Regulation of cell junctions is crucial for the integrity of epithelial tissues and organs. Cell junctions also play roles in controlling cell proliferation for organ growth. Translationally controlled tumor protein (TCTP) is a conserved protein involved in growth control, but its role in cell junctions is unknown. Here we show that Drosophila Tctp directly interacts with the septate junction protein Coracle (Cora) to regulate epithelial integrity and organ growth. Tctp localizes together with Cora in the epidermis of the embryo. Loss of Cora reduces the level of Tctp in the epidermis but not vice versa. cora/+ or Tctp/+ single heterozygotes develop normally to adulthood. However, double heterozygotes for cora and Tctp mutations show severe disruption of epithelia causing synthetic lethality in the embryo. Double knockdown of Cora and Tctp in eye imaginal disc synergistically leads to disruption of the eye disc, resulting in a severe reduction or loss of eye and head. Conversely, double knockdown of Cora and Tctp in wing disc causes overgrowth as well as cell death. Inhibition of cell death under this condition causes hyperplastic growth of the wing disc. Tctp also shows direct and functional interaction with Cora-associated factors like Yurt and Na⁺/K⁺-ATPase. This study suggests that proper levels of Tctp and Cora are essential for the maintenance of the Cora complex and the integrity of epithelia. Our data also provide evidence that both Cora and Tctp are required to suppress overgrowth in developing wing.

细胞连接的调节对于上皮组织和器官的完整性至关重要。细胞连接在控制细胞增殖以促进器官生长中也发挥着作用。翻译控制的肿瘤蛋白（TCTP）是一种参与生长控制的保守蛋白，但其在细胞连接中的作用尚不清楚。在这里，我们显示果蝇Tctp直接与分隔连接蛋白Coracle（Cora）相互作用，以调节上皮完整性和器官生长。Tctp与Cora一起位于胚胎的表皮中。Cora的损失会降低表皮中Tctp的水平，反之亦然。cora / +或Tctp / +单杂合子正常发育到成年。但是，对于双重杂合子CORATctp和Tctp突变表明上皮细胞受到严重破坏，导致胚胎合成致死。眼睛假想椎间盘中的Cora和Tctp的双重敲除会协同作用导致眼睛椎间盘破裂，从而导致眼睛和头部严重减少或丢失。相反，翼盘中Cora和Tctp的双重敲除会导致过度生长以及细胞死亡。在这种条件下抑制细胞死亡会导致翼盘增生性生长。Tctp还显示与Cora相关因子（如Yurt和Na ⁺ / K ⁺-ATP酶。这项研究表明，适当的Tctp和Cora水平对于维持Cora复合物和上皮的完整性至关重要。我们的数据还提供了证据，表明Cora和Tctp都需要抑制发育中的机翼过度生长。