scholarly journals The role of cell surface sialic acid in insulin receptor function and insulin action.

1986 ◽  
Vol 261 (6) ◽  
pp. 2791-2798
Author(s):  
G R Hayes ◽  
D H Lockwood
Keyword(s):  
Sialic Acid ◽  
Cell Surface ◽  
Insulin Receptor ◽  
Insulin Action ◽  
Receptor Function

Decreased muscle insulin receptor kinase correlates with insulin resistance in normoglycemic Pima Indians

1997 ◽  
Vol 273 (2) ◽  
pp. E276-E283 ◽  
Author(s):  
J. F. Youngren ◽  
I. D. Goldfine ◽  
R. E. Pratley
Keyword(s):  
Insulin Resistance ◽  
Insulin Receptor ◽  
Body Fat ◽  
Insulin Action ◽  
Enzyme Linked Immunosorbent Assay ◽  
Percent Body Fat ◽  
Receptor Function ◽  
Pima Indians ◽  
Insulin Receptor Tyrosine Kinase

Defects in insulin receptor tyrosine kinase activity are present in insulin-resistant non-insulin-dependent diabetes mellitus patients and certain nondiabetic individuals, both lean and obese. However, the relationship between insulin receptor function, insulin action, and obesity is unclear. To address this issue, we have employed a new and highly sensitive enzyme-linked immunosorbent assay to measure in vitro insulin-stimulated autophosphorylation of immunocaptured muscle insulin receptors in a group of 25 normoglycemic Pima Indians. Insulin action, determined during two-step euglycemic insulin clamps, varied widely in these subjects. Maximal in vitro insulin stimulation of insulin receptor autophosphorylation strongly correlated with both low (Mlow)- and high (Mhigh)-dose insulin-stimulated glucose disposal (r = 0.62 and 0.51, P < 0.002 and 0.011, respectively). Insulin receptor autophosphorylation was inversely related to percent body fat (r = -0.52, P < 0.009). After control for percent body fat, receptor autophosphorylation remained correlated with Mlow (partial r = 0.49, P < 0.025). These data therefore suggest that defects in insulin receptor function are major contributors to insulin resistance in both lean and obese normoglycemic Pima Indians.

scholarly journals The Role of Sialic Acids in the Establishment of Infections by Pathogens, With Special Focus on Leishmania

2021 ◽  
Vol 11 ◽  
Author(s):  
Tainá Cavalcante ◽  
Mariana Medina Medeiros ◽  
Simon Ngao Mule ◽  
Giuseppe Palmisano ◽  
Beatriz Simonsen Stolf
Keyword(s):  
Sialic Acid ◽  
Cell Surface ◽  
Host Cell ◽  
Functional Diversity ◽  
Sialic Acids ◽  
Cellular Communication ◽  
Special Focus ◽  
Functional Studies ◽  
Sialic Acid Binding

Carbohydrates or glycans are ubiquitous components of the cell surface which play crucial biological and structural roles. Sialic acids (Sias) are nine-carbon atoms sugars usually present as terminal residues of glycoproteins and glycolipids on the cell surface or secreted. They have important roles in cellular communication and also in infection and survival of pathogens. More than 20 pathogens can synthesize or capture Sias from their hosts and incorporate them into their own glycoconjugates and derivatives. Sialylation of pathogens’ glycoconjugates may be crucial for survival inside the host for numerous reasons. The role of Sias in protozoa such as Trypanosoma and Leishmania was demonstrated in previous studies. This review highlights the importance of Sias in several pathogenic infections, focusing on Leishmania. We describe in detail the contributions of Sias, Siglecs (sialic acid binding Ig-like lectins) and Neuraminidase 1 (NEU 1) in the course of Leishmania infection. A detailed view on the structural and functional diversity of Leishmania-related Sias and host-cell receptors will be provided, as well as the results of functional studies performed with different Leishmania species.

The Role of Calcium and Calmodulin in Insulin Receptor Function in the Adipocyte

1986 ◽  
Vol 488 (1 Membrane Path) ◽  
pp. 406-418 ◽  
Author(s):  
JAY M. McDONALD ◽  
HARRIHAR A. PERSHADSINGH ◽  
JERRY COLCA
Keyword(s):  
Insulin Receptor ◽  
Receptor Function

Role of sialic acid in insulin action and the insulin resistance of diabetes mellitus

1988 ◽  
Vol 255 (2) ◽  
pp. E173-E179 ◽  
Author(s):  
A. I. Salhanick ◽  
J. M. Amatruda
Keyword(s):  
Diabetes Mellitus ◽  
Insulin Resistance ◽  
Sialic Acid ◽  
Cell Surface ◽  
Acid Content ◽  
Insulin Action ◽  
Diabetic Rats ◽  
Hepatic Insulin Resistance ◽  
Sialic Acid Content ◽  
Insulin Responsiveness

Adipocytes treated with neuraminidase show markedly reduced responsiveness to insulin without any alteration in insulin binding. In addition, several studies have separately demonstrated both insulin resistance and decreases in membrane sialic acid content and associated biosynthetic enzymes in diabetes mellitus. In the present study, we investigated the role that sialic acid residues may play in insulin action and in the hepatic insulin resistance associated with nonketotic diabetes. Primary cultures of hepatocytes from normal rats treated with neuraminidase demonstrated a dose-dependent decrease in insulin-stimulated lipogenesis. At a concentration of neuraminidase that decreases insulin action by 50%, 23% of total cellular sialic acid content was released. Neuraminidase-releasable sialic acid was significantly decreased in hepatocytes from diabetic rats and this was associated with significant insulin resistance. Treatment of hepatocytes from diabetic rats with cytidine 5'-monophospho-N-acetylneuraminic acid (CMP-NANA) enhanced insulin responsiveness 39%. The enhanced insulin responsiveness induced by CMP-NANA was blocked by cytidine 5'-monophosphate (CMP) suggesting that the CMP-NANA effect was catalyzed by a cell surface sialyltransferase. CMP reduced neuraminidase-releasable [14C]sialic acid incorporation into hepatocytes by 43%. The data demonstrate a role for cell surface sialic acid residues in hepatic insulin action and support a role for decreased cell surface sialic acid residues in the insulin resistance of diabetes mellitus.

scholarly journals The role of sialated glycoproteins in endocytosis, permeability and transmural passage in the myeloid endothelium.

1979 ◽  
Vol 27 (8) ◽  
pp. 1174-1176 ◽  
Author(s):  
P P De Bruyn
Keyword(s):  
Sialic Acid ◽  
Cell Surface ◽  
Charge Distribution ◽  
Surface Modifications ◽  
Low Ph ◽  
Cell Passage ◽  
Colloidal Iron ◽  
Endothelial Cell Surface ◽  
Anionic Charge

Changes in the anionic charge distribution at the luminal face of the endothelium of the sinusoids of the bone marrow have been studied at sites of endocytosis by large bristle coated vesicles and at the sites of molecular permeability through diaphragmed fenestrae. The anionic charge distribution has also been studied at the abluminal aspect of these vessels at sites of transmural blood cell passage. Cationic surface markers such as colloidal iron, native ferritin and polycationic ferritin used at low pH, 1.8, and the use of neuraminidase show that the nonmodified endothelial cell surface has exposed sialic acid groups, which are absent at the sites of these functional specializations. Polycationic ferritin binding over a range of pH levels indicates the prsence of another species of anionic materials present at both the nonmodified cell surface and at the sites of the cell surface modifications. This second group of anionic compounds is neuraminidase resistant and has a pKa higher than that of sialic acid (pKa:2.6).

Role of sialic acid in the maintenance of cell surface rigidity

1975 ◽  
Vol 31 (9) ◽  
pp. 1075-1077 ◽  
Author(s):  
P. K. Ray ◽  
S. Chatterjee
Keyword(s):  
Sialic Acid ◽  
Cell Surface ◽  
Surface Rigidity

scholarly journals Phosphoinositides in insulin action on GLUT4 dynamics: not just PtdIns(3,4,5)P3

2008 ◽  
Vol 295 (3) ◽  
pp. E536-E544 ◽  
Author(s):  
Assia Shisheva
Keyword(s):  
Plasma Membrane ◽  
Cell Surface ◽  
Insulin Receptor ◽  
Experimental Evidence ◽  
Functional Significance ◽  
Insulin Action ◽  
Complementary Function ◽  
Intracellular Storage ◽  
Insulin Responsiveness ◽  
Rate Limiting

Accumulated evidence over the last several years indicates that insulin regulates multiple steps in the overall translocation of GLUT4 vesicles to the fat/muscle cell surface, including formation of an intracellular storage pool of GLUT4 vesicles, its movement to the proximity of the cell surface, and the subsequent docking/fusion with the plasma membrane. Insulin-stimulated formation of phosphatidylinositol 3,4,5-trisphosphate [PtdIns(3,4,5)P3; and in some cases, of its catabolite PtdIns(3,4)P2] plays a pivotal role in this process. PtdIns(3,4,5)P3 is synthesized by the activated wortmannin-sensitive class IA phosphoinositide (PI) 3-kinase and controls the rate-limiting cell surface terminal stages of the GLUT4 journey. However, recent research is consistent with the conclusion that signals by each of the remaining five PIs, i.e., PtdIns(3)P, PtdIns(4)P, PtdIns(5)P, PtdIns(3,5)P2, and PtdIns(4,5)P2, may act in concert with that of PtdIns(3,4,5)P3 in integrating the insulin receptor-issued signals with GLUT4 surface translocation and glucose transport activation. This review summarizes the experimental evidence supporting the complementary function of these PIs in insulin responsiveness of fat and muscle cells, with particular reference to mechanistic insights and functional significance in the regulation of overall GLUT4 vesicle dynamics.

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