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Full-Text Articles in Medicine and Health Sciences
Sphk2−/− Mice Are Protected From Obesity And Insulin Resistance, Shwetha Ravichandran, Brian S. Finlin, Philip A. Kern, Sabire Özcan
Sphk2−/− Mice Are Protected From Obesity And Insulin Resistance, Shwetha Ravichandran, Brian S. Finlin, Philip A. Kern, Sabire Özcan
Clinical and Translational Science Faculty Publications
Sphingosine kinases phosphorylate sphingosine to sphingosine 1‑phosphate (S1P), which functions as a signaling molecule. We have previously shown that sphingosine kinase 2 (Sphk2) is important for insulin secretion. To obtain a better understanding of the role of Sphk2 in glucose and lipid metabolism, we have characterized 20- and 52-week old Sphk2−/− mice using glucose and insulin tolerance tests and by analyzing metabolic gene expression in adipose tissue. A detailed metabolic characterization of these mice revealed that aging Sphk2−/− mice are protected from metabolic decline and obesity compared to WT mice. Specifically, we found that 52-week old …
Impact Of Sleep And Circadian Disruption On Energy Balance And Diabetes: A Summary Of Workshop Discussions, Deanna M. Arble, Joseph Bass, Cecilia Diniz Behn, Matthew P. Butler, Etienne Challet, Charles Czeisler, Christopher M. Depner, Joel Elmquist, Paul Franken, Michael A. Grandner, Erin C. Hanlon, Alex C. Keene, Michael J. Joyner, Ilia Karatsoreos, Philip A. Kern, Samuel Klein, Christopher J. Morris, Allan I. Pack, Satchidananda Panda, Louis J. Ptacek, Naresh M. Punjabi, Paolo Sassone-Corsi, Frank A. Scheer, Richa Saxena, Elizabeth R. Seaquest, Matthew S. Thimgan, Eve Van Cauter, Kenneth P. Wright
Impact Of Sleep And Circadian Disruption On Energy Balance And Diabetes: A Summary Of Workshop Discussions, Deanna M. Arble, Joseph Bass, Cecilia Diniz Behn, Matthew P. Butler, Etienne Challet, Charles Czeisler, Christopher M. Depner, Joel Elmquist, Paul Franken, Michael A. Grandner, Erin C. Hanlon, Alex C. Keene, Michael J. Joyner, Ilia Karatsoreos, Philip A. Kern, Samuel Klein, Christopher J. Morris, Allan I. Pack, Satchidananda Panda, Louis J. Ptacek, Naresh M. Punjabi, Paolo Sassone-Corsi, Frank A. Scheer, Richa Saxena, Elizabeth R. Seaquest, Matthew S. Thimgan, Eve Van Cauter, Kenneth P. Wright
Clinical and Translational Science Faculty Publications
A workshop was held at the National Institute for Diabetes and Digestive and Kidney Diseases with a focus on the impact of sleep and circadian disruption on energy balance and diabetes. The workshop identified a number of key principles for research in this area and a number of specific opportunities. Studies in this area would be facilitated by active collaboration between investigators in sleep/circadian research and investigators in metabolism/diabetes. There is a need to translate the elegant findings from basic research into improving the metabolic health of the American public. There is also a need for investigators studying the impact …
Regulation Of Pten Inhibition By The Pleckstrin Homology Domain Of P-Rex2 During Insulin Signaling And Glucose Homeostasis, Cindy Hodakoski, Benjamin D. Hopkins, Douglas Barrows, Sarah M. Mense, Megan Keniry, Karen E. Anderson, Philip A. Kern, Phillip T. Hawkins, Len R. Stephens, Ramon Parsons
Regulation Of Pten Inhibition By The Pleckstrin Homology Domain Of P-Rex2 During Insulin Signaling And Glucose Homeostasis, Cindy Hodakoski, Benjamin D. Hopkins, Douglas Barrows, Sarah M. Mense, Megan Keniry, Karen E. Anderson, Philip A. Kern, Phillip T. Hawkins, Len R. Stephens, Ramon Parsons
Clinical and Translational Science Faculty Publications
Insulin activation of phosphoinositide 3-kinase (PI3K) signaling regulates glucose homeostasis through the production of phosphatidylinositol 3,4,5-trisphosphate (PIP3). The dual-specificity phosphatase and tensin homolog deleted on chromosome 10 (PTEN) blocks PI3K signaling by dephosphorylating PIP3, and is inhibited through its interaction with phosphatidylinositol 3,4,5-trisphosphate-dependent Rac exchanger 2 (P-REX2). The mechanism of inhibition and its physiological significance are not known. Here, we report that P-REX2 interacts with PTEN via two interfaces. The pleckstrin homology (PH) domain of P-REX2 inhibits PTEN by interacting with the catalytic region of PTEN, and the inositol polyphosphate 4-phosphatase domain of P-REX2 provides high-affinity binding to the postsynaptic …
Oxpat/Pat-1 Is A Ppar-Induced Lipid Droplet Protein That Promotes Fatty Acid Utilization, Nathan E. Wolins, Benjamin K. Quaynor, James R. Skinner, Anatoly Tzekov, Michelle A. Croce, Matthew C. Gropler, Vijayalakshmi Varma, Aiwei Yao-Borengasser, Neda Rasouli, Philip A. Kern, Brian N. Finck, Perry E. Bickel
Oxpat/Pat-1 Is A Ppar-Induced Lipid Droplet Protein That Promotes Fatty Acid Utilization, Nathan E. Wolins, Benjamin K. Quaynor, James R. Skinner, Anatoly Tzekov, Michelle A. Croce, Matthew C. Gropler, Vijayalakshmi Varma, Aiwei Yao-Borengasser, Neda Rasouli, Philip A. Kern, Brian N. Finck, Perry E. Bickel
Clinical and Translational Science Faculty Publications
Lipid droplet proteins of the PAT (perilipin, adipophilin, and TIP47) family regulate cellular neutral lipid stores. We have studied a new member of this family, PAT-1, and found that it is expressed in highly oxidative tissues. We refer to this protein as "OXPAT." Physiologic lipid loading of mouse liver by fasting enriches OXPAT in the lipid droplet tissue fraction. OXPAT resides on lipid droplets with the PAT protein adipophilin in primary cardiomyocytes. Ectopic expression of OXPAT promotes fatty acid-induced triacylglycerol accumulation, long-chain fatty acid oxidation, and mRNAs associated with oxidative metabolism. Consistent with these observations, OXPAT is induced in mouse …
Pioglitazone Induces Apoptosis Of Macrophages In Human Adipose Tissue, Angela M. Bodles, Vijayalakshmi Varma, Aiwei Yao-Borengasser, Bounleut Phanavanh, Charlotte A. Peterson, Robert E. Mcgehee Jr., Neda Rasouli, Martin Wabitsch, Philip A. Kern
Pioglitazone Induces Apoptosis Of Macrophages In Human Adipose Tissue, Angela M. Bodles, Vijayalakshmi Varma, Aiwei Yao-Borengasser, Bounleut Phanavanh, Charlotte A. Peterson, Robert E. Mcgehee Jr., Neda Rasouli, Martin Wabitsch, Philip A. Kern
Clinical and Translational Science Faculty Publications
Metabolic syndrome and type 2 diabetes mellitus are associated with an increased number of macrophage cells that infiltrate white adipose tissue (WAT). Previously, we demonstrated that the treatment of subjects with impaired glucose tolerance (IGT) with the peroxisome proliferator-activated receptor γ (PPARγ) agonist pioglitazone resulted in a decrease in macrophage number in adipose tissue. Here, adipose tissue samples from IGT subjects treated with pioglitazone were examined for apoptosis with terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) staining. TUNEL-positive cells were identified, and there was a significant 42% increase in TUNEL-positive cells following pioglitazone treatment. Overlay experiments with anti-CD68 antibody …
The Translational Regulation Of Lipoprotein Lipase In Diabetic Rats Involves The 3′-Untranslated Region Of The Lipoprotein Lipase Mrna, Gouri Ranganathan, Chunling Li, Philip A. Kern
The Translational Regulation Of Lipoprotein Lipase In Diabetic Rats Involves The 3′-Untranslated Region Of The Lipoprotein Lipase Mrna, Gouri Ranganathan, Chunling Li, Philip A. Kern
Clinical and Translational Science Faculty Publications
Adipose tissue lipoprotein lipase (LPL) activity is decreased in patients with poorly controlled diabetes, and this contributes to the dyslipidemia of diabetes. To study the mechanism of this decrease in LPL, we studied adipose tissue LPL expression in male rats with streptozotocin-induced diabetes. Heparin releasable and extractable LPL activity in the epididymal fat decreased by 75-80% in the diabetic group and treatment of the rats with insulin prior to sacrifice reversed this effect. Northern blot analysis indicated no corresponding change in LPL mRNA levels. However, LPL synthetic rate, measured using [35S]methionine pulse labeling, was decreased by 75% in …
Exposure To 2,3,7,8-Tetrachlorodibenzo-P-Dioxin (Tcdd) Is Associated With Hyperinsulinemia And Insulin Resistance, Morris Cranmer, Shirley Louie, Richard H. Kennedy, Philip A. Kern, Vivian A. Fonseca
Exposure To 2,3,7,8-Tetrachlorodibenzo-P-Dioxin (Tcdd) Is Associated With Hyperinsulinemia And Insulin Resistance, Morris Cranmer, Shirley Louie, Richard H. Kennedy, Philip A. Kern, Vivian A. Fonseca
Clinical and Translational Science Faculty Publications
High exposures of Vietnam veterans to 2,3,7,8-Tetrachlorodibenzo-p- dioxin, a dioxin contained in the herbicide mixture Agent Orange, have previously been demonstrated to be associated with an increased prevalence of diabetes and hyperinsulinemia in non-diabetic subjects. Sixty-nine persons were identified who were in good health and had normal glucose levels during glucose tolerance testing. These subjects lived within 25 miles of the Vertac/Hercules Superfund site located in Jacksonville, Arkansas. The blood sera lipid concentrations of TCDD for the 69 subjects ranged between 2 and 94 ppt. When subjects with blood sera lipid TCDD levels in the top 10% (TCDD > 15 ppt, …
Role Of Protein Kinase C In The Translational Regulation Of Lipoprotein Lipase In Adipocytes, Gouri Ranganathan, Rami Kaakaji, Philip A. Kern
Role Of Protein Kinase C In The Translational Regulation Of Lipoprotein Lipase In Adipocytes, Gouri Ranganathan, Rami Kaakaji, Philip A. Kern
Clinical and Translational Science Faculty Publications
The hypertriglyceridemia of diabetes is accompanied by decreased lipoprotein lipase (LPL) activity in adipocytes. Although the mechanism for decreased LPL is not known, elevated glucose is known to increase diacylglycerol, which activates protein kinase C (PKC). To determine whether PKC is involved in the regulation of LPL, we studied the effect of 12-O-tetradecanoyl phorbol 13-acetate (TPA) on adipocytes. LPL activity was inhibited when TPA was added to cultures of 3T3-F442A and rat primary adipocytes. The inhibitory effect of TPA on LPL activity was observed after 6 h of treatment, and was observed at a concentration of 6 nM. …
Thiazolidinediones Inhibit Lipoprotein Lipase Activity In Adipocytes, Subramanian Ranganathan, Philip A. Kern
Thiazolidinediones Inhibit Lipoprotein Lipase Activity In Adipocytes, Subramanian Ranganathan, Philip A. Kern
Clinical and Translational Science Faculty Publications
The thiazolidinediones troglitazone and BRL 49653 improve insulin sensitivity in humans and animals with insulin resistance. Adipose tissue lipoprotein lipase is an insulin-sensitive enzyme. We examined the effects of thiazolidinediones on lipoprotein lipase expression in adipocytes. When added to 3T3-F442A, 3T3-L1, and rat adipocytes in culture, troglitazone and BRL 49653 inhibited lipoprotein lipase activity. This inhibition was observed at concentrations as low as 0.1 μM and within 2 h after addition of the drug. Lipoprotein lipase activity was inhibited in differentiated adipocytes as well as the differentiating cells. Despite this decrease in enzyme activity, these drugs increased mRNA levels in …
Effects Of Tumor Necrosis Factor-Α On Glucose Metabolism In Cultured Human Muscle Cells From Nondiabetic And Type 2 Diabetic Subjects, Theodore P. Ciaraldi, Leslie Carter, Sunder Mudaliar, Philip A. Kern, Robert R. Henry
Effects Of Tumor Necrosis Factor-Α On Glucose Metabolism In Cultured Human Muscle Cells From Nondiabetic And Type 2 Diabetic Subjects, Theodore P. Ciaraldi, Leslie Carter, Sunder Mudaliar, Philip A. Kern, Robert R. Henry
Clinical and Translational Science Faculty Publications
The effects of tumor necrosis factor-a (TNFα) on glucose uptake and glycogen synthase (GS) activity were studied in human skeletal muscle cell cultures from nondiabetic and type 2 diabetic subjects. In nondiabetic muscle cells, acute (90-Min) exposure to TNFα (5 ng/ml) stimulated glucose uptake (73 ± 14% increase) to a greater extent than insulin (37 ± 4%; P < 0.02). The acute uptake response to TNFα in diabetic cells (51 ± 6% increase) was also greater than that to insulin (31 ± 3%; P < 0.05). Prolonged (24-h) exposure of nondiabetic muscle cells to TNFα resulted in a further stimulation of uptake (152 ± 31%; P < 0.05), whereas the increase in cells from type 2 diabetics was not significant compared with that in cells receiving acute treatment. After TNFα treatment, the level of glucose transporter-1 protein was elevated in nondiabetic (4.6-fold increase) and type 2 (1.7-fold) cells. Acute TNFα treatment had no effect on the fractional velocity of GS in either nondiabetic or type 2 cells. Prolonged exposure reduced the GS fractional velocity in both nondiabetic and diabetic cells. In summary, both acute and prolonged treatment with TNFα up-regulate glucose uptake activity in cultured human muscle cells, but reduce GS activity. Increased skeletal muscle glucose uptake in conditions of TNFα excess may serve as a compensatory mechanism in the insulin resistance of type 2 diabetes.