Left-right asymmetric localization of flectin in the extracellular matrix during heart looping.
Left-right asymmetric localization of flectin in the extracellular matrix during heart looping.
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心脏循环过程中细胞外基质中 flectin 的左右不对称定位。
DOI：
10.1006/dbio.1996.0005
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发表时间：
1996
期刊：
影响因子：
--
通讯作者：
Linask,KK
中科院分区：
文献类型：
--
作者：
Tsuda,T;Philp,N;Zile,MH;Linask,KK
早期胚胎最初是两侧对称的。胚胎不对称的第一个明显迹象之一发生在心脏循环过程中。在鸟类模型中，中线管状心脏在发育约 30 小时后开始向右弯曲，形成 C 形结构。尽管心肌固有的因素被认为是形成环的基础，但心脏不对称和环的方向的分子基础尚不清楚。先前尚未报道过双侧心脏形成区域中特定分子的左右不对称定位。我们称之为flectin（flectere，L.，弯曲或成环）的一种分子在心脏形成中胚层的早期显示出双侧不对称定位，并且在心脏成环期间继续以高度组织化的方式在心脏胶中不对称地表达。这种大的细胞外基质分子已使用单克隆抗体 F-22 进行了鉴定（Mieziewskaet al.,1994a,b）。 Flectin 在禽类心脏发育过程中显示出细胞外基质表达的离散时空模式。在 7+/8− 阶段的心脏发育过程中观察到 flectin 的不对称表达（大约在 3 体节阶段的发育 24 小时）。在这个发育时期，它主要在左心前中胚层中表达。在第12阶段和第14阶段之间，flectin继续在心肌中不对称表达，并且以高水平定位于心肌的基底侧和延伸至心内膜细胞表面的心肌胶内。在心脏的循环部分的同一平面中，它在凸侧和外环区域的贲门胶内以不同的方式组织。沿着管状心脏的前后表达明显减少。最初的定位不对称性在整个管状心脏中得以维持。在第 22 阶段（胚胎第 3.5 天），flectin 的免疫定位强度显着降低，左右不对称性变得不太明显或消失。它再次在第 10 天的胚胎心脏中表达。 Flectin 表达似乎受类维生素A 调节。在缺乏维生素 A 且不形成环的鹌鹑胚胎心脏中（Dersch 和 Zile，1993；Twalet al.，1995），flectin 蛋白表达降低且紊乱，构成心脏胶的其他细胞外基质成分也是如此。
The early embryo is initially bilaterally symmetrical. One of the first distinct indications of asymmetry in the embryo occurs during heart looping. The midline tubular heart begins to bend to the right to form a C-shaped structure around 30 hr of development in the avian model. A molecular basis for heart asymmetry and direction of looping is not known, although factors inherent to the myocardium are believed to underlie looping. A left–right asymmetric localization of a specific molecule in the bilateral heart forming regions has not been reported previously. One molecule that we are calling flectin (flectere,in L., to bend or to loop) shows a bilateral asymmetric localization early in the heart forming mesoderm and continues to be expressed asymmetrically in a highly organized manner in the cardiac jelly during heart looping. This large extracellular matrix molecule has been identified using a monoclonal antibody F-22 (Mieziewskaet al.,1994a,b). Flectin shows a discrete spatiotemporal pattern of extracellular matrix expression during avian heart development. An asymmetric expression of flectin is observed during heart development at stage 7+/8− (approximately at 24 hr of development around the 3-somite stage). It is predominantly expressed in the left precardiac mesoderm at this developmental period. Between stages 12 and 14, flectin continues to be asymmetrically expressed in the myocardium and is localized at high levels on the basal side of the myocardium and within the cardiac jelly extending to the endocardial cell surfaces. In the same plane of the looping part of the heart it is differentially organized within the cardiac jelly on the convex side and in the outer loop areas. A reduced expression is apparent anteriorly and posteriorly along the tubular heart. The initial asymmetry of localization is maintained throughout the tubular heart. At stage 22 (Embryonic Day 3.5), intensity of immunolocalization of flectin is significantly decreased, with left–right asymmetry becoming less discernible or absent. It again is expressed in Day 10 embryonic hearts. Flectin expression appears to be modulated by retinoids. In vitamin A-deficient quail embryonic hearts that do not loop (Dersch and Zile, 1993; Twalet al.,1995), flectin protein expression is decreased and disorganized, as are other extracellular matrix components comprising the cardiac jelly.