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

Increased severity of limb phenotypes in Tbx3  mutants (Tbx3Δfl/Δfl) compared to Tbx3;PrxCre is independent of Tbx3 in the AER.(A–D) Skeleton preparations comparing control (A: Tbx3Δfl/+, C:Tbx3fl/fl), Tbx3Δfl/Δfl(B, ), Tbx3fl/fl and Tbx3fl/fl;PrxCre (D, conditional mutant) forelimbs. Note single digit, absent ulna, and shortened humerus in Tbx3Δfl/Δflmutant (B) compared to preaxial polysyndactyly and absent digit 5 in Tbx3;PrxCre mutants (D). s, scapula; h, humerus; r, radius; u, ulna; digits are numbered; red arrowhead highlights loss of digit 5. (E, F) X-gal stained E10.0 (E) and E11.5 (F) RosaLacZ/+;Fgf8mcm/+embryos after the administration of tamoxifen at E8.5; black arrow indicates staining indicative of previous Cre activity in the AER. (G–J) mRNA in situ for Tbx3 expression shows the absence of signal in the AER of Tbx3fl/fl;Fgf8mcm/mcmE9.5 and E10.5 mutants (H, J, respectively) compared to controls (G, I). White arrows point to AER in G–J; note persistent mesenchymal Tbx3 expression as expected. (K–N) Skeleton preparations comparing E15.5 control (K,M), and Tbx3 fl/fl;Fgf8mcm/mcm (L) and Tbx3fl/fl;RarCre (N) mutants. Forelimbs of Tbx3 fl/fl;Fgf8mcm/mcm mutants are normal (L), while defects in Tbx3fl/fl;RarCre (N) phenocopy those of Tbx3;PrxCre mutants (compare panel N to D and also to Figure 1, panel H).DOI:http://dx.doi.org/10.7554/eLife.07897.005
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fig1s2: Increased severity of limb phenotypes in Tbx3 mutants (Tbx3Δfl/Δfl) compared to Tbx3;PrxCre is independent of Tbx3 in the AER.(A–D) Skeleton preparations comparing control (A: Tbx3Δfl/+, C:Tbx3fl/fl), Tbx3Δfl/Δfl(B, ), Tbx3fl/fl and Tbx3fl/fl;PrxCre (D, conditional mutant) forelimbs. Note single digit, absent ulna, and shortened humerus in Tbx3Δfl/Δflmutant (B) compared to preaxial polysyndactyly and absent digit 5 in Tbx3;PrxCre mutants (D). s, scapula; h, humerus; r, radius; u, ulna; digits are numbered; red arrowhead highlights loss of digit 5. (E, F) X-gal stained E10.0 (E) and E11.5 (F) RosaLacZ/+;Fgf8mcm/+embryos after the administration of tamoxifen at E8.5; black arrow indicates staining indicative of previous Cre activity in the AER. (G–J) mRNA in situ for Tbx3 expression shows the absence of signal in the AER of Tbx3fl/fl;Fgf8mcm/mcmE9.5 and E10.5 mutants (H, J, respectively) compared to controls (G, I). White arrows point to AER in G–J; note persistent mesenchymal Tbx3 expression as expected. (K–N) Skeleton preparations comparing E15.5 control (K,M), and Tbx3 fl/fl;Fgf8mcm/mcm (L) and Tbx3fl/fl;RarCre (N) mutants. Forelimbs of Tbx3 fl/fl;Fgf8mcm/mcm mutants are normal (L), while defects in Tbx3fl/fl;RarCre (N) phenocopy those of Tbx3;PrxCre mutants (compare panel N to D and also to Figure 1, panel H).DOI:http://dx.doi.org/10.7554/eLife.07897.005

Mentions: Germline Tbx3 mutants (genotype Tbx3Δfl/Δfl) have more severe forelimb defects than Tbx3;PrxCre conditional mutants: of the few Tbx3Δfl/Δfl mutants that survive to E13.5, 100% have agenesis of the ulna and digits 3–5 (Figure 1—figure supplement 2B). Their hindlimbs have a single digit and no fibula (Frank et al., 2013), phenocopying Shh and Hand2 mutants (Galli et al., 2010). Variable timing of Tbx3 loss of function by PrxCre may account for the disparate forelimb phenotypes of Tbx3Δfl/Δfland Tbx3;PrxCre mutants, however, our skeletal data and phenotypes of Tbx3Δfl/fl;PrxCre mutants indicate that such variability manifests as incomplete penetrance of the ulnar and digit 5 defects (Figure 1 H, H',J, and Colesanto et al., in preparation).


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)

Increased severity of limb phenotypes in Tbx3  mutants (Tbx3Δfl/Δfl) compared to Tbx3;PrxCre is independent of Tbx3 in the AER.(A–D) Skeleton preparations comparing control (A: Tbx3Δfl/+, C:Tbx3fl/fl), Tbx3Δfl/Δfl(B, ), Tbx3fl/fl and Tbx3fl/fl;PrxCre (D, conditional mutant) forelimbs. Note single digit, absent ulna, and shortened humerus in Tbx3Δfl/Δflmutant (B) compared to preaxial polysyndactyly and absent digit 5 in Tbx3;PrxCre mutants (D). s, scapula; h, humerus; r, radius; u, ulna; digits are numbered; red arrowhead highlights loss of digit 5. (E, F) X-gal stained E10.0 (E) and E11.5 (F) RosaLacZ/+;Fgf8mcm/+embryos after the administration of tamoxifen at E8.5; black arrow indicates staining indicative of previous Cre activity in the AER. (G–J) mRNA in situ for Tbx3 expression shows the absence of signal in the AER of Tbx3fl/fl;Fgf8mcm/mcmE9.5 and E10.5 mutants (H, J, respectively) compared to controls (G, I). White arrows point to AER in G–J; note persistent mesenchymal Tbx3 expression as expected. (K–N) Skeleton preparations comparing E15.5 control (K,M), and Tbx3 fl/fl;Fgf8mcm/mcm (L) and Tbx3fl/fl;RarCre (N) mutants. Forelimbs of Tbx3 fl/fl;Fgf8mcm/mcm mutants are normal (L), while defects in Tbx3fl/fl;RarCre (N) phenocopy those of Tbx3;PrxCre mutants (compare panel N to D and also to Figure 1, panel H).DOI:http://dx.doi.org/10.7554/eLife.07897.005
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fig1s2: Increased severity of limb phenotypes in Tbx3 mutants (Tbx3Δfl/Δfl) compared to Tbx3;PrxCre is independent of Tbx3 in the AER.(A–D) Skeleton preparations comparing control (A: Tbx3Δfl/+, C:Tbx3fl/fl), Tbx3Δfl/Δfl(B, ), Tbx3fl/fl and Tbx3fl/fl;PrxCre (D, conditional mutant) forelimbs. Note single digit, absent ulna, and shortened humerus in Tbx3Δfl/Δflmutant (B) compared to preaxial polysyndactyly and absent digit 5 in Tbx3;PrxCre mutants (D). s, scapula; h, humerus; r, radius; u, ulna; digits are numbered; red arrowhead highlights loss of digit 5. (E, F) X-gal stained E10.0 (E) and E11.5 (F) RosaLacZ/+;Fgf8mcm/+embryos after the administration of tamoxifen at E8.5; black arrow indicates staining indicative of previous Cre activity in the AER. (G–J) mRNA in situ for Tbx3 expression shows the absence of signal in the AER of Tbx3fl/fl;Fgf8mcm/mcmE9.5 and E10.5 mutants (H, J, respectively) compared to controls (G, I). White arrows point to AER in G–J; note persistent mesenchymal Tbx3 expression as expected. (K–N) Skeleton preparations comparing E15.5 control (K,M), and Tbx3 fl/fl;Fgf8mcm/mcm (L) and Tbx3fl/fl;RarCre (N) mutants. Forelimbs of Tbx3 fl/fl;Fgf8mcm/mcm mutants are normal (L), while defects in Tbx3fl/fl;RarCre (N) phenocopy those of Tbx3;PrxCre mutants (compare panel N to D and also to Figure 1, panel H).DOI:http://dx.doi.org/10.7554/eLife.07897.005
Mentions: Germline Tbx3 mutants (genotype Tbx3Δfl/Δfl) have more severe forelimb defects than Tbx3;PrxCre conditional mutants: of the few Tbx3Δfl/Δfl mutants that survive to E13.5, 100% have agenesis of the ulna and digits 3–5 (Figure 1—figure supplement 2B). Their hindlimbs have a single digit and no fibula (Frank et al., 2013), phenocopying Shh and Hand2 mutants (Galli et al., 2010). Variable timing of Tbx3 loss of function by PrxCre may account for the disparate forelimb phenotypes of Tbx3Δfl/Δfland Tbx3;PrxCre mutants, however, our skeletal data and phenotypes of Tbx3Δfl/fl;PrxCre mutants indicate that such variability manifests as incomplete penetrance of the ulnar and digit 5 defects (Figure 1 H, H',J, and Colesanto et al., in preparation).

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