SPECC1L regulates palate development downstream of IRF6

Area of Science:

• Developmental Biology
• Genetics
• Craniofacial Development

Background:

• SPECC1L mutations are linked to syndromic and atypical orofacial clefts.
• These mutations impair SPECC1L's microtubule-binding capacity.
• Previous Specc1l knockout models showed embryonic lethality.

Purpose of the Study:

• To investigate the role of SPECC1L in palate development using a novel truncation mutant mouse model.
• To explore the functional consequences of SPECC1L deficiency on palate elevation and cleft palate.
• To examine the relationship between SPECC1L, IRF6, and non-syndromic cleft lip and/or palate (CL/P).

Main Methods:

• Generation and analysis of a Specc1l truncation mutant mouse allele (Specc1lΔC510).
• Cross-breeding Specc1lΔC510 with a gene-trap allele (Specc1lcGT) to create compound heterozygotes.
• Histological examination of palatal shelves, including assessment of epithelial adhesions and adherens junction markers.
• Sequencing of SPECC1L in patients with non-syndromic CL/P from diverse ethnic backgrounds.

Main Results:

• Specc1lΔC510 homozygotes exhibited abnormal palate rugae but not cleft palate.
• Specc1lcGT/ΔC510 compound heterozygotes displayed palate elevation delay and incomplete cleft palate.
• Transient oral epithelial adhesions and periderm abnormalities were observed in Specc1lcGT/ΔC510 embryos.
• SPECC1L expression was significantly reduced in Irf6 mutant palatal shelves.
• Three rare SPECC1L coding variants were identified in patients with non-syndromic CL/P.

Conclusions:

• Palate elevation is sensitive to SPECC1L dosage and function.
• SPECC1L acts downstream of IRF6 in the process of palatogenesis.
• Mild SPECC1L variants may contribute to non-syndromic cleft lip and/or palate.