A novel gene is transcribed in the chicken alpha-globin gene domain in thedirection opposite to the globin genes

A novel gene transcribed in the direction opposite to that of the globin ge nes was found in the chicken alpha-globin gene domain. Northern hybridisati on with single-stranded riboprobes revealed that a 4.5-kb poly(A)(+) RNA is transcribed in antisense polarity with respect to the globin genes. The tr anscription unit encoding this RNA seems to overlap the entire cluster of a lpha-globin genes and extends at least 15 kb upstream from pi, the first of the alpha-globin genes. This new transcript shows partial sequence homolog y with that encoded by the human "-14" gene. An oligonucleotide based on pa rt of a restriction fragment of thicken DNA that is 80% homologous to exon 4 of the human "-14" gene hybridises with a 4.5-kb RNA molecule. In situ hy bridisation of globin-antisense probes, that detect polyribosomal mRNAs of 1.7 and 2.5 kb on Northern blots, shows these "antisense" transcripts to be present in the cytoplasm. The 4.5-kb RNA is absent in polyribosomal poly(A )(+) RNA and may, hence, represent a nuclear pre-mRNA transcribed from the chicken gene that is homologous to the human "-14" gene. The expression of this gene is not specific to erythroid cells; analogous transcripts were al so detected in poly(A)(+) RNA extracted from a chicken lymphoblastoma cell line (HP50). Taken together, these data allow us to postulate the existence in the chicken genome of a novel gene, for which we suggest the name "ggPR X" in analogy to the murine mProx1, a gene identified in the upstream regio n of the alpha-globin gene domain in mice.