title: Murine Pif1 interacts with telomerase and is dispensable for telomere function in vivo.
abstract: Pif1 is a 5'-to-3' DNA helicase critical to DNA replication and telomere length maintenance in the budding yeast Saccharomyces cerevisiae. ScPif1 is a negative regulator of telomeric repeat synthesis by telomerase, and recombinant ScPif1 promotes the dissociation of the telomerase RNA template from telomeric DNA in vitro. In order to dissect the role of mPif1 in mammals, we cloned and disrupted the mPif1 gene. In wild-type animals, mPif1 expression was detected only in embryonic and hematopoietic lineages. mPif1(-/-) mice were viable at expected frequencies, displayed no visible abnormalities, and showed no reproducible alteration in telomere length in two different null backgrounds, even after several generations. Spectral karyotyping of mPif1(-/-) fibroblasts and splenocytes revealed no significant change in chromosomal rearrangements. Furthermore, induction of apoptosis or DNA damage revealed no differences in cell viability compared to what was found for wild-type fibroblasts and splenocytes. Despite a novel association of mPif1 with telomerase, mPif1 did not affect the elongation activity of telomerase in vitro. Thus, in contrast to what occurs with ScPif1, murine telomere homeostasis or genetic stability does not depend on mPif1, perhaps due to fundamental differences in the regulation of telomerase and/or telomere length between mice and yeast or due to genetic redundancy with other DNA helicases.
authors.affiliation: Ontario Cancer Institute, Campbell Family Institute for Breast Cancer Research, 620 University Avenue, Room 706, Toronto M5G 2C1, Canada.
authors.forename: Bryan E
authors.initials: BE
authors.lastname: Snow
authors.forename: Maria
authors.initials: M
authors.lastname: Mateyak
authors.forename: Jana
authors.initials: J
authors.lastname: Paderova
authors.forename: Andrew
authors.initials: A
authors.lastname: Wakeham
authors.forename: Caterina
authors.initials: C
authors.lastname: Iorio
authors.forename: Virginia
authors.initials: V
authors.lastname: Zakian
authors.forename: Jeremy
authors.initials: J
authors.lastname: Squire
authors.forename: Lea
authors.initials: L
authors.lastname: Harrington
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002470:Cell Survival; D043171:Chromosomal Instability; D033481:Chromosomes, Mammalian / Q000378:metabolism; D003001:Cloning, Molecular; D004265:DNA Helicases / Q000737:chemistry / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D053595:Embryonic Stem Cells / Q000166:cytology / Q000378:metabolism; D020869:Gene Expression Profiling; D015971:Gene Expression Regulation, Enzymologic; D018390:Gene Targeting; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae; D016415:Sequence Alignment; D013154:Spleen / Q000166:cytology; D019098:Telomerase / Q000378:metabolism*; D016615:Telomere / Q000235:genetics / Q000378:metabolism*; D013950:Thymus Gland / Q000166:cytology
chemical_list: D012333:RNA, Messenger; D019098:Telomerase; D004265:DNA Helicases; C517519:Pif1 protein, mouse