Abstract

Involvement of Human MCM8 in Prereplication Complex Assembly by Recruiting hcdc6 to Chromatin Melanie Volkening 1 and Ingrid Hoffmann 1 , * 1 Cell Cycle Control and Carcinogenesis, DKFZ, German Cancer Research Center, Heidelberg, Germany ABSTRACT The MCM2-MCM7 complex is an essential component of the prereplication complex (pre-RC), which is recruited by the cdc6 and cdt1 proteins to origins of DNA replication during G 1 phase. Here, we report that the accumulation on chromatin of another member of the MCM protein family, human MCM8 (hMCM8), occurs during early G 1 phase, before the hMCM2-hMCM7 complex binds. hMCM8 interacts in vivo with two components of the pre-RC, namely, hcdc6 and hORC2. Depletion of endogenous hMCM8 protein by RNA interference leads to a delay of entry into S phase, suggesting a role for hMCM8 in G 1 progression. Furthermore, down-regulation of hMCM8 also leads to a reduced loading of hcdc6 and the hMCM2-hMCM7 complex on chromatin. These results suggest that hMCM8 is a crucial component of the pre-RC and that the interaction between hMCM8 and hcdc6 is required for pre-RC assembly.