LAUSR

Hypoxia-inducible factors (HIFs) are master transcription factor regulating hypoxic responses in vertebrates. Species of Schizothoracine, a sub-family of cyprinidae, are highly endemic to the hypoxic Qinghai-Tibetan Plateau (QTP). What roles the HIFs play in hypoxic adaptation in the Schizothoracine fish is little known. In this study, the HIF-1α/B gene from Gymnocypris dobula ( Gd ) was characterized. The predicted protein for Gd -HIF-1α/B contains the main domains (bHLH, PAS, PAC, ODD, N-TAD, and C-TAD). Moreover, a specific mutation that the proline hydroxylation motif (LXXLAP) mutated into PxxLAP was observed in Gd -HIF-1α/B CODD domain, which may lead to changes in the function. To clarify whether HIF-1α/B of G. dobula possesses hypoxic adaptive features, Gd -HIF1α/B and Schizothorax prenanti- HIF1α/B ( Sp -HIF1α/B) were cloned into an expression vector and transfected into 293T cells. Cell viability was found to be significantly higher in cells transfected with Gd -HIF-1α/B than those transfected with Sp -HIF-1α/B under hypoxic conditions. In addition, G. dobula HIF-1α/B showed stronger activity in transactivating the expression of nitric oxide (NO)–synthesizing enzyme, NOS2B under hypoxia stresses than the orthologous gene from S. prenanti , which were accompanied with upregulated expressions of NOS2B in heart of G. dobula , which may attribute to elevated NO levels detected in G. dobula than the lower land species. These results indicated that the HIF-1α plays an important role in mediating the iNOS signaling system in the process of evolutionary adaptation of the Schizothoracine to the highland environment.