Limits...
T-box3 is a ciliary protein and regulates stability of the Gli3 transcription factor to control digit number.

Emechebe U, Kumar P P, Rozenberg JM, Moore B, Firment A, Mirshahi T, Moon AM - Elife (2016)

Bottom Line: In contrast, loss of anterior T-box3 results in preaxial polydactyly, as seen with dysfunction of primary cilia or Gli3-repressor.T-box3 interacts with Kif7 and is required for normal stoichiometry and function of a Kif7/Sufu complex that regulates Gli3 stability and processing.Thus, T-box3 controls digit number upstream of Shh-dependent (posterior mesenchyme) and Shh-independent, cilium-based (anterior mesenchyme) Hedgehog pathway function.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurobiology and Anatomy, University of Utah, Salt Lake City, United States.

ABSTRACT
Crucial roles for T-box3 in development are evident by severe limb malformations and other birth defects caused by T-box3 mutations in humans. Mechanisms whereby T-box3 regulates limb development are poorly understood. We discovered requirements for T-box at multiple stages of mouse limb development and distinct molecular functions in different tissue compartments. Early loss of T-box3 disrupts limb initiation, causing limb defects that phenocopy Sonic Hedgehog (Shh) mutants. Later ablation of T-box3 in posterior limb mesenchyme causes digit loss. In contrast, loss of anterior T-box3 results in preaxial polydactyly, as seen with dysfunction of primary cilia or Gli3-repressor. Remarkably, T-box3 is present in primary cilia where it colocalizes with Gli3. T-box3 interacts with Kif7 and is required for normal stoichiometry and function of a Kif7/Sufu complex that regulates Gli3 stability and processing. Thus, T-box3 controls digit number upstream of Shh-dependent (posterior mesenchyme) and Shh-independent, cilium-based (anterior mesenchyme) Hedgehog pathway function.

No MeSH data available.


Related in: MedlinePlus

Fgf8 expression and downstream in Tbx3;PrxCre mutant forelimb buds.(A–F) In situ hybridization for the transcripts listed on panels at ages specified. (A, B) View of AER stained for Fgf8. (C–F) Dorsal view of left forelimb buds stained for Erm (Etv5) and Pea3 (Etv4) transcripts which are regulated by FGF signaling in the limb bud.DOI:http://dx.doi.org/10.7554/eLife.07897.015
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fig3s5: Fgf8 expression and downstream in Tbx3;PrxCre mutant forelimb buds.(A–F) In situ hybridization for the transcripts listed on panels at ages specified. (A, B) View of AER stained for Fgf8. (C–F) Dorsal view of left forelimb buds stained for Erm (Etv5) and Pea3 (Etv4) transcripts which are regulated by FGF signaling in the limb bud.DOI:http://dx.doi.org/10.7554/eLife.07897.015

Mentions: Proliferation of limb mesenchyme depends on activity of FGF8 and FGF4 from the AER (Boulet et al., 2004; Moon and Capecchi, 2000; Sun et al., 2002) and integrity of this structure requires Shh activity in posterior mesenchyme (Chiang et al., 2001). Despite decreased Shh expression in Tbx3;PrxCre mutants, Fgf4 transcripts were increased in posterior mesenchyme while decreased in anterior (detected by RNA-Seq, Supplementary files 3,4 and qPCR, Figure 3—figure supplement 4), the latter consistent with an expanded digit 1 region. qPCR detected increased Fgf8 expression in the posterior AER (Figure 3—figure supplement 4). Despite these changes in transcript levels, there was no evidence of altered downstream FGF signaling as expression of Etv4, Etv5, Dusp6 and Sprys was unchanged (Figure 3—figure supplement 5, note these transcripts are not listed in Supplementary files 3 or 4 because they did not meet criteria for differential expression). We conclude that despite the decrement in Shh pathway activity in posterior mesenchyme of Tbx3;PrxCre mutants, the level is sufficient to maintain ectodermal FGF signaling, consistent with preserved limb outgrowth.


T-box3 is a ciliary protein and regulates stability of the Gli3 transcription factor to control digit number.

Emechebe U, Kumar P P, Rozenberg JM, Moore B, Firment A, Mirshahi T, Moon AM - Elife (2016)

Fgf8 expression and downstream in Tbx3;PrxCre mutant forelimb buds.(A–F) In situ hybridization for the transcripts listed on panels at ages specified. (A, B) View of AER stained for Fgf8. (C–F) Dorsal view of left forelimb buds stained for Erm (Etv5) and Pea3 (Etv4) transcripts which are regulated by FGF signaling in the limb bud.DOI:http://dx.doi.org/10.7554/eLife.07897.015
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4829432&req=5

fig3s5: Fgf8 expression and downstream in Tbx3;PrxCre mutant forelimb buds.(A–F) In situ hybridization for the transcripts listed on panels at ages specified. (A, B) View of AER stained for Fgf8. (C–F) Dorsal view of left forelimb buds stained for Erm (Etv5) and Pea3 (Etv4) transcripts which are regulated by FGF signaling in the limb bud.DOI:http://dx.doi.org/10.7554/eLife.07897.015
Mentions: Proliferation of limb mesenchyme depends on activity of FGF8 and FGF4 from the AER (Boulet et al., 2004; Moon and Capecchi, 2000; Sun et al., 2002) and integrity of this structure requires Shh activity in posterior mesenchyme (Chiang et al., 2001). Despite decreased Shh expression in Tbx3;PrxCre mutants, Fgf4 transcripts were increased in posterior mesenchyme while decreased in anterior (detected by RNA-Seq, Supplementary files 3,4 and qPCR, Figure 3—figure supplement 4), the latter consistent with an expanded digit 1 region. qPCR detected increased Fgf8 expression in the posterior AER (Figure 3—figure supplement 4). Despite these changes in transcript levels, there was no evidence of altered downstream FGF signaling as expression of Etv4, Etv5, Dusp6 and Sprys was unchanged (Figure 3—figure supplement 5, note these transcripts are not listed in Supplementary files 3 or 4 because they did not meet criteria for differential expression). We conclude that despite the decrement in Shh pathway activity in posterior mesenchyme of Tbx3;PrxCre mutants, the level is sufficient to maintain ectodermal FGF signaling, consistent with preserved limb outgrowth.

Bottom Line: In contrast, loss of anterior T-box3 results in preaxial polydactyly, as seen with dysfunction of primary cilia or Gli3-repressor.T-box3 interacts with Kif7 and is required for normal stoichiometry and function of a Kif7/Sufu complex that regulates Gli3 stability and processing.Thus, T-box3 controls digit number upstream of Shh-dependent (posterior mesenchyme) and Shh-independent, cilium-based (anterior mesenchyme) Hedgehog pathway function.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurobiology and Anatomy, University of Utah, Salt Lake City, United States.

ABSTRACT
Crucial roles for T-box3 in development are evident by severe limb malformations and other birth defects caused by T-box3 mutations in humans. Mechanisms whereby T-box3 regulates limb development are poorly understood. We discovered requirements for T-box at multiple stages of mouse limb development and distinct molecular functions in different tissue compartments. Early loss of T-box3 disrupts limb initiation, causing limb defects that phenocopy Sonic Hedgehog (Shh) mutants. Later ablation of T-box3 in posterior limb mesenchyme causes digit loss. In contrast, loss of anterior T-box3 results in preaxial polydactyly, as seen with dysfunction of primary cilia or Gli3-repressor. Remarkably, T-box3 is present in primary cilia where it colocalizes with Gli3. T-box3 interacts with Kif7 and is required for normal stoichiometry and function of a Kif7/Sufu complex that regulates Gli3 stability and processing. Thus, T-box3 controls digit number upstream of Shh-dependent (posterior mesenchyme) and Shh-independent, cilium-based (anterior mesenchyme) Hedgehog pathway function.

No MeSH data available.


Related in: MedlinePlus