CHARACTERIZATION AND LOCALIZATION OF THE MPROX1 GENE DIRECTLY UPSTREAM OF THE MOUSE ALPHA-GLOBIN GENE-CLUSTER - IDENTIFICATION OF A POLYMORPHIC DIRECT REPEAT IN THE 5'UTR

The alpha-globin major regulatory element (alpha MRE) positioned far u pstream of the gene cluster is essential for the proper expression of the alpha-globin genes. Analysis of the human and mouse alpha-globin U pstream Flanking Regions (alpha UFR) has identified three nonglobin ge nes in the order Dist1-MPG-Prox1-alpha-globin. Further characterizatio n of the whole region indicates that the alpha MRE and several other e rythroid DNase HSSs are associated with the transcription unit of the Prox1 gene. In this paper we describe the characterization and localiz ation of the mouse Prox1 cDNA and compare it with its human homolog, t he -14 gene, and another human cDNA sequence named hProx1. Our results show a strong conservation between the -14 gene and the mouse Prox1 g ene with the exception of the first exon of the mProx1 gene. This exon is absent in the -14 cDNA but is present and conserved in the human P rox1 cDNA, indicating that the human -14/hProx1 gene is alternatively spliced or transcribed. The mProx1 gene encodes a predicted protein of 491 amino acids (aa) whose function is not known. In the 5'UTR of thi s gene, a 35-bp repeat (VNTR) is positioned, which is highly polymorph ic among laboratory inbred mice (Mus domesticus). Our results strongly suggest that the mProx1 VNTR arose during the divergence of M. spretu s and M. domesticus. Besides its use in evolutionary studies and posit ional cloning, the mProx1 VNTR might be invaluable for monitoring the expression of a transgenic mProx1 gene. The cloning of the mProx1 gene will be helpful to analyze its possible role on alpha-globin as well on MPG expression in the mouse.