CLONING AND CHARACTERIZATION OF A 2ND AP-2 TRANSCRIPTION FACTOR - AP-2-BETA

AP-2 has been characterized previously as a unique 52x10(3) M(r) trans cription activator encoded by a single gene that is expressed in a res tricted pattern during embryonic morphogenesis of the peripheral nervo us system, face, skin and nephric tissues, Here we report the isolatio n of genomic and cDNA clones encoding for a second AP-2 related transc ription factor, designated AP-2 beta. AP-2 beta binds specifically to a series of well-characterized AP-2 binding sites, consensus to the se quence G/CCCN(3)GGC, and transactivates transcription from a reporter plasmid under the control of an AP-2-dependent promoter, A C-terminal domain known to mediate homodimerization of the previously cloned AP-2 alpha transcription activator is highly conserved and sufficient to m ediate interaction between the two proteins, Northern blot and in situ hybridizations revealed that the two genes are expressed in murine em bryos between days 9.5 and 19.5 p.c. Coexpression of both mRNAs was de tected in many tissues at day 13.5 and 15.5 of embryogenesis but some regions of the developing brain and face including the primordium of m idbrain and the facial mesenchyme differed in their expression pattern of AP-2 genes, AP-2 alpha and AP-2 beta signals in the central and pe ripheral nervous system overlapped with regions of developing sensory neurons. In adult tissues AP-2 alpha expression was found mainly in th e skin, eye and prostate and AP-2 beta expression in the kidney. In su mmary, our analyses of embryonic and adult mice demonstrate that two d ifferent AP-2 transcription factors are specifically expressed during differentiation of many neural, epidermal and urogenital tissues.