| Summary: | 碩士 === 國立成功大學 === 細胞生物及解剖學研究所 === 99 === CCN1, a member of the CCN family, is an extracellular matrix-associated protein. The functions of CCN1 include cell adhesion, migration, proliferation, survival, and differentiation through binding to different integrin receptors. CCN1 RNA is highly expressed from embryonic day (E) 9.5 and declines after birth. CCN1 plays an important role in developing cardiovascular system, demonstrated by gene-targeting studies. CCN1-null mice suffered embryonic lethality due to insufficient placental vascularization and compromised vessel integrity. In addition, CCN1-deficient embryos display atrioventricular septal defects, reminiscent of AVSD in humans. The functions of CCN1 in late embryogenesis have been reported, but CCN1 expression is still not clear in early developing embryo. Furthermore, in in vitro embryoid body (EB) culture, CCN1 expression was specifically associated with differentiated beating cardiomyocytes, and greater proportion of EB cells differentiated into cardiomyocytes upon treatment with purified CCN1 protein. EB mimicked early embryonic forming and expressed CCN1, hence the CCN1 local expression could be fined through early embryogenesis. A lacZ gene was previously placed under the control of the endogenous CCN1 promoter in the Ccn1+/- mice. Hence, CCN1 expression in embryos can be reflected by the X-gal staining. CCN1 started to express as early as E7.5 in embryos. CCN1 expression was mainly in developing mesoderm, including cardiovascular system and notochord. CCN1 also displayed in embryonic endoderm forming foregut and hindgut. CCN1 in extraembryonic part could go back at E6.5. In conclusion, CCN1was firstly expressed when cardiac crescent just formed. The cardiomyocytes do not beat this stage, meaning that CCN1 may play a key role for stem cells differentiating to cardiomyocytes.
CCN1 expression subsides in adult, but the expression of CCN1 increases after heart injury. FasL has been shown to induce cardiomyocytes apoptosis. Using rat H9c2 cardiomyoblast cells, we further examined ant possible interaction between CCN1and FasL in cardiomycytes apoptosis. In our study, we proved that ROS (reactive oxygen species) was involved in CCN1-induced cardiomyocytes apoptosis by using DCF-DA ROS detection reagent. Besides, we found that CCN1 can synergize with FasL to induce H9c2 cells apoptosis. Furthermore, we showed that the synergistic effect of CCN1 and FasL cotreatment was not due to increased expression of Fas on cell membrane. However, the mechanism of CCN1 and FasL synergistic effect needs to be further examined. In conclusion, we proved that CCN1 synergized with FasL to induce apoptosis in H9c2 cells.
|
|---|
