The Axial Organ and the Pharynx Are Sites of Hematopoiesis in the Sea Urchin
The Axial Organ and the Pharynx Are Sites of Hematopoiesis in the Sea Urchin
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DOI：
10.3389/fimmu.2019.00870
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发表时间：
2019-04-25
影响因子：
7.3
通讯作者：
Smith, L. Courtney
中科院分区：
文献类型：
--
作者：
Golconda, Preethi;Buckley, Katherine M.;Smith, L. Courtney
背景：成年海胆的体腔细胞增殖的位置尚不清楚，自19世纪初以来的推测一直基于显微解剖和示踪剂摄取研究。在免疫系统下调的成年海胆中，体细胞数量随着免疫攻击的增加而增加，目前尚不清楚这些细胞是否全部或部分是新增殖的。编码控制胚胎和幼体海胆造血的转录因子的基因调控网络尚未在成年海胆中进行研究。因此，为了鉴定成体海胆的造血组织，对几种组织的细胞增殖、吞噬细胞特异性基因的表达和转录因子的编码基因的表达进行了研究。这些基因在控制胚胎和幼体造血的保守调控网络中发挥作用。结果：成体海胆的细胞增殖是通过注射热灭活的重氮营养弧菌进行免疫攻击或通过吸入体腔液来耗尽细胞来诱导的。对这两种刺激的反应中，新增殖的体腔细胞仅占体腔液中细胞的10%左右。在组织中，新增殖的细胞和表达SpTransformer蛋白(以前称为Sp185/333)的细胞存在于轴器官、性腺、咽、食道和肠道中，组织之间没有差异。调控造血的转录因子编码基因的表达水平表明，与体腔细胞、食道、肠道和性腺相比，中枢器官和咽部的表达都有所增加。同样，RNAseq数据集对中轴器和咽部也显示了类似的结果，但也表明中轴器可能是体腔腔中细胞移除和再循环的场所。结论：本文的结果与先前的推测一致，即中轴器可能是体腔细胞增殖的场所，也可能是细胞移除和再循环的中心。第二个部位，咽部，可能也有造血活动，一种组织被认为只作为肠道的一部分发挥作用。
Background: The location of coelomocyte proliferation in adult sea urchins is unknown and speculations since the early 1800s have been based on microanatomy and tracer uptake studies. In adult sea urchins (Strongylocentrotus purpuratus) with down-regulated immune systems, coelomocyte numbers increase in response to immune challenge, and whether some or all of these cells are newly proliferated is not known. The gene regulatory network that encodes transcription factors that control hematopoiesis in embryonic and larval sea urchins has not been investigated in adults. Hence, to identify the hematopoietic tissue in adult sea urchins, cell proliferation, expression of phagocyte specific genes, and expression of genes encoding transcription factors that function in the conserved regulatory network that controls hematopoiesis in embryonic and larval sea urchins were investigated for several tissues.Results: Cell proliferation was induced in adult sea urchins either by immune challenge through injection of heat-killed Vibrio diazotrophicus or by cell depletion through aspiration of coelomic fluid. In response to either of these stimuli, newly proliferated coelomocytes constitute only about 10% of the cells in the coelomic fluid. In tissues, newly proliferated cells and cells that express SpTransformer proteins (formerly Sp185/333) that are markers for phagocytes are present in the axial organ, gonad, pharynx, esophagus, and gut with no differences among tissues. The expression level of genes encoding transcription factors that regulate hematopoiesis show that both the axial organ and the pharynx have elevated expression compared to coelomocytes, esophagus, gut, and gonad. Similarly, an RNAseq dataset shows similar results for the axial organ and pharynx, but also suggests that the axial organ may be a site for removal and recycling of cells in the coelomic cavity.Conclusions: Results presented here are consistent with previous speculations that the axial organ may be a site of coelomocyte proliferation and that it may also be a center for cellular removal and recycling. A second site, the pharynx, may also have hematopoietic activity, a tissue that has been assumed to function only as part of the intestinal tract.