Arrest of Cell Cycle Progression During First Interphase in Murine Zygotes Microinjected With Anti-PCM-1 Antibodies R. Balczon, 1 * C. Simerly, 2 D. Takahashi, 2 and G. Schatten 2 1 The Department of Cell Biology and Neuroscience, The University of South Alabama, Mobile 2 Pittsburgh Developmental Center of Magee-Women’s Research Institute and Departments of Obstetrics-Gynecology-Reproductive Sciences and Cell Biology and Physiology, University of Pittsburgh, Pittsburgh, Pennsylvania To investigate the function of the centrosome protein PCM-1, antibodies against PCM-1 were microinjected into either germinal vesicle stage meiotic oocytes or fertilized mouse eggs, and cell cycle progression events (i.e., microtubule assembly, chromosome and centrosome organization, meiotic maturation) were assayed. These studies determined that microinjected PCM-1 antibodies arrested cell cycle progres- sion, with anti-PCM-1 arresting fertilized eggs at the pronucleate stage when injected during G 1 . Analysis of the injected eggs determined that centrosome disruption and microtubule cytaster disorganization accompanied the cell cycle arrest. Anti-PCM-1 blocked neither pronuclear centration, completion of mitosis when microinjected into zygotes at G 2 , nor meiotic maturation when microinjected into immature oocytes. These results identify a novel role for PCM- 1 in cell cycle regulation, and indicate that PCM-1 must fulfill an essential function for cells to complete interphase. Cell Motil. Cytoskeleton 52:183–192, 2002. © 2002 Wiley-Liss, Inc. Key words: centrosome; pericentriolar material; cell cycle; PCM-1; microtubules; fertilization INTRODUCTION The centrosome, which is responsible for assembly and organization of microtubules, is comprised of a pair of centrioles and pericentriolar material (PCM) in most mammalian cells [Schatten, 1994; Balczon, 1996]. In addition to its well-defined microtubule nucleating role, tightly regulated centrosome activity also appears to be necessary for progression through the cell cycle. For example, the centrosome undergoes modifications, such as fluctuations in microtubule nucleation [Verde et al., 1990] and doubling during interphase [Balczon et al., 1995; Balczon, 1996], that are necessary for a cell divi- sion. In addition, centrosome activity also has been shown to be essential for the completion of interphase [Maniotis and Schliwa, 1991; Hinchcliffe et al., 2001], although the role that the centrosome plays in progres- sion into mitosis remains to be established. Centrosome behavior during meiosis, gametogene- sis, and fertilization is distinct from that observed during the somatic cell cycle [Schatten, 1994]. Studies have Abbreviations used: BrdU = bromodeoxyuridine; dbcAMP = dibu- tyryl cyclic AMP; GV = germinal vesicle; hCG = human chorionic gonadotropin; MTOC = microtubule-organizing center; PCM = peri- centriolar material; PBS = phosphate-buffered saline. Contract grant sponsor: American Heart Association; Contract grant sponsor: National Institutes of Health. *Correspondence to: Dr. Ron Balczon, MSB 1201, The University of South Alabama, Mobile, AL 36688. E-mail: balczonr@sungcg.usouthal.edu Received 12 October 2001; Accepted 8 March 2002 Published online in Wiley InterScience (www.interscience.wiley. com). DOI: 10.1002/cm.10043 Cell Motility and the Cytoskeleton 52:183–192 (2002) © 2002 Wiley-Liss, Inc.