Page 225 - 《水产学报》2026年第3期

3 期 水 产 学 报 50 卷

Abstract: SGT1 (Suppressor of G2 allele of SKP1) acts as an essential regulatory factor that coordinates the balance between
autophagy and apoptosis, and maintains the protein homeostasis in higher animals. However, the immune functions of SGT1 in
invertebrates remain unclear. Here, we investigate the molecular characteristics and antibacterial role of SGT1 in the giant
freshwater prawn Macrobrachium rosenbergii, with particular emphasis on its modulation of autophagic and apoptotic signal-
ing. The full-length M. rosenbergii SGT1 transcript (MrSGT1) was amplified by PCR and subjected to comprehensive bioin-
formatic analyses to delineate its sequence characteristics, domain organization, and phylogenetic affiliation. The expression
changes of MrSGT1 were quantified by qRT-PCR under basal conditions and following challenge with Aeromonas hydrophila
or lipopolysaccharide (LPS). The function of MrSGT1 was investigated using RNA interference coupled with qRT-PCR, West-
ern blotting, and enzymatic assays to assess the impact of MrSGT1 silencing on autophagy, apoptosis, and antioxidant capacity.
The results showed that, the open reading frame (ORF) of MrSGT1 was 687 bp encoding a peptide of 228 amino acids with CS
and SGS domains. The predicted molecular weight of MrSGT1 protein was 25.41 ku with an isoelectric point of 5.54. Sequence
homology analysis and phylogenetic analysis showed that the amino acid sequence of MrSGT1 shared 95.61% similarity with
that of SGT1 from M. nipponense, and clustered with crustaceans, indicating that the protein has evolved relatively conservat-
ively in crustaceans. MrSGT1 was ubiquitously expressed in all examined tissues, with maximal expression in hepatopancreas,
where its expression level is 18.33-fold higher than that in hemolymph. The relative expression of MrSGT1 in the hepatopan-
creas and gills of M. rosenbergii increased significantly after challenge with A. hydrophila and LPS, indicating its involvement
in the prawn’s antibacterial immune response. Following A. hydrophila stimulation, the peak levels of MrSGT1 in the hepato-
pancreas and gill tissues were 5.51-fold and 5.15-fold higher than those of the control group, respectively, while the peak levels
of MrSGT1 were 1.74-fold and 5.23-fold higher than the control group after LPS stimulation, respectively. Knockdown of
MrSGT1 in combination with A. hydrophila infection resulted in a significant change in autophagic activity, an increase in
apoptosis, and a decrease in antioxidant enzyme levels in M. rosenbergii. These findings revealed that MrSGT1 fortifies the
antioxidant defenses of M. rosenbergii against pathogenic invasion by modulating the dynamic interplay between autophagy
and apoptosis. These results provide pivotal foundational data to guide future investigations into the antibacterial defense mech-
anisms of M. rosenbergii.

Key words: Macrobrachium rosenbergii; Aeromonas hydrophila; suppressor of G2 allele of SKP1 (SGT1); apoptosis; auto-
phagy
Corresponding author: WANG Feifei. E-mail: ffwong0101@163.com
Funding projects: Central Public-interest Scientific Institution Basal Research Fund, CAFS (2025XK04, 2025XK02,
2023TD48); Guangdong Basic and Applied Basic Research Foundation (2023A1515110194); Guangdong Rural Science and
Technology Special Envoy Project (KTP20240662); Project of Guangzhou Science and Technology (2023B03J1305); Inde-
pendent Project of Zhaoqing Branch Center of Guangdong Laboratory for Lingnan Modern Agricultural Science and Techno-
logy (P20211154-0102-01)

https://www.china-fishery.cn 中国水产学会主办 sponsored by China Society of Fisheries
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