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J.H. Joo, Y.J. Lee, M.R. Jackson, P. Oh, S.P. Sugrue; Potential Role of Pinin in Regulation of Wnt Signaling and Neural Crest Cell Migration during Mouse Development . Invest. Ophthalmol. Vis. Sci. 2006;47(13):3012.
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© ARVO (1962-2015); The Authors (2016-present)
Many studies have demonstrated that Pinin (Pnn), a nuclear and cell adhesion–related protein, functions as a critical mediator of various multiprotein complexes involved in regulation of gene expression, pre–mRNA splicing, and cell adhesion. To study Pnn’s role in mouse development, we generated conditional Pnn knockout mice.
Three loxP sites (3f) flanking exon 3 to exon 8 and a neomycin resistance cassette were inserted by homologous recombination into the Pnn gene. ß–Actin–Cre and EIIa–Cre mice were utilized to generate constitutive Pnn–null (1f) and conditional Pnn–KO (2f) alleles, respectively. Tissue–specific ablation of Pnn was accomplished by breeding with Wnt1–Cre mice.
Constitutive Pnn–deficient mice (1f/1f) exhibited peri–implantation lethality. Interestingly, insertion of the neo cassette between exons 8 and 9 of Pnn resulted in reduced Pnn protein expression, mainly due to incorrect splicing. Those hypomorphic 3f/3f mice died around birth and exhibited disorganized epidermis, subepidermal blisters, cleft palate, axial skeletal defects, cardiac outflow tract defects, and anterior eye segment dysgenesis. Since some of these phenotypes seemed to be related to defective neural crest cells (NCC) and it has been well known that Wnt signaling is critical for the proliferation and migration of NCCs, we first examined Wnt activity in ES cells. Indeed, homozygous 3f/3f ES cells displayed highly up–regulated activity of Wnt downstream transcription factor (TCF). Furthermore, altered TCF activity was observed in 3f/3f mice. Finally, tissue–specific ablation of Pnn by Wnt1–Cre mice revealed severe cardiac and craniofacial defects similar to those of DiGeorge Syndrome. The eyes of Wnt1–Cre Pnn1f/2f animals exhibited anterior segment dysgenesis (Peter’s anomaly).
These data implicate Pnn’s essential role in proliferation and/or migration of NCCs. The results also suggest that Pnn may be involved in regulation of Wnt signaling. (Supported by NIH grant EY07883)
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