Analysis of Cyp26b1/Rarg compound-null mice reveals two genetically separable effects of retinoic acid on limb outgrowth

Pennimpede, Tracie; Cameron, Don; MacLean, Glenn; Petkovich, Martin

doi:10.1016/j.ydbio.2009.12.024

“…S1C). Quantitative RT-PCR (qPCR) demonstrated that Cyp26b1 is more highly expressed in the distal region of the developing limb bud at E11.5 and E12.5, as previously reported (Pennimpede et al, 2010b;Yashiro et al, 2004) (Fig. 2B) (Mendelsohn et al, 1991;Mollard et al, 2000).…”

Section: Cyp26b1supporting

confidence: 82%

Genetic deletion of Cyp26b1 negatively impacts limb skeletogenesis by inhibiting chondrogenesis

Dranse

¹

,

Sampaio

²

,

Petkovich

³

et al. 2011

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SummaryCyp26b1, a retinoic acid (RA)-metabolising enzyme, is expressed in the developing limb bud, and Cyp26b1 -/-mice present with severe limb defects. These malformations might be attributable to an RA-induced patterning defect; however, recent reports suggest that RA is dispensable for limb patterning. In this study, we examined the role of endogenous retinoid signalling in skeletogenesis using Cyp26b1 -/-mice and transgenic mice in which Cyp26b1 is conditionally deleted under control of the Prrx1 promoter beginning at E9.5 (Prrx1Cre + /Cyp26b1 fl/fl ). We found that the limb phenotype in Prrx1Cre + /Cyp26b1 fl/fl mice was less severe than that observed in Cyp26b1 -/-animals and that a change in retinoid signalling contributed to the difference in phenotypes. We systematically examined the role of endogenous RA signalling in chondrogenesis and found that Cyp26b1 -/-cells and limb mesenchymal cells treated with a CYP inhibitor, are maintained in a pre-chondrogenic state, exhibit reduced chondroblast differentiation and have modestly accelerated chondrocyte hypertrophy. Furthermore, Cyp26b1 -/-mesenchyme exhibited an increase in expression of genes in a closely related tendogenic lineage, indicating that retinoid signals in the limb interfere with differentiation and maintain progenitor status. Together, these findings support an important function for RA in regulating the behaviour of mesenchymal progenitors, and their subsequent differentiation and maturation.

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“…Cyp26b1 fl/fl mice were crossed with PcxNLSCre + transgenic mice to achieve deletion of Cyp26b1 in the germline and to generate Cyp26b1 -/-animals. These animals exhibited a spectrum of developmental malformations as previously described (Pennimpede et al, 2010b;Yashiro et al, 2004).…”

Section: Prrx1crementioning

confidence: 58%

“…However, new evidence suggests that RA is dispensable for early limb patterning, because Aldh1a2,Aldh1a3 double-knockout mice have normal hindlimb development and disruption of Rarg partially rescues the Cyp26b1 -/-limb phenotype despite altered expression of P-D genes (Pennimpede et al, 2010b;Zhao et al, 2009). In this work, we demonstrate that the severity of limb malformations in Cyp26b1 -/-mice is tightly correlated to levels of retinoid signalling, and that a lack of Cyp26b1 negatively impacts chondrogenesis and tendogenesis before the onset of Ihh and Mkx expression, respectively.…”

Section: The Limb Defects Observed In Cyp26b1mentioning

confidence: 99%

“…Throughout development, too much or too little RA has been associated with skeletal malformations characterised by loss or gain of skeletal elements (Underhill and Weston, 1998;Weston et al, 2003b). Accordingly, Cyp26b1-null mice exhibit pronounced skeletal abnormalities that are characterised by either underossification or loss of endochondral and intramembranousderived bones (Maclean et al, 2009;Pennimpede et al, 2010b). To understand the cellular and molecular basis underlying these defects, we explored the function of endogenous retinoid signalling in the limb chondrogenic programme using the Cyp26b1-knockout mouse as a model system.…”

Section: Introductionmentioning

confidence: 99%

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Genetic deletion ofCyp26b1negatively impacts limb skeletogenesis by inhibiting chondrogenesis

Dranse

¹

,

Sampaio

²

,

Petkovich

³

et al. 2011

Journal of Cell Science

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SummaryCyp26b1, a retinoic acid (RA)-metabolising enzyme, is expressed in the developing limb bud, and Cyp26b1 -/-mice present with severe limb defects. These malformations might be attributable to an RA-induced patterning defect; however, recent reports suggest that RA is dispensable for limb patterning. In this study, we examined the role of endogenous retinoid signalling in skeletogenesis using Cyp26b1 -/-mice and transgenic mice in which Cyp26b1 is conditionally deleted under control of the Prrx1 promoter beginning at E9.5 (Prrx1Cre + /Cyp26b1 fl/fl ). We found that the limb phenotype in Prrx1Cre + /Cyp26b1 fl/fl mice was less severe than that observed in Cyp26b1 -/-animals and that a change in retinoid signalling contributed to the difference in phenotypes. We systematically examined the role of endogenous RA signalling in chondrogenesis and found that Cyp26b1 -/-cells and limb mesenchymal cells treated with a CYP inhibitor, are maintained in a pre-chondrogenic state, exhibit reduced chondroblast differentiation and have modestly accelerated chondrocyte hypertrophy. Furthermore, Cyp26b1 -/-mesenchyme exhibited an increase in expression of genes in a closely related tendogenic lineage, indicating that retinoid signals in the limb interfere with differentiation and maintain progenitor status. Together, these findings support an important function for RA in regulating the behaviour of mesenchymal progenitors, and their subsequent differentiation and maturation.

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“…However, the effect on chondrocyte differentiation is clearly a distinct and later effect of RA that can be uncoupled from the patterning effect by the simultaneous elimination of RARγ; this is demonstrated by the fact that Cyp26b1;RARγ double mutant embryos still show the proximalization of the PD molecular code, whereas chondrocyte differentiation is mostly rescued (Pennimpede et al, 2010).…”

Section: Ra and Limb Developmentmentioning

confidence: 99%

Diffusible signals and epigenetic timing cooperate in late proximo-distal limb patterning

Roselló-Díez

¹

,

Arqués

²

,

Delgado

³

et al. 2014

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Developing vertebrate limbs initiate proximo-distal patterning by interpreting opposing gradients of diffusible signaling molecules. We report two thresholds of proximo-distal signals in the limb bud: a higher threshold that establishes the upper-arm to forearm transition; and a lower one that positions a later transition from forearm to hand. For this last transition to happen, however, the signal environment seems to be insufficient, and we show that a timing mechanism dependent on histone acetylation status is also necessary. Therefore, as a consequence of the time dependence, the lower signaling threshold remains cryptic until the timing mechanism reveals it. We propose that this timing mechanism prevents the distal transition from happening too early, so that the prospective forearm has enough time to expand and form a properly sized segment. Importantly, the gene expression changes provoked by the first transition further regulate proximo-distal signal distribution, thereby coordinating the positioning of the two thresholds, which ensures robustness. This model is compatible with the most recent genetic analyses and underscores the importance of growth during the time-dependent patterning phase, providing a new mechanistic framework for understanding congenital limb defects.

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Analysis of Cyp26b1/Rarg compound-null mice reveals two genetically separable effects of retinoic acid on limb outgrowth

Cited by 28 publications

References 40 publications

Genetic deletion of Cyp26b1 negatively impacts limb skeletogenesis by inhibiting chondrogenesis

Genetic deletion of Cyp26b1 negatively impacts limb skeletogenesis by inhibiting chondrogenesis

Genetic deletion ofCyp26b1negatively impacts limb skeletogenesis by inhibiting chondrogenesis

Diffusible signals and epigenetic timing cooperate in late proximo-distal limb patterning

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