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Fig. 2
TTC12 c.1446 + 2 T > C causes exon skipping and downregulates its expression, which further leads to ultrastructural defects in IDA. A Sequence alignment of TTC21B and TTC12 variants in different species, including zebrafish (Danio rerio) and tropical clawed frogs (Xenopus tropicalis). B AlphaFold protein structure prediction showing the potential effects of amino acid substitutions (G542 V, V600E, and G691S) on hydrogen bonds that might exert a direct influence on the protein structure of TTC12. C TTC12 exon 16 was entirely skipped in the patient (F3-II-1) carrying c.1446 + 2 T > C of TTC12 (NM_017868) by cDNA amplification followed by gel extraction and Sanger sequencing. cDNA derived from fresh nasal samples of this patient and two healthy volunteers was amplified. Representative images from three independent experiments are displayed. D mRNA levels of TTC12 were downregulated in the patient carrying c.1446 + 2 T > C by real-time quantitative PCR. **p value < 0.01, (two-tailed Student’s t test; n = 4). E Immunofluorescence staining with anti-TTC12 antibody showed the decreased signal intensity of TTC12 in the cytoplasm of cells derived from the patients (F3-II-1) when compared with healthy controls (Ctrl). Scale bar, 10 µm. F Representative images of transmission electron micrographs (TEM) of cross sections of ciliary axonemes from the patients (F3-II-1) and a healthy control (Ctrl). Distal absence of IDA is indicated by the yellow arrow. Scale bar, 50 nm