Del-Pozo-Rodriguez Jordi, Tilly Peggy, Lecat Romain, Vaca Hugo Rolando, Mosser Laureline, Brivio Elena, Balla Till, Gomes Marina Vitoria, Ramos-Morales Elizabeth, Schwaller Noémie, Salinas-Giegé Thalia, VanNoy Grace, England Eleina M, Kern Lovgren Alysia, O'Leary Melanie, Chopra Maya, Ojeda Naomi Meave, Toosi Mehran Beiraghi, Eslahi Atieh, Alerasool Masoome, Mojarrad Majid, Pais Lynn S, Yeh Rebecca C, Gable Dustin L, Hashem Mais O, Abdulwahab Firdous, Rakiz Alqurashi Muath, Sbeih Loai Z, Adas Blanco Omar Abu, Khater Renad Abu, Oprea Gabriela, Rad Aboulfazl, Alzaidan Hamad, Aldhalaan Hesham, Tous Ehab, Alsagheir Afaf, Alowain Mohammed, Tamim Abdullah, Alfayez Khowlah, Alhashem Amal, Alnuzha Aisha, Kamel Mona, Al-Awam Bashayer S, Elnaggar Walaa, Almenabawy Nihal, O'Donnell-Luria Anne, Neil Jennifer E, Gleeson Joseph G, Walsh Christopher A, Alkuraya Fowzan S, AlAbdi Lama, Elkhateeb Nour, Selim Laila, Srivastava Siddharth, Nedialkova Danny D, Drouard Laurence, Romier Christophe, Bayam Efil, Godin Juliette D
IGBMC, Institut de Génétique et de Biologie Moléculaire et Cellulaire, 67400 Illkirch, France.
CNRS, Centre National de la Recherche Scientifique, UMR 7104, 67400 Illkirch, France.
Brain. 2025 Mar 22. doi: 10.1093/brain/awaf109.
The ADAT2/ADAT3 (ADAT) complex catalyzes the adenosine to inosine modification at the wobble position of eukaryotic tRNAs. Mutations in ADAT3, the catalytically inactive subunit of the ADAT2/ADAT3 complex, have been identified in patients presenting with severe neurodevelopmental disorders. Yet, the physiological function of ADAT2/ADAT3 complex during brain development remains totally unknown. Here, we investigated the role of the ADAT2/ADAT3 complex in cortical development. First, we reported 21 neurodevelopmental disorders patients carrying biallelic variants in ADAT3. Second, we used structural, biochemical, and enzymatic assays to deeply characterize the impact of those variants on ADAT2/ADAT3 structure, biochemical properties, enzymatic activity and tRNAs editing and abundance. Finally, in vivo complementation assays were performed to correlate functional deficits with neuronal migration defects in the developing mouse cortex. Our results showed that maintaining a proper level of ADAT2/ADAT3 catalytic activity is essential for radial migration of projection neurons in the developing mouse cortex. We demonstrated that the identified ADAT3 variants significantly impaired the abundance and, for some, the activity of the complex, leading to a substantial decrease in I34 levels with direct consequence on their steady-state. We correlated the severity of the migration phenotype with the degree of the loss of function caused by the variants. Altogether, our results highlight the critical role of ADAT2/ADAT3 during cortical development and provide cellular and molecular insights into the pathogenic mechanisms underlying ADAT3-related neurodevelopmental disorders.
ADAT2/ADAT3（ADAT）复合物催化真核生物tRNA摆动位置上腺苷到肌苷的修饰。在患有严重神经发育障碍的患者中已鉴定出ADAT3（ADAT2/ADAT3复合物中无催化活性的亚基）的突变。然而，ADAT2/ADAT3复合物在大脑发育过程中的生理功能仍然完全未知。在此，我们研究了ADAT2/ADAT3复合物在皮质发育中的作用。首先，我们报告了21例携带ADAT3双等位基因变异的神经发育障碍患者。其次，我们使用结构、生化和酶学分析来深入表征这些变异对ADAT2/ADAT3结构、生化特性、酶活性以及tRNA编辑和丰度的影响。最后，进行体内互补分析以将功能缺陷与发育中小鼠皮质中的神经元迁移缺陷相关联。我们的结果表明，维持适当水平的ADAT2/ADAT3催化活性对于发育中小鼠皮质中投射神经元的径向迁移至关重要。我们证明，所鉴定的ADAT3变异显著损害了复合物的丰度，并且对其中一些变异而言，损害了复合物的活性，导致I34水平大幅下降，直接影响其稳态。我们将迁移表型的严重程度与变异导致的功能丧失程度相关联。总之，我们的结果突出了ADAT2/ADAT3在皮质发育过程中的关键作用，并为ADAT3相关神经发育障碍的致病机制提供了细胞和分子层面的见解。
