Jue D M, Sherry B, Luedke C, Manogue K R, Cerami A
Laboratory of Medical Biochemistry, Rockefeller University, New York, New York 10021.
Biochemistry. 1990 Sep 11;29(36):8371-7. doi: 10.1021/bi00488a025.
The biosynthesis and processing of cachetin/tumor necrosis-factor (TNF) were examined in the murine macrophage-like cell line RAW 264.7. Lipopolysaccharide-stimulated cells secreted both glycosylated and nonglycosylated 17-kilodalton (kDa) mature cachectin/TNF into the culture medium. Secreted cachectin/TNF was derived from membrane-associated precursors that were precipitated by polyclonal antisera raised against either the mature protein or synthetic peptide fragments of the 79 amino acid cachectin/TNF prohormone sequence. About half of the precursors were N-glycosylated, apparently cotranslationally. The cachectin/TNF precursors were then proteolytically cleaved to release soluble mature cytokine into the medium, while the membrane-bound 14-kDa presequence remained cell associated. During the period of LPS stimulation, the amount of macrophage cell surface cachectin/TNF remained at a low level, suggesting that both nonglycosylated and glycosylated precursors of cachectin/TNF are efficiently cleaved by these cells. These findings suggest the presence of a unique mechanism for the secretion of cachectin/TNF.
在鼠巨噬细胞样细胞系RAW 264.7中研究了恶病质素/肿瘤坏死因子（TNF）的生物合成及加工过程。经脂多糖刺激的细胞将糖基化和非糖基化的17千道尔顿（kDa）成熟恶病质素/TNF分泌到培养基中。分泌的恶病质素/TNF来源于膜相关前体，这些前体可被针对成熟蛋白或79个氨基酸的恶病质素/TNF激素原序列的合成肽片段制备的多克隆抗血清沉淀。大约一半的前体是N - 糖基化的，显然是共翻译过程中发生的。随后恶病质素/TNF前体被蛋白水解切割，释放出可溶性成熟细胞因子到培养基中，而膜结合的14 kDa前序列仍与细胞相关。在脂多糖刺激期间，巨噬细胞表面恶病质素/TNF的量保持在低水平，这表明恶病质素/TNF的非糖基化和糖基化前体都能被这些细胞有效切割。这些发现提示存在一种独特的恶病质素/TNF分泌机制。
