PVRL1 variants contribute to non-syndromic cleft lip and palate in multiple populations

Abstract

Poliovirus Receptor Like-1 (PVRL1) is a member of the immunoglobulin super family that acts in the initiation and maintenance of epithelial adherens junctions and is mutated in the cleft lip and palate/ectodermal dysplasia 1 syndrome (CLPED1, OMIM #225000). In addition, a common non-sense mutation in PVRL1 was discovered more often among non-syndromic sporadic clefting cases in Northern Venezuela in a previous case-control study. The present work sought to ascertain the role of PVRL1 in the sporadic forms of orofacial clefting in multiple populations. Multiple rare and common variants from all three splice isoforms were initially ascertained by sequencing 92 Iowan and 86 Filipino cases and CEPH controls. Using a family-based analysis to examine these variants, the common glycine allele of the G361V coding variant was significantly overtransmitted among all orofacial clefting phenotypes (P = 0.005). This represented G361V genotyping from over 800 Iowan, Danish, and Filipino families. Among four rare amino acid changes found within the V1 and C1 domains, S112T and T131A were found adjacent to critical amino acid positions within the V1 variable domain, regions previously shown to mediate cell-to-cell and cell-to-virus adhesion. The T131A variant was not found in over 1,300 non-affected control samples although the alanine is found in other species. The serine of the S112T variant position is conserved across all known PVRL1 sequences. Together these data suggest that both rare and common mutations within PVRL1 make a minor contribution to disrupting the initiation and regulation of cell-to-cell adhesion and downstream morphogenesis of the embryonic face.

FIG. 1

Multisequence alignment of representative PVRL1/Nectin1 V1 and C1 domains with human Nectin2. The putative beta strands of PVRL1 V1-domain are indicated by the overbars. The beta strands labeled as A through G make up the two beta sheets of the V1 immunoglobulin domain. Sites that are 100% conserved across all sequences are indicated by dashes (-), gaps by underscores (_). Bolded residues within the Nectin1 sequences are 100% conserved with the positions shown as dashes below, while those conserved between Nectin1 and Nectin2 are also dashed. The sites of the amino acid variants reported in this document are indicated in bold red in all conserved species. The red letters correspond to amino acid variants S112T and T131A in the V-domain and amino acid variants R199Q and R210H in the C1-domain, respectively. N1 represents Nectin1; N2 represents Nectin2. Hs=Homo sapiens, Le=Lemur catta, Ca=Cercopithecus aethiops (African green monkey), Mm=Mus Musculus, Rn=Rattus Norvegicus, Ma=Mesocricetus auratus, Ss Sus scrofa, Bt=Bos Taurus. Regions=I, II, and III, indicated by “●” are sites of mutations affecting viral binding or homotypic transbinding [Struyf et al., 2002]. ▼=Represents the position of the point mutation, F136L, discovered during subcloning of Nectin2 alpha fragments, which prevented the transinteraction and cell-to-cell aggregation [Miyahara et al., 2000]. [Color figure can be viewed in the online issue, which is available at www.interscience.wiley.com.]