Data from: Evolutionary suppression of erythropoiesis via the modulation of TGF-β signaling in an Antarctic icefish

The Antarctic icefish, a family (Channichthyidae) of teleosts within the
perciform suborder Notothenioidei, are the only known vertebrates without
oxygen-transporting haemoglobins and that are largely devoid of
circulating erythrocytes. To elucidate the evo-devo mechanisms
underpinning the suppressed erythropoiesis in the icefish, we conducted
comparative studies on the transcriptomes and microRNAomes of the primary
haematopoietic tissues between an icefish (Chionodraco hamatus) and two
red-blooded notothenioids (Trematomus bernacchii and Gymnodraco
acuticeps). We identified substantial remodelling of the haematopoietic
programs in the icefish through which erythropoiesis is selectively
suppressed. Experimental verification showed that erythropoietic
suppression in the icefish may be attributable to the upregulation of
TGF-β signalling, which coincides with reductions in multiple
transcription factors essential for erythropoiesis and the upregulation of
hundreds of microRNAs, the majority (> 80%) of which potentially
target erythropoiesis regulating factors. Of the six microRNAs selected
for verification, three miRNAs (miR-152, miR-1388 and miR-16b)
demonstrated suppressive functions on GATA1 and ALAS2, which are two
factors important for erythroid differentiation, resulting in reduced
numbers of erythroids in microinjected zebra fish embryos. Codon
substitution analyses of the genes of the TGF-β superfamily revealed signs
of positive selection in TGF-β1 and endoglin in the lineages leading to
Antarctic notothenioids. Both genes are previously known to function in
erythropoietic suppression. These findings implied a general trend of
erythropoietic suppression in the cold-adapted notothenioid lineages
through evolutionary modulation of the multi-functional TGF-β signalling
pathway. This trend is more pronounced in the haemoglobin-less icefish,
which may pre-emptively hinder the otherwise defective erythroids from
production.