Retinoic acid, neoplasia, differentiation and development

The Expression of Retinoic Acid Receptors in Lymph Nodes of Young Children and the Effect of All-trans-Retinoic Acid on the B Cells from Lymph Nodes

To elucidate the mechanism of vitamin A enhancing the production of antibody, we examined the expression and distribution of retinoic acid receptors mRNA in lymph nodes of young children ( < or = 5 years of age), and investigated the affection of all-trans-retinoic acid on the maturation and activation of the B cells isolated from the lymph nodes and cultured in vitro. Twenty-four normal lymph nodes were collected. By in situ hybridization, we found that all six retinoic acid receptor genes expressed and distributed widely in the lymph nodes, and the levels of mRNA for retinoic acid receptor genes (detected by RT-fluorescent quantitative PCR) were increased with the development of children. In vitro culture, all-trans retinoic acid promoted the maturation and activation of the B cells from the lymph nodes. Thus, promotion on B cells in lymph node may be the important mechanism of vitamin A reinforcing the humoral immunity in young children.

Saturation of retinol-binding protein correlates closely to the severity of alcohol-induced liver disease

Impaired metabolism of retinol has been shown to occur in alcohol-induced liver disease (ALD). The purpose of the present study was to investigate the saturation of retinol-binding protein (RBP) in 6 patients with different stages of ALD. Hospitalized alcohol consumers (n=118) with different stages of ALD (ALD1: mild stage of liver damage; ALD2: moderately severe changes of the liver with signs of hepatic inflammation; ALD3: severely impaired liver function) and 45 healthy control subjects were nutritionally assessed, and retinol and RBP content was measured in plasma by high-performance liquid chromatography and enzyme-linked immunosorbent assay methods, respectively. No differences were noted in daily retinol intake, but subjects with ALD had significantly lower concentrations of retinol in plasma (ALD1: 1.81+/-0.17 micromol/l [mean+/-S.E.M.]; ALD2: 1.95+/-0.24 micromol/l; ALD3: 0.67+/-0.13 micromol/l) compared to controls (2.76+/-0.19 micromol/l). Subjects of group ALD2 had significantly higher plasma RBP levels than controls (P<.05) and patients with ALD1 (P<.05) and ALD3 (P<.001). The relative saturation of RBP with retinol decreased with severity of ALD (controls: 76.8+/-5.0%; ALD1: 55.8+/-6.5%; ALD2: 43.5+/-6.2%; ALD3: 29.0+/-5.1%). The present study indicates that plasma concentrations of retinol and RBP per se do not correlate to severity of ALD, but rather that the retinol/RBP ratio links to the severity of alcohol-induced liver damage. From these results, a reduced availability of retinol in the periphery due to an altered saturation of RBP can be concluded.

Functional concerted motions in the bovine serum retinol-binding protein

The large concerted motions in the apo/holo bovine serum retinol-binding protein were studied using molecular dynamics simulation and 'essential dynamics' analysis. Initially, concerted motions were calculated from conformational differences between various crystal structures. The dynamic behaviour of the protein in the configurational space directions, described by these concerted motions, is analysed. This reveals that the large backbone dynamics of the protein is not influenced by the presence of retinol. Study of free retinol dynamics and retinol in the retinol binding site reveals that the protein binds retinol in a favourable conformation, as opposed to what has been previously described for the bovine cellular retinol-binding protein.