French P J, Bunce C M, Stephens L R, Lord J M, McConnell F M, Brown G, Creba J A, Michell R H
School of Biochemistry, University of Birmingham, U.K.
Proc Biol Sci. 1991 Sep 23;245(1314):193-201. doi: 10.1098/rspb.1991.0109.
HL60 cells were adapted to grow in a serum-free medium containing 1 mg l-1 inositol, in which they differentiated normally towards neutrophils (in 0.9% by volume dimethylsulphoxide) and towards monocytes (in 10 nM phorbol myristate acetate). Cells that had been equilibrium-labelled with [2-3H]myo-inositol contained a complex pattern of inositol metabolites, several of which were at relatively high concentrations. These included InsP5 and InsP6, which were present at concentrations of about 25 microM and 60 microM, respectively. Striking and different changes occurred in the levels of some of the inositol polyphosphates as the cells differentiated towards either neutrophils or monocytes. Most notable were a large but gradual accumulation of Ins(1,3,4,5,6)P5 as HL60 cells decreased in size and acquired neutrophil characteristics, and much more rapid and sequential declines in InsP4, InsP5 and InsP6 as the cells started to take on monocyte character. There was a marked accumulation of free inositol and of phosphatidylinositol in the cells during neutrophil differentiation, probably caused at least in part by an increased rate of inositol uptake providing an increased intracellular inositol supply. The same accumulation of Ins(1,3,4,5,6)P5 occurred during neutrophil differentiation, whether it was induced by dimethylsulphoxide or by a combination of retinoic acid and a T-lymphocyte cell line-derived differentiation factor. Ins(1,4,5)P3, a physiological intracellular mediator of Ca2+ release from membrane stores, did not change in concentration during these differentiation processes. These observations suggest that some of the more abundant cellular inositol polyphosphates play some important, but not yet understood, role either in the processes of haemopoietic differentiation or in the expression of differentiated cell character in myeloid cells.
HL60细胞经适应后可在含1 mg l-1肌醇的无血清培养基中生长，在此培养基中它们可正常分化为中性粒细胞（在体积分数为0.9%的二甲基亚砜中）和单核细胞（在10 nM佛波醇肉豆蔻酸酯乙酸酯中）。用[2-3H]肌醇进行平衡标记的细胞含有复杂的肌醇代谢物模式，其中几种代谢物浓度相对较高。这些代谢物包括InsP5和InsP6，其浓度分别约为25 microM和60 microM。当细胞向中性粒细胞或单核细胞分化时，一些肌醇多磷酸的水平发生了显著且不同的变化。最显著的是，随着HL60细胞体积减小并获得中性粒细胞特征，Ins(1,3,4,5,6)P5大量但逐渐积累；而当细胞开始呈现单核细胞特征时，InsP4、InsP5和InsP6则更快且相继下降。在中性粒细胞分化过程中，细胞内游离肌醇和磷脂酰肌醇显著积累，这可能至少部分是由于肌醇摄取速率增加，从而提供了更多的细胞内肌醇供应。无论中性粒细胞分化是由二甲基亚砜诱导还是由视黄酸和T淋巴细胞系衍生的分化因子组合诱导，Ins(1,3,4,5,6)P5都会在分化过程中积累。Ins(1,4,5)P3是一种从膜储存中释放Ca2+的生理性细胞内介质，在这些分化过程中其浓度没有变化。这些观察结果表明，一些细胞中较为丰富的肌醇多磷酸在造血分化过程或髓系细胞分化细胞特征的表达中发挥了一些重要但尚未明确的作用。
