Decreased neoblast progeny and increased cell death during starvation-induced planarian degrowth
Decreased neoblast progeny and increased cell death during starvation-induced planarian degrowth
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DOI：
10.1387/ijdb.113452cg
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发表时间：
2012-01-01
影响因子：
0.7
通讯作者：
Aboobaker, A. Aziz
中科院分区：
文献类型：
--
作者：
Gonzalez-Estevez, Cristina;Felix, Daniel A.;Aboobaker, A. Aziz
一个复杂的多细胞生物体的发展需要生长，细胞分裂，细胞分化和细胞死亡的仔细协调。所有这些过程必须在复杂和协调的控制下，因为它们必须在所有组织中整合。淡水真涡虫是特别可塑的，因为它们不断地从成体干细胞池中替换体组织，并作为成年动物不断地经历生长和退化，以应对营养的可用性。在这些过程中，它们似乎保持着组织和器官的完美比例。这些生活史特征使它们成为研究生长和退化的理想模式系统。我们研究了独特的涡虫退化过程。当没有食物时，涡虫能够退化到最小尺寸，而没有任何不良生理结果的迹象。例如，它们保持完全的再生能力。我们目前的知识，这是如何在分子和细胞水平上调节是非常有限的。据报道，Planarian退化是由于细胞数量减少而不是细胞大小减少。因此，退化的一个明显的解释是干细胞增殖的减少。然而，文献中的证据表明情况并非如此。我们发现，涡虫维持正常的基础有丝分裂率在退化，但干细胞后代的数量减少饥饿和退化。这些观察结果在喂食后会发生逆转，表明它们取决于营养状况。在退化过程中也观察到细胞死亡增加，这在进食时不会迅速逆转。我们的结论是，退化是细胞死亡的结果，减少细胞数量和neoblast自我更新和分化的动态适应营养条件，使维持neoblast人口在饥饿期间。
The development of a complex multicellular organism requires a careful coordination of growth, cell division, cell differentiation and cell death. All these processes must be under intricate and coordinated control, as they have to be integrated across all tissues. Freshwater planarians are especially plastic, in that they constantly replace somatic tissues from a pool of adult somatic stem cells and continuously undergo growth and degrowth as adult animals in response to nutrient availability. During these processes they appear to maintain perfect scale of tissues and organs. These life history traits make them an ideal model system to study growth and degrowth. We have studied the unique planarian process of degrowth. When food is not available, planarians are able to degrow to a minimum size, without any signs of adverse physiological outcomes. For example they maintain full regenerative capacity. Our current knowledge of how this is regulated at the molecular and cellular level is very limited. Planarian degrowth has been reported to result from a decrease in cell number rather than a decrease in cell size. Thus one obvious explanation for degrowth would be a decrease in stem cell proliferation. However evidence in the literature suggests this is not the case. We show that planarians maintain normal basal mitotic rates during degrowth but that the number of stem cell progeny decreases during starvation and degrowth. These observations are reversed upon feeding, indicating that they are dependent on nutritional status. An increase in cell death is also observed during degrowth, which is not rapidly reversed upon feeding. We conclude that degrowth is a result of cell death decreasing cell numbers and that the dynamics of neoblast self-renewal and differentiation adapt to nutrient conditions to allow maintenance of the neoblast population during the period of starvation.