Impaired p53-Mediated DNA Damage Response Contributes to Microcephaly in Nijmegen Breakage Syndrome Patient-Derived Cerebral Organoids

Abstract

Nijmegen Breakage Syndrome (NBS) is a rare autosomal recessive genetic disorder caused by mutations within nibrin (NBN), a DNA damage repair protein. Hallmarks of NBS include chromosomal instability and clinical manifestations such as growth retardation, immunodeficiency, and progressive microcephaly. We employed induced pluripotent stem cell-derived cerebral organoids from two NBS patients to study the etiology of microcephaly. We show that NBS organoids carrying the homozygous 657del5 NBN mutation are significantly smaller with disrupted cyto-architecture. The organoids exhibit premature differentiation, and Neuronatin (NNAT) over-expression. Furthermore, pathways related to DNA damage response and cell cycle are differentially regulated compared to controls. After exposure to bleomycin, NBS organoids undergo delayed p53-mediated DNA damage response and aberrant trans-synaptic signaling, which ultimately leads to neuronal apoptosis. Our data provide insights into how mutations within NBN alters neurogenesis in NBS patients, thus providing a proof of concept that cerebral organoids are a valuable tool for studying DNA damage-related disorders.

Bilirubin-Induced Neurological Damage: Current and Emerging iPSC-Derived Brain Organoid Models

“…Further expansions in iPSC research have increasingly revealed the multifaceted use of these cells in modeling various diseases in vitro [ 17 , 18 , 19 , 20 , 100 ]. With the development of iPSCs, researchers have been able to replicate many diseases, including Parkinson’s disease, Nijmegen Breakage Syndrome, and Alzheimer’s disease, all by generating different types of cells that mimic the in vivo environment very closely [ 19 , 101 , 102 , 103 , 104 , 105 , 106 , 107 , 108 , 109 ]. For instance, deriving iPSCs from patients with genetic-based neurological conditions and differentiating them into neurons opens up more possibilities to closely observe the pathological mechanisms underlying the disease in vitro [ 106 , 110 , 111 , 112 ].…”

“…Genetic mutations affect cell type, cell behavior, their interactions, neuronal network, and components of the various neurodevelopmental and physiological processes. iPSC-derived brain organoids afford studying these genetic mutations and multi-faceted brain diseases [ 108 , 148 , 151 , 152 , 153 ]. Moreover, being cultured in vitro, organoids provide easy accessibility genetically and for live assays [ 154 ].…”

“…Considering various incorporated features in cerebral organoids, these models are closer to the developing human brain and mimic the neural environment much better compared to other in vitro models. This facilitates the understanding of disease pathology, drug mechanism and customized medication [ 108 , 153 , 169 , 170 , 171 ]. Cerebral organoids represent a higher degree of maturation and developmental dynamics mimicking the early second trimester of the fetal brain tissue; nevertheless, the accurate human brain equivalent age of the organoids still remains an unanswered question [ 172 ].…”

Editorial for Special Issue: iPS Cells (iPSCs) for Modelling and Treatment of Human Diseases

“…In this Special Issue, we have collected articles that emphasise the wide application possibilities of iPSCs. The publications cover diseases of brain [ 2 , 3 , 4 , 5 ], kidney [ 6 ], blood [ 7 , 8 ], cartilage [ 9 ] and primordial germ cells [ 10 ] in 2D and 3D models.…”

“…Martins et al employed 3D brain organoids to model the rare neurodevelopmental disease Nijmegen Breakage syndrome (NBS) [ 4 ]. This disease is caused by mutations in the DNA double-strand repair gene nibrin.…”