Gene expression profile (GEP) of MAF-overexpressing CD34+ hematopoietic progenitor cells (HPCs)

Primary Myelofibrosis (PMF) is a myeloproliferative neoplasm characterized by hyperplastic megakaryopoiesis and myelofibrosis. Through a gene expression profile (GEP) study we recently highlighted the MAF upregulation in PMF versus healthy donor (HD) CD34+ hematopoietic progenitor cells (HPCs). To shed some light into the role of MAF in PMF pathogenesis, here we unravelled the effects of the overexpression of MAF in HPCs forcing its expression in HPCs. We showed that MAF overexpression favours the megakaryocyte and monocyte/macrophage commitment and leads to the abnormal expression of genes coding for proinflammatory and profibrotic mediators. Due to the key role of the above-mentioned processes in PMF pathogenesis, we selected a subset of genes coding for secreted molecules for further validation by quantitative enzyme-linked immunoassays. Noteworthy, our data unveiled a causal connection between the upregulation of MAF and the increased plasma levels of key proinflammatory/profibrotic mediators (IL8, CCL2, PLAUR and MMP9) in PMF patients. Similarly, the upregulation of MAF was responsible for the deranged expression of LGALS3 and SPP1, that are profibrotic mediators increased in PMF patients compared with HDs. RNA from CD34+ HPCs retrovirally transduced to overexpress either the MAF splicing variant 1 (RefSeq NM_005360.3) or the MAF variant 2 (RefSeq NM_001031804.1). RNA was collected from a set of 3 independent experiments.

原发性骨髓纤维化（Primary Myelofibrosis, PMF）是一类以增生性巨核细胞生成及骨髓纤维化为特征的骨髓增殖性肿瘤。本团队近期通过基因表达谱（gene expression profile, GEP）研究证实，相较于健康供者（healthy donor, HD）的CD34+造血祖细胞（CD34+ hematopoietic progenitor cells, HPCs），PMF患者样本中MAF基因表达上调。为阐明MAF在PMF发病机制中的作用，本研究通过在造血祖细胞中强制过表达MAF，解析了其对造血祖细胞的调控效应。研究结果显示，MAF过表达可促进巨核细胞及单核细胞/巨噬细胞系定向分化，并引发促炎及促纤维化介质编码基因的异常表达。鉴于上述过程在PMF发病机制中的关键作用，本研究筛选了一组分泌型分子编码基因，通过定量酶联免疫吸附测定进行进一步验证。值得注意的是，本研究数据揭示了MAF上调与PMF患者体内关键促炎/促纤维化介质（IL8、CCL2、PLAUR及MMP9）血浆水平升高之间的因果关联。同样，MAF上调可导致LGALS3及SPP1表达紊乱，这两个基因编码的促纤维化介质在PMF患者体内的表达水平相较于健康供者显著升高。本研究采集了经逆转录病毒转导、分别过表达MAF剪接变体1（RefSeq NM_005360.3）与MAF剪接变体2（RefSeq NM_001031804.1）的CD34+造血祖细胞的RNA样本，所有RNA均来自3次独立重复实验。