Transient laminin beta 1a Induction Defines the Wound Epidermis during Zebrafish Fin Regeneration.
Transient laminin beta 1a Induction Defines the Wound Epidermis during Zebrafish Fin Regeneration.
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DOI：
10.1371/journal.pgen.1005437
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发表时间：
2015-08
期刊：
影响因子：
4.5
通讯作者：
Poss KD
中科院分区：
文献类型：
--
作者：
Chen CH;Merriman AF;Savage J;Willer J;Wahlig T;Katsanis N;Yin VP;Poss KD
蝾螈或硬骨鱼附肢再生的第一个关键阶段是建立一个专门的表皮，指导从下面的树桩组织生长。在这里，我们进行了一个正向遗传筛选突变，损害这一过程中截肢斑马鱼鳍。定位克隆和互补分析确定了ECM组分层粘连蛋白β 1a（β 1a）的温度敏感等位基因，该等位基因阻断鳍再生。在鳍切断后，在上皮细胞的一个亚群中急剧地诱导p1a，而不是其parp1b，在那里需要建立和维持极化的基底上皮细胞层。这些事件促进了形态发生因子shha和lef1的表达、磷酸化Igf1r的基底外侧定位、新成骨细胞的形成和骨再生。相比之下，p1a的功能是幼年体生长，稳态成人组织的维护，修复分裂的鳍，或基因消融的成骨细胞的更新。fgf20a突变或转基因Fgf受体抑制破坏了p53 1a的表达，在再生过程中将中心生长因子与上皮成熟联系起来。我们的研究结果揭示了在上皮细胞中瞬时诱导E1a是形成具有信号传导能力的再生表皮的关键生长因子引导步骤。与哺乳动物不同，成年硬骨鱼和有尾目两栖动物可以完全再生失去的附肢。了解是什么启动了这些脊椎动物的再生是科学界的极大兴趣。人们早就知道，截肢残端上迅速形成的表皮对启动再生程序至关重要。然而，很少有人了解的分子和细胞机制，一个简单的成人上皮细胞转化为这个关键的信号源。在这里，我们进行了一个大规模的，无偏见的遗传筛选上皮细胞信号转导缺陷的再生过程中截肢的成年斑马鱼鳍，从中我们确定了几个新的突变体。从该筛选中鉴定出的一个基因破坏了细胞外基质材料层粘连蛋白的特定组分，层粘连蛋白β 1a，我们发现该因子在未受伤的成年动物中是可降解的，但在鳍再生的所有阶段都是必需的。通过截肢对该组分的瞬时诱导使新生上皮的基底层极化，并且反过来促进信号传导因子的合成、配体受体的定位和新骨细胞的形成。我们还发现损伤对层粘连蛋白β 1a的正常诱导依赖于成纤维细胞生长因子的功能，成纤维细胞生长因子是在损伤早期释放的分泌多肽信号。我们的研究结果确定了脊椎动物附肢再生内源性程序的关键早期步骤。
The first critical stage in salamander or teleost appendage regeneration is creation of a specialized epidermis that instructs growth from underlying stump tissue. Here, we performed a forward genetic screen for mutations that impair this process in amputated zebrafish fins. Positional cloning and complementation assays identified a temperature-sensitive allele of the ECM component laminin beta 1a (lamb1a) that blocks fin regeneration. lamb1a, but not its paralog lamb1b, is sharply induced in a subset of epithelial cells after fin amputation, where it is required to establish and maintain a polarized basal epithelial cell layer. These events facilitate expression of the morphogenetic factors shha and lef1, basolateral positioning of phosphorylated Igf1r, patterning of new osteoblasts, and regeneration of bone. By contrast, lamb1a function is dispensable for juvenile body growth, homeostatic adult tissue maintenance, repair of split fins, or renewal of genetically ablated osteoblasts. fgf20a mutations or transgenic Fgf receptor inhibition disrupt lamb1a expression, linking a central growth factor to epithelial maturation during regeneration. Our findings reveal transient induction of lamb1a in epithelial cells as a key, growth factor-guided step in formation of a signaling-competent regeneration epidermis. Unlike mammals, adult teleost fish and urodele amphibians can fully regenerate lost appendages. Understanding what initiates regeneration in these vertebrates is of great interest to the scientific community. It has long been known that the epidermis that forms quickly over an amputated limb stump is critical for initiating regenerative programs. Yet, little of understood of the molecular and cellular mechanisms by which a simple adult epithelium transforms into this key signaling source. Here, we performed a large-scale, unbiased genetic screen for epithelial signaling deficiencies during the regeneration of amputated adult zebrafish fins, from which we identified several new mutants. One gene identified from this screen disrupts a specific component of the extracellular matrix material Laminin, Laminin beta 1a, a factor that we find to be dispensable in uninjured adult animals but required for all stages fin regeneration. Transient induction of this component by amputation polarizes the basal layer of the nascent epithelium, and, in turn, facilitates the synthesis of signaling factors, the positioning of ligand receptors, and the patterning of new bone cells. We also find that normal induction of Laminin beta 1a by injury relies on the function of Fibroblast growth factors, secreted polypeptide signals that are released early upon injury. Our results identify key early steps in the endogenous program for vertebrate appendage regeneration.