Expression of Ins1 and Ins2 genes in mouse fetal liver

Among Other Tissues, Short-Term Garlic Oral Treatment Incrementally Improves Indicants of Only Pancreatic Islets of Langerhans Histology and Insulin mRNA Transcription and Synthesis in Diabetic Rats

BACKGROUND

The source, mRNA transcription, and synthesis of insulin in the pancreas, in addition to the bile duct and liver, in streptozotocin (STZ)-induced diabetic rats (DR) in response to garlic oral treatment are not yet clear.

OBJECTIVE

This study investigated the accumulative effects of continued garlic oral treatment on changes in the pancreas, bile duct, and liver with regards to: 1-Insulin mRNA transcription, synthesis, and concentration in relation to changes in serum insulin (SI); 2-Insulinogenic cells insulin intensity and distribution, proliferation, and morphology.

METHOD

Fasting blood glucose (FBG) and insulin concentration in serum and pancreas (PI) and sources and mRNA transcription in the pancreas, bile duct, and liver in normal rats given normal saline (NR-NS) and DR given either NS (DR-NS) or garlic extract (DR-GE) before and after 1, 4, and 8 weeks of oral treatment were examined.

RESULTS

Compared to NR-NS, DR-NS showed a significant increase in FBG and reductions in SI and PI and deterioration in islets histology, associated pancreatic insulin numerical intensities, and mRNA transcription. However, compared to DR-NS, the targeted biochemical, histological, and genetic variables of DR-GE were significantly and incrementally improved as garlic treatment continued. Insulin or its indicators were not detected either in the bile duct or the liver in DR-GE.

CONCLUSIONS

8 weeks of garlic oral treatment is enough to incrementally restore only pancreatic islets of Langerhans insulin intensity and insulinogenic cells proliferation, morphology, and distribution. These indices were associated with enhanced pancreatic insulin mRNA transcription and synthesis. Eight weeks of garlic treatment were not enough to stimulate insulinogenesis in either the bile duct or the liver.

Autonomous regulation of retinal insulin biosynthesis in diabetes

Diabetic retinopathy (DR) is a neurodegenerative disease that results as a complication of dysregulated glucose metabolism, or diabetes. The signaling of insulin is lost or dampened in diabetes, but this hormone has also been shown to be an important neurotrophic factor which supports neurons of the brain. The role of local insulin synthesis and secretion in the retina, however, is unclear. We have investigated whether changes in local insulin synthesis occur in the diabetic retina and in response to stressors known to initiate retinal neurodegenerative processes. The expression of insulin and its cleavage product, c-peptide, were examined in retinas of a Type I diabetes animal model and human postmortem donors with DR. We detected mRNAs for insulin I (Ins1), insulin II (Ins2) and human insulin (Ins) by quantitative real-time polymerase chain reaction (qRT-PCR) and in situ hybridization. Using an ex-vivo system, isolated neuroretinas and retinal pigmented epithelium (RPE) layers were exposed to glycemic, oxidative and inflammatory environments to measure insulin gene transcripts produced de novo in the retina under disease-relevant conditions. The expression of insulin in the retina was altered with the progression of diabetes in STZ mice and donors with DR. Transcription factors for insulin, were simultaneously expressed in a pattern matching insulin genes. Furthermore, de novo insulin mRNA in isolated retinas was induced by acute stress. RPE explants displayed the most pronounced changes in Ins1 and Ins2. This data reveals that the retina, like the brain, is an organ capable of producing local insulin and this synthesis is altered in diabetes.

Intermittent Hypoxia Upregulates the Renin and Cd38 mRNAs in Renin-Producing Cells via the Downregulation of miR-203

Sleep apnea syndrome is characterized by recurrent episodes of oxygen desaturation and reoxygenation (intermittent hypoxia [IH]), and it is a known risk factor for hypertension. The upregulation of the renin-angiotensin system has been reported in IH, and the correlation between renin and CD38 has been noted. We exposed human HEK293 and mouse As4.1 renal cells to experimental IH or normoxia for 24 h and then measured the mRNA levels using a real-time reverse transcription polymerase chain reaction. The mRNA levels of Renin (Ren) and Cd38 were significantly increased by IH, indicating that they could be involved in the CD38-cyclic ADP-ribose signaling pathway. We next investigated the promotor activities of both genes, which were not increased by IH. Yet, a target mRNA search of the microRNA (miRNA) revealed both mRNAs to have a potential target sequence for miR-203. The miR-203 level of the IH-treated cells was significantly decreased when compared with the normoxia-treated cells. The IH-induced upregulation of the genes was abolished by the introduction of the miR-203 mimic, but not the miR-203 mimic NC negative control. These results indicate that IH stress downregulates the miR-203 in renin-producing cells, thereby resulting in increased mRNA levels of Ren and Cd38, which leads to hypertension.

Gestational bisphenol A exposure induces fatty liver development in male offspring mice through the inhibition of HNF1b and upregulation of PPARγ

Bisphenol A (BPA) is an endocrine-disrupting chemical (EDC) associated with non-alcoholic fatty liver disease (NAFLD). The effects of gestational BPA exposure on hepatic lipid accumulation in offspring are not fully understood. Here, we investigate the sex-dependent effects of gestational BPA exposure on hepatic lipid and glucose metabolism in the offspring of mice to reveal the mechanisms underlying gestational BPA exposure-associated NAFLD. Pregnant mice were administered gavage with or without 1 μg kg-1 day-1 BPA at embryonic day 7.5 (E7.5)-E16.5. Hepatic glucose and lipid metabolism were evaluated in these models. Both male and female offspring mice exhibited hepatic fatty liver after BPA treatment. Lipid accumulation and dysfunction of glucose metabolism were observed in male offspring. We revealed abnormal expression of lipid regulators in the liver and that inhibition of peroxisome proliferator-activated receptor γ (PPARγ) repressed hepatic lipid accumulation induced by gestational BPA exposure. We also found a sex-dependent decrease of hepatocyte nuclear factor 1b (HNF1b) expression in male offspring. The transcriptional repression of PPARγ by HNF1b was confirmed in L02 cells. Downregulation of HNF1b, upregulation of PPARγ, and subsequent upregulation of hepatic lipid accumulation were essential for NAFLD development in male offspring gestationally exposed to BPA as well as BPA-exposed adult male mice. Dysregulation of the HNF1b/PPARγ pathway may be involved in gestational BPA exposure-induced NAFLD in male offspring. These data provide new insights into the mechanism of gestational BPA exposure-associated sex-dependent glucose and lipid metabolic dysfunction. Graphical abstract Schematic of the mechanism of gestational BPA exposure-induced glucose and lipid metabolic dysfunction.

Involvement of Receptor for Advanced Glycation Endproducts in Hypertensive Disorders of Pregnancy

Preeclampsia/hypertensive disorders of pregnancy (PE/HDP) is a serious and potentially life-threatening disease. Recently, PE/HDP has been considered to cause adipose tissue inflammation, but the detailed mechanism remains unknown. We exposed human primary cultured adipocytes with serum from PE/HDP and healthy controls for 24 h, and analyzed mRNA expression of several adipokines, cytokines, and ligands of the receptor for advanced glycation endproducts (RAGE). We found that the mRNA levels of interleukin-6 (IL-6), C-C motif chemokine ligand 2 (CCL2), high mobility group box 1 (HMGB1), and RAGE were significantly increased by the addition of PE/HDP serum. Among RAGE ligands, advanced glycation endproducts (AGE) and HMGB1 increased mRNA levels of IL-6 and CCL2 in SW872 human adipocytes and mouse 3T3-L1 cells. The introduction of small interfering RNA for RAGE (siRAGE) into SW872 cells abolished the AGE- and HMGB1-induced up-regulation of IL-6 and CCL2. In addition, lipopolysaccharide (LPS), a ligand of RAGE, increased the expression of IL-6 and CCL2 and siRAGE attenuated the LPS-induced expression of IL-6 and CCL2. These results strongly suggest that the elevated AGE, HMGB1, and LPS in pregnant women up-regulate the expression of IL-6 and CCL2 via the RAGE system, leading to systemic inflammation such as PE/HDP.

Intermittent Hypoxia Up-Regulates CCL2, RETN, and TNFα mRNAs in Adipocytes via Down-regulation of miR-452

Sleep apnea syndrome (SAS), characterized by recurrent episodes of oxygen desaturation and reoxygenation (intermittent hypoxia [IH]), is a risk factor for insulin resistance. Recently, IH is considered to independently cause adipose tissue inflammation/dysfunction, leading to worsening insulin resistance; however, the detailed mechanism remains unknown. We exposed mouse 3T3-L1 and human SW872 adipocytes to experimental IH or normoxia for 24 h, and analyzed mRNA expression of several adipokines. We found that the mRNA levels of RETN, TNFα, and CCL2 in SW872 and 3T3-L1 adipocytes were significantly increased by IH, whereas the promoter activities of these genes were not increased. A target mRNA search of microRNA (miR)s revealed that all human mRNAs have a potential target sequence for miR-452. The miR-452 level of IH-treated cells was significantly decreased compared to normoxia-treated cells. MiR-452 mimic and non-specific control RNA (miR-452 mimic NC) were introduced into SW872 cells, and the IH-induced up-regulation of the genes was abolished by introduction of the miR-452 mimic but not by the miR-452 mimic NC. These results indicate that IH stress down-regulates the miR-452 in adipocytes, resulting in increased levels of RETN, TNFα, and CCL2 mRNAs, leading to insulin resistance in SAS patients.

Effects of concentration of amyloid β (Aβ) on viability of cultured retinal pigment epithelial cells

Background

Amyloid beta (Aβ) is a constituent of drusen that is a common sign of age-related macular degeneration (AMD). The purpose of this study was to investigate the effect of Aβ on human retinal pigment epithelial (RPE) cells in culture.

Methods

Cells from a human RPE cell line (ARPE-19) were exposed to 0 to 25 μM of Aβ 1–40 for 48 h, and the number of living cells was determined by WST-8 cleavage. Replicative DNA synthesis was measured by the incorporation of 5′-bromo-2′-deoxyuridine. The cell death pathway was investigated by the WST-8 cleavage assay after the addition of caspase-9 inhibitor, an anti-apoptotic factor. Real-time qRT-PCR was performed using Aβ-exposed cellular RNA to determine the level of vascular endothelial growth factor (VEGF)-A and pigment epithelium derived factor (PEDF). To determine the effect of receptor-for-advanced glycation end products (RAGE), the siRNA for RAGE was inserted into ARPE-19 treated with Aβ, and the levels of expression of VEGF-A and PEDF were determined.

Results

The number of living ARPE-19 cells was increased by exposure to 5 μM Aβ but was decreased by exposure to 25 μM of Aβ. Replicative DNA synthesis by ARPE-19 cells exposed to 25 μM of Aβ was significantly decreased indicating that 25 μM of Aβ inhibited cell proliferation. Real-time RT-PCR showed that the level of the mRNA of PEDF was increased by exposure to 5 μM Aβ, and the levels of the mRNAs of PEDF and VEGF-A were also increased by exposure to 25 μM Aβ. The addition of an inhibitor of caspase-9 blocked the decrease the number of ARPE-19 cells exposed to 25 μM Aβ. Exposure to si-RAGE attenuated the increase of VEGF-A and PEDF mRNA expression in ARPE-19 exposed to Aβ.

Conclusions

Exposure of ARPE-19 cells to low concentrations of Aβ increases the level of PEDF which then inhibits the apoptosis of ARPE-19 cells leading to RPE cell proliferation. Exposure to high concentrations of Aβ induces RPE cell death and enhances the expression of the mRNA of VEGF-A in RPE cells. The Aβ-RAGE pathway may lead to the expression VEGF-A and PEDF in RPE cells. These results suggest that Aβ is strongly related to the pathogenesis of choroidal neovascularization.

Up-regulation of selenoprotein P and HIP/PAP mRNAs in hepatocytes by intermittent hypoxia via down-regulation of miR-203

Sleep apnea syndrome is characterized by recurrent episodes of oxygen desaturation and reoxygenation (intermittent hypoxia [IH]) and is a risk factor for insulin resistance/type 2 diabetes. However, the mechanisms linking IH stress and insulin resistance remain elusive. We exposed human hepatocytes (JHH5, JHH7, and HepG2) to experimental IH or normoxia for 24 h, measured mRNA levels by real-time reverse transcription polymerase chain reaction (RT-PCR), and found that IH significantly increased the mRNA levels of selenoprotein P (SELENOP) — a hepatokine — and hepatocarcinoma-intestine-pancreas/pancreatitis-associated protein (HIP/PAP) — one of REG (Regenerating gene) family. We next investigated promoter activities of both genes and discovered that they were not increased by IH. On the other hand, a target mRNA search of micro RNA (miRNA) revealed that both mRNAs have a potential target sequence for miR-203. The miR-203 level of IH-treated cells was significantly lower than that of normoxia-treated cells. Thus, we introduced miR-203 inhibitor and a non-specific control RNA (miR-203 inhibitor NC) into HepG2 cells and measured the mRNA levels of SELENOP and HIP/PAP. The IH-induced expression of SELENOP and HIP/PAP was abolished by the introduction of miR-203 inhibitor but not by miR-203 inhibitor NC. These results demonstrate that IH stress up-regulates the levels of SELENOP in human hepatocytes to accelerate insulin resistance and up-regulates the levels of HIP/PAP mRNAs to proliferate such hepatocytes, via the miR-203 mediated mechanism.

Glucose metabolism and hepatic Igf1 DNA methylation are altered in the offspring of dams fed a low-salt diet during pregnancy

A low-salt (LS) diet during pregnancy has been linked to insulin resistance in adult offspring, at least in the experimental setting. However, it remains unclear if this effect is due to salt restriction during early or late pregnancy. To better understand this phenomenon, 12-week-old female Wistar rats were fed a LS or normal-salt (NS) diet during gestation or a LS diet during either the first (LS10) or second (LS20) half of gestation. Glucose tolerance test, HOMA-IR, gene expression analysis and DNA methylation measurements were conducted for the Insr, Igf1, Igf1r, Ins1 and Ins2 genes in the livers of neonates and in the liver, white adipose tissue and muscle of 20-week-old male offspring. Birth weight was lower in the LS20 and LS animals compared with the NS and LS10 rats. In the liver, the Igf1 levels in the LS10, LS20 and LS neonates were lower than those in the NS neonates. Methylation of the Insr, Igf1r, Ins1 and Ins2 genes was influenced in a variable manner by low salt intake during pregnancy. Increased liver Igf1 methylation was observed in the LS and LS20 neonates compared with their NS and LS10 counterparts. Glucose intolerance was observed in adult offspring as an effect of low salt intake over the duration of pregnancy. Compared to the NS animals, the HOMA-IR was higher in the 12-week-old LS and 20-week-old LS-10 rats. Based on these results, it appears that the reason a LS diet during pregnancy induces a low birth weight is its negative correlation with Igf1 DNA methylation in neonates.

Human retinal pigment epithelial cell proliferation by the combined stimulation of hydroquinone and advanced glycation end-products via up-regulation of VEGF gene

Although recent research showed that advanced glycation endproduct (AGE) and hydroquinone (HQ) are related to the pathogenesis of age-related macular degeneration (AMD), the mechanism how AGE and HQ induce or accelerate AMD remains elusive. In the present study, we examined the effects of AGE and HQ on changes of human retinal pigment epithelial (RPE) cell numbers and found that the viable cell numbers were markedly reduced by HQ by apoptosis and that AGE prevented the decreases of HQ-treated cell numbers by increased replicative DNA synthesis of RPE cells without changing apoptosis. Real-time RT-PCR revealed that vascular endothelial growth factor (VEGF)-A mRNA was increased by HQ treatment and the addition of HQ+AGE resulted in a further increment. The increase of VEGF secretion was confirmed by ELISA, and inhibition of VEGF signaling by chemical inhibitors and small interfering RNA decreased the HQ+AGE-induced increases in RPE cell numbers. The deletion analysis demonstrated that -102 to -43 region was essential for the VEGF-A promoter activation. Site-directed mutaions of specificity protein 1 (SP1) binding sequences in the VEGF-A promoter and RNA interference of SP1 revealed that SP1 is an essential transcription factor for VEGF-A expression. These results indicate that HQ induces RPE cell apoptosis, leading to dry AMD, and suggest that AGE stimulation in addition to HQ enhances VEGF-A transcription via the AGE-receptor for AGE pathway in HQ-damaged cells. As a result, the secreted VEGF acts as an autocrine/paracrine growth factor for RPE and/or adjacent vascular cells, causing wet AMD.

Hormones in the immune system and their possible role. A critical review

Immune cells synthesize, store and secrete hormones, which are identical with the hormones of the endocrine glands. These are: the POMC hormones (ACTH, endorphin), the thyroid system hormones (TRH, TSH, T3), growth hormone (GH), prolactin, melatonin, histamine, serotonin, catecholamines, GnRH, LHRH, hCG, renin, VIP, ANG II. This means that the immune cells contain all of the hormones, which were searched at all and they also have receptors for these hormones. From this point of view the immune cells are similar to the unicells (Tetrahymena), so it can be supposed that these cells retained the properties characteristic at a low level of phylogeny while other cells during the evolution accumulated to form endocrine glands. In contrast to the glandular endocrine cells, immune cells are polyproducers and polyreceivers. As they are mobile cells, they are able to transport the stored hormone to different places (packed transport) or attracted by local factors, accumulate in the neighborhood of the target, synthesizing and secreting hormones locally. This is taking place, e.g. in the case of endorphin, where the accumulating immune cells calms pain caused by the inflammation. The targeted packed transport is more economical than the hormone-pouring to the blood circulation of glandular endocrines and the targeting also cares the other receptor-bearing cells timely not needed the effect. Mostly the immune-effects of immune-cell derived hormones were studied (except endorphin), however, it is not exactly cleared, while the system could have scarcely studied important roles in other cases. The evolutionary aspects and the known as well, as possible roles of immune-endocrine system and their hormones are listed and discussed.