Selective up-regulation of PDE1B2 upon monocyte-to-macrophage differentiation
Selective up-regulation of PDE1B2 upon monocyte-to-macrophage differentiation
复制标题
DOI：
10.1073/pnas.0408535102
复制
发表时间：
2005-01-11
影响因子：
11.1
通讯作者：
Beavo, JA
中科院分区：
文献类型：
--
作者：
Bender, AT;Ostenson, CL;Beavo, JA
粒细胞-巨噬细胞集落刺激因子（GM-CSF）是单核细胞向巨噬细胞分化的主要调节因子。在人和小鼠中，GM-CSF功能下降的主要表型是肺泡巨噬细胞功能异常引起的肺蛋白沉积症。最近，这种细胞因子被证明可以上调环核苷酸磷酸二酯酶PDE1B。已鉴定出两个具有独特n端序列的PDE1B变体PDE1B1和PDE1B2。在这里，我们报道了以前未被表征的PDE1B2被GM-CSF通过刺激一个以前未知的转录起始位点的转录而选择性地增加。对PDE1B基因的外显子和内含子组织的分析表明，PDE1B2基因的n端序列不同，因为PDE1B1基因的第一个外显子位于PDE1B1基因的第一个外显子下游11.5 kb处。通过使用5'-RACE、EST序列比对和荧光素酶报告系统，我们提供了证据，证明PDE1B2与PDE1B1有一个单独的转录起始位点，可以被单核细胞分化激活。此外，IL-4在GM-CSF存在下处理，将巨噬细胞的分化转变为树突状细胞表型，抑制PDE1B2的上调。经PHA激活的T细胞中也发现PDE1B2的诱导。因此，PDE1B2可能在多种免疫细胞类型中具有调节作用。最后，重组PDE1B2的催化特性表征表明，它比cAMP更倾向于cGMP作为底物，因此可能调节巨噬细胞中的cGMP。此外，PDE1B2被钙调素激活的EC50比PDE1B1低近3倍。
Granulocyte-macrophage colony-stimulating factor (GM-CSF) is a major regulator of monocyte to macrophage differentiation. In both humans and mice, the main phenotype of decreased GM-CSF function is pulmonary proteinosis due to aberrant function of alveolar macrophages. Recently, this cytokine has been shown to up-regulate a cyclic nucleotide phosphodiesterase, PDE1B. Two PDE1B variants with unique N-terminal sequences, PDE1B1 and PDE1B2, have been identified. Here, we report that the previously uncharacterized PDE1B2 is selectively increased by GM-CSF by stimulation of transcription at a previously unknown transcriptional start site. Analysis of the exon and intron organization of the PDE1B gene reveals that PDE1B2 has a different N-terminal sequence because of a separate first exon that is located 11.5 kb downstream from the PDE1B1 first exon. By using 5'-RACE, alignment of EST sequences, and a luciferase-reporter system, we provide evidence that PDE1B2 has a separate transcriptional start site from PDE1B1 that can be activated by monocyte differentiation. Furthermore, IL-4 treatment in the presence of GM-CSF, which shifts the differentiation from a macrophage to a dendritic cell phenotype, suppresses the up-regulation of PDE1B2. Induction of PDE1B2 is also found in T cells upon activation by PHA. Therefore, PDE1B2 may have a regulatory role in multiple immune cell types. Last, characterization of the catalytic properties of recombinant PDE1B2 shows that it prefers cGMP over cAMP as a substrate and, thus, is likely to regulate cGMP in macrophages. Also, PDE1B2 has a nearly 3-fold lower EC50 for activation by calmodulin than PDE1B1.