TY - JOUR
T1 - Functional analysis of TLK2 variants and their proximal interactomes implicates impaired kinase activity and chromatin maintenance defects in their pathogenesis
AU - Pavinato, Lisa
AU - Villamor-Payà, Marina
AU - Sanchiz-Calvo, Maria
AU - Andreoli, Cristina
AU - Gay, Marina
AU - Vilaseca, Marta
AU - Arauz-Garofalo, Gianluca
AU - Ciolfi, Andrea
AU - Bruselles, Alessandro
AU - Pippucci, Tommaso
AU - Prota, Valentina
AU - Carli, Diana
AU - Giorgio, Elisa
AU - Radio, Francesca Clementina
AU - Antona, Vincenzo
AU - Giuffrè, Mario
AU - Ranguin, Kara
AU - Colson, Cindy
AU - De Rubeis, Silvia
AU - Dimartino, Paola
AU - Buxbaum, Joseph D.
AU - Ferrero, Giovanni Battista
AU - Tartaglia, Marco
AU - Martinelli, Simone
AU - Stracker, Travis H.
AU - Brusco, Alfredo
N1 - Publisher Copyright:
© Author(s) (or their employer(s)) 2020. No commercial re-use. See rights and permissions. Published by BMJ.
PY - 2020
Y1 - 2020
N2 - Introduction: The Tousled-like kinases 1 and 2 (TLK1 and TLK2) are involved in many fundamental processes, including DNA replication, cell cycle checkpoint recovery and chromatin remodelling. Mutations in TLK2 were recently associated with âMental Retardation Autosomal Dominant 57' (MRD57, MIM# 618050), a neurodevelopmental disorder characterised by a highly variable phenotype, including mild-to-moderate intellectual disability, behavioural abnormalities, facial dysmorphisms, microcephaly, epilepsy and skeletal anomalies. Methods: We re-evaluate whole exome sequencing and array-CGH data from a large cohort of patients affected by neurodevelopmental disorders. Using spatial proteomics (BioID) and single-cell gel electrophoresis, we investigated the proximity interaction landscape of TLK2 and analysed the effects of p.(Asp551Gly) and a previously reported missense variant (c.1850C>T; p.(Ser617Leu)) on TLK2 interactions, localisation and activity. Results: We identified three new unrelated MRD57 families. Two were sporadic and caused by a missense change (c.1652A>G; p.(Asp551Gly)) or a 39 kb deletion encompassing TLK2, and one was familial with three affected siblings who inherited a nonsense change from an affected mother (c.1423G>T; p.(Glu475Ter)). The clinical phenotypes were consistent with those of previously reported cases. The tested mutations strongly impaired TLK2 kinase activity. Proximal interactions between TLK2 and other factors implicated in neurological disorders, including CHD7, CHD8, BRD4 and NACC1, were identified. Finally, we demonstrated a more relaxed chromatin state in lymphoblastoid cells harbouring the p.(Asp551Gly) variant compared with control cells, conferring susceptibility to DNA damage. Conclusion: Our study identified novel TLK2 pathogenic variants, confirming and further expanding the MRD57-related phenotype. The molecular characterisation of missense variants increases our knowledge about TLK2 function and provides new insights into its role in neurodevelopmental disorders.
AB - Introduction: The Tousled-like kinases 1 and 2 (TLK1 and TLK2) are involved in many fundamental processes, including DNA replication, cell cycle checkpoint recovery and chromatin remodelling. Mutations in TLK2 were recently associated with âMental Retardation Autosomal Dominant 57' (MRD57, MIM# 618050), a neurodevelopmental disorder characterised by a highly variable phenotype, including mild-to-moderate intellectual disability, behavioural abnormalities, facial dysmorphisms, microcephaly, epilepsy and skeletal anomalies. Methods: We re-evaluate whole exome sequencing and array-CGH data from a large cohort of patients affected by neurodevelopmental disorders. Using spatial proteomics (BioID) and single-cell gel electrophoresis, we investigated the proximity interaction landscape of TLK2 and analysed the effects of p.(Asp551Gly) and a previously reported missense variant (c.1850C>T; p.(Ser617Leu)) on TLK2 interactions, localisation and activity. Results: We identified three new unrelated MRD57 families. Two were sporadic and caused by a missense change (c.1652A>G; p.(Asp551Gly)) or a 39 kb deletion encompassing TLK2, and one was familial with three affected siblings who inherited a nonsense change from an affected mother (c.1423G>T; p.(Glu475Ter)). The clinical phenotypes were consistent with those of previously reported cases. The tested mutations strongly impaired TLK2 kinase activity. Proximal interactions between TLK2 and other factors implicated in neurological disorders, including CHD7, CHD8, BRD4 and NACC1, were identified. Finally, we demonstrated a more relaxed chromatin state in lymphoblastoid cells harbouring the p.(Asp551Gly) variant compared with control cells, conferring susceptibility to DNA damage. Conclusion: Our study identified novel TLK2 pathogenic variants, confirming and further expanding the MRD57-related phenotype. The molecular characterisation of missense variants increases our knowledge about TLK2 function and provides new insights into its role in neurodevelopmental disorders.
KW - genetic research
KW - genetics
KW - loss of function mutation
KW - medical
KW - missense
KW - molecular biology
KW - mutation
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U2 - 10.1136/jmedgenet-2020-107281
DO - 10.1136/jmedgenet-2020-107281
M3 - Article
AN - SCOPUS:85097999119
JO - Journal of Medical Genetics
JF - Journal of Medical Genetics
SN - 0022-2593
ER -