PUBLICATION

Bi-allelic KICS2 mutations impair KICSTOR complex-mediated mTORC1 regulation, causing intellectual disability and epilepsy

Authors
Buchert, R., Burkhalter, M.D., Huridou, C., Sofan, L., Roser, T., Cremer, K., Alvi, J.R., Efthymiou, S., Froukh, T., Gulieva, S., Guliyeva, U., Hamdallah, M., Holder-Espinasse, M., Kaiyrzhanov, R., Klingler, D., Koko, M., Matthies, L., Park, J., Sturm, M., Velic, A., Spranger, S., Sultan, T., Engels, H., Lerche, H., Houlden, H., Pagnamenta, A.T., Borggraefe, I., Weber, Y., Bonnen, P.E., Maroofian, R., Riess, O., Weber, J.J., Philipp, M., Haack, T.B.
ID
ZDB-PUB-250119-2
Date
2025
Source
American journal of human genetics : (Journal)
Registered Authors
Burkhalter, Martin, Philipp, Melanie
Keywords
C12orf66, KICS2, KICSTOR complex, MTOR regulation, ciliogenesis, intellectual disability
MeSH Terms
  • Child
  • Humans
  • Animals
  • Cilia/genetics
  • Cilia/metabolism
  • Cilia/pathology
  • Female
  • Child, Preschool
  • Adolescent
  • Epilepsy*/genetics
  • Mechanistic Target of Rapamycin Complex 1*/genetics
  • Mechanistic Target of Rapamycin Complex 1*/metabolism
  • Zebrafish*/genetics
  • Alleles*
  • Mutation*
  • Male
  • Intellectual Disability*/genetics
PubMed
39824192 Full text @ Am. J. Hum. Genet.
Abstract
Nutrient-dependent mTORC1 regulation upon amino acid deprivation is mediated by the KICSTOR complex, comprising SZT2, KPTN, ITFG2, and KICS2, recruiting GATOR1 to lysosomes. Previously, pathogenic SZT2 and KPTN variants have been associated with autosomal recessive intellectual disability and epileptic encephalopathy. We identified bi-allelic KICS2 variants in eleven affected individuals presenting with intellectual disability and epilepsy. These variants partly affected KICS2 stability, compromised KICSTOR complex formation, and demonstrated a deleterious impact on nutrient-dependent mTORC1 regulation of 4EBP1 and S6K. Phosphoproteome analyses extended these findings to show that KICS2 variants changed the mTORC1 proteome, affecting proteins that function in translation, splicing, and ciliogenesis. Depletion of Kics2 in zebrafish resulted in ciliary dysfunction consistent with a role of mTORC1 in cilia biology. These in vitro and in vivo functional studies confirmed the pathogenicity of identified KICS2 variants. Our genetic and experimental data provide evidence that variants in KICS2 are a factor involved in intellectual disability due to its dysfunction impacting mTORC1 regulation and cilia biology.
Genes / Markers
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Expression
Phenotype
Mutations / Transgenics
Human Disease / Model
Sequence Targeting Reagents
Fish
Antibodies
Orthology
Engineered Foreign Genes
Mapping