Roles of basal keratinocytes in actinotrichia formation. (October 2018)

• Record Type: Journal Article
• Authors: Kuroda, Junpei; Iwane, Atsuko H.; Kondo, Shigeru
• Is Part Of: Mechanisms of development. Volume 153(2018)
• Page Start: 54
• Page End: 63
• Publication Date: 2018-10
• Subjects: Developmental biology -- Periodicals; Molecular biology -- Periodicals; Developmental Biology -- Periodicals; Molecular Biology -- Periodicals; Biologie du développement -- Périodiques; Biologie moléculaire -- Périodiques; Developmental biology; Molecular biology; Periodicals; Electronic journals; 571.8
• DOI: 10.1016/j.mod.2018.08.010
• Languages: English
• ISSNs: 0925-4773

Abstract

Abstract: The embryonic fins and the tip of adult fins of teleost fish are supported by rows of straight, unmineralized fibrils called actinotrichia. The proximal ends of the actinotrichia are bundled and the mineralized bones called lepidotrichia are made along them. Since malformation in actinotrichia causes wavy fin bones, the correct configuration of actinotrichia is essential for the correct construction of the fin shape. Past studies suggested that two types of cells, basal keratinocytes, and mesenchymal cells involve in the formation of actinotrichia. However, the mechanism how these cells contribute is unknown. In this study, we elucidated the role of basal keratinocytes in actinotrichia formation. First, we developed the imaging tool that specifically visualizes the basal keratinocytes and actinotrichia. Then, we established the in vitro culture method of the basal keratinocytes and found that the keratinocytes developed fine needle-like structures in it. The TEM image of them showed the specific shadow pattern of actinotrichia, indicating that the fine needle-like structures are the newly made actinotrichia. Finally, we cultured the basal keratinocytes with mature actinotrichia and observed that the basal keratinocytes actively holded actinotrichia with their membrane, and often generated a linear array of cells holding a single actinotrichium. This behavior suggested a mechanism with which long actinotrichia are made by relatively small cells. Our results clarified the role of basal keratinocyte and provided a novel insight into understanding the mechanism of actinotrichia formation. Highlights: The expression of GFP-tagged actinodin enabled to observe clearly the contour of actinotrichia in zebrafish fin. Basal keratinocytes generate small actinotrichia fibrils by themselves in vitro . Basal keratinocytes actively envelope actinotrichia with their membrane in vitro .