title: Loss of Foxm1 Results in Reduced Somatotrope Cell Number during Mouse Embryogenesis.
abstract: FOXM1, a member of the forkhead box transcription factor family, plays a key role in cell cycling progression by regulating the expression of critical G1/S and G2/M phase transition genes. In vivo studies reveal that Foxm1 null mice have a 91% lethality rate at e18.5 due to significant cardiovascular and hepatic hypoplasia. Thus, FOXM1 has emerged as a key protein regulating mitotic division and cell proliferation necessary for embryogenesis. In the current study, we assess the requirement for Foxm1 in the developing pituitary gland. We find that Foxm1 is expressed in the pituitary at embryonic days 10.5-e18.5 and localizes with markers for active cell proliferation (BrdU). Interestingly, direct analysis of Foxm1 null mice at various embryonic ages, reveals no difference in gross pituitary morphology or cell proliferation. We do observe a downward trend in overall pituitary cell number and a small reduction in pituitary size in e18.5 embryos suggesting there may be subtle changes in pituitary proliferation not detected with our proliferation makers. Consistent with this, Foxm1 null mice have reductions in both the somatotrope and gonadotrope cell populations.
authors.affiliation: Department of Physiology, Southern Illinois University, Carbondale, Illinois, United States of America.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Calderon
authors.affiliation: Department of Physiology, Southern Illinois University, Carbondale, Illinois, United States of America.
authors.forename: Adam G
authors.initials: AG
authors.lastname: Ploegman
authors.affiliation: Department of Physiology, Southern Illinois University, Carbondale, Illinois, United States of America.
authors.forename: Brock
authors.initials: B
authors.lastname: Bailey
authors.affiliation: Department of Physiology, Southern Illinois University, Carbondale, Illinois, United States of America.
authors.forename: Deborah O
authors.initials: DO
authors.lastname: Jung
authors.affiliation: Department of Zoology and Physiology, University of Wyoming, Laramie, Wyoming, United States of America.
authors.forename: Amy M
authors.initials: AM
authors.lastname: Navratil
authors.affiliation: Department of Physiology, Southern Illinois University, Carbondale, Illinois, United States of America.
authors.forename: Buffy S
authors.initials: BS
authors.lastname: Ellsworth
mesh_terms: D000818:Animals; D002452:Cell Count; D049109:Cell Proliferation; D047108:Embryonic Development / Q000235:genetics*; D000072278:Forkhead Box Protein M1; D051858:Forkhead Transcription Factors / Q000172:deficiency*; D015870:Gene Expression; D006728:Hormones / Q000096:biosynthesis; D051379:Mice; D018345:Mice, Knockout; D010902:Pituitary Gland / Q000196:embryology / Q000378:metabolism / Q000473:pathology; D052683:Somatotrophs / Q000378:metabolism*
chemical_list: D000072278:Forkhead Box Protein M1; D051858:Forkhead Transcription Factors; C491524:Foxm1 protein, mouse; D006728:Hormones