title: Identification of G1-regulated genes in normally cycling human cells.
abstract: BACKGROUND
  Obtaining synchronous cell populations is essential for cell-cycle studies. Methods such as serum withdrawal or use of drugs which block cells at specific points in the cell cycle alter cellular events upon re-entry into the cell cycle. Regulatory events occurring in early G1 phase of a new cell cycle could have been overlooked.
  
  
  RESULTS
  We used a robotic mitotic shake-off apparatus to select cells in late mitosis for genome-wide gene expression studies. Two separate microarray experiments were conducted, one which involved isolation of RNA hourly for several hours from synchronous cell populations, and one experiment which examined gene activity every 15 minutes from late telophase of mitosis into G1 phase. To verify synchrony of the cell populations under study, we utilized methods including BrdU uptake, FACS, and microarray analyses of histone gene activity. We also examined stress response gene activity. Our analysis enabled identification of 200 early G1-regulated genes, many of which currently have unknown functions. We also confirmed the expression of a set of genes candidates (fos, atf3 and tceb) by qPCR to further validate the newly identified genes.
  
  
  CONCLUSIONS
  Genome-scale expression analyses of the first two hours of G1 in naturally cycling cells enabled the discovery of a unique set of G1-regulated genes, many of which currently have unknown functions, in cells progressing normally through the cell division cycle. This group of genes may contain future targets for drug development and treatment of human disease.
authors.affiliation: Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee, Florida, United States of America.
authors.forename: Maroun J
authors.initials: MJ
authors.lastname: Beyrouthy
authors.forename: Karen E
authors.initials: KE
authors.lastname: Alexander
authors.forename: Amy
authors.initials: A
authors.lastname: Baldwin
authors.forename: Michael L
authors.initials: ML
authors.lastname: Whitfield
authors.forename: Hank W
authors.initials: HW
authors.lastname: Bass
authors.forename: Dan
authors.initials: D
authors.lastname: McGee
authors.forename: Myra M
authors.initials: MM
authors.lastname: Hurt
mesh_terms: D000818:Animals; D001973:Bromodeoxyuridine / Q000378:metabolism; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D015536:Down-Regulation / Q000235:genetics; D005434:Flow Cytometry; D016193:G1 Phase / Q000235:genetics*; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation; D015894:Genome, Human / Q000235:genetics; D006367:HeLa Cells; D006657:Histones / Q000235:genetics; D006801:Humans; D008938:Mitosis / Q000235:genetics; D013314:Stress, Mechanical; D015854:Up-Regulation / Q000235:genetics
chemical_list: D006657:Histones; D001973:Bromodeoxyuridine