The bicoid -related Pitx gene family in development

Gage, Philip J.; Suh, Hoonkyo

doi:10.1007/s003359900970

Cited by 147 publications

(119 citation statements)

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“…In tooth formation, as in all organs, developmental programs are usually initiated by more than one gene and cell type acting in concert to promote cell proliferation, migration, and/or differentiation. Tooth development is arrested in Pitx2 Ϫ/Ϫ mice (19,35,37). ␤-catenin is expressed at the same time as Lef-1 and Pitx2 in the developing tooth bud and epithelial tissues (17).…”

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PITX2 and β-Catenin Interactions Regulate Lef-1 Isoform Expression

Amen

Liu

Vadlamudi

et al. 2007

Molecular and Cellular Biology

104

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Lef-1 and PITX2 function in the Wnt signaling pathway by recruiting and interacting with ␤-catenin to activate target genes. Chromatin immunoprecipitation (ChIP) assays identified the Lef-1 promoter as a PITX2 downstream target. Transgenic mice expressing LacZ driven by the 2.5-kb LEF-1 promoter demonstrated expression in the tooth epithelium correlated with endogenous Lef-1 FL epithelial expression. PITX2 isoforms regulate the LEF-1 promoter, and ␤-catenin synergistically enhanced activation of the LEF-1 promoter in combination with PITX2 and Lef-1 isoforms. PITX2 enhances endogenous expression of the full-length ␤-catenin-dependent Lef-1 isoform (Lef-1 FL) while decreasing expression of the N-terminally truncated ␤-catenin-independent isoform. Our research revealed a novel interaction between PITX2, Lef-1, and ␤-catenin in which the Lef-1 ␤-catenin binding domain is dispensable for its interaction with PITX2. PITX2 interacts with two sites within the Lef-1 protein. Furthermore, ␤-catenin interacts with the PITX2 homeodomain and Lef-1 interacts with the PITX2 C-terminal tail. Lef-1 and ␤-catenin interact simultaneously and independently with PITX2 through two different sites to regulate PITX2 transcriptional activity. These data support a role for PITX2 in cell proliferation, migration, and cell division through differential Lef-1 isoform expression and interactions with Lef-1 and ␤-catenin.Pitx2 and Lef-1 encode two transcription factors whose expression can be regulated by early signaling events involved in numerous developmental programs. Pitx2 and Lef-1 are differentially expressed in many tissues, and they demonstrate overlapping expression during tooth development. Lef-1 can be activated by BMP, Wnt, Smads, and transforming growth factor ␤ signaling (18,32,33). Furthermore, Lef-1 transcriptional activity is regulated by its interaction with ␤-catenin. Secreted

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confidence: 99%

PITX2 and β-Catenin Interactions Regulate Lef-1 Isoform Expression

Amen

Liu

Vadlamudi

et al. 2007

Molecular and Cellular Biology

104

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“…Pitx3 gene expression is restricted to the developing eye and DA progenitor cells from embryonic day 11 throughout adult life in mice (13,14). In the brain, Pitx3 mRNA localizes specifically to the SN and VTA (14).…”

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Pitx3 is required for development of substantia nigra dopaminergic neurons

Nunes

Tovmasian

Silva

et al. 2003

Proc. Natl. Acad. Sci. U.S.A.

347

270

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Dopaminergic (DA) neurons of substantia nigra in the midbrain control voluntary movement, and their degeneration is the cause of Parkinson's disease. The complete set of genes required to specifically determine the development of midbrain DA subgroups is not known yet. We report here that mice lacking the bicoidrelated homeoprotein Pitx3 fail to develop DA neurons of the substantia nigra. Other mesencephalic DA neurons of the ventral tegmental area and retrorubral field are unaltered in their dopamine expression and histological organization. These data suggest that Pitx3-dependent gene expression is specifically required for the differentiation of DA progenitors within the mesencephalic DA system. M idbrain dopaminergic (DA) cells contribute to the control of voluntary movement, cognition, and emotional behavior. Degeneration of these cells results in Parkinson's disease, and aberrant dopamine neurotransmitter signaling is implicated in schizophrenia and addictive behavioral disorders (1-3). Within the midbrain there are three subgroups of DA neurons, the ventral tegmental area (VTA͞A10), substantia nigra (SN͞ A9), and retrorubral field (RRF͞A8), that together constitute the mesencephalic (mes) system (4). Those DA cells in the SN that innervate the striatum preferentially degenerate in Parkinson's disease, whereas other DA subgroups regulate emotional and reward behaviors.Transcription factors regulate the differentiation of midbrain DA neuron precursors. Two transcription factors have been shown to contribute to different aspects of mesDA neuronal differentiation. One of these, the orphan nuclear hormone receptor Nurr1, is required for maturation of mesDA neuron precursors. Mice harboring null alleles of Nurr1 do not express tyrosine hydroxylase (TH), which catalyzes the initial step of dopamine neurotransmitter biosynthesis (5-11). The other factor, LIM homeodomain transcription factor Lmx1b, contributes partially to the specification of mesDA neuronal progenitors beginning on embryonic day 12.5 in the mouse but is not essential for TH gene expression (12).A third transcription factor, the bicoid-related homeodomain-containing transcription factor Pitx3, which is also known as Ptx3, has been implicated in the development of DA neurons. Pitx3 gene expression is restricted to the developing eye and DA progenitor cells from embryonic day 11 throughout adult life in mice (13,14). In the brain, Pitx3 mRNA localizes specifically to the SN and VTA (14). A reduction in Pitx3 mRNA levels is observed in the ventral midbrain of Lmx1b knockout mice, 6-hydroxydopamine-lesioned rats, and Parkinson's patients (8,11,12,14). Yet, Pitx3 expression is maintained in the ventral midbrain of Nurr1 null mutant embryos (12). These data have been interpreted to suggest that Pitx3 contributes to the combinatorial code defined by multiple transcription factors that establish specification and differentiation of midbrain DA progenitors (12). Here we report that Pitx3 is essential for the development of neurons specific to the SN. The D...

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“…Other features associated with this syndrome include abnormal cardiac, limb, and pituitary development. PITX2 is a member of the bicoid/paired-like homeodomain family (3,4). There are three isoforms, PITX2a, b, c, that differ only in their amino-terminal regions.…”

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“…There are three isoforms, PITX2a, b, c, that differ only in their amino-terminal regions. The Pitx2 knock-out mouse is lethal at embryonic day 15 because of cardiac abnormalities and shows defects in cardiac positioning, atrial septation, and outflow tract development (4). Pitx2 is a proliferation target in the Wnt/Dvl pathway, which, when disrupted, leads to cardiac outflow tract abnormalities (5).…”

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Cell-specific Activation of the Atrial Natriuretic Factor Promoter by PITX2 and MEF2A

Toro¹,

Saadi²,

Kuburas

et al. 2004

Journal of Biological Chemistry

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The PITX2 homeodomain protein is mutated in patients with Axenfeld-Rieger syndrome and is involved in the development of multiple organ systems, including the heart. We have examined the interaction of PITX2 isoforms with myocyte-enhancing factor 2A (MEF2A), which is a known regulator of cardiac development. A direct interaction between PITX2a and MEF2A was demonstrated using yeast two-hybrid and GST pulldown assays. To study the functional significance of this interaction, we used the atrial natriuretic factor (ANF) promoter. Coexpression of MEF2A and PITX2a or Pitx2c resulted in a strong synergistic activation of the ANF promoter in LS8 oral epithelial cells but not in other cell lines (NIH/3T3, Chinese hamster ovary, or C2C12). The synergism was dependent on promoter context, because it required MEF2 binding sites and was not seen with two other PITX2 target promoters. DNA binding by MEF2A was required but not sufficient for synergism. Upstream activators of p38 MAP kinases, MKK3 and MKK6, increased PITX2a and Pitx2c activity to yield up to 90-fold activation of the ANF promoter in LS8 cells. Because Axenfeld-Rieger syndrome is autosomal dominant and affects development of the oral epithelium, we tested one of the known PITX2 mutants. The PITX2a-K88E mutant protein suppressed wild type PITX2a synergism with MEF2A. These results demonstrate a promoter-and cell-specific functional interaction between PITX2 and MEF2A and suggest the possibility of coordinate control by these factors in the oral epithelium.The PITX2 gene was cloned based on its linkage in AxenfeldRieger syndrome (ARS) 1 (1). ARS is an autosomal dominant human disorder characterized by ocular anterior chamber anomalies causing glaucoma in Ͼ50% of affected individuals as well as dental hypoplasia, mild craniofacial dysmorphism, and umbilical stump abnormalities (1-3). Other features associated with this syndrome include abnormal cardiac, limb, and pituitary development. PITX2 is a member of the bicoid/paired-like homeodomain family (3, 4). There are three isoforms, PITX2a, b, c, that differ only in their amino-terminal regions. The Pitx2 knock-out mouse is lethal at embryonic day 15 because of cardiac abnormalities and shows defects in cardiac positioning, atrial septation, and outflow tract development (4). Pitx2 is a proliferation target in the Wnt/Dvl pathway, which, when disrupted, leads to cardiac outflow tract abnormalities (5). Pitx2 has also been shown to be a downstream target in left-right asymmetry pathways and organogenesis (6 -9). It is expressed asymmetrically on the left side of the lateral plate mesoderm and derivative organs, including the heart and the gut.We have used the yeast two-hybrid assay to analyze candidate PITX2 interacting partners. With respect to the role of PITX2 in heart development, we were intrigued by the recent findings that PITX2 could activate the promoter of the atrial natriuretic factor (ANF) gene (10). ANF plays a key role in electrolyte and fluid homeostasis in the cardiovascular system by causing natriure...

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The bicoid -related Pitx gene family in development

Cited by 147 publications

References 41 publications

PITX2 and β-Catenin Interactions Regulate Lef-1 Isoform Expression

PITX2 and β-Catenin Interactions Regulate Lef-1 Isoform Expression

Pitx3 is required for development of substantia nigra dopaminergic neurons

Cell-specific Activation of the Atrial Natriuretic Factor Promoter by PITX2 and MEF2A

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