Park M Y, Lee R H, Lee S H, Jung J S
Department of Physiology, College of Medicine, Pusan National University, Pusan, Korea.
Nephron. 1999;83(4):341-51. doi: 10.1159/000045426.
Cell-matrix interactions have major effects upon phenotypic features such as gene regulation, cytoskeletal structure, differentiation and aspects of cell growth control. Detachment from the matrix epithelial cells induces programmed cell death, and this cell detachment induced apoptosis has been referred to as 'anoikis'. This study was undertaken to determine whether apoptosis is induced by inhibition of contact with extracellular matrix (ECM) in collecting duct cells and to investigate the signaling mechanisms of the process. Upon detachment from ECM, mouse inner medullary collecting duct cells (mIMCD-3) and mouse outer cortical collecting duct cells (M-1), which were derived from an SV40 transgenic mouse, entered into programmed cell death. Forced suspension of mIMCD-3 or M-1 cells did not affect the expression of Bcl-2-related proteins and did not activate c-Jun NH(2)-terminal kinase. Detachment of cells from ECM activated p38 mitogen-activated protein kinase (p38), but its inhibition with SB203580 did not protect cells from anoikis. Detachment of cells from matrix inhibited NF-kappaB activity, and the inhibition of NF-kappaB activity by overexpression of nonphosphorylatable I-kappaB increased detachment-induced apoptotic cell death in M-1 cells. Forced suspension of M-1 cells still activated p53 activity. Caspase-8 was activated during anoikis, but the time course of its activation was in accordance with DNA fragmentation. These results indicate that detachment from ECM induces apoptosis in the kidney collecting duct cells. Changes in expression levels of Bcl-2-related proteins or activation of JNK/p38 kinase are not critical for anoikis. Decrease in NF-kappaB activity and activation of p53 induced by inhibition of interaction with ECM play roles in anoikis in SV-40-transformed collecting duct cells. Caspase-8 is activated during detachment-induced apoptosis, the mechanisms of which are independent of activation of cell death receptors.
细胞与基质的相互作用对表型特征有重大影响，如基因调控、细胞骨架结构、分化以及细胞生长控制的各个方面。上皮细胞与基质脱离会诱导程序性细胞死亡，这种细胞脱离诱导的凋亡被称为“失巢凋亡”。本研究旨在确定在集合管细胞中，细胞与细胞外基质（ECM）接触的抑制是否会诱导凋亡，并研究该过程的信号传导机制。从小鼠内髓集合管细胞（mIMCD-3）和从小鼠外皮质集合管细胞（M-1，来自SV40转基因小鼠）脱离ECM后，进入程序性细胞死亡。mIMCD-3或M-1细胞的强制悬浮不影响Bcl-2相关蛋白的表达，也不激活c-Jun NH(2)-末端激酶。细胞从ECM脱离激活了p38丝裂原活化蛋白激酶（p38），但其用SB203580抑制并不能保护细胞免于失巢凋亡。细胞从基质脱离会抑制NF-κB活性，通过过表达非磷酸化的I-κB抑制NF-κB活性会增加M-1细胞中脱离诱导的凋亡细胞死亡。M-1细胞的强制悬浮仍会激活p53活性。在失巢凋亡过程中半胱天冬酶-8被激活，但其激活的时间进程与DNA片段化一致。这些结果表明，与ECM脱离会诱导肾集合管细胞凋亡。Bcl-2相关蛋白表达水平的变化或JNK/p38激酶的激活对失巢凋亡并不关键。与ECM相互作用的抑制所诱导的NF-κB活性降低和p53激活在SV-40转化的集合管细胞的失巢凋亡中起作用。在脱离诱导的凋亡过程中半胱天冬酶-8被激活，其机制独立于细胞死亡受体的激活。
