Targeted exome sequencing reveals a novel GLI3 mutation in a Chinese family with nonsyndromic polydactyly

All-trans-retinoic acid suppresses rat embryo hindlimb bud mesenchymal chondrogenesis by modulating HoxD9 expression

In vertebrates, 5ʹ-Hoxd genes (Hoxd9), which are expressed in the hindlimb bud mesenchyme, participate in limb growth and patterning in early embryonic development. In the present study, We investigated the mechanisms by which ATRA regulates cultured E12.5 rat embryo hindlimb bud mesenchymal cells (rEHBMCs). Following exposure to ATRA over 24 h, mRNA and protein expression levels of HoxD9 were evaluated by reverse transcription-polymerase chain reaction (RT-PCR), quantitative real-time PCR (qPCR), and western blotting. Flow cytometry was used to detect apoptosis. ATRA inhibited the condensation and proliferation, and promoted the apoptosis rate of the rEHBMCs in a dose-dependent manner. Sox9 and Col2a1 in rEHBMCs were downregulated by ATRA in a dose-dependent manner at both mRNA and protein levels. Similarly, HoxD9 was downregulated by ATRA in a dose-dependent manner, in parallel with the cartilage-specific molecules Sox9 and Col2a1. Both qPCR and western blotting showed that both Shh and Gli3 were downregulated. Overexpression of HoxD9 reversed the effects of ATRA. These results demonstrate that ATRA suppresses chondrogenesis in rEHBMCs by inhibiting the expression of HoxD9 and its downstream protein targets, including Sox9 and Col2a1. This effect may also be correlated with inhibition of the Shh-Gli3 signaling pathway.

Novel frameshift mutations of ANKUB1, GLI3, and TAS2R3 associated with polysyndactyly in a Chinese family

BACKGROUND

Polysyndactyly (PSD) is an autosomal dominant genetic limb malformation caused by mutations.

METHODS

Whole exome sequencing and Sanger sequencing were used to determine the mutations in PSD patients. Luciferase reporter assay was performed to determine the effect of GLI3 mutation on its transcriptional activity.

RESULTS

In this study, we investigated the gene mutations of three affected individuals across three generations. The frameshift mutations of GLI3 (NM_000168:c.4659del, NP_000159.3: p.Ser1553del), ANKUB1 (NM_001144960:c.1385del, NP_001138432.1: p.Pro462del), and TAS2R3 (NM_016943:c.128_131del, NP_058639.1: p.Leu43del) were identified in the three affected individuals, but not in three unaffected members by whole exome sequencing and sanger sequencing. Luciferase reporter assay demonstrated that GLI3 mutation reduced the transcriptional activity of GLI3. The results from SMART analysis showed that the frameshift mutation of TAS2R3 altered most protein sequence, which probably destroyed protein function. Although the frameshift mutation of ANKUB1 did not locate in ankyrin repeat domain and ubiquitin domain, it might influence the interaction between ANKUB1 and other proteins, and further affected the ubiquitinylation.

CONCLUSION

These results indicated that the frameshift mutations of GLI3, ANKUB1, and TAS2R3 might alter the functions of these proteins, and accelerated PSD progression.