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Hum Pathol. 2014 May;45(5):1057-64. doi: 10.1016/j.humpath.2014.01.002. Epub 2014 Jan 23.

The use of Yes-associated protein expression in the diagnosis of persistent neonatal cholestatic liver disease.

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  • 1Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD 21287.
  • 2Department of Molecular Biology and Genetics, Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21287.
  • 3Department of Pediatrics, Division of Pediatric Gastroenterology and Nutrition, Johns Hopkins University School of Medicine, Baltimore, MD 21287.
  • 4Department of Pathology, Johns Hopkins University School of Medicine, Baltimore, MD 21287. Electronic address:


Although physiologic jaundice of neonates is common, persistent neonatal cholestasis is life-threatening and has multiple etiologies. Among these etiologies, biliary atresia (BA) requires rapid diagnosis and treatment. In diagnosing BA, the surgical pathologist must recognize subtle histologic changes, often with only a small core liver biopsy. To aid in the differential diagnosis of neonatal cholestasis, we investigated Yes-associated protein (YAP), a regulator of organ size and bile duct development. We examined whether a YAP immunostain can highlight emerging hepatobiliary epithelium in BA (n = 28) versus other causes of persistent cholestasis (non-BA; n = 15) and thus serve as a useful diagnostic marker in persistent neonatal jaundice. We show significantly (P < .01) more high-grade (<2) fibrosis and ductular proliferation among BA versus non-BA cases. Likewise, there was significantly more high-grade (2-3/3) cytoplasmic and nuclear YAP staining in BA (97% and 89%) versus non-BA (20% and 13%). High-grade nuclear YAP staining was both sensitive (88%) and specific (87%) for the diagnosis of BA. In contrast to neonatal cholestasis, the differences in YAP localization in cholestatic/obstructed versus nonobstructed adult livers were not significant. Lastly, we found that pharmacologic inhibition of the YAP complex in both cholangiocyte and cholangiocarcinoma cell lines blocked compensatory bile duct proliferation, an early marker of BA that requires nuclear YAP expression, in a time- and dose-dependent manner. In summary, we show that YAP expression modulates both bile duct proliferation and liver damage/fibrosis while acting as a sensitive and specific marker in the differential diagnosis of persistent neonatal cholestasis.

Copyright © 2014 Elsevier Inc. All rights reserved.


Bile duct obstruction; Bile ductular reaction; Biliary atresia; Hippo pathway; Neonatal cholestasis; Neurofibromatosis 2 (NF2); Verteporfin (VP); Yes-associated protein (YAP)

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