Department of Molecular Genetics, Oncode Institute, Erasmus MC, University Medical Center Rotterdam, Dr. Molewaterplein 40, 3015 GD, Rotterdam, The Netherlands.
Department of Cardiology and European Reference Network for Rare Multisystemic Vascular Disease (VASCERN), HTAD Rare Disease Working Group, Erasmus MC, University Medical Center Rotterdam, Dr. Molewaterplein 40, 3015 GD, Rotterdam, The Netherlands.
Hum Mol Genet. 2024 Jun 5;33(12):1090-1104. doi: 10.1093/hmg/ddae044.
Pathogenic (P)/likely pathogenic (LP) SMAD3 variants cause Loeys-Dietz syndrome type 3 (LDS3), which is characterized by arterial aneurysms, dissections and tortuosity throughout the vascular system combined with osteoarthritis.
Investigate the impact of P/LP SMAD3 variants with functional tests on patient-derived fibroblasts and vascular smooth muscle cells (VSMCs), to optimize interpretation of SMAD3 variants.
A retrospective analysis on clinical data from individuals with a P/LP SMAD3 variant and functional analyses on SMAD3 patient-derived VSMCs and SMAD3 patient-derived fibroblasts, differentiated into myofibroblasts.
Individuals with dominant negative (DN) SMAD3 variant in the MH2 domain exhibited more major events (66.7% vs. 44.0%, P = 0.054), occurring at a younger age compared to those with haploinsufficient (HI) variants. The age at first major event was 35.0 years [IQR 29.0-47.0] in individuals with DN variants in MH2, compared to 46.0 years [IQR 40.0-54.0] in those with HI variants (P = 0.065). Fibroblasts carrying DN SMAD3 variants displayed reduced differentiation potential, contrasting with increased differentiation potential in HI SMAD3 variant fibroblasts. HI SMAD3 variant VSMCs showed elevated SMA expression and altered expression of alternative MYH11 isoforms. DN SMAD3 variant myofibroblasts demonstrated reduced extracellular matrix formation compared to control cell lines.
Distinguishing between P/LP HI and DN SMAD3 variants can be achieved by assessing differentiation potential, and SMA and MYH11 expression. The differences between DN and HI SMAD3 variant fibroblasts and VSMCs potentially contribute to the differences in disease manifestation. Notably, myofibroblast differentiation seems a suitable alternative in vitro test system compared to VSMCs.
致病性（P）/可能致病性（LP）SMAD3 变体导致洛伊茨-迪茨综合征 3 型（LDS3），其特征为动脉瘤、血管系统各处的夹层和扭曲，以及骨关节炎。
通过对患者来源的成纤维细胞和血管平滑肌细胞（VSMC）进行 P/LP SMAD3 变体的功能测试，研究 P/LP SMAD3 变体的影响，从而优化 SMAD3 变体的解释。
对携带 P/LP SMAD3 变体的个体进行回顾性临床数据分析，并对 SMAD3 患者来源的 VSMC 和 SMAD3 患者来源的成纤维细胞（分化为肌成纤维细胞）进行功能分析。
在 MH2 结构域中携带显性负性（DN）SMAD3 变体的个体发生主要事件的比例更高（66.7%比 44.0%，P=0.054），且发病年龄较携带杂合不足（HI）变体的个体更早。在 MH2 中携带 DN SMAD3 变体的个体首次发生主要事件的年龄为 35.0 岁[IQR 29.0-47.0]，而携带 HI 变体的个体为 46.0 岁[IQR 40.0-54.0]（P=0.065）。携带 DN SMAD3 变体的成纤维细胞显示出分化潜能降低，而携带 HI SMAD3 变体的成纤维细胞分化潜能增加。HI SMAD3 变体 VSMC 表现出 SMA 表达升高和替代 MYH11 异构体表达改变。与对照细胞系相比，DN SMAD3 变体肌成纤维细胞的细胞外基质形成减少。
通过评估分化潜能以及 SMA 和 MYH11 的表达，可以区分 P/LP HI 和 DN SMAD3 变体。DN 和 HI SMAD3 变体成纤维细胞和 VSMC 之间的差异可能导致疾病表现的差异。值得注意的是，与 VSMC 相比，肌成纤维细胞分化似乎是一种合适的体外替代测试系统。
