Fabp4-Cre-mediated Sirt6 deletion impairs adipose tissue function and metabolic homeostasis in mice

SIRT6 is a member of sirtuin family of deacetylases involved in diverse processes including genome stability, metabolic homeostasis and anti-inflammation. However, its function in the adipose tissue is not well understood. To examine the metabolic function of SIRT6 in the adipose tissue, we generated two mouse models that are deficient in Sirt6 using the Cre-lox approach. Two commonly used Cre lines that are driven by either the mouse Fabp4 or Adipoq gene promoter were chosen for this study. The Sirt6-knockout mice generated by the Fabp4-Cre line (Sirt6f/f:Fabp4-Cre) had a significant increase in both body weight and fat mass and exhibited glucose intolerance and insulin resistance as compared with the control wild-type mice. At the molecular levels, the Sirt6f/f :Fabp4-Cre-knockout mice had increased expression of inflammatory genes including F4/80, TNFα, IL-6 and MCP-1 in both white and brown adipose tissues. Moreover, the knockout mice showed decreased expression of the adiponectin gene in the white adipose tissue and UCP1 in the brown adipose tissue, respectively. In contrast, the Sirt6 knockout mice generated by the Adipoq-Cre line (Sirt6f/f :Adipoq-Cre) only had modest insulin resistance. In conclusion, our data suggest that the function of SIRT6 in the Fabp4-Cre-expressing cells in addition to mature adipocytes plays a critical role in body weight maintenance and metabolic homeostasis

SIRT6 protects against palmitate-induced pancreatic β-cell dysfunction and apoptosis

Chronic exposure of pancreatic β-cells to abnormally elevated levels of free fatty acids can lead to β-cell dysfunction and even apoptosis, contributing to type 2 diabetes pathogenesis. In pancreatic β-cells, SIRT6 has been shown to regulate insulin secretion in response to glucose stimulation. However, what roles SIRT6 play in β-cells in response to lipotoxicity remain poorly understood. Our data indicated that SIRT6 protein and mRNA levels were reduced in islets from diabetic and aged mice. High concentrations of palmitate also led to a decrease in SIRT6 expression in MIN6 β-cells and resulted in cell dysfunction and apoptosis. Knockdown of Sirt6 caused an increase in cell apoptosis and impairment in insulin secretion in response to glucose in MIN6 cells even in the absence of high palmitate. Furthermore, overexpression of SIRT6 alleviated the palmitate-induced lipotoxicity with improved cell viability and increased glucose-stimulated insulin secretion. In summary, our data suggest that SIRT6 can protect against palmitate-induced β-cell dysfunction and apoptosis

Finishing the euchromatic sequence of the human genome

The sequence of the human genome encodes the genetic instructions for human physiology, as well as rich information about human evolution. In 2001, the International Human Genome Sequencing Consortium reported a draft sequence of the euchromatic portion of the human genome. Since then, the international collaboration has worked to convert this draft into a genome sequence with high accuracy and nearly complete coverage. Here, we report the result of this finishing process. The current genome sequence (Build 35) contains 2.85 billion nucleotides interrupted by only 341 gaps. It covers ∼99% of the euchromatic genome and is accurate to an error rate of ∼1 event per 100,000 bases. Many of the remaining euchromatic gaps are associated with segmental duplications and will require focused work with new methods. The near-complete sequence, the first for a vertebrate, greatly improves the precision of biological analyses of the human genome including studies of gene number, birth and death. Notably, the human enome seems to encode only 20,000-25,000 protein-coding genes. The genome sequence reported here should serve as a firm foundation for biomedical research in the decades ahead

MicroRNA-384 Inhibits the Progression of Papillary Thyroid Cancer by Targeting PRKACB

Background. Growing evidence shows that dysregulation of miRNAs plays a significant role in papillary thyroid cancer (PTC) tumorigenesis and development. The abnormal expression of miR-384 has been acknowledged in the proliferation or metastasis of some cancers. However, the function and the underlying mechanism of miR-384 in PTC progression remain largely unknown. Methods. Real-time PCR was conducted to detect miR-384 expression in 58 cases of PTC and their adjacent noncancerous tissues. MTT, soft agar assay Transwell assay, and wound-healing assay were carried out to explore the biological function of miR-384 in PTC cell lines of BCPAP and K1. Bioinformatics analysis, dual-luciferase reporter assay, western blot, and functional complementation analysis were conducted to explore the target gene of miR-384. Moreover, Spearman’s correlation analysis was conducted to reveal the correlation between miR-384 and PRKACB mRNA in PTC. Results. The expression of miR-384 decreased obviously in PTC, especially in the tumors with lymph node metastasis or larger tumor size. The ectopic upregulation of miR-384 significantly suppressed PTC progression, and the inhibition of miR-384 had the opposite effects. Moreover, PRKACB gene was confirmed as the target of miR-384. Conclusion. The study suggests that miR-384 serves as a tumor suppressor in PTC progression by directly targeting the 3′-UTR of PRKACB gene

Cysteine-Rich Intestinal Protein 1 Silencing Inhibits Migration and Invasion in Human Colorectal Cancer

Background/Aims: Cysteine-rich intestinal protein 1 (CRIP1), a member of the LIM/double zinc finger protein family, is abnormally expressed in several tumour types. However, few data are available on the role of CRIP1 in cancer. In the present study, we aimed to investigate the expression profile and functions of CRIP1 in colorectal cancer. Methods: To examine the protein expression level of CRIP1, immunohistochemistry (IHC) was performed on 56 pairs of colon cancer tissue samples. Western blotting was performed to investigate CRIP1 protein expression in four colon cancer cell lines. The endogenous expression of CRIP1 was suppressed using short interfering RNAs (siRNAs). Cell proliferation assays were used to determine whether CRIP1 silencing affected cell proliferation. Flow cytometry analysis was used to detect cell apoptosis. The effects of silencing CRIP1 on cell migration and invasion was detected using the transwell and wound-healing assays. Results: IHC analysis showed that protein level of CRIP1 was significantly higher in tumour tissue samples than in paired non-tumour tissue samples and that the CRIP1 level was higher in metastatic tissue samples than in non-metastatic tissue samples. In addition, protein levels of CRIP1 were higher in highly metastatic colon cancer cell lines than in colon cancer cell lines with low metastasis. Further, CRIP1 silencing had no effect on cell proliferation or apoptosis in SW620 and HT29 cells. CRIP1 silencing suppressed cell migration and invasion obviously in SW620 and HT29 cells. Conclusion: The present study provides new evidence that abnormal expression of CRIP1 might be related to the degree of metastasis in colorectal cancer and that CRIP1 silencing could effectively inhibit migration and invasion during colorectal cancer development. These findings might aid the development of a biomarker for colon cancer prognosis and metastasis, and thus help to treat this common type of cancer

The Effects of Angelica Sinensis Polysaccharide on Tumor Growth and Iron Metabolism by Regulating Hepcidin in Tumor-Bearing Mice

Background/Aims: Iron plays a fundamental role in cell biology and its concentration must be precisely regulated. It is well documented that excess iron burden contributes to the occurrence and progression of cancer. Hepcidin secreted by liver plays an essential role in orchestrating iron metabolism. In the present study, we aimed to investigate the ability of angelica sinensis polysaccharide (ASP) to decrease iron burden in tumor-bearing mice and the mechanism of ASP regulation hepcidin expression. Methods: Western blot, RT-PCR, immunohistochemistry (IHC), and enzyme-linked immunosorbent assay (ELISA) were used to detect the regulation of hepcidin and related cytokines by ASP. The role of ASP in tumor proliferation was investigated using in vivo assays. Iron depositions and iron concentrations in organs were determined by hematoxylin-eosin (H&E) staining and atomic absorption spectrophotometer. Results: We found that ASP could inhibit tumor growth in mice xenografted with 4T1 and H22 cancer cells. In vivo experiments also showed that ASP could potently regulate hepcidin expression in liver and serum and decrease iron burden in liver, spleen and grafted tumors in mouse model. Treatment with ASP in hepatic cell lines reproduced comparable results in decreasing hepcidin as in mouse liver. Furthermore, we found that ASP markedly suppressed the expression of interleukin-6 (IL-6), JAK2, p-STAT3, and p-SMAD1/5/8 in liver, suggesting that JAK/STAT and BMP-SMAD pathways were involved in the regulation of hepcidin expression by ASP. We also found down-regulation of iron-related cytokines in ASP treated mice. Conclusion: The present study provides new evidence that ASP decreases hepcidin expression, which can reduce iron burden and inhibit tumor proliferation. These findings might aid ASP developed as a potential candidate for cancer treatment in patients with iron overload

The Synthesis of a Coumarin Carbohydrazide Dinuclear Copper Complex Based Fluorescence Probe and Its Detection of Thiols.

Small-molecule thiols, such as cysteine (CYS) and glutathione (GSH), are essential for maintaining the cellular redox environment and play important roles in regulating various cellular physiological functions. A fluorescence probe (compound 1-Cu2+) for thiols based on coumarin carbohydrazide dinuclear copper complex was developed. Compound 1 was synthesized from the reaction of 7-(diethylamino)-2-oxo-2H-chromene-3-carbohydrazide with 4-tert-butyl-2,6- diformylphenol. Accordingly, the copper complex (compound 1-Cu2+) was prepared by mixing compound 1 with 2 equivalents copper ions. Compound 1 had strong fluorescence while compound 1-Cu2+ hardly possessed fluorescence owing to the quenching nature of paramagnetism Cu2+ to the fluorescence molecule excited state. However, the fluorescence intensity of compound 1-Cu2+ was increased dramatically after the addition of thiol-containing amino acids, but not the other non-sulfhydryl amino acids. UV-vis absorption and fluorescence spectra indicated that compound 1-Cu2+ had good selectivity and sensitivity for thiols such as glutathione in CH3CN:H2O (3:2, v/v) PBS solution. The fluorescence imaging experiments implied that compound 1-Cu2+ has potential application in thiol-containing amino acids detection in living cells

Design and synthesis of a fluorescent probe based on naphthalene anhydride and its detection of copper ions - Fig 7

<p>The fluorescence images of LO-2 cells incubated with probe L (3 μM) (A); probe L after addition of 5 equivalents of Cu²⁺ ions (C); and their corresponding bright field images (B and D).</p