Department of Medicine, University of Pennsylvania School of Medicine, Philadelphia, PA, USA.
Neurogastroenterol Motil. 2010 Oct;22(10):1100-e285. doi: 10.1111/j.1365-2982.2010.01545.x. Epub 2010 Jun 28.
The smooth muscle actin binding proteins Caldesmon and Tropomyosin (Tm) promote thin filament assembly by stabilizing actin polymerization, however, whether filament assembly affects either the stability or activation of these and other smooth muscle regulatory proteins is not known.
Measurement of smooth muscle regulatory protein levels in wild type zebrafish larvae following antisense knockdown of smooth muscle actin (Acta2) and myosin heavy chain (Myh11) proteins, and in colourless mutants that lack enteric nerves. Comparison of intestinal peristalsis in wild type and colourless larvae.
Knockdown of Acta2 led to reduced levels of phospho-Caldesmon and Tm. Total Caldesmon and phospho-myosin light chain (p-Mlc) levels were unaffected. Knockdown of Myh11 had no effect on the levels of either of these proteins. Phospho-Caldesmon and p-Mlc levels were markedly reduced in colourless mutants that have intestinal motility comparable with wild type larvae.
CONCLUSIONS & INFERENCES: These in vivo findings provide new information regarding the activation and stability of smooth muscle regulatory proteins in zebrafish larvae and their role in intestinal peristalsis in this model organism.
平滑肌肌球蛋白结合蛋白钙调蛋白和原肌球蛋白(Tm)通过稳定肌动蛋白聚合来促进细肌丝组装,然而,细丝组装是否会影响这些和其他平滑肌调节蛋白的稳定性或激活尚不清楚。
在斑马鱼幼虫中反义敲低平滑肌肌动蛋白(Acta2)和肌球蛋白重链(Myh11)蛋白后,以及在缺乏肠神经的无色突变体中,测量平滑肌调节蛋白的水平。比较野生型和无色幼虫的肠道蠕动。
Acta2 的敲低导致磷酸钙调蛋白和 Tm 的水平降低。钙调蛋白总量和磷酸肌球蛋白轻链(p-Mlc)水平不受影响。Myh11 的敲低对这两种蛋白的水平均无影响。无色突变体中磷酸钙调蛋白和 p-Mlc 的水平明显降低,其肠道蠕动与野生型幼虫相当。
这些体内发现为斑马鱼幼虫中平滑肌调节蛋白的激活和稳定性及其在该模型生物中肠道蠕动中的作用提供了新的信息。