Lu Wenge, Seeholzer Steven H, Han Mingda, Arnold Anne-Sophie, Serrano Maria, Garita Barbara, Philp Nancy J, Farthing Cassandra, Steele Peter, Chen Jizhen, Linask Kersti K
Department of Pediatrics, USF/ACH-Children's Research Institute, St. Petersburg, Florida 33701, USA.
Dev Dyn. 2008 Dec;237(12):3577-90. doi: 10.1002/dvdy.21645.
Flectin, a protein previously described to be expressed in a left-dominant manner in the embryonic chick heart during looping, is a member of the nonmuscle myosin II (NMHC-II) protein class. During looping, both NMHC-IIA and NMHC-IIB are expressed in the mouse heart on embryonic day 9.5. The patterns of localization of NMHC-IIB, rather than NMHC-IIA in the mouse looping heart and in neural crest cells, are equivalent to what we reported previously for flectin. Expression of full-length human NMHC-IIA and -IIB in 10 T1/2 cells demonstrated that flectin antibody recognizes both isoforms. Electron microscopy revealed that flectin antibody localizes in short cardiomyocyte cell processes extending from the basal layer of the cardiomyocytes into the cardiac jelly. Flectin antibody also recognizes stress fibrils in the cardiac jelly in the mouse and chick heart; while NMHC-IIB antibody does not. Abnormally looping hearts of the Nodal(Delta 600) homozygous mouse embryos show decreased NMHC-IIB expression on both the mRNA and protein levels. These results document the characterization of flectin and extend the importance of NMHC-II and the cytoskeletal actomyosin complex to the mammalian heart and cardiac looping.
Flectin是一种先前被描述为在胚胎期鸡心脏成环过程中以左优势方式表达的蛋白质，属于非肌肉肌球蛋白II（NMHC-II）蛋白家族。在成环过程中，NMHC-IIA和NMHC-IIB在胚胎第9.5天的小鼠心脏中均有表达。在小鼠成环心脏和神经嵴细胞中，NMHC-IIB而非NMHC-IIA的定位模式与我们之前报道的flectin相同。在10 T1/2细胞中全长人NMHC-IIA和-IIB的表达表明，flectin抗体可识别这两种异构体。电子显微镜显示，flectin抗体定位于从心肌细胞基底层延伸至心胶的短心肌细胞突起中。flectin抗体还可识别小鼠和鸡心脏心胶中的应力纤维；而NMHC-IIB抗体则不能。Nodal(Delta 600)纯合小鼠胚胎的异常成环心脏在mRNA和蛋白质水平上均显示NMHC-IIB表达降低。这些结果记录了flectin的特征，并将NMHC-II和细胞骨架肌动球蛋白复合物对哺乳动物心脏和心脏成环的重要性扩展到了新的层面。
