Delbé J, Vacherot F, Laaroubi K, Barritault D, Courty J
Laboratoire de Recherche sur la Croissance Cellulaire, la Réparation et la Régénération Tissulaires (CRRET), URA CNRS, Créteil, France.
J Cell Physiol. 1995 Jul;164(1):47-54. doi: 10.1002/jcp.1041640107.
HARP (heparin affin regulatory peptide) is an 18 kDa heparin binding protein, also known as HB-GAM or pleiotrophin (PTN) which has been primarily isolated from brain and uterus, and displays neurite outgrowth, angiogenic and mitogenic activities. Previously, we have expressed the human cDNA encoding human HARP in NIH 3T3 cells. Purified recombinant HARP displayed mitogenic activity for endothelial cells. Its NH2-terminal sequence indicates that the HARP molecule possesses a three amino acid extension from the signal peptide more than the NH2-terminal described. For HB-GAM or PTN, these three amino acids may be essential for the stability and the mitogenic activity of this growth factor. In an attempt to further study the mode of action of this growth factor, we have investigated the mitogenic effect of HARP on various cell types. In contrast to FGF-2, HARP failed to induce stimulation of DNA synthesis on a CCL39 cell line. However, we found that in quiescent bovine epithelial lens (BEL) cells, the stimulation of DNA synthesis induced by HARP is dose-dependent (EC50: 2.5 ng/ml) and maximal stimulation is as potent as that induced by FGF-2 (EC50: 25 pg/ml). Interestingly, when BEL cells were allowed to quiesce in the presence of serum, the stimulation induced by HARP is considerably less potent. In this highly responsive cell system, heparin could potentiate the mitogenic activity of HARP at very low doses (0.1-1 microgram/ml) and inhibit this activity at concentrations of 10 micrograms/ml. In contrast to its protective effect on FGF-1 and -2, heparin was unable to preserve HARP from tryptic and chymotryptic degradations.
肝素亲和调节肽（HARP）是一种18 kDa的肝素结合蛋白，也被称为HB-GAM或多效生长因子（PTN），最初是从脑和子宫中分离出来的，具有神经突生长、血管生成和促有丝分裂活性。此前，我们已在NIH 3T3细胞中表达了编码人HARP的人cDNA。纯化的重组HARP对内皮细胞显示出促有丝分裂活性。其NH2末端序列表明，HARP分子的信号肽比所述的NH2末端多三个氨基酸延伸。对于HB-GAM或PTN，这三个氨基酸可能对该生长因子的稳定性和促有丝分裂活性至关重要。为了进一步研究这种生长因子的作用模式，我们研究了HARP对各种细胞类型的促有丝分裂作用。与FGF-2不同，HARP未能在CCL39细胞系上诱导DNA合成的刺激。然而，我们发现，在静止的牛晶状体上皮（BEL）细胞中，HARP诱导的DNA合成刺激是剂量依赖性的（EC50：2.5 ng/ml），最大刺激与FGF-2诱导的刺激一样有效（EC50：25 pg/ml）。有趣的是，当BEL细胞在血清存在下静止时，HARP诱导的刺激效力明显较低。在这个高反应性细胞系统中，肝素可以在非常低的剂量（0.1-1微克/毫升）下增强HARP的促有丝分裂活性，并在10微克/毫升的浓度下抑制这种活性。与它对FGF-1和-2的保护作用不同，肝素不能保护HARP免受胰蛋白酶和糜蛋白酶的降解。
