Molecular characterization and expression analysis of three hypoxia-inducible factor alpha subunits, HIF-1α, -2α and -3α in hypoxia-tolerant Indian catfish, Clarias batrachus [Linnaeus, 1758].
The present study aimed at characterization of three HIF-α subunits, HIF-1α -2α and -3α from hypoxia-tolerant Clarias batrachus, as well as to elucidate their expression pattern under short and long-term hypoxic conditions and identification of biomarker candidate. The complete cDNAs of HIF-1α, -2α and -3α were 2,833, 4,270 and 3,256 bp in length, encoding 774, 818 and 628 amino acid residues, respectively. In C. batrachus, HIF-α subunits were structurally similar in DNA binding, dimerization, degradation and transcriptional activation domains, but differed in their oxygen-dependent degradation domains. Presence of c-Jun N-terminal kinase binding domain in HIF-α subunits was reported here for the first time in fish. In adult C. batrachus, three HIF-α mRNAs were detected in different tissues under normoxic conditions, however HIF-1α was highly expressed in all the tissues studied, in comparison to HIF-2α and -3α. Short-term hypoxia exposure caused significant increase in three HIF-α transcripts in brain, liver and head kidney, while after long-term hypoxia exposure, significant up-regulation of HIF-1α in spleen and -2α in muscle was observed and HIF-3α significantly down-regulated in head kidney. These observations suggest that the differential expression of HIF-α subunits in C. batrachus was hypoxic time period dependent and may play specialized roles in adaptive response to hypoxia. HIF-2α, with its highly elevated expression in muscle tissues, can be a robust biomarker candidate for exposure to hypoxic environment.
National Bureau of Fish Genetic Resources (ICAR), Canal Ring Road, P.O. Dilkusha, Lucknow, 226002, UP, India, vindhyamohindra@gmail.com.
Vindhya
V
Mohindra
Ratnesh Kumar
RK
Tripathi
Rajeev Kumar
RK
Singh
Kuldeep K
KK
Lal
D000222:Adaptation, Physiological / Q000235:genetics*; D000595:Amino Acid Sequence; D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics* / Q000378:metabolism; D002397:Catfishes / Q000235:genetics*; D018076:DNA, Complementary / Q000235:genetics; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D000860:Hypoxia / Q000235:genetics*; D008969:Molecular Sequence Data; D016366:Open Reading Frames / Q000235:genetics; D020033:Protein Isoforms / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D021122:Protein Subunits / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment
D051792:Basic Helix-Loop-Helix Proteins; D018076:DNA, Complementary; D020033:Protein Isoforms; D021122:Protein Subunits; D012333:RNA, Messenger