Lobb R R
Center for Biochemical and Biophysical Sciences and Medicine, Harvard Medical School, Boston, Massachusetts.
Biochemistry. 1988 Apr 5;27(7):2572-8. doi: 10.1021/bi00407a045.
Incubation of bovine brain derived acidic fibroblast growth factor (aFGF) with bovine or human thrombin, 0.5 NIH unit/mL, for 24 h at 37 degrees C results in cleavage of the mitogen, generating a 14-kilodalton fragment which has significantly reduced affinity for immobilized heparin as compared to aFGF, and is at least 50-fold less potent at stimulating mitogenesis. In addition, an 18 amino acid peptide, aFGF(123-140), is generated, identifying one of the thrombin cleavage sites as the Arg-122/Thr-123 bond. The peptide, aFGF(123-140), is neither mitogenic itself nor an inhibitor of the mitogenic activity of aFGF. The cleavage of aFGF by thrombin is inhibited by heparin (50 micrograms/mL) and is completely blocked by the irreversible thrombin inhibitors D-Phe-Pro-Arg chloromethyl ketone and hirudin. Incubation of aFGF with 50 units/mL thrombin at 37 degrees C results in rapid cleavage of the mitogen into several fragments. In contrast, incubation of bovine brain derived basic fibroblast growth factor with 1 unit/mL thrombin for 24 h, or 50 units/mL thrombin for 6 h, does not result in significant cleavage of mitogen. The results show that the C-terminal region of aFGF is of functional importance in both mitogenesis and heparin binding. Most importantly, a novel role for anionic heparin-binding growth factors and their fragments is indicated in physiologic and pathologic situations associated with thrombin generation.
将牛脑源性酸性成纤维细胞生长因子（aFGF）与0.5 NIH单位/毫升的牛或人凝血酶在37℃孵育24小时，会导致该促细胞分裂剂被切割，产生一个14千道尔顿的片段，与aFGF相比，该片段对固定化肝素的亲和力显著降低，且在刺激细胞增殖方面的效力至少低50倍。此外，还产生了一个18个氨基酸的肽段，即aFGF(123 - 140)，确定其中一个凝血酶切割位点为精氨酸-122/苏氨酸-123键。该肽段aFGF(123 - 140)本身既无促细胞增殖作用，也不是aFGF促细胞增殖活性的抑制剂。肝素（50微克/毫升）可抑制凝血酶对aFGF的切割，不可逆凝血酶抑制剂D - 苯丙氨酸-脯氨酸-精氨酸氯甲基酮和水蛭素可完全阻断这种切割。将aFGF与50单位/毫升凝血酶在37℃孵育会导致该促细胞分裂剂迅速切割成几个片段。相比之下，将牛脑源性碱性成纤维细胞生长因子与1单位/毫升凝血酶孵育24小时，或与50单位/毫升凝血酶孵育6小时，不会导致促细胞分裂剂发生显著切割。结果表明，aFGF的C末端区域在细胞增殖和肝素结合方面均具有功能重要性。最重要的是，阴离子肝素结合生长因子及其片段在与凝血酶生成相关的生理和病理情况下具有新的作用。
