Molecular Characteristics and Functions of PKHD1 / 生物化学与生物物理进展

ABSTRACT

PKHD1 ( polycystic kidney and hepatic disease 1), the causal gene of human autosomal recessive polycystic kidney disease(ARPKD), is located on chromosome 6p12.2 and covers a genomic region of ～500 kb. PKHD1 is among the largest human genes, with a minimum of 86 exons from which multiple transcripts may be generated by alternative splicing. The longest continuous open reading frame consists of 12 222 bp, encoding a 4 074 amino acid protein, designated as fibrocystin/polyductin (FPC). FPC is predicted to be a receptor like protein, with single transmembrane domain and a short cytoplasmic tail. The expression of mouse FPC can be detected in various duct-containing organs. In mouse embryogenesis, FPC appears in developing neural tube, bronchi, and the primordial gut as early as the day of E9.5. In fetal human kidneys, high level of FPC expression is present in ureteric bud and its expression continues throughout the process of renal tubuobranching. In adult human kidneys, FPC mainly expresses in the epithelia of renal collecting ducts. FPC is subcellularly localized to the primary cilia and concentrated on the basal bodies in renal epithelial cells. The detail function of FPC is still unrevealed, most recent studies demonstrate that FPC, as a receptor, may transduce cell signal by interacting with a trp superfamily TRPP2 (PKD2), which is a causal gene for ADPKD, and mediate intracellular calcium homeostasis to regulate differentiation, proliferation, migration and polarity of various duct/tubular epithelia, in turn, to modulate the formation of all physiologic ducts, tubules and tracts.