通过转录组分析鉴定人肥大细胞瘤细胞系（HMC-1（V560G c-Kit））中神经生长因子（NGF）的新靶基因。
Identification of novel target genes of nerve growth factor (NGF) in human mastocytoma cell line (HMC-1 (V560G c-Kit)) by transcriptome analysis.
机构信息
Institut fuer Biochemie, OE4310, Medizinische Hochschule Hannover, Carl-Neuberg-Str, 1, D-30623 Hannover, Germany.
出版信息
BMC Genomics. 2011 Apr 18;12:196. doi: 10.1186/1471-2164-12-196.
BACKGROUND
Nerve growth factor (NGF) is a potent growth factor that plays a key role in neuronal cell differentiation and may also play a role in hematopoietic differentiation. It has been shown that NGF induced synergistic action for the colony formation of CD34 positive hematopoietic progenitor cells treated with macrophage-colony stimulating factor (M-CSF or CSF-1), or stem cell factor (SCF). However, the exact role of NGF in hematopoietic system is unclear. It is also not clear whether NGF mediated signals in hematopoietic cells are identical to those in neuronal cells.
RESULTS
To study the signal transduction pathways induced by NGF treatment in hematopoietic cells, we utilized the mastocytoma cell line HMC-1(V560G c-Kit) which expresses the NGF receptor, tropomyosin-receptor-kinase (Trk)A, as well as the constitutively activated SCF receptor, V560G c-Kit, which can be inhibited completely by treatment with the potent tyrosine kinase inhibitor imatinib mesylate (imatinib). NGF rescues HMC-1(V560G c-Kit) cells from imatinib mediated cell death and promotes proliferation. To examine the NGF mediated proliferation and survival in these cells, we compared the NGF mediated upregulated genes (30 and 120 min after stimulation) to the downregulated genes by imatinib treatment (downregulation of c-Kit activity for 4 h) by transcriptome analysis. The following conclusions can be drawn from the microarray data: Firstly, gene expression profiling reveals 50% overlap of genes induced by NGF-TrkA with genes expressed downstream of V560G c-Kit. Secondly, NGF treatment does not enhance expression of genes involved in immune related functions that were down regulated by imatinib treatment. Thirdly, more than 55% of common upregulated genes are involved in cell proliferation and survival. Fourthly, we found Kruppel-like factor (KLF) 2 and Smad family member 7 (SMAD7) as the NGF mediated novel downstream genes in hematopoietic cells. Finally, the downregulation of KLF2 gene enhanced imatinib induced apoptosis.
CONCLUSION
NGF does not induce genes which are involved in immune related functions, but induces proliferation and survival signals in HMC-1(V560G c-Kit) cells. Furthermore, the current data provide novel candidate genes, KLF2 and SMAD7 which are induced by NGF/TrkA activation in hematopoietic cells. Since the depletion of KLF2 causes enhanced apoptosis of HMC-1(V560G c-Kit), KLF2 may play a role in the NGF mediated survival signal.
背景
神经生长因子（NGF）是一种有效的生长因子，在神经元细胞分化中起着关键作用，并且可能在造血分化中也起着作用。已经表明，NGF 诱导 CD34 阳性造血祖细胞与巨噬细胞集落刺激因子（M-CSF 或 CSF-1）或干细胞因子（SCF）处理的集落形成的协同作用。然而，NGF 在造血系统中的确切作用尚不清楚。也不清楚 NGF 在造血细胞中介导的信号是否与神经元细胞中相同。
结果
为了研究 NGF 处理在造血细胞中诱导的信号转导途径，我们利用表达 NGF 受体、原肌球蛋白受体激酶（Trk）A 以及组成型激活的 SCF 受体 V560G c-Kit 的肥大细胞瘤细胞系 HMC-1（V560G c-Kit），该受体可被强力酪氨酸激酶抑制剂伊马替尼甲磺酸盐（imatinib）完全抑制。NGF 可挽救 HMC-1（V560G c-Kit）细胞免受伊马替尼介导的细胞死亡并促进增殖。为了研究这些细胞中 NGF 介导的增殖和存活，我们通过转录组分析比较了 NGF 介导的上调基因（刺激后 30 和 120 分钟）与伊马替尼处理下调的基因（c-Kit 活性下调 4 小时）。从微阵列数据中得出以下结论：首先，基因表达谱揭示了 NGF-TrkA 诱导的基因与 V560G c-Kit 下游表达的基因有 50%重叠。其次，NGF 处理不会增强伊马替尼处理下调的与免疫相关功能相关的基因的表达。第三，超过 55%的共同上调基因参与细胞增殖和存活。第四，我们发现 Kruppel 样因子（KLF）2 和 Smad 家族成员 7（SMAD7）作为造血细胞中 NGF 介导的新下游基因。最后，KLF2 基因的下调增强了伊马替尼诱导的细胞凋亡。
结论
NGF 不会诱导参与免疫相关功能的基因，但会在 HMC-1（V560G c-Kit）细胞中诱导增殖和存活信号。此外，目前的数据提供了新的候选基因，即 KLF2 和 SMAD7，它们在造血细胞中被 NGF/TrkA 激活诱导。由于 KLF2 的耗尽导致 HMC-1（V560G c-Kit）的凋亡增加，因此 KLF2 可能在 NGF 介导的存活信号中发挥作用。
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