LncRNA-SNHG16 promotes proliferation and migration of acute myeloid leukemia cells via PTEN/PI3K/AKT axis through suppressing CELF2 protein.

The silence of lncRNA small nucleolar RNA host gene 16 (SNHG16) suppressed acute lymphoblastic leukemia (ALL) cell proliferation and migration, whereas its role in acute myeloid leukemia (AML) still lacks clarity. This study showed that SNHG16 was upregulated in AML patients and cells. And SNHG16 overexpression remarkably enhanced the proliferation and migration capacities of HL60 and AML-193 cells, while SNHG16 knockdown acted the opposite way. Subsequently, we revealed that SNHG16 directly bound to CELF2 (CUGBP Elav-like family member 2) protein, and caused CELF2 mRNA unstably and proteins reducing. CELF2 was decreased both in AML patients and cells. CELF2 overexpression or interference weakened the effect of overexpressing or silencing SNHG16 on proliferation and migration. Moreover, the transfection of pcDNA-CELF2 elevated PTEN (phosphatase and tensin homolog) activity and hindered the phosphoinositide 3-kinase (PI3K)/AKT signaling. And SNHG16 reduced PTEN activity and promoted the PI3K/AKT pathway activation by restraining CELF2. Furthermore, GDC-0941 (a specific inhibitor of the PI3K/AKT pathway) impeded the effect of SNHG16 increase, and bpV(pic) (a specific PTEN inhibitor) declined the effect of SNHG16 decrease on cell proliferation and migration. Taken together, the present study indicated that SNHG16 promoted proliferation and migration of AML cells via PTEN/PI3K/AKT axis through suppressing CELF2 protein.

Anti-diabetic effect of citrus pectin in diabetic rats and potential mechanism via PI3K/Akt signaling pathway.

This study was performed to investigate the anti-diabetic effect of citrus pectin in type 2 diabetic rats and its potential mechanism of action. The results showed that fasting blood glucose levels were significantly decreased after 4 weeks of citrus pectin administration. Citrus pectin improved glucose tolerance, hepatic glycogen content and blood lipid levels (TG, TC, LDL-c and HDL-c) in diabetic rats. Citrus pectin also significantly reduced insulin resistance, which played an important role in the resulting anti-diabetic effect. Moreover, after the pectin treatment, phosphorylated Akt expression was upregulated and GSK3ß expression was downregulated, indicating that the potential anti-diabetic mechanism of citrus pectin might occur through regulation of the PI3K/Akt signaling pathway. Together, these results suggested that citrus pectin could ameliorate type 2 diabetes and potentially be used as an adjuvant treatment.

Exenatide exerts direct protective effects on endothelial cells through the AMPK/Akt/eNOS pathway in a GLP-1 receptor-dependent manner.

Glucagon-like peptide-1 (GLP-1) may have direct favorable effects on cardiovascular system. The aim of this study was to investigate the effects of the GLP-1 analog exenatide on improving coronary endothelial function in patients with type 2 diabetes and to investigate the underlying mechanisms. The newly diagnosed type 2 diabetic subjects were enrolled and given either lifestyle intervention or lifestyle intervention plus exenatide treatment. After 12-wk treatment, coronary flow velocity reserve (CFVR), an important indicator of coronary endothelial function, was improved significantly, and serum levels of soluble intercellular adhesion molecule-1 (sICAM-1) and soluble vascular cell adhesion molecule-1 (sVCAM-1) were remarkably decreased in the exenatide treatment group compared with the baseline and the control group. Notably, CFVR was correlated inversely with hemoglobin A1c (Hb A1c) and positively with high-density lipoprotein cholesterol (HDL-C). In human umbilical vein endothelial cells, exendin-4 (a form of exenatide) significantly increased NO production, endothelial NO synthase (eNOS) phosphorylation, and GTP cyclohydrolase 1 (GTPCH1) level in a dose-dependent manner. The GLP-1 receptor (GLP-1R) antagonist exendin (9-39) or GLP-1R siRNA, adenylyl cyclase inhibitor SQ-22536, AMPK inhibitor compound C, and PI3K inhibitor LY-294002 abolished the effects of exendin-4. Furthermore, exendin-4 reversed homocysteine-induced endothelial dysfunction by decreasing sICAM-1 and reactive oxygen species (ROS) levels and upregulating NO production and eNOS phosphorylation. Likewise, exendin (9-39) diminished the protective effects of exendin-4 on the homocysteine-induced endothelial dysfunction. In conclusion, exenatide significantly improves coronary endothelial function in patients with newly diagnosed type 2 diabetes. The effect may be mediated through activation of AMPK/PI3K-Akt/eNOS pathway via a GLP-1R/cAMP-dependent mechanism.

Impaired activation of phosphatidylinositol 3-kinase by leptin is a novel mechanism of hepatic leptin resistance in NAFLD.

BACKGROUND/AIMS: The aim of this study was to detect the levels of leptin in serum and the expression of leptin, obesity receptor (OB-R), phosphatidylinositol 3-Kinase (p85) (PI3-K p85) and phospho-Akt-kinase (Akt) in non-alcoholic fatty liver disease (NAFLD). METHODOLOGY: The expressions of leptin, OB-R and PI3-K/ Akt kinase pathway were examined by immunohistochemistry. The level of leptin in serum was measured by radioimmunoassay. RESULTS: In agreement with significantly elevated serum leptin levels in NAFLD patients (p<0.05), expression of leptin, OB-R and PI3-K (p85) was significant higher in NAFLD patients (p<0.05) compared with the control patients. In contrast, expression of Akt was significantly down-regulated in the NAFLD patients (p<0.05). Moreover, PI3-K (p85) expression was significantly, positively correlated with leptin (r= 0.365, p<0.05) but negatively correlated with Akt (r=-0.854, p<0.01). CONCLUSIONS: Leptin may be involved in NAFLD pathogenesis by activating the PI3-K/Akt kinase pathway via OB-R and the defective leptin activation of PI3-K is a novel mechanism of leptin resistance in NAFLD.

Whole blood processing for measurement of signaling proteins by flow cytometry.

Signal transduction pathways link external stimuli with cellular responses, which normally regulate cell proliferation, death, and differentiation. The study of signal transduction was revolutionized through the development of phospho-specific antibodies that recognize proteins only when they are phosphorylated at specific sites. As discussed by Nolan and co-workers (UNIT ), one of the unique features of flow cytometry is its ability to perform correlated measurements of multiple phosphorylation states at the single cell level. This provides insight into the complexity of signaling networks that is not obtained by standard biochemical techniques. Furthermore, in combination with other phenotypic markers, flow cytometry can measure alterations in signaling pathways in subpopulations of cells. This clearly has wide potential for studying disorders of the hematopoietic and immune systems.