A Primary Study On Calcium Ion Regulation In Human Lens Epithelial Cells Induced By Basic Fibroblast Growth Factor

Cataract is a major disease leading to blindness and surgery is still the most available therapy method for it. While posterior capsule opacification (PCO) occurs in approximately 18-48% cases of adults and even almost 100% of kids after planned extracapsular cataract extraction (ECCE). Although Laser Nd:YAG capsulotomy or secondary surgery can help restore visual acuity, the complications such as retinal detachment and macular edema will bring the patients more troubles. Therefore, finding some other ways to prevent the occurrence of the cataract and PCO or cure the disease is an emergency problem.As established, PCO is due to the proliferation, differentiation, and migration of the residual cells over the lens capsule equator and under the anterior capsule. Growth factors such as basic fibroblast growth factor (bFGF) play a vital role in this process.On the other hand, we have known the imbalance of intracellular calcium ion concentration especially the increase of calcium ion concentration in lens epithelial cells is one of the causes of cataract and PCO. In almost all of kinds of cataract, the calcium ion level is higher than normal. Many researches have done on drug usage to inhibit the calcium increase in order to prevent cataract.In early researches, it is found that many growth factors including epidermal growth factor, platelet derived growth factor and basic fibroblast growth factor could regulate the intracellular calcium in various patterns. For example: bFGF increases functional L-type Ca2+ channels on fetal rat hippocampal neurons; in human retinal pigment epithelial cells, EGF, PDGF, FGF can all induce a transient calcium increase; both of FGF and PDGF havebeen shown to induce calcium release from intracellular stores in a range of different cell types.Calcium mobilisation also contributes to lens epithelial cells growth obviously. In some studies, intracellular calcium release can increase bFGF expression in cerebellar granule neurons. Calcium and growth factors have interactions in intracelluar signal transduction, cell proliferation and differentiation.In view of the backgroud above, we guess grwoth factor (GF) can also regulate the intracellular calcium in lens epithelial cells, and the two play some important role together in lens epithelial cells proliferation, migragation, differentiation. Therefore to find their relationship, detect their action pattern and block their interaction specifically will provide a new foregroud for cataract and PCO prevention or treatment.In my reaserch, I focued on the function of inositol 1,4,5-trisphosphate receptor (IP3R) and the ryanodine receptor (RyR), which present the two intracellular calcium pool in LEG during the calcium signal transduction especially in duced by bFGF. First, to determinate the existence of IP3R and RyR expression and assess their function during calcium ion concentration modulation in cultured human lens epithelial cells. Then try to find out the effects of bFGF (basic fibroblast growth factor) on the Ca2+ concentration and the expression of IP3R and RyR. Finally, to investigate the pathway of calcium regulated by bFGF through pharmacological reaction. What we have done will provide theory basis for further drug application in order to block GF and Ca2+ interaction for LEG proliferation inhibition.The reaserch is divided into three parts:Parti:The Coexistence of IP3R and RyanodineR in Human Lens Epithelial CellsObjective: To determinate the existence of the inositol 1,4,5-trisphosphate receptor (IP3R) and the ryanodine receptor (RyR), identify their isoforms and assess their functions during calcium ion concentration modulation in cultured human lens epithelial cells. Methods: Human lens epithelial cells were subcultured, the 3rd passage cellswere chosen as object when they become confluent. Then the total cellular RNA was extracted with TRIzol from the cells and positive control tissues (from term dead fetus). The expression of mRNA of IP3R and RyR isoforms I, II, III was analyzed by...