Key Laboratory of Agricultural Animal Genetics, Breeding and Reproduction of Ministry of Education, College of Life Science and Technology, Huazhong Agricultural University, Wuhan, 430070, PR China.
BMC Neurosci. 2011 Feb 5;12:17. doi: 10.1186/1471-2202-12-17.
Disabled-1 (Dab1) is an adaptor protein that is essential for the intracellular transduction of Reelin signaling, which regulates the migration and differentiation of postmitotic neurons during brain development in vertebrates. Dab1 function depends on its tyrosine phosphorylation by Src family kinases, especially Fyn.
We have isolated alternatively spliced forms of porcine Dab1 from brain (sDab1) and liver (sDab1-Li) and Fyn from brain (sFyn-B) and spleen (sFyn-T). Radiation hybrid mapping localized porcine Dab1 (sDab1) and Fyn (sFyn) to chromosomes 6q31-35 and 1p13, respectively. Real-time quantitative RT-PCR (qRT-PCR) demonstrated that different isoforms of Dab1 and Fyn have tissue-specific expression patterns, and sDab1 and sFyn-B display similar temporal expression characteristics in the developing porcine cerebral cortex and cerebellum. Both sDab1 isoforms function as nucleocytoplasmic shuttling proteins. It was further shown that sFyn phosphorylates sDab1 at tyrosyl residues (Tyr) 185, 198/200 and 232, whereas sDab1-Li was phosphorylated at Tyr 185 and Tyr 197 (corresponding to Y232 in sDab1) in vitro.
Alternative splicing generates natural sDab1-Li that only carries Y185 and Y197 (corresponding to Y232 in sDab1) sites, which can be phosphorylated by Fyn in vitro. sDab1-Li is an isoform that is highly expressed in peripheral organs. Both isoforms are suggested to be nucleocytoplasmic shuttling proteins. Our results imply that the short splice form sDab1-Li might regulate cellular responses to different cell signals by acting as a dominant negative form against the full length sDab1 variant and that both isoforms might serve different signaling functions in different tissues.
Disabled-1（Dab1）是一种衔接蛋白，对 Reelin 信号的细胞内转导至关重要，该信号在脊椎动物大脑发育过程中调节放射状胶质细胞的迁移和分化。Dab1 的功能依赖于Src 家族激酶，特别是 Fyn 的酪氨酸磷酸化。
我们从脑（sDab1）和肝（sDab1-Li）中分离出了猪 Dab1 的选择性剪接形式，从脑中分离出了 Fyn（sFyn-B）和脾中分离出了 Fyn（sFyn-T）。辐射杂交作图将猪 Dab1（sDab1）和 Fyn（sFyn）定位在染色体 6q31-35 和 1p13 上。实时定量 RT-PCR（qRT-PCR）表明，Dab1 和 Fyn 的不同异构体具有组织特异性表达模式，sDab1 和 sFyn-B 在发育中的猪大脑皮层和小脑显示出相似的时间表达特征。两种 sDab1 异构体均作为核质穿梭蛋白发挥作用。进一步表明，sFyn 在 Tyr185、198/200 和 232 残基处磷酸化 sDab1，而 sDab1-Li 在体外仅在 Tyr185 和 Tyr197（对应于 sDab1 中的 Y232）残基处被磷酸化。
选择性剪接产生了天然的 sDab1-Li，它只携带 Y185 和 Y197（对应于 sDab1 中的 Y232）位点，该位点可在体外被 Fyn 磷酸化。sDab1-Li 是一种在外周器官中高表达的异构体。两种异构体均被推测为核质穿梭蛋白。我们的结果表明，短剪接形式 sDab1-Li 可能通过作为全长 sDab1 变体的显性负形式来调节细胞对不同细胞信号的反应，并且两种异构体可能在不同组织中发挥不同的信号功能。
