Deregulations　of　erythroid　differentiation　may　lead　to　erythroleukemia　and　other　hemoglobinopathies,　yet　the　molecular　mechanisms　underlying　these　events　are　not　fully　understood.　Here,　we　found　that　KAP-1-associated　complexes　contribute　to　the　regulation　of　the　beta-globin　locus,　the　key　events　of　erythroid　differentiation.　We　show　that　RNAi-mediated　knockdown　of　KAP-1　in　mouse　erythroleukemia　(MEL)　cells　increases　expression　of　the　Ey　and　beta-major　globin　genes　during　hexamethylenebisacetamide　(HMBA)　induced　differentiation　process.　This　indicates　that　at　least　part　of　KAP-1-associated　complexes　negatively　regulates　beta-globin　gene　expression　during　definitive　erythroid　differentiation.　ChIP-PCR　analysis　revealed　that　one　or　more　KAP-1-associated　complexes　are　targeted　to　the　promoter　region　of　the　Ey　and　beta-major　globin　genes.　Since　KAP-1　is　only　a　scaffold　molecule,　there　must　be　some　transcriptional　regulators　allowing　its　targeted　recruitment　to　the　beta-globin　locus.　To　further　discover　these　novel　regulators,　proteins　interacting　with　KAP-1　were　isolated　by　endogenous　immunoprecipitation　and　identified　by　LC-ESI-MS/MS.　Among　the　proteins　identified,　MafK　and　Zfp445　were　studied　further.　We　found　that　KAP-1　may　contribute　to　the　repression　of　Ey　and　beta-major　globin　gene　transcription　through　recruitment　to　the　promoters　of　these　two　genes,　mediated　by　the　interaction　of　KAP-1　with　either　Zfp445　or　MafK,　respectively.　(C)　2012　Elsevier　B.V.　All　rights　reserved.