Stimulation by 1,25-Dihydroxyvitamin D3 of Insulin Receptor Expression and Insulin Responsiveness for Glucose Transport in U-937 Human Promonocytic Cells.

Abstract

Abstract.In the present work, we demonstrate that treatment with 1,25-dihydroxyvitamin D3 for 24 hours increased in a dose-dependent manner the levels of the two major insulin receptor (IR) mRNAs (11 and 8.5 Kb) present in U-937 human promonocytic cells. These levels reached maximum values (1.8-fold 11 Kb; 1.4-fold 8.5 Kb) with the addition of 108 M 1,25-dihydroxyvitamin D3. In these optimal conditions the stimulatory effect of 1,25-dihydroxyvitamin D3 was accompanied by increases in both IR capacity, and insulin responsiveness for glucose transport in these cells. Moreover, such increases appear to be mediated by an enhanced expression of the receptor for 1,25-dihydroxyvitamin D3, measured at the level of both RNA and protein. These results provide evidence of 1,25-dihydroxyvitamin D3 acting as genomic stimulator of the insulin response in the control of glucose transport.

Inverse relationship between vitamin D status and insulin resistance and the risk of impaired fasting glucose in Korean children and adolescents: the Korean National Health and Nutrition Examination Survey (KNHANES) 2009–2010

“…The mechanism by which VitD deficiency and T2DM risk are related is unclear. The theoretical evidence that VitD reduces IR (11)(12)(13) and maintains insulin secretion (13)(14)(15)(16) supports the hypothesis that VitD reduces the risk of T2DM. However, VitD deficiency, impaired fasting glucose (IFG) and T2DM share the same risk factors, including African-American, Asian or Hispanic ethnicity, increased adiposity, older age and physical inactivity (16) .…”

Maternal vitamin D status in Type 1 diabetic pregnancy: Impact on neonatal vitamin D status and association with maternal glycaemic control

“…Potential mechanisms by which vitamin D might influence glycaemic control in T1DM include, the impact of this vitamin on intracellular calcium regulation and, thus, glucose transport in target tissues, influences on insulin receptor expression and the effect of vitamin D on systemic inflammation associated with insulin resistance [31,32]. While traditionally associated with T2DM, the importance of insulin resistance in the etiology of T1DM is being increasingly recognised, albeit that the underlying mechanisms may differ from those in T2DM [33,34].…”

Vitamin D and assisted reproduction: should vitamin D be routinely screened and repleted prior to ART? A systematic review

“…This increase is suspected to be involved in glucose metabolism and decreased insulin sensitivity. Other studies suggest that vitamin D stimulates the expression of insulin receptors, which in turn augments insulin responsiveness for glucose transport [43,44]. Another important consideration is that the vitamin D/VDR complex regulates over 300 genes, including genes involved in glucose metabolism [45].…”