Department of Ophthalmology, Northwestern University, Feinberg School of Medicine, Chicago, Illinois, USA.
Invest Ophthalmol Vis Sci. 2010 Aug;51(8):4096-103. doi: 10.1167/iovs.10-5177. Epub 2010 Apr 7.
The authors investigated the role of myosin light chain kinase (MYLK) and transforming growth factor beta (TGFbeta) receptor pathways in optic nerve head (ONH) astrocyte migration. They further investigated how the expression of these genes is altered by elevated hydrostatic pressure (HP).
PCR was used to determine the isoforms of MYLK expressed in ONH astrocytes. siRNAs against MYLK (all isoforms) and TGFbeta receptor 2 (TGFBR2) were prepared and tested for effects on the migration of cultured ONH astrocytes. Finally, the effects of elevated HP (24-96 hours) on the expression of MYLK isoforms and selected TGFbeta pathway components were measured.
Multiple isoforms of MYLK are present in ONH astrocytes from Caucasian (CA) and African American (AA) donors. Both populations express the short form (MYLK-130) and the long form (MYLK-210) of MYLK and a splicing variant within MYLK-210. MYLK-directed siRNA decreased MYLK expression and cell migration compared with control siRNA. siRNA directed against TGFbeta receptor 2 also decreased cell migration compared with control and decreased extracellular matrix genes regulated by TGFbeta signaling. Elevated HP increased the expression of MYLK-130 and MYLK-210 in both populations of astrocytes. However, TGFbeta2 was uniquely upregulated by exposure to elevated HP in CA compared with AA astrocytes.
Differential expression of TGFbeta pathway genes and MYLK isoforms observed in populations of glaucomatous astrocytes applies to the elevated HP model system. MYLK may be a new target for intervention in glaucoma to alter reactive astrocyte migration in the ONH.
作者研究了肌球蛋白轻链激酶（MYLK）和转化生长因子β（TGFβ）受体通路在视神经头（ONH）星形胶质细胞迁移中的作用。他们进一步研究了这些基因的表达如何被升高的静水压力（HP）改变。
PCR 用于确定在 ONH 星形胶质细胞中表达的 MYLK 同工型。制备针对 MYLK（所有同工型）和 TGFβ 受体 2（TGFBR2）的 siRNA，并测试其对培养的 ONH 星形胶质细胞迁移的影响。最后，测量升高的 HP（24-96 小时）对 MYLK 同工型和选定 TGFβ 途径成分表达的影响。
来自白种人（CA）和非裔美国人（AA）供体的 ONH 星形胶质细胞中存在多种 MYLK 同工型。两种人群均表达短形式（MYLK-130）和长形式（MYLK-210）以及 MYLK-210 内的剪接变体。与对照 siRNA 相比，针对 MYLK 的 siRNA 降低了 MYLK 表达和细胞迁移。与对照相比，针对 TGFβ 受体 2 的 siRNA 也降低了细胞迁移，并降低了 TGFβ 信号转导调节的细胞外基质基因。升高的 HP 增加了两种人群的星形胶质细胞中 MYLK-130 和 MYLK-210 的表达。然而，与 AA 星形胶质细胞相比，CA 中的 TGFbeta2 仅在暴露于升高的 HP 时被上调。
在青光眼星形胶质细胞群体中观察到的 TGFβ 途径基因和 MYLK 同工型的差异表达适用于升高的 HP 模型系统。MYLK 可能是改变 ONH 中反应性星形胶质细胞迁移的青光眼干预的新靶点。
