Characterization of the AP-1 μ1A and μ1B Adaptins in Zebrafish (Danio rerio)

Protein transport between the trans-Golgi network and endosomes is mediated by transport vesicles formed by the adaptor-protein complex AP-1, consisting of the adaptins gamma 1, beta 1, mu 1, sigma 1. Mammalia express mu 1A ubiquitously and isoform mu 1B in polarized epithelia. Mouse gamma 1 or mu 1A 'knock out's revealed that AP-1 is indispensable for embryonic development. We isolated mu 1A and mu 1B from Danio rerio. Analysis of mu 1A and mu 1B expression revealed tissue-specific expression for either one during embryogenesis and in adult tissues in contrast to their expression in mammalia. mu 1B transcript was detected in organs of endodermal derivation and knock-down experiments gave rise to embryos defective in formation of intestine, liver, and pronephric ducts. Development ceased at 7-8 dpf. mu 1B is not expressed in murine liver, indicating loss of mu 1B expression and establishment of alternative sorting mechanisms during mammalian development. Developmental Dynamic's 239:2404-2412, 2010. (c) 2010 Wiley-Liss, Inc.