Prieto Daniel, Zolessi Flavio R
Facultad de Ciencias, Sección Biología Celular, Universidad de la República, Montevideo, Uruguay.
Cell Biology of Neural Development Lab, Institut Pasteur de Montevideo, Montevideo, Uruguay.
J Exp Zool B Mol Dev Evol. 2017 Jan;328(1-2):119-138. doi: 10.1002/jez.b.22691. Epub 2016 Aug 24.
Myristoylated alanin-rich C-kinase substrate (MARCKS) and MARCKS-like 1, each encoded by a different gene, comprise a very small family of actin-modulating proteins with essential roles in mammalian neural development. We show here that four genes (two marcks and two marcksl1) are present in teleosts including zebrafish, while ancient actinopterigians, sarcopterigian fishes, and chondrichtyans only have two. No marcks genes were found in agnaths or invertebrates. All four zebrafish genes are expressed during development, and we show here how their early knockdown causes defects in neural development, with some phenotypical differences. Knockdown of marcksa generated embryos with smaller brain and eyes, while marcksb caused different morphogenetic defects, such as larger hindbrain ventricle and folded retina. marcksl1a and marcksl1b morpholinos also caused smaller eyes and brain, although marcksl1a alone generated larger brain ventricles. At 24 hpf, marcksb caused a wider angle of the hindbrain walls, while marcksl1a showed a "T-shaped" neural tube and alterations in neuroepithelium organization. The double knockdown surprisingly produced new features, which included an increased neuroepithelial disorganization and partial neural tube duplications evident at 48 hpf, suggesting defects in convergent extension. This disorganization was also evident in the retina, although retinal ganglion cells were still able to differentiate. marcksl1b morphants presented a unique retinal phenotype characterized by the occurrence of sporadic ectopic neuronal differentiation. Although only marcksl1a morphant had a clear "ciliary phenotype," all presented significantly shorter cilia. Altogether, our data show that all marcks genes have functions in zebrafish neural development, with some differences that suggest the onset of protein diversification.
豆蔻酰化富含丙氨酸的蛋白激酶C底物（MARCKS）和类MARCKS 1，分别由不同基因编码，构成了一个非常小的肌动蛋白调节蛋白家族，在哺乳动物神经发育中起重要作用。我们在此表明，硬骨鱼包括斑马鱼中有四个基因（两个marcks和两个marcksl1），而古代辐鳍鱼、肉鳍鱼和软骨鱼只有两个。在无颌类动物或无脊椎动物中未发现marcks基因。斑马鱼的所有四个基因在发育过程中均有表达，我们在此展示了它们早期敲低如何导致神经发育缺陷，且存在一些表型差异。敲低marcksa会产生脑和眼睛较小的胚胎，而marcksb会导致不同的形态发生缺陷，如后脑脑室较大和视网膜折叠。marcksl1a和marcksl1b的吗啉代寡核苷酸也会导致眼睛和脑较小，尽管单独敲低marcksl1a会产生更大的脑室。在24 hpf时，marcksb会导致后脑壁角度变宽，而marcksl1a显示出“T形”神经管和神经上皮组织改变。双重敲低令人惊讶地产生了新特征，包括在48 hpf时神经上皮紊乱增加和部分神经管重复，提示在汇聚延伸方面存在缺陷。这种紊乱在视网膜中也很明显，尽管视网膜神经节细胞仍能分化。marcksl1b的吗啉代寡核苷酸注射胚胎呈现出独特的视网膜表型，其特征是散发性异位神经元分化。尽管只有marcksl1a的吗啉代寡核苷酸注射胚胎有明显的“纤毛表型”，但所有胚胎的纤毛都明显变短。总之，我们的数据表明，所有marcks基因在斑马鱼神经发育中都有功能，一些差异表明蛋白质多样化的开始。
