Expression of p53 isoforms in response to two levels of hypoxia and effects of p53 knock‐down in glyceraldehyde‐3‐phosphate dehydrogenase in the white shrimp Litopenaeus vannamei

Abstract

In response to hypoxia, aquatic organisms rely on anaerobic glycolysis. In the white shrimp Litopenaeus vannamei, hypoxia induces glyceraldehyde-3-phosphate dehydrogenase (GAPDH) expression, a key enzyme in glycolysis. In mammals, GAPDH has additional functions in cellular activities besides glucose metabolism, such as interaction with the transcription factor p53 to form a complex that participates in apoptosis. We investigated the effect of two levels of hypoxia (1.5 and 1.0 mg dissolved oxygen (DO) L−1) on the expression of the two shrimp p53 isoforms known, FLp53 and ∆Np53, and the effect of p53 silencing during hypoxia on GAPDH expression and activity in hepatopancreas. The FLp53 transcripts were down-regulated after 24 and 48 h exposure to both hypoxic conditions, but not the ∆Np53. p53 silencing using RNAi, induced expression of GAPDH at 48 h in the 1.5 mg DO L−1 hypoxic condition compared with the unsilenced shrimp, contrary to the 1.0 mg DO L−1 where expression was induced in the silenced animals in normoxia after 48 h, but no significant changes were detected in enzyme activity in any case. These results indicate differential expression of p53 isoforms under two hypoxic conditions and maintenance of GAPDH transcripts and activity in p53-silenced shrimp.