PF-4/CXCL4 蛋白, Human

PF-4/CXCL4 is a member of the CXC chemokine family that is released from the alpha-granules of activated platelets. PF-4/CXCL4 binds with high affinity to heparin, with antiheparin, antiangiogenic and immunomodulatory activities. PF-4/CXCL4 plays a role in hematopoiesis and immune cell modulation^[1][2]. PF-4/CXCL4 Protein, Human is produced in E. coli , and consists of 70 amino acids (E32-S101).

CXCL4，也称为 PF-4（血小板因子 4），是巨核细胞谱系细胞产生的 CXC 趋化因子家族的成员。在巨核细胞中，CXCL4 被合成，封装在囊泡中，并转移到 α 颗粒中，并在血小板激活后从该颗粒中分泌出来。CXCL4 也在小胶质细胞、单核细胞和活化 T 细胞中表达^[1][2]。
成熟人类 CXCL4 与以下细胞有 70% 的氨基酸序列同一性小鼠和大鼠 CXCL4。
CXCL4 储存在血小板的分泌颗粒中，并响应蛋白激酶 C 和 Rac1 激活而释放。血小板被认为是 CXCL4 的主要细胞来源。在血小板的 α 颗粒中，CXCL4 以四聚体形式与两个硫酸软骨素分子结合。CXCL4 在其氨基末端不具有 ELR 酸序列，因此不与 CXCR1 或 CXCR2 结合。CXCL4 调节肝素样分子对血管内皮细胞表面的作用，从而抑制局部抗凝血酶 III 活性，从而发挥 CXCL4 的促凝血作用。CXCL4 在体外和体内表现出抗血管生成特性，并通过多种机制抑制肿瘤新生血管形成。首先，CXCL4能够直接与血管生成生长因子（例如FGF和VEGF）相互作用，并抑制它们与细胞表面受体的相互作用。其次，CXCL4 可能结合蛋白聚糖并干扰蛋白聚糖旁观者对生长因子活性的影响。此外，最近鉴定出一种由人内皮细胞 (EC) 以细胞周期依赖性方式表达并介导 CXCL4 的抗血管生成作用的细胞表面受体，并将其命名为 CXCR3-B。CXCL4 已被证明可以调节免疫细胞的增殖、表型和功能。例如，据报道 CXCL4 可以促进单核细胞存活和巨噬细胞活化。CXCL4 诱导活化 T 淋巴细胞迁移^[1][2][3]。
CXCL4 显示出多效性生物学功能。首先，CXCL4 激活血小板、调节血小板聚集并刺激 α 颗粒蛋白的释放。CXCL4 在肝素诱导的血小板减少症 (HIT) 中发挥作用。其次，CXCL4抑制内皮细胞增殖和迁移，从而抑制血管生成。第三，CXCL4 表达免疫调节活性，例如下调 1 型 T 辅助细胞 (Th1) 细胞产生的 IFN-α，上调 2 型 T 辅助细胞中的 IL-4、IL-5 和 IL-13。Th2) 细胞。第四，CXCL4影响造血，抑制巨核细胞生成和定向红系和粒细胞-巨噬细胞集落以及原始CD34⁺祖细胞的增殖。此外，CXCL4 在系统性硬化症的浆细胞样树突状细胞 (pDC) 和严重创伤后的树突状细胞 (DC) 中也高度上调^[1][2][3]。

Recombinant human CXCL4 (1 μg/mL; for 6 days) treatment monocytes differentiating into dendritic cells (moDCs) induces a higher IL-17 production by CD4⁺ T cells. CXCL4 treatment also increases the percentage of IFN-γ-producing cells and the percentage of co-expressing IL17+IL-22⁺ cells. CXCL4-treated moDCs also significantly potentiates CD4⁺ T cell proliferation^[4].
Recombinant human CXCL4/PF-4 (8 μg/ml) affects the production of cytokines by human Th1 and Th2 cell lines, in particular, it down-regulated the Th1 cytokine IFN-γ and increased the mRNA levels of Th2 cytokines IL-4, IL-5 and IL-13^[5].

Measured by its ability to inhibit bFGF-dependent proliferation of human umbilical vein endothelial cells (HUVEC). The ED₅₀ for this effect is typically 1-5 μg/mL in the presence of 5 ng/mL bFGF.

Human

E. coli

Tag Free

P02776 (E32-S101)

5196  [NCBI]

Approximately 7.8 kDa

Greater than 90% as determined by reducing SDS-PAGE

溶液.

Supplied as a 0.2 μm filtered solution of PBS, pH 7.4.

<1 EU/μg, determined by LAL method.

N/A.

Stored at -80°C for 1 year. It is stable at -20°C for 3 months after opening. It is recommended to freeze aliquots at -80°C for extended storage. Avoid repeated freeze-thaw cycles.

Shipping with dry ice.

• [1]. Lasagni L, et al. PF-4/CXCL4 and CXCL4L1 exhibit distinct subcellular localization and a differentially regulated mechanism of secretion. Blood. 2007 May 15;109(10):4127-34.  [Content Brief]

  [2]. Pieter Ruytinx, et al. CXCL4 and CXCL4L1 in cancer. Cytokine. 2018 Sep;109:65-71.  [Content Brief]

  [3]. Gabriele Domschke, et al. CXCL4-induced macrophages in human atherosclerosis. Cytokine. 2019 Oct;122:154141.  [Content Brief]

  [4]. Alsya J Affandi, et al. CXCL4 is a novel inducer of human Th17 cells and correlates with IL-17 and IL-22 in psoriatic arthritis. Eur J Immunol. 2018 Mar;48(3):522-531.  [Content Brief]

  [5]. Jo Vandercappellen, et al. The role of the CXC chemokines platelet factor-4 (CXCL4/PF-4) and its variant (CXCL4L1/PF-4var) in inflammation, angiogenesis and cancer. Cytokine Growth Factor Rev. 2011 Feb;22(1):1-18.  [Content Brief]