Expression pattern and cellular distribution of the murine homologue of AF10

We have cloned Af10, the murine homologue of the MLL partner gene AF10. The predicted open reading frame of Af10 contains 1069 aa which are 90% identi cal to those of AF10. Af10 contains an N-terminal cysteine-rich region with a LAP/PHD finger, a leucine zipper domain and a glutamine-rich region at t he C-terminus, features also found in the human proteins AF10 and AF17. A s ingle 5.5-kb transcript was detected in murine tissues with the highest lev el of expression in the testes. A polyclonal antibody raised to the cystein e-rich region of AF10 was able to identify a double band of 140 kDa on West ern analysis in mouse testicular extracts. After subcellular separation Af1 0 was identified in both the nuclear and cytoplasmic extracts, again as a d ouble band of 140 kDa in size. In situ hybridisation studies were performed with sense and antisense digoxigenin-labelled oligonucleotides. High level s of expression were noted in postmeiotic germ cells, especially in spermat ids from around stage VI to stage VIII. High levels of expression were also seen in the white matter of the cerebellum, extending into the granular la yer. The expression in differentiated rather than in proliferating cells su ggests that the role of Af10 may lie in the suppression of proliferation ra ther than in differentiation. Since the LAP/PHD finger domains are lost in the MLL-AF10 fusion, arguably such a function could be carried out by this domain. (C) 1998 Elsevier Science B.V. All rights reserved.