Department of Marine Biosciences, Tokyo University of Marine Science and Technology, Konan 4-5-7, Minato, Tokyo 108-8477, Japan.
Department of Marine Biosciences, Tokyo University of Marine Science and Technology, Konan 4-5-7, Minato, Tokyo 108-8477, Japan.
Gene. 2021 Jan 10;765:145116. doi: 10.1016/j.gene.2020.145116. Epub 2020 Sep 4.
In contrast to most mammals including human, fish cell lines have long been known to be immortal, with little sign of cellular senescence, despite the absence of transformation. Recently, our laboratory reported that DNA demethylation with 5-aza-2'-deoxycytidine (5-Aza-dC) induces telomere-independent cellular senescence and senescence-associated secretory phenotype (SASP) in an immortal fish cell line, EPC (Epithelioma papulosum cyprini). However, it is not known how fish derived cultured cells are usually resistant to aging in vitro. In this study, we focused on Ras, which carries out the main role of Ras-induced senescence (RIS), and investigated the role of Ras in the regulation of senescence in EPC cells. Our results show that 5-Aza-dC induced the expression of the ras (hras, kras, nras) gene in EPC cells. EPC cells overexpressing HRas or its constitutively active form (HRas) showed p53-dependent senescence-like growth arrest and senescence-associated β-galactosidase (SA-β-gal) activity with a large and/or flat morphology characteristic of cell senescence. On the other hand, the SASP was not induced. These results imply that the increased expression of HRas contributes to early senescence in EPC cells, but it alone may not be sufficient for the full senescence, even if HRas is aberrantly activated. Thus, the limited mechanism of RIS may play a role in the senescence-resistance of fish cell lines.
与包括人类在内的大多数哺乳动物不同，尽管没有发生转化，鱼类细胞系长期以来一直被认为是永生的，几乎没有细胞衰老的迹象。最近，我们实验室报道，用 5-氮杂-2'-脱氧胞苷（5-Aza-dC）进行 DNA 去甲基化可诱导永生鱼类细胞系 EPC（鲤鱼表皮瘤细胞）中出现端粒非依赖性细胞衰老和衰老相关分泌表型（SASP）。然而，目前尚不清楚鱼类来源的培养细胞通常如何在体外抵抗衰老。在这项研究中，我们专注于 Ras，它在 Ras 诱导的衰老（RIS）中发挥主要作用，并研究了 Ras 在 EPC 细胞衰老调节中的作用。我们的结果表明，5-Aza-dC 可诱导 EPC 细胞中 ras（hras、kras、nras）基因的表达。过表达 HRas 或其组成激活形式（HRas）的 EPC 细胞表现出 p53 依赖性衰老样生长停滞和衰老相关的β-半乳糖苷酶（SA-β-gal）活性，具有细胞衰老的大而/或扁平形态特征。另一方面，未诱导 SASP。这些结果表明，HRas 的表达增加有助于 EPC 细胞的早期衰老，但即使 HRas 异常激活，它本身可能不足以完全衰老。因此，RIS 的有限机制可能在鱼类细胞系的抗衰性中发挥作用。
