Segment-specific c-ErbB2 expression in human autosomal recessive polycystic kidney disease

c-ErbB2 (also referred to as Neu or HER2), a transmembrane glycoprotein wit h intrinsic tyrosine kinase activity, is structurally related to epidermal growth factor receptor (EGFR) and forms active heterodimers with EGFR as we ll as other members of the EGFR family. c-ErbB2 is reported to mediate diff erentiation and proliferation in epithelial cells and is expressed in a tis sue-specific and developmental stage-specific manner. Given the role of EGF R in cystic renal epithelial hyperplasia and the immature phenotype of cyst ic renal epithelial cells, the segment-specific expression pattern of c-Erb B2 in human autosomal recessive polycystic kidney disease (ARPKD) was exami ned in nine ARPKD kidney specimens ranging from gestational age 17 wk throu gh postnatal age 4 wk. c-ErbB2 staining of human ARPKD samples showed incre ased expression with increasing gestational age compared with normal human fetal and postnatal kidneys. This increased c-ErbB2 expression was primaril y localized to the apical surfaces of cystic collecting tubule cells, simil ar to the pattern of EGFR expression, and paralleled collecting tubular cys t formation and growth.