ABSTRACT: We have identified an ENU-induced recessive mouse mutation (Vcc) with a pleiotropic phenotype overlapping including cardiac, tracheo-esophageal, anorectal, axial skeletal antero-posterior patterning defects, limb malformations, presacral mass, renal and palatal agenesis, and pulmonary hypoplasia. It results from a C470R mutation in the proprotein convertase PCSK5 (PC5/6, SPC6) that fails to complement a null allele, which also has a similar phenotype. The mutation ablates a predicted disulfide bond in the P domain, and results in reduced secretion, abnormal cellular localisation, and loss of proprotein convertase activity. We analysed whole genome gene expression in a mouse line carrying ENU-generated point mutation in Pcsk5 gene on a mixed background : 25% C57BL6/J on C3H/HeH (mutation originally introduced into C57BL6/J). We show that GDF11, a regulator of Hox expression, anteroposterior patterning and nephrogenesis, is a PCSK5 target, and that Pcsk5 mutation results in abnormal expression of several paralogous caudal Hox genes (Hoxa, Hoxc, Hoxd), and Mnx1 (Hlxb9) that are necessary for caudal embryo development. Our data establishes novel and pleiotropic functions for Pcsk5 in mammalian development and the coordinated expression of caudal Hox genes; and identifies GDF11 as a novel cleavage target for PCSK5. We propose that Pcsk5, at least in part via GDF11, coordinately regulates the expression of caudal Hox paralogs, to control antero-posterior patterning, nephrogenesis, and skeletal and anorectal development.
