Recent studies have introduced serum uric acid (UA) as a potential risk factor for developing diabetes, hypertension, stroke, and cardiovascular diseases. The value of elevated levels of UA in serum as a risk factor for diabetes development is still under scrutiny. Recent data suggest that clearance of UA is being reduced with increase in insulin resistance and UA as a marker of prediabetes period. However, conflicting data related to UA in serum of patients with Type 2 diabetes prompted us to study the urine/serum ratio of UA levels (USRUA) in these patients and healthy controls. All subjects included in the study were free of evidence of hepatitis B or C viral infection or active liver and kidney damage. Patients receiving drugs known to influence UA levels were also excluded from this study. Analysis of glucose and uric acid were performed on Dade Behring analyzer using standard IFCC protocols. Interestingly, our data demonstrated about 2.5 fold higher USRUA values in diabetic patients as compared to control subjects. Furthermore, there was a trend of correlation of USRUA value with the blood glucose levels in diabetic patients, which was more prominent in diabetic men than in women. With aging, levels of uric acid increased in serum of diabetic patients, and this effect was also more profound in male than in female diabetics. In conclusion, this study showed significantly elevated USRUA levels in patients with Type 2 diabetes, a negative USRUA correlation with the blood glucose levels in diabetic patients, and an effect of sex and age on the uric acid levels. Since literature data suggest a strong genetic effect on UA levels, it would be pertinent to perform further, possibly genetic studies, in order to clarify gender and ethnic differences in UA concentrations.

Th is is the fi rst study performed in population from Bosnia & Herzegovina (BH), in which we analysed a signifi cance of genetic variations in drug-metabolising enzyme, cytochrome P (CYP), in pathogenesis of Type  diabetes. We have determined allele frequencies for CYPC*, CYPC*, and CYPD* in diabetic patients and nondiabetic controls. Genomic DNA was extracted from blood samples collected from  diabetic and  nondiabetic subjects. A real-time polymerase chain reaction was used for the detection of specifi c CYP polymorphisms, with the application of the specifi c TaqMan® SNP genotyping tests (Applied Biosystems). Interestingly, results from this study have demonstrated that frequencies of CYPC* and CYPD* variants were in line, while frequency of CYPC* polymorphism seemed to be lower in this sample of BH population as compared to the Caucasians genotype data. Furthermore, no signifi cant diff erence in allele frequencies for CYPC*, CYPC*, and CYPD* was demonstrated between diabetic and nondiabetic subjects. Th us, results form this study seem to indicate no relationship between CYPC, CYPC, and CYPD genotype and diabetes susceptibility in Bosnian population. Th is in part may refl ect a limited study population included in our study and would require larger cohorts to reveal potential relationships between analysed CYP genetic variants and diabetes risk. In addition, it would be pertinent to further explore possible eff ects of CYP genetic variations on therapeutic and adverse outcomes of oral antidiabetics, which might be the key in optimising therapy for individual patient with Type  diabetes. ©  Association of Basic Medical Sciences of FBIH. All rights reserved

Glucose transporter 4 (GLUT4) moves from perinuclear storage regions to the plasma membrane in response to insulin and facilitates glucose uptake. This MQP examined the roles of three proteins (GAPDH, PGK, and PGAM) in glucose uptake and GLUT4 trafficking in 3T3-L1 adipocytes by performing glucose uptake assays on adipocytes in which these proteins were selectively knocked down using RNAi. GLUT4 trafficking was visualized by transfection with Myc-tagged GLUT4-GFP and immunofluorescence. The data indicate no effect by PGK, while PGAM and GAPDH inhibited both glucose uptake and GLUT4 fusion to the plasma membrane. GAPDH may be required for general cellular secretion pathways.

Using siRNA-mediated gene silencing in cultured adipocytes, we have dissected the insulin-signalling pathway leading to translocation of GLUT4 glucose transporters to the plasma membrane. RNAi (RNA interference)-based depletion of components in the putative TC10 pathway (CAP, CrkII and c-Cbl plus Cbl-b) or the phospholipase Cgamma pathway failed to diminish insulin signalling to GLUT4. Within the phosphoinositide 3-kinase pathway, loss of the 5'-phosphatidylinositol 3,4,5-trisphosphate phosphatase SHIP2 was also without effect, whereas depletion of the 3'-phosphatase PTEN significantly enhanced insulin action. Downstream of phosphatidylinositol 3,4,5-trisphosphate and PDK1, silencing the genes encoding the protein kinases Akt1/PKBalpha, or CISK(SGK3) or protein kinases Clambda/zeta had little or no effect, but loss of Akt2/PKBbeta significantly attenuated GLUT4 regulation by insulin. These results show that Akt2/PKBbeta is the key downstream intermediate within the phosphoinositide 3-kinase pathway linked to insulin action on GLUT4 in cultured adipocytes, whereas PTEN is a potent negative regulator of this pathway.

Insulin stimulates glucose uptake in muscle and adipose cells by mobilizing intracellular membrane vesicles containing GLUT4 glucose transporter proteins to the plasma membrane. Here we show in live cultured adipocytes that intracellular membranes containing GLUT4–yellow fluorescent protein (YFP) move along tubulin–cyan fluorescent protein‐labeled microtubules in response to insulin by a mechanism that is insensitive to the phosphatidylinositol 3 (PI3)‐kinase inhibitor wortmannin. Insulin increased by several fold the observed frequencies, but not velocities, of long‐range movements of GLUT4–YFP on microtubules, both away from and towards the perinuclear region. Genomics screens show conventional kinesin KIF5B is highly expressed in adipocytes and this kinesin is partially co‐localized with perinuclear GLUT4. Dominant‐negative mutants of conventional kinesin light chain blocked outward GLUT4 vesicle movements and translocation of exofacial Myc‐tagged GLUT4–green fluorescent protein to the plasma membrane in response to insulin. These data reveal that insulin signaling targets the engagement or initiates the movement of GLUT4‐containing membranes on microtubules via conventional kinesin through a PI3‐kinase‐independent mechanism. This insulin signaling pathway regulating KIF5B function appears to be required for GLUT4 translocation to the plasma membrane.