Choi Dong Hee, Kim Eun-Mee, Son Hyo Jin, Joh Tong H, Kim Yoon Seong, Kim Donghou, Flint Beal M, Hwang Onyou
Department of Biochemistry and Molecular Biology, University of Ulsan College of Medicine, Seoul, Korea.
J Neurochem. 2008 Jul;106(1):405-15. doi: 10.1111/j.1471-4159.2008.05399.x. Epub 2008 Jul 1.
We have previously demonstrated that the active form of matrix metalloproteinase-3 (actMMP-3) is released from dopamine(DA)rgic neurons undergoing apoptosis. Herein, whether actMMP-3 might be generated intracellularly, and if so, whether it is involved in apoptosis of DArgic neurons itself was investigated in primary cultured DArgic neurons of wild-type, MMP-3 knockout animals, and CATH.a cells. During apoptosis, gene expression of MMP-3 is induced, specifically among the various classes of MMPs, generating the proform (55 kDa) which is subsequently cleaved to the catalytically active actMMP-3 (48 kDa) involving a serine protease. Intracellular actMMP-3 activity is directly linked to apoptotic signaling in DArgic cells: (i) Pharmacologic inhibition of enzymatic activity, repression of gene expression by siRNA, and gene deficiency all lead to protection; (ii) pharmacologic inhibition causes attenuation of DNA fragmentation and caspase 3 activation, the indices of apoptosis; and (iii) inhibition of the pro-apoptotic enzyme c-Jun N-terminal protein kinase leads to repression of MMP-3 induction. Under the cell stress condition, MMP-3 is released as actMMP-3 rather than the proform (proMMP-3), and catalytically active MMP-3 added to the medium does not cause cell death. Thus, actMMP-3 seems to have a novel intracellular role in apoptotic DArgic cells and this finding provides an insight into the pathogenesis of Parkinson's disease.
我们之前已经证明，基质金属蛋白酶-3（actMMP-3）的活性形式是从正在经历凋亡的多巴胺能（DA）神经元中释放出来的。在此，我们在野生型、MMP-3基因敲除动物的原代培养多巴胺能神经元以及CATH.a细胞中研究了actMMP-3是否可能在细胞内产生，如果是，它是否参与多巴胺能神经元自身的凋亡。在凋亡过程中，MMP-3的基因表达被诱导，特别是在各类基质金属蛋白酶中，产生前体形式（55 kDa），随后该前体被切割成具有催化活性的actMMP-3（48 kDa），这一过程涉及一种丝氨酸蛋白酶。细胞内的actMMP-3活性与多巴胺能细胞中的凋亡信号直接相关：（i）酶活性的药理抑制、siRNA对基因表达的抑制以及基因缺陷都能导致细胞得到保护；（ii）药理抑制会导致DNA片段化和半胱天冬酶3激活减弱，而这两者是凋亡的指标；（iii）对促凋亡酶c-Jun N末端蛋白激酶的抑制会导致MMP-3诱导的抑制。在细胞应激条件下，MMP-3以actMMP-3而非前体形式（proMMP-3）释放，并且添加到培养基中的具有催化活性的MMP-3不会导致细胞死亡。因此，actMMP-3似乎在凋亡的多巴胺能细胞中具有一种新的细胞内作用，这一发现为帕金森病的发病机制提供了深入了解。
