Molecular evolution of SPARC: absence of the acidic module and expression in the endoderm of the starlet sea anemone, Nematostella vectensis
Molecular evolution of SPARC: absence of the acidic module and expression in the endoderm of the starlet sea anemone, Nematostella vectensis
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DOI：
10.1007/s00427-009-0313-9
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发表时间：
2009-10-01
影响因子：
2.4
通讯作者：
Ringuette, Maurice
中科院分区：
文献类型：
--
作者：
Koehler, Anne;Desser, Sherwin;Ringuette, Maurice
从线虫到哺乳动物，基质细胞糖蛋白G1由三个进化上保守的功能结构域组成：N端的Ca 2+结合谷氨酸丰富的酸性结构域（结构域I），卵泡抑素样模块（结构域II）和含有两个EF-手和两个胶原结合表位的细胞外Ca 2+结合（EC）模块（结构域III）。我们报告说，四个同源（指定nvSPARC 1 -4）的基因组的星海葵Nematostella vectensis，双胚层的基础刺胞动物的外胚层和内胚层分离的胶原蛋白为基础的中胶层组成的。我们还报告说，域I是缺席的所有N。vectensis orthologs.原位杂交结果表明，N.在原肠胚后发育过程中，vectensis-grainmRNA局限于内胚层。在刺胞动物和保护胶原结合表位的Ca 2+结合的N-末端结构域的情况下，表明，ESTA第一次演变为胶原结合matricellular糖蛋白，相互作用可能是依赖于Ca 2+离子的结合的两个EF-手在EC域。我们建议，进一步的钙离子依赖的活动出现了收购的酸性N-末端模块在三倍体生物。
The matricellular glycoprotein SPARC is composed of three functional domains that are evolutionarily conserved in organisms ranging from nematodes to mammals: a Ca2+-binding glutamic acid-rich acidic domain at the N-terminus (domain I), a follistatin-like module (domain II), and an extracellular Ca2+-binding (EC) module that contains two EF-hands and two collagen-binding epitopes (domain III). We report that four SPARC orthologs (designated nvSPARC1-4) are expressed by the genome of the starlet anemone Nematostella vectensis, a diploblastic basal cnidarian composed of an ectoderm and endoderm separated by collagen-based mesoglea. We also report that domain I is absent from all N. vectensis SPARC orthologs. In situ hybridization data indicate that N. vectensis SPARC mRNAs are restricted to the endoderm during post-gastrula development. The absence of the Ca2+-binding N-terminal domain in cnidarians and conservation of collagen-binding epitopes suggests that SPARC first evolved as a collagen-binding matricellular glycoprotein, an interaction likely to be dependent on the binding of Ca2+-ions to the two EF-hands in the EC domain. We propose that further Ca2+-dependent activities emerged with the acquisition of an acidic N-terminal module in triplobastic organisms.