and N-acetyl-$\beta$-glucosaminidase were measured to investigate the relationships of them to sexual maturity. Peritoneal injections of testosterone and dibutyryl cAMP to rats were carried out. As a result, the activities of $\beta$-glucosidase and N-acetyl-$\beta$-glucosaminidase were significantly decreased from the third day and that of P -glucurondiase on the seventh day in the castrated groups. In addition, ihe activities of these three enzymes were significantly increased in the testosterone treated groups for 7 days. In case of dbcAMP injection, the activities of these three enzymes were similar to those of castrated groups or had a tendency to be decreased. On electron microscopic examination, principal cells, basal cells and narrow cells were observed in all regions of epididymis. Principal cells were general forms of columnar epithelial cells. Narrow cells had a number of small vesicles and light cells showed low electron density in comparison to other epithelial cells in cauda epididymis. Halo cells were migrating leucocytes btween epithelial cells.

• IMMUNE NETWORK
• /
• v.9 no.4
• /
• pp.122-126
• /
• 2009

Transforming growth factor-$\beta$ (TGF-$\beta$) is a highly pleiotropic cytokine playing pivotal roles in immune regulation. TGF-$\beta$ facilitates tumor cell survival and metastasis by targeting multiple cellular components. Focusing on its immunosuppressive functions, TGF-$\beta$ antagonists have been employed for cancer treatment to enhance tumor immunity. TGF-$\beta$ antagonists exert anti-tumor effects through #1 activating effector cells such as NK cells and cytotoxic $CD8^+$ Tcells (CTLs), #2 inhibiting regulatory/suppressor cell populations, #3 making tumor cells visible to immune cells, #4 inhibiting the production of tumor growth factors. This review focuses on the effect of TGF-$\beta$ on T cells, which are differentiated into effector T cells or newly identified tumor-supporting T cells.

• Nutritional Sciences
• /
• v.8 no.3
• /
• pp.159-168
• /
• 2005

Phytoestrogens, especially Yak-kong or soybean-derived isoflavones have been traditionally used as a supplement of estrogen for preventing postmemopausal osteoporosis in oriental folk medicine. In our previous study, the treatment of Yak-kong and soybean increased estrogen receptor-a (ERa) expression and proliferation of MG-63 osteoblastic cells. In contrast, the increase of estrogen receptor-$\beta$ (ER$\beta$) expression in proliferating MG-63 cells with Yak-kong and soybean treatment was less pronounced, which suggested that ER$\beta$ may play a role rather in the regulation of bone cell differentiation To determine the role of ER$\beta$ in Yak-kong or soybean mediated regulation of bone cell differentiation, we established MG-63 cell lines stably expressing either ER$\beta$ or antisense ER$\beta$ RNAs. Increased expression of ER$\beta$ did not affect ERa expression and proliferation of MG-63 cells. However, increased expression of ER$\beta$ in MG-63 cells (ER$\beta$-MG63 cells) selectively enhanced Yak-kong or soybean induced expression of osteoprotegerin (OPG), a novel soluble glycoprotein which is secreted from osteoblasts and mediates the signal for osteoclast differentiation. Inhibition of ER$\beta$ expression by antisense ER$\beta$ RNAs (As-ER$\beta$-MG63) caused these cells to insensitize Yak-kong or soybean induced expression of OPG but increased MG-63 cell proliferation. Furthermore, the comparable effects between Yak-kong and the combined treatment of genistein and daidzein at $0.5{\times}l0^{-8}$ M, which is a concentration of these two isoflavones similar to Yak-kong at 0.001 mg/mL, on OPG expression in ER$\beta$-MG63 cell demonstrate that the enhanced expression of OPG with Yak-kong treatment is mediated by the synergistic effect of low leveled isoflavones in the extracts. Together, coupled with low level of ER expression in osteoclasts, our data demonstrate that ER$\beta$ in osteoblasts plays an important role in Yak-kong and soybean mediated inhibition of osteoclast differentiation indirectly by enhancing the expression of OPG.

• International Journal of Oral Biology
• /
• v.43 no.3
• /
• pp.161-169
• /
• 2018

We previously demonstrated that epidermal growth factor (EGF) enhances cell migration and invasion of breast cancer cells in a SMAD ubiquitination regulatory factor 1 (SMURF1)-dependent manner and that SMURF1 induces degradation of ${\beta}-catenin$ in C2C12 cells. However, the relationship between EGF-induced SMURF1 and ${\beta}-catenin$ expression in breast cancer cells remains unclear. So, we investigated if EGF and SMURF1 regulate ${\beta}-catenin$ expression in MDAMB231 human breast cancer cells. When MDAMB231 cells were incubated with EGF for 24, 48, and 72 hours, EGF significantly increased expression levels of SMURF1 mRNA and protein while suppressing expression levels of ${\beta}-catenin$ mRNA and protein. Overexpression of SMURF1 downregulated ${\beta}-catenin$ mRNA and protein, whereas knockdown of SMURF1 increased ${\beta}-catenin$ expression and blocked EGF-induced ${\beta}-catenin$ downregulation. Knockdown of ${\beta}-catenin$ enhanced cell migration and invasion of MDAMB231 cells, while ${\beta}-catenin$ overexpression suppressed EGF-induced cell migration and invasion. Furthermore, knockdown of ${\beta}-catenin$ enhanced vimentin expression and decreased cytokeratin expression, whereas ${\beta}-catenin$ overexpression decreased vimentin expression and increased cytokeratin expression. These results suggest that EGF downregulates ${\beta}-catenin$ in a SMURF1-dependent manner and that ${\beta}-catenin$ downregulation contributes to EGF-induced cell migration and invasion in MDAMB breast cancer cells.

• BMB Reports
• /
• v.30 no.3
• /
• pp.194-199
• /
• 1997

Previous studies have shown that the HD3 human enterocytic differentiated colon carcinoma cell lines having low $PKC{\beta}$ activity did not respond to diacylglycerol and basic FGF by growth and by activation of pp57 MAP kinase, but undifferentiated cell lines exhibiting high $PKC{\beta}$ activity did. To confirm a role of $PKC{\beta}$ in colonocyte mitogenesis, derivatives of HD3 cell line that stably overexpress a full-length of cDNA encoding the ${\beta}_1$ isoform of human PKC were generated. The abundance and activity of $PKC{\beta}$ in two of the these cell lines, PKC3 and PKC8 were much higher than those in the C1 control cell line that carries the vector lacking the $PKC{\beta}_1\;cDNA$ insert. Following exposure to diacylglycerol or basic FGF, proliferation of PKC3 and PKC8 cells increased about 50%; but this effect was not seen with the control C1 cells. Also, in contrast to the control cells, the $PKC{\beta}_1-overproducing$ cells displayed activation of pp57 MAP kinase when treated with diacylglycerol and basic FGF as undifferentiated cell lines did. These results provide direct evidence that $PKC{\beta}_1$ which plays a key role in mitogenic responses of colon carcinoma cells to diacylglycerol and basic FGF is down-regulated in enterocytic differentiation of colon cells.