Hwang S-M, Li J, Koo N-Y, Choi S-Y, Lee S J, Oh S-B, Castro R, Kim J-S, Park K
Department of Physiology, School of Dentistry, Seoul National University and Dental Research Institute, Yeongeon Dong 28, Chongno Ku, Seoul 110-749, Korea.
J Dent Res. 2009 Oct;88(10):927-32. doi: 10.1177/0022034509342227.
Autoantibodies specific for alpha-fodrin fragments are found in the tissues of persons afflicted with Sjögren's syndrome (SS). However, the mechanism for alpha-fodrin degradation remains elusive. The following experiments utilized Par C5 cells to examine the role of P2X7 receptor (P2X7R) in apoptosis, particularly in the cleavage and release of alpha-fodrin, an apparent SS autoantigen. Five mM ATP stimulation induced apoptotic cell death with a sustained Ca2+ influx, which was mimicked in HEK cells transfected with P2X7R. ATP also induced cleavage of alpha-fodrin mediated by caspase-3 and calpain, releasing alpha-fodrin fragments through membrane blebs. However, both apoptotic cell death and alpha-fodrin cleavage were inhibited in the presence of 300 microM oxidized-ATP (ox-ATP), an irreversible blocker of P2X7R, or in Ca(2+)-free solution. We concluded that P2X7R plays an important role in apoptosis and alpha-fodrin degradation in salivary epithelial cells, providing an important clue elucidating the presence of alpha-fodrin fragments in SS tissues.
在患有干燥综合征（SS）的患者组织中发现了针对α- fodrin片段的自身抗体。然而，α- fodrin降解的机制仍然不清楚。以下实验利用Par C5细胞来研究P2X7受体（P2X7R）在细胞凋亡中的作用，特别是在α- fodrin（一种明显的SS自身抗原）的切割和释放中的作用。5 mM ATP刺激诱导细胞凋亡性死亡，并伴有持续的Ca2+内流，这在用P2X7R转染的HEK细胞中也有类似表现。ATP还诱导由caspase - 3和钙蛋白酶介导的α- fodrin切割，通过膜泡释放α- fodrin片段。然而，在存在300 microM氧化ATP（ox - ATP，一种P2X7R的不可逆阻滞剂）或无钙溶液的情况下，细胞凋亡性死亡和α- fodrin切割均受到抑制。我们得出结论，P2X7R在唾液腺上皮细胞的细胞凋亡和α- fodrin降解中起重要作用，为阐明SS组织中α- fodrin片段的存在提供了重要线索。
