TAIL1: an isthmin-like gene, containing type 1 thrombospondin-repeat and AMOP domain, mapped to ARVD1 critical region Valeria Rossi a, * , Giorgia Beffagna a , Alessandra Rampazzo a , Barbara Bauce b , Gian Antonio Danieli a a Department of Biology, University of Padua, via U. Bassi 58/B, I-35131 Padua, Italy b Department of Cardiology, University of Padua, I-35131 Padua, Italy Received 7 October 2003; received in revised form 4 February 2004; accepted 9 March 2004 Available online 6 May 2004 Received by M. D’Urso Abstract Isthmins represent a novel family of vertebrate secreted proteins containing one copy of the thrombospondin type 1 repeat (TSR), which in mammals is shared by several proteins with diverse biological functions, including cell adhesion, angiogenesis, and patterning of developing nervous system. We have determined the genomic organization of human TAIL1 (thrombospondin and AMOP containing isthmin-like 1), a novel isthmin-like gene encoding a protein that contains a TSR and a C-terminal AMOP domain (adhesion-associated domain in MUC4 and other proteins), characteristic of extracellular proteins involved in adhesion processes. TAIL1 gene encompasses more than 24.4 kb. Analysis of the DNA sequence surrounding the putative transcriptional start region revealed a TATA-less promoter located in a CpG island. Several consensus binding sites for the transcription factors Sp1 and MZF-1 were identified in this promoter region. In humans, TAIL1 gene is located on chromosome 14q24.3 within ARVD1 (arrhythmogenic right ventricular dysplasia/ cardiomyopathy, type 1) critical region; preliminary evidence suggests that it is expressed in several tissues, showing multiple alternative splicing. D 2004 Elsevier B.V. All rights reserved. Keywords: TSR; TATA-less; CpG island; Glycoprotein; Heart 1. Introduction Isthmin is a novel secreted protein which has recently been demonstrated to be involved in the organization of the Xenopus midbrain – hindbrain (Pera et al., 2002). Orthologous Isthmin genes have been found also in other vertebrates, including human and mouse; they encode secreted proteins containing one copy of the thrombospon- din type 1 repeat (TSR), originally described by Lawler and Hynes (1986). Proteins of the Isthmin family share a conserved C-terminal region, while their N-terminal exten- sion is more variable. Thrombospondins are a family of multimeric extracellu- lar glycoproteins playing a multiplicity of functions includ- ing cell attachment, motility, proliferation, contact and aggregation, extracellular protease activities, and regulation of angiogenesis and vascular homeostasis (see Adams, 2001 for a review). TSR repeat has been found to play a pivotal role in neuronal development, possibly by regulat- ing cell and growth cone migration (Adams and Tucker, 2000). In addition, it is involved in biological activities as diverse as complement pathway (Patthy, 1988), regulation of apoptosis of endothelial cells (Guo et al., 1997), and invasion process by Plasmodium falciparum (Wengelnik et al., 1999). In fact, TSR is an ancient protein module, which arose before the evolutionary separation of nematodes and 0378-1119/$ - see front matter D 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.gene.2004.03.008 Abbreviations: AMOP domain, adhesion-associated domain in MUC4 and other proteins; ARVD1, arrhythmogenic right ventricular dysplasia/ cardiomyopathy, type 1; bp, base pair; cDNA, DNA complementary to RNA; EST, expressed sequence tag; kb, kilobase; kDa, kilodalton(s); MED- 1, multiple start site element downstream; PCR, polymerase chain reaction; RACE, rapid amplification of cDNA ends; RT – PCR, reverse transcription – polymerase chain reaction; Tail1 (and TAIL1), thrombospondin and AMOP containing isthmin-like 1 protein (and gene); UTR, untranslated region. * Corresponding author. Tel.: +39-049-8276272; fax: +39-049- 8276260. E-mail address: vrossi@mail.bio.unipd.it (V. Rossi). www.elsevier.com/locate/gene Gene 335 (2004) 101 – 108