Biochimica et Biophysica Acta, 1172 (1993) 197-199 197 Elsevier Science Publishers B.V. BBAEXP9~56 Short Sequence-Paper The 5' sequence of human Factor XII gene contains transcription regulatory elements typical of liver specific, estrogen-modulated genes F. Citarella, S. Misiti, A. Felici, A. Aiuti, C. La Porta and A. Fantoni Dipartimento di Biopatologia Umana, Sezione di Biologia Cellulare, Universith di Roma 'La Sapienza ', Roma (Italy) (Received 13 October 1992) Key words: Factor XII; Liver; Estrogen; Fibrinolysis; Promoter The human Factor XII gene codes for a serine proteinase synthesized in liver that activates both the coagulation and the fibrinolytic cascades. The nucleotide sequence analysis of a HincII-HincII 3129 bp fragment was performed showing that the FXII promoter region contains neither CAAT and TATA regulatory elements, nor GC islands, but revealing the presence of two tandemly repeated sequences in opposite orientation, two LFoA1 elements typical of the liver specific genes and one estrogen responsive element, that substantiates the observation of Factor XII gene modulation by estrogens. Human coagulation Factor XII (FXII) is a serine proteinase zymogen secreted by the liver and present in plasma (25-30/zg/ml). Factor XII gene is localized on chromosome 5 [1], at chromosome map position 5q33-qter [2]. The gene measures about 12 kb and is organized in 14 exons and 13 introns [3]. The complete nucleotide structure of the coding sequence was re- ported by Cool et al. [4] and completed by Tripodi et al. [5]. The primary structure of FXII has revealed [6] that FXII has a structural organization similar to that of other serine proteinases involved in blood coagula- tion and in fibrinolysis. The function of FXII is not clear and indeed, FXII deficiency is not associated with bleeding disorders. However, active FXII may have an important role in the pathophysiology of inflammation [7] as it is in- volved in kinin formation, complement activation and fibrinolysis. Recent evidence indicates that FXII con- centration in plasma is enhanced by estrogens [8]. Information relevant to FXII role in human physiol- ogy may be obtained either from the study of properly engineered, recombinant FXII proteins [9] or else, Correspondence to: F. Citarella, Dipartimento di Biopatologia Umana, Sezione di Biologia Cellulare, Viale Regina Elena 324, 00161 Roma, Italy. The sequence data reported in this paper have been submitted to the EMBL/Genbank Data Libraries under the accession number X67330. from the regulatory pattern of FXII gene transcription. On this purpose we have isolated a 3174 bp fragment of human genomic DNA at the 5' of the FXII tran- scription unit and we have analyzed its nucleotide sequence. A human genomic library in pCOS 2EMBL cosmid vectors was screened with a 280 bp fragment at the 5' of the FXII cDNA, starting with the coding position 1 [5]. From HincII digests of a positive cosmid a 3.17 kb fragment was subcloned in pBluescript (clone 5' FXII 3174) and a restriction map of the region was derived. This fragment (3.174 kb) was subdivided by PvulI digestion into four pieces of which two of 1810 and 1290 bp were subcloned in pBlueScript (clone 5' FXII- 1810 and 5' FXII-1290). Clones FXII 3174, 5'FXII- 1810 and 5' FXII-1290 were used to derive the nu- cleotide sequence of the FXII 5' region by the dideoxy chain-termination method (see Fig. 1). At least 30% of the sequence analysis was performed on both strands. The sequenced region is comprehensive of 3077 bp 5' to first transcription initiation site, and 97 bp of the transcription unit. As it does not contain any valid open reading frame, control elements encountered in this region may be relevant to FXII gene regulation. By SI mapping and primer extension experiments [3] five sites of transcription initiation were identified at positions +1, +14, +22, +27, +33, where transcrip- tion initiation ranges from 49 to 17 bp prior to AUG. This indicates that FXII mRNA has a very short non translated 5' flanking region.