An activating transcription factor 6 beta (ATF6β) regulates apoptosis of hemocyte during immune response in Crassostrea gigas. Issue 99 (April 2020)

• Record Type: Journal Article
• Authors: Liu, Shujing; Wang, Weilin; Ge, Wenjing; Lv, Xiaojing; Han, Zirong; Li, Yinan; Wang, Lingling; Song, Linsheng
• Is Part Of: Fish & shellfish immunology. Issue 99(2020)
• Page Start: 442
• Page End: 451
• Publication Date: 2020-04
• Subjects: Crassostrea gigas -- Activating transcription factor 6 beta -- Vibrio splendidus -- Cellular homeostasis -- Unfolded protein response; Fishes -- Immunology -- Periodicals; Shellfish -- Immunology -- Periodicals; Poissons -- Immunologie -- Périodiques; Crustacés -- Immunologie -- Périodiques; 571.9617
• DOI: 10.1016/j.fsi.2020.02.042
• Languages: English
• ISSNs: 1050-4648

Abstract

Abstract: The homeostasis of immune cells during immune response is vital for hosts to defend against invaders. Activating transcription factor 6 (ATF6) is an important transcription factor in the unfolded protein response (UPR) to maintaining cellular homeostasis. In the present study, one ATF6 homologue was identified from Pacific oyster Crassostrea gigas (designated as Cg ATF6β). The full length cDNA of Cg ATF6β was of 2645 bp with a 1596 bp open reading frame (ORF) encoding a polypeptide of 531 amino acids. The deduced amino acid sequence of Cg ATF6β was predicted to contain a transmembrane region, a conserved basic leucine zipper (bZIP) domain, a site 1 protease cleavage site, a site 2 protease cleavage site, and a Golgi localization signal. Cg ATF6β mRNA was constitutively expressed in hemocytes, gill, mantle, gonad, hepatopancreas and labial palp, with a slightly higher expression level in muscle (2.45-fold of that in gill, p < 0.05). After oysters were challenged with Vibrio splendidus, the mRNA expression levels of Cg ATF6β in hemocytes were significantly up-regulated at 3 h (2.68-fold of that in seawater group, p < 0.01) and peaked at 12 h (3.14-fold of that in seawater group, p < 0.01). The endogenic Cg ATF6β protein was mainly located in the cytoplasm of oyster hemocytes, and it was significantly transported into the nuclei of hemocytes at 1.5 h after the challenge with V. splendidus . After an injection with Cg ATF6β dsRNA, the mRNA expression of Cg ATF6β was knocked down to 0.26-fold of that in dsGFP group ( p < 0.01). In Cg ATF6β dsRNA-injected oysters, the mRNA expressions of glucose-regulated protein 78 (GRP78), calnexin (CNX) and anti-apoptotic B-cell lymphoma-2 (Bcl-2) in hemocytes were significantly decreased at 12 h after V . splendidus challenge, which were 0.65-fold ( p < 0.01), 0.54-fold ( p < 0.01) and 0.17-fold ( p < 0.01) of that in dsGFP-injected oysters, while the apoptotic rate of hemocytes was significantly up-regulated (1.97-fold of that in dsGFP group, p < 0.05). Collectively, these results suggested that Cg ATF6β was involved in apoptosis inhibition of oyster hemocytes upon V. splendidus challenge by regulating the expression of Cg GRP78, Cg CNX and Cg Bcl-2. Highlights: An ATF6β was identified from C. gigas, which was constitutively expressed in hemocytes. Cg ATF6β mRNA in oyster hemocytes increased significantly after V. splendidus stimulation. The mRNA expressions of Cg GRP78, Cg CNX and Cg Bcl-2 were inhibited after Cg ATF6β was knockdown. Cg ATF6β regulated apoptosis of hemocyte during immune response in oyster.