Assignment of the erythropoietin receptor (EPOR) gene to mouse chromosome 9 and human chromosome 19

Erythropoietin (EPO), the primary regulator of mammalian erythropoiesis, binds and activates a specific receptor on erythroid progenitors. The human and mouse cDNAs for this receptor (EPOR) have recently been isolated. These cDNAs were used to establish the genomic location of the EPOR gene. By somatic cell hybrid analysis, the locus for the EPOR maps to human chromosome (Chr) 19pter-q12. By interspecific backcross mapping the locus is tightly linked to the murine Ldlr locus near the centromere of mouse Chr9. This region of mouse Chr9 is homologous to a region of human Chr 19p13 carrying the human LDLR and MEL loci, strongly suggesting that the human EPOR gene is at 19p13 near the human LDLR locus.     

Assignment of the gene for intercellular adhesion molecule-1 (Icam-1) to proximal mouse chromosome 9.

Intercellular adhesion molecule-1 (ICAM-1) is an integral membrane protein, a member of the immunoglobulin superfamily, and a ligand for LFA-1, a beta 2 leukocyte integrin. ICAM-1 has a tissue distribution similar to that of the major histocompatibility complex class II antigens and is likely to play a role in inflammatory responses. We have mapped this gene to proximal mouse chromosome 9 by using mouse-hamster somatic cell hybrids and an interspecies backcross. Since human ICAM-1 maps to chromosome 19, it joins the LDL receptor to establish a new conserved syntenic segment between human chromosome 19 and proximal mouse chromosome 9. Murine Icam-1 maps between Cbl-2 and the centromere in the same region as one of the susceptibility genes for insulin-dependent diabetes mellitus (Idd-2) that is postulated to play a role in immune function and inflammation leading to insulitis. The mapping of Icam-1 to the region known to contain the Idd-2 gene raises the question of whether the phenotypic differences attributed to the Idd-2 locus might be due to genetic variation in Icam-1.     

Assignment of the dipeptidylpeptidase IV (DPP4) gene to pig Chromosome 15q21

A porcine 2-kb partial dipeptidylpeptidase IV (DPP4, EC 3.4.14.5) cDNA clone and a porcine 16-kb genomic fragment containing parts of the DPP4 gene were isolated, characterized, and used as probes to map the DPP4 gene to pig Chr (Chr) 15q21 by fluorescence in situ hybridization. A two-allele RFLP was revealed for the DPP4 gene. This polymorphism was utilized in a linkage test against the erythrocyte antigen G (EAG), previously assigned to Chr 15, and the microsatellite S0088, which is linked to EAG. The linkage analyses revealed significant evidence for linkage confirming the assignment of DPP4 to Chr 15.     

Assignment of the gene coding for hepatocyte growth factor-like protein to mouse chromosome 9

The gene coding for hepatocyte growth factor-like protein has been localized to mouse chromosome 9 at a locus (Hgfl) distal to the Trf locus. The likely gene order in this region is centromere-Trf-Gnai-2-Hgfl-Cck. The region surrounding the Hgfl locus shows homology of syntenty to band p21 on human chromosome 3.