Comparative integromics on FAT1, FAT2, FAT3 and FAT4

WNT5A, WNT5B, WNT11, FZD3, FZD6, VANGL1, VANGL2, DVL1, DVL2, DVL3, PRICKLE1, PRICKLE2, ANKRD6, NKD1, NKD2, DAAM1, DAAM2, CELSR1, CELSR2, CELSR3, ROR1 and ROR2 are planar cell polarity (PCP) signaling molecules implicated in the regulation of cellular polarity, convergent extension, and invasion. FAT1, FAT2, FAT3 and FAT4 are Cadherin superfamily members homologous to Drosophila Fat, functioning as a positive regulator of PCP in the Drosophila wing. Complete coding sequence (CDS) for human FAT1 (NM_005245.3) and FAT2 (NM_001447.1) are available, while artificial CDS for human FAT3 (XM_926199 and XM_936538) and partial CDS for FAT4 (NM_024582.2). Here, complete CDS of human FAT3 and FAT4 were determined by using bioinformatics and human intelligence (Humint). FAT3 gene, consisting of 26 exons, encoded a 4557-aa protein with extracellular 33 Cadherin repeats, one Laminin G (LamG) domain and two EGF domains. FAT4 gene encoded a 4924-aa protein with extracellular 34 Cadherin repeats, two LamG domains and three EGF domains. Cytoplasmic VCSVxPxLP and SDYxS motifs were identified as novel motifs conserved among FAT1, FAT2 and FAT3 orthologs. Domain architecture comparison and phylogenetic analysis revealed that FAT1, FAT2 and FAR3 were divergent from FAT4. FAT1-MTNR1A locus at 4q35.2 and FAT3-MTNR1B locus at 11q14.3-q21 were paralogous regions within the human genome. FAT1 mRNA was expressed in embryonic stem (ES) cells, neural tissues, gastric cancer, pancreatic cancer, colorectal cancer, breast cancer, lung cancer and brain tumors. FAT2 mRNA was expressed in infant brain, cerebellum, gastric cancer, pancreatic cancer, ovarian cancer, esophageal cancer, skin squamous cell carcinoma, head and neck cancer. FAT3 mRNA was expressed in ES cells, primitive neuroectoderm, fetal brain, infant brain, adult neural tissues and prostate. FAT4 mRNA was expressed in fetal brain, infant brain, brain tumor and colorectal cancer. FAT family members were revealed to be targets of systems medicine in the fields of oncology and neurology.