Clinical and Experimental Pharmacology and Physiology zyxwvu (1993) 20,283-288 zyxw SHORT COMMUNICATION SPECIES DIFFERENCES IN BINDING OF SUBMANDIBULAR NUCLEAR PROTEINS TO RENIN PROMOTER DNA John A. Loudon,* Akiyoshi Fukamizu? Kazuo Murakami' and Brian J. Morris Molecular Biology zyxwvut & Hypertension Laboratory, Department zyx of Physiology, The University of Sydney, Sydney, New South Wales, Australia and 'Institute of Applied Biochemistry, University of Tsukuba, Ibaraki, Japan (Received 14 December 1992) SUMMARY 1. Renin is highly expressed in submandibular gland (SMG) of mouse, which has two genes, Ren-Id and Ren-2d, but not at all in rat SMG. Differences in nuclear protein binding to renin promoter DNA were, therefore, explored. 2. Rat - 169 to +23 renin DNA formed complexes with both mouse and rat extract, whereas a corresponding fragment of mouse Ren-Id DNA (- 121 to +4) bound with rat extract, but much less so with mouse extract. Rat extract bound a -704 to -450 fragment of the Ren-Id promoter. For Ren-2d - 578 to - 383 and - 786 to - 718 DNA bound with mouse extract and - 383 to + 11 and - 664 to - 578 DNA bound with rat extract. 3. The results support a role for differences in presence or binding of species-specific trans-acting factors in the differential regulation of the renin gene in SMG of mouse and rat. Strong binding near the rat RNA polymerase zyxwvut I1 binding site could repress transcription in rat SMG, and binding peculiar to the Ret~-2~ B2 element might contribute to high expression in mouse SMG. Key words: gel retardation, mouse, rat, renin gene control, trans-acting factors. INTRODUCTION Rats (Burnham et al. 1987), like humans (Hardman et al. 1984; Fukamizu et al. 1986) have only one renin gene, whereas mice can have one gene Ren-1' (Sigmund & Gross 1991; Morris 1992a) or two genes, Ren-Id and Ren-2d (Mullins et al. 1982; Panthier & Rougeon 1983; Burt et al. 1989; Sigmund & Gross 1991; Morris 1992a), or Ren-lh and Ren-2h in the wild mouse, M. hortulanus (Abel et al. 1992). Mouse submandibular gland (SMG) granular ducts (20% of volume; Hirose et al. 1983) show high expression of Ren-2 (Morris et al. 1980; Catanzaro et al. 1985; Morris 1992b) which is second-order of magnitude >Ren-I' (Catanzaro et al. 1985), with no (Field & Gross 1985) or very low (Miller et al. 1989) Ren-I expression. In sharp contrast, rats show no SMG renin expression (Morris et al. 1980; Tronik et al. 1988; Ekker et al. 1989b). Such species differences could arise from differences in 5'-flanking DNA, as mouse genes have, at rat residue -75, a 476 base pair (bp) insertion, designated M3 (mouse insertion 3; Tronik et al. 1988; Sigmund & Gross 1991). Within this, at - 205, Ren-Zd has a 220 bp mouse type-2 Alu-equivalent sequence, B2 (Field & Gross 1985; Correspondence: Dr Brian J. Morris, Molecular Biology & Hypertension Laboratory, Department of Physiology, Building F13, The *Present address: J. A. Loudon, Institute of Applied Biochemistry, University of Tsukuba, Ibaraki 305, Japan. Presented at the High Blood Pressure Research Council of Australia meeting on zyxwv 10-1 1 December 1992. University of Sydney, Sydney, NSW 2006, Australia.