Phan S H, McGarry B M, Loeffler K M, Kunkel S L
Department of Pathology, University of Michigan Medical School, Ann Arbor 48109.
Biochemistry. 1988 Apr 19;27(8):2846-53. doi: 10.1021/bi00408a028.
Arachidonate metabolites are potent biological mediators affecting multiple cellular functions. Although prostaglandins of the E series, which are products of the cyclooxygenase pathway, have been known as inhibitors or down-regulators of fibroblast proliferation and collagen synthesis, the more recently discovered products of the 5-lipoxygenase pathway have not been as extensively investigated with regard to fibroblast function. In this study, a sulfidopeptide product of the lipoxygenase pathway, leukotriene C4 (LTC4), was examined for its ability to modulate rat lung fibroblast collagen synthesis and proliferation in vitro. The data revealed the ability of LTC4 and to a lesser extent leukotriene D4 (LTD4) to stimulate collagen synthesis in a dose-dependent (10(-11)-10(-8) M) manner without affecting cellular proliferation as determined by radiolabeled thymidine incorporation; 1 nM LTC4 caused an 85% (p less than 0.02) increase above untreated controls in [3H]proline incorporation into collagenous protein in the media, which was blocked by the putative leukotriene receptor antagonist FPL55712 (10 microM) and inhibited by cycloheximide and actinomycin D. This LTC4 stimulatory effect was slightly more specific for collagen synthesis vs noncollagenous protein synthesis but was not accompanied with any change in the collagen type composition. Binding of [3H]LTC4 to these cells was specific, reversible, and saturable, with a Kd of 1.8 +/- 0.95 nM. Under equilibrium conditions, there was an estimated 2.39 X 10(4) receptors per cell. This binding was also inhibited by 10 microM FPL55712. Competitive binding studies show specificity of this binding for LTC4 relative to LTD4 and FPL55712. Furthermore, no significant conversion of LTC4 to LTD4 or leukotriene E4 was noted during the binding studies.(ABSTRACT TRUNCATED AT 250 WORDS)
花生四烯酸代谢产物是影响多种细胞功能的强效生物介质。虽然环氧合酶途径产物E系列前列腺素已知是成纤维细胞增殖和胶原合成的抑制剂或下调剂，但5-脂氧合酶途径最近发现的产物在成纤维细胞功能方面尚未得到广泛研究。在本研究中，检测了脂氧合酶途径的一种硫肽产物白三烯C4（LTC4）在体外调节大鼠肺成纤维细胞胶原合成和增殖的能力。数据显示，LTC4以及程度稍轻的白三烯D4（LTD4）能够以剂量依赖性（10⁻¹¹ - 10⁻⁸ M）方式刺激胶原合成，而不影响通过放射性标记胸苷掺入法测定的细胞增殖；1 nM LTC4使培养基中[³H]脯氨酸掺入胶原蛋白的量比未处理对照增加85%（p < 0.02），这被推定的白三烯受体拮抗剂FPL55712（10 μM）阻断，并被环己酰亚胺和放线菌素D抑制。这种LTC4刺激作用对胶原合成比对非胶原蛋白合成稍具特异性，但不伴有胶原类型组成的任何变化。[³H]LTC4与这些细胞的结合是特异性、可逆和饱和的，Kd为1.8 ± 0.95 nM。在平衡条件下，估计每个细胞有2.39×10⁴个受体。这种结合也被10 μM FPL55712抑制。竞争性结合研究表明这种结合对LTC4相对于LTD4和FPL55712具有特异性。此外，在结合研究期间未观察到LTC4向LTD4或白三烯E4的显著转化。（摘要截短于250字）
