Li J, Tripathi B J, Chalam K V, Tripathi R C
Department of Ophthalmology, University of South Carolina School of Medicine, Columbia 29203, USA.
Invest Ophthalmol Vis Sci. 1996 Dec;37(13):2778-82.
To determine whether transforming growth factor (TGF)-beta 1 and -beta 2 and basic fibroblast growth factor (bFGF) induce the gene expression of TGF-beta 1 in the first-passage trabecular meshwork cells of the eye.
Trabecular meshwork cells were cultured from fresh porcine eyes and treated with 1 ng/ml of TGF-beta 1, TGF-beta 2, or bFGF for 1 hour. Cells maintained in serum-free medium were used as controls. Total cellular RNA was extracted, and the first-strand cDNA was synthesized. Multiplex polymerase chain reaction (PCR) and competitive PCR were performed on aliquots of the cDNAs by using either endogenous (glyceraldehyde-3-phosphate dehydrogenase [G3PDH]) or exogenous sequence (PCR mimic for TGF-beta 1) as internal standards, respectively. The obtained products were quantitated by laser densitometry, and statistical analysis was performed.
The findings show that trabecular cells in vitro express the TGF-beta 1 messenger RNA constitutively. Both the techniques of multiplex PCR and competitive PCR demonstrated that the addition of either TGF-beta 1 or TGF-beta 2 at a concentration present in normal aqueous humor increased the mRNA levels of TGF-beta 1 by 2.82-to 3.07-fold over the controls, and these results were statistically significant (P < 0.01). Basic fibroblast growth factor did not have an effect on TGF-beta 1 expression (P < 0.05).
Transforming growth factor-beta 1 activates its own gene expression in trabecular cells. Considering the multifunctional property of this cytokine, which includes increased deposition of extracellular matrix material and growth inhibition of trabecular cells, a change in its concentration within the eye would have a profound effect because of this autoinductive activity. Transforming growth factor-beta 2 treatment of trabecular cells also increased their expression of the TGF-beta 1 gene. The authors previously showed that the level of TGF-beta 2 in the aqueous humor of glaucomatous eyes is significantly higher than that of age-matched nonglaucomatous controls. The current finding suggests that this growth modulator may exert its effects directly on the trabecular cells or that it may act indirectly through upregulating the production of TGF-beta 1.
确定转化生长因子（TGF）-β1、-β2和碱性成纤维细胞生长因子（bFGF）是否能诱导眼小梁网细胞原代培养物中TGF-β1的基因表达。
从新鲜猪眼中培养小梁网细胞，并用1 ng/ml的TGF-β1、TGF-β2或bFGF处理1小时。将无血清培养基中培养的细胞用作对照。提取总细胞RNA，并合成第一链cDNA。分别以内源性（甘油醛-3-磷酸脱氢酶[G3PDH]）或外源性序列（TGF-β1的PCR模拟物）作为内标，对cDNA的等分试样进行多重聚合酶链反应（PCR）和竞争性PCR。通过激光密度测定法定量获得的产物，并进行统计分析。
研究结果表明，体外培养的小梁细胞组成性表达TGF-β1信使RNA。多重PCR和竞争性PCR技术均表明，添加正常房水中存在浓度的TGF-β1或TGF-β2后，TGF-β1的mRNA水平比对照增加了2.82至3.07倍，这些结果具有统计学意义（P<0.01）。碱性成纤维细胞生长因子对TGF-β1表达无影响（P<0.05）。
转化生长因子-β1在小梁细胞中激活其自身的基因表达。鉴于这种细胞因子具有多种功能特性，包括增加细胞外基质物质的沉积和抑制小梁细胞生长，由于这种自诱导活性，其在眼内浓度的变化将产生深远影响。用转化生长因子-β2处理小梁细胞也增加了它们TGF-β1基因的表达。作者之前表明，青光眼患者房水中TGF-β2的水平明显高于年龄匹配的非青光眼对照。目前的发现表明，这种生长调节剂可能直接作用于小梁细胞，或者可能通过上调TGF-β1的产生而间接发挥作用。
