Article
Pitx2 deletion in pituitary gonadotropes is compatible with gonadal development, puberty, and fertility.
Department of Human Genetics, University of Michigan, Ann Arbor, Michigan 48109-0618, USA.
genesis (impact factor:
2.53).
10/2008;
46(10):507-14.
DOI:10.1002/dvg.20398
Source: PubMed
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Article: Minireview: genetic models for the study of gonadotropin actions.
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ABSTRACT: Fertility in both sexes relies on complex physiological and molecular processes with many levels of regulation, and our ability to alter the mammalian genome using transgenic technology has greatly enhanced our understanding of these processes. There are numerous commonalities in human and mouse physiology, and the list of mouse models recapitulating recognized and idiopathic human reproductive defects is growing at an ever-increasing rate. In this review, we focus on genetic models of gonadotropin actions, summarizing features of transgenic mice that phenocopy defects in gonadotropin production and gonadotropin receptor responses seen in patients. In addition, we provide examples of mouse models with genetic alterations influencing pituitary FSH and LH production and their effects. These include: 1) transgenic mice with aberrations in steroid hormone, inhibin, and activin feedback pathways; 2) knockouts that demonstrate specific in vivo functions of pituitary transcription factors; and 3) models with alterations in other pituitary hormones, IGF-1, and leptin signaling pathways, which affect both the central and peripheral endocrine axis. What we have to learn from these and other models will continue to revise our conceptions of physiology, identify new targets for contraception, and improve our tools for understanding, diagnosing, and treating cases of human endocrinopathies and pathologies of the reproductive tissues.Endocrinology 09/2002; 143(8):2823-35. · 4.46 Impact Factor -
Article: Hindlimb patterning and mandible development require the Ptx1 gene.
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ABSTRACT: The restricted expression of the Ptx1 (Pitx1) gene in the posterior half of the lateral plate mesoderm has suggested that it may play a role in specification of posterior structures, in particular, specification of hindlimb identity. Ptx1 is also expressed in the most anterior ectoderm, the stomodeum, and in the first branchial arch. Ptx1 expression overlaps with that of Ptx2 in stomodeum and in posterior left lateral plate mesoderm. We now show that targeted inactivation of the mouse Ptx1 gene severely impairs hindlimb development: the ilium and knee cartilage are absent and the long bones are underdeveloped. Greater reduction of the right femur size in Ptx1 null mice suggests partial compensation by Ptx2 on the left side. The similarly sized tibia and fibula of mutant hindlimbs may be taken to resemble forelimb bones: however, the mutant limb buds appear to have retained their molecular identity as assessed by forelimb expression of Tbx5 and by hindlimb expression of Tbx4, even though Tbx4 expression is decreased in Ptx1 null mice. The hindlimb defects appear to be, at least partly, due to abnormal chondrogenesis. Since the most affected structures derive from the dorsal side of hindlimb buds, the data suggest that Ptx1 is responsible for patterning of these dorsal structures and that as such it may control development of hindlimb-specific features. Ptx1 inactivation also leads to loss of bones derived from the proximal part of the mandibular mesenchyme. The dual role of Ptx1 revealed by the gene knockout may reflect features of the mammalian jaw and hindlimbs that were acquired at a similar time during tetrapod evolution.Development 06/1999; 126(9):1805-10. · 6.60 Impact Factor -
Article: Function of Rieger syndrome gene in left-right asymmetry and craniofacial development.
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ABSTRACT: Rieger syndrome, an autosomal dominant disorder, includes ocular, craniofacial and umbilical abnormalities. The pitx2 homeobox gene, which is mutated in Rieger syndrome, has been proposed to be the effector molecule interpreting left-right axial information from the early embryonic trunk to each organ. Here we have used gene targeting in mice to generate a loss-of-function allele that would be predicted to result in organ randomization or isomerization. Although pitx2-/- embryos had abnormal cardiac morphogenesis, mutant hearts looped in the normal direction. Pitx2-/- embryos had correctly oriented, but arrested, embryonic rotation and right pulmonary isomerism. They also had defective development of the mandibular and maxillary facial prominences, regression of the stomodeum and arrested tooth development. Fgf8 expression was absent, and Bmp4 expression was expanded in the branchial-arch ectoderm. These data reveal a critical role for pitx2 in left-right asymmetry but indicate that pitx2 may function at an intermediate step in cardiac morphogenesis and embryonic rotation.Nature 10/1999; 401(6750):276-8. · 36.28 Impact Factor
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Keywords
ablating floxed genes
gonadotrope-specific cre transgenic mouse capable
gonadotrope-specific Pitx2 knockout mice exhibit normal expression
Initial analysis
LHbeta
LHbeta-producing cell
mature pituitary gonadotropes
organs exhibit
produce luteinizing hormone beta
remaining hormone-producing cell types
reporter gene
sexual maturation
Tg(Lhb-cre)1Sac
Tg(Lhb-cre)1Sac strain
