The Cloning and Analysis of LEK1 Identifies Variations in the LEK/Centromere Protein F/Mitosin Gene Family

Abstract

We report the cloning of a novel murine cDNA, LEK1, that is related to human CENP-F and mitosin and more distantly to chicken CMF1. The proteins from these three organisms have significant homology, yet differ in their temporal, spatial, and subcellular localizations. The human proteins bind the kinetochore in mitotic cells, whereas the chicken protein is found only in skeletal and cardiac muscle and is developmentally regulated. Mouse LEK1 is a single copy gene that codes for two developmentally regulated transcripts. The LEK1 protein is expressed early and ubiquitously in mouse development and is generally down-regulated as development proceeds in a manner that correlates to a cessation of mitosis. In adult tissues, the LEK1 protein is detected exclusively in the pronucleus of the oocyte and was not observed in other actively dividing tissues. Subcellular localization revealed that the LEK1 protein in mitotic cells does not bind the kinetochore. From these data, we hypothesize that chicken CMF1, human CENP-F, mitosin, and mouse LEK1 are members of an emerging family of genes that have important and functionally distinct roles in development and cell division.

Silencing CENPF in bovine preimplantation embryo induces arrest at 8-cell stage

“…Only four of its orthologs -murine CENPF (Goodwin et al 1999, Ashe et al 2003, Dees et al 2005, Soukolis et al 2005, Evans et al 2007, avian CMF1 (Wei et al 1996, Redkar et al 2002 and worm hcp1 and hcp2 (Cheeseman et al 2005, Hajeri et al 2008) have been studied slightly more intensively. However, these proteins are expressed throughout the whole cell cycle, do not strictly localize to the nucleus or have a somewhat different function (Wei et al 1996, Goodwin et al 1999, Redkar et al 2002, Cheeseman et al 2005, Dees et al 2005, Soukolis et al 2005, Evans et al 2007, Hajeri et al 2008. This suggests that bovine CENPF does not necessarily have to be expressed in a cell-cycle-dependent manner.…”

Mitosin/CENP-F is a conserved kinetochore protein subjected to cytoplasmic dynein-mediated poleward transport

“…LEK1 also implicated in muscle differentiation [9]. It is ubiquitously expressed in early mouse embryo.…”

“…Orthologs of mitosin, including avian CMF1 and murine LEK1, have recently been characterized [8][9][10][11]. These proteins share overall similarities ranging from 60% to 80% and are characteristic of multiple hydrophobic zippers.…”

CMF1–Rb interaction promotes myogenesis in avian skeletal myoblasts

“…Presence of this and other functional domains place CMF1 within the LEK family of proteins. Other family members include murine LEK1 and human CENP-F (Goodwin et al, 1999). CMF1 expression is restricted to developing striated muscle, while the other family members are ubiquitously expressed (Goodwin et al, 1999;Pabon-Pena et al, 2000).…”

“…Other family members include murine LEK1 and human CENP-F (Goodwin et al, 1999). CMF1 expression is restricted to developing striated muscle, while the other family members are ubiquitously expressed (Goodwin et al, 1999;Pabon-Pena et al, 2000). Human CENP-F was characterized first as a kinetochore binding protein with the ability to bind Rb in a yeast two-hybrid screen (Rattner et al, 1993;Zhu et al, 1995b).…”