Meeting Abstract
P2.107 Wednesday, Jan. 5 HIF-1α and HIF-1β gene transcription exhibits tissue-dependent responses to hypoxia and hypercapnic hypoxia in the Atlantic blue crab, Callinectes sapidus HARDY, KM*; FOLLETT, CR; BIRK, MA; BURNETT, LE; LEMA, SC; Medical Univ of South Carolina; Univ of North Carolina Wilmington; Univ of North Carolina Wilmington; College of Charleston; Univ of North Carolina Wilmington hardykm@musc.edu
Hypoxia inducible factor 1 (HIF-1) is a key mammalian transcription factor, which under low environmental oxygen regulates the expression of a suite of genes involved in metabolism, immune function, growth and vascularization. In its activated form, HIF-1 is a dimer comprised of two protein subunits, HIF-1α and HIF-1β. Both subunits are constitutively expressed in the cell, but under normoxia HIF-1α is tagged for proteasomal degradation. Only under hypoxia do elevated HIF-1α levels allow for the formation of the HIF-1 dimer. We obtained cDNA sequences of HIF-1α and HIF-1β from the blue crab, Callinectes sapidus, an estuarine species that frequently encounters concurrent hypoxia (low O2) and hypercapnia (elevated CO2). Further, we compared the effects of short-term exposure (1h) to normoxia (N), hypoxia (H) and hypercapnic hypoxia (HH) on HIF-1α and β transcript abundance in five different tissues (light muscle, dark muscle, hepatopancreas, gill, and gonads) using quantitative real-time RT-PCR. Our results thus far demonstrated that under normoxia HIF-1α and β mRNAs were both expressed at higher levels in the glycolytic light muscle than the oxidative dark muscle. In the light muscle, HIF-1α mRNA levels were significantly lower under H and HH as compared to N, although this effect was fiber-type dependent since no decrease was detected in the dark muscle. HIF-1β transcript levels were not altered by H or HH in either fiber type, which is consistent with vertebrate and Drosophila HIF-1β homologues. Thus, HIF-1α transcript abundance in C. sapidus is regulated by oxygen levels, as hypothesized, but the particular pattern of change occurs in a tissue specific manner.
