Projet EQUIPE FRM - rapport final (3 ans)

Projet DEQ29545

« Génétique et physiopathologie des cardiopathies rythmiques et dégénératives : des maladies rares aux maladies communes »

Schott Jean-Jacques

l'institut du thorax Unité Inserm UMR 1087 / CNRS UMR 6291

Figure 1: Manhattan plot montrant les signaux d’association génétique obtenus par GWAS sur 2212 cas atteints de SBR et 6731 contrôles. Pour chaque locus, le gène identifié est indiqué en rouge (signal significatif) ou vert (signal suggestif).Figure 1

Figure 2. The TRPM4-p.I376T variant is responsible for PFHBI. (A) Distribution of rare coding variation detected among 95 patients with PCCD in the TRPM4 channel. Novel variants are shown in red, low-frequency ones in blue. The two rare variants previously reported as causing PFHBI [6] and [7] are indicated in green. (B) Capillary sequencing of the exon 9 of TRPM4 for thFigure 2e patient 9 confirms the presence of a novel variant resulting in the p.Ile376Thr substitution. (C) Family tree of patient 9 (the proband, IV-5). Plus symbols (+) denote p.Ile376Thr mutation carriers and minus symbol (−) non-carriers. ‘PM’ indicates patients implanted with a pacemaker, ‘LVNC’ stands for Left Ventricular Non-Compaction and ‘C′ indicates congenital forms of conduction defects.

Figure 3Figure 3. Whole cell patch clamp recording for the WT and p.I376T TRPM4 channels. (A) Time course recording of the TRPM4 current. (B) Individual current traces of the WT and p.I376T TRPM4 channels recorded as transient and plateau phases. (C) Quantification of current density of the WT and p.I376T TRPM4 channels for both phases. The current densities are measured at the pic current at − 100 mV. (D) Current–voltage relationships of the WT and p.I376T TRPM4 channels. *P < 0.05, **P < 0.01, ***P < 0.001.
Figure 4Figure 4. Clinical features of congenital AV block families with a GJC1 mutation. (A) An identical Cx45-p.R75H heterozygous mutation was identified in a de novo case in French family A and in a three-generation Japanese family B. (+/-) stands for an obligate carrier. Arrows and asterisks represent probands and pacemaker implantation, respectively. Lower panel shows the sequence electrophoregram of GJC1-c.G224A and the transmembrane topology of Cx45 and the location of Cx45-p.R75H. (B) Time course of atrial conduction abnormalities. The proband of the family A exhibited complete AV block at 2 years-old (yo), which was progressed to loss of P waves (red arrows) by 7 yo. The proband of the family B showed 1st degree AV block at the age of 6. P waves were progressively diminished by 14 yo. (C-E) Extracardiac phenotypes represented in the II:2 of family B. Brachyfacial pattern demonstrated by significantly smaller cephalometric indices compared with the average values despite normal body height and weight. Clinodactyly on the 5th fingers and camptodactyly on 3rd through 5th fingers of hand. Bilateral small maxillary lateral incisors (microdontia, asterisks), and defect of bilateral mandibular central incisors and right mandibular lateral incisor (arrows) were observed.
Figure 5. In vitro and in vivo studies of the novel GJC1 mutation. (A) Co-immunoprecipitation of myc- and flag-tagged Cx45 molecules expressed in N2a cells was not affected by the mutation Cx45-p.R75H. (B) Immunofluorescent images Figure 5of myc-tagged Cx45 in N2a cells showed normal expression pattern of GJ plaques in Cx45-p.R75H. (C) Time course of Lucifer yellow dye transfer in cell pairs of homomeric channels of WT or R75H, and heteromeric WT/R75H. (D) Relative dye intensity of the injected cells (open symbols) and the adjoining cells (filled symbols) indicates severely impaired dye transfer in R75H and WT/R75H. (E) Representative current traces from the holding potential of -40 mV and stepped from -40 mV to +20 mV in 20 mV increments (left), and the macroscopic Gj measured at +20 mV (right; mean ± SD) (WT: 24.2 ± 7.9 nS, n=5; WT/R75H: 4.9 ± 5.3 nS, n=11; R75H: 0 nS, n=8; p=1.05 x 10-7). Statistical comparisons were made by one-way ANOVA with Bonferroni correction. NS: statistically not significant. (F) ECG recordings of a Gjc1-CKO mouse before and after tamoxifen administration. Atrial activities (arrows) were frequently disappeared after tamoxifen administration.