Reconstitution of the Ataxia-Telangiectasia Cellular Phenotype With Lentiviral Vectors

Abstract

Ataxia-telangiectasia (A-T) is a complex disease arising from mutations in the ATM gene (Ataxia-Telangiectasia Mutated), which plays crucial roles in repairing double-strand DNA breaks (DSBs). Heterogeneous immunodeficiency, extreme radiosensitivity, frequent appearance of tumors and neurological degeneration are hallmarks of the disease, which carries high morbidity and mortality because only palliative treatments are currently available. Gene therapy was effective in animal models of the disease, but the large size of the ATM cDNA required the use of HSV-1 or HSV/AAV hybrid amplicon vectors, whose characteristics make them unlikely tools for treating A-T patients. Due to recent advances in vector packaging, production and biosafety, we developed a lentiviral vector containing the ATM cDNA and tested whether or not it could rescue cellular defects of A-T human mutant fibroblasts. Although the cargo capacity of lentiviral vectors is an inherent limitation in their use, and despite the large size of the transgene, we successfully transduced around 20% of ATM-mutant cells. ATM expression and phosphorylation assays indicated that the neoprotein was functional in transduced cells, further reinforced by their restored capacity to phosphorylate direct ATM substrates such as p53 and their capability to repair radiation-induced DSBs. In addition, transduced cells also restored cellular radiosensitivity and cell cycle abnormalities. Our results demonstrate that lentiviral vectors can be used to rescue the intrinsic cellular defects of ATM-mutant cells, which represent, in spite of their limitations, a proof-of-concept for A-T gene therapy.

Neurofilament Light Chain Is a Biomarker of Neurodegeneration in Ataxia Telangiectasia

“…In recent years, various therapeutic approaches like bone marrow transplantation [5][6][7], dexamethasone treatment [8][9][10], and gene therapy [11][12][13] have been developed to positively influence the course of A-T, but still no treatment to cure the disease is available. There is considerable clinical variation between patients with A-T.…”

New human ATM variants are able to regain ATM functions in Ataxia Telangiectasia disease

“…Together, these data support the beneficial roles of ATM variants in restoring cellular functionalities missing in AT patients. Furthermore, the smaller size of ATM variants cDNA overcomes the cargo limit of approved gene therapy vectors, improving the efficiency of viral particles production and infection efficiency compared with the whole ATM gene, as reported by Carranza et al, who constructed a lentiviral vector containing a full-length ATM capable of rescuing AT deficiencies, but with a low transduction efficiency [89]. Hence, ATM variants could be used in gene therapy, or their administration could also be achieved by using nanoparticle delivery or vesicle delivery, both of which are less immunogenic, less expensive, and more efficient in crossing the blood-brain barrier.…”

Diabetes in Patients With Ataxia Telangiectasia: A National Cohort Study

“…Due to better care, life expectancy of A-T patients has emerged over the last decades ( 45 ). Especially in the light of new treatment options such as bone marrow transplantation ( 46 – 48 ), dexamethasone treatment ( 49 – 51 ), and gene therapy ( 52 – 54 ) disease facets with manifestation in the later disease course should be screened and treated. According to our data, diabetes screening is indicated starting for the age of 12 years.…”