Zempleni J, Mock D M
Department of Nutritional Science & Dietetics, University of Nebraska-Lincoln, 316 Ruth Leverton Hall, Lincoln, NE 68583, USA.
Nutr Res Rev. 2001 Jun;14(1):45-64. doi: 10.1079/NRR200117.
Peripheral blood mononuclear cells (PBMC) accumulate biotin by a Na-dependent energy-requiring transporter. This transporter might be the so-called Na-dependent multivitamin transporter, but kinetic observations suggest the existence of a second, more specific, biotin transporter. PBMC respond to proliferation by increased uptake of biotin; the increase is probably mediated by an increased number of transporters on the cell surface. The inferred increase in the biotin transporter synthesis is relatively specific. The increased uptake of biotin into proliferating PBMC is consistent with the hypothesis that these cells have an increased demand for biotin. Indeed, proliferating PBMC increase expression of genes encoding beta-methylcrotonyl-CoA carboxylase and propionyl-CoA carboxylase, generating a quantitatively significant increased demand for biotin as a coenzyme in newly-synthesized carboxylases. Moreover, expression of the holocarboxylase synthetase gene increases, consistent with the synthesis of new holocarboxylases. In addition, proliferating PBMC increase both the density of biotinylation of histones and the mass of biotinylated histones per cell, suggesting a potential role for biotin in transcription and replication of DNA.
外周血单个核细胞（PBMC）通过一种依赖钠且需要能量的转运蛋白积累生物素。这种转运蛋白可能就是所谓的依赖钠的多种维生素转运蛋白，但动力学观察结果表明存在另一种更具特异性的生物素转运蛋白。PBMC通过增加生物素摄取来应对增殖；这种增加可能是由细胞表面转运蛋白数量增加介导的。推测生物素转运蛋白合成的增加具有相对特异性。生物素摄取到增殖的PBMC中增加，这与这些细胞对生物素需求增加的假设一致。实际上，增殖的PBMC增加了编码β-甲基巴豆酰辅酶A羧化酶和丙酰辅酶A羧化酶的基因表达，导致作为新合成羧化酶中辅酶的生物素需求在数量上显著增加。此外，全羧化酶合成酶基因的表达增加，这与新的全羧化酶合成一致。另外，增殖的PBMC增加了组蛋白生物素化的密度以及每个细胞中生物素化组蛋白的质量，表明生物素在DNA转录和复制中可能发挥作用。
