Post-synaptic scaffold protein TANC2 in psychiatric and somatic disease risk

Understanding the shared genetic aetiology of psychiatric and medical comorbidity in neurodevelopmental disorders (NDDs) could improve patient diagnosis, stratification and treatment options. Rare tetratricopeptide repeat, ankyrin repeat and coiled-coil containing 2 (TANC2)-disrupting variants were disease causing in NDD patients. The post-synaptic scaffold protein TANC2 is essential for dendrite formation in synaptic plasticity and plays an unclarified but critical role in development. We here report a novel homozygous-viable Tanc2-disrupted function model in which mutant mice were hyperactive and had impaired sensorimotor gating consistent with NDD patient psychiatric endophenotypes. Yet, a multi-systemic analysis revealed the pleiotropic effects of Tanc2 outside the brain, such as growth failure and hepatocellular damage. This was associated with aberrant liver function including altered hepatocellular metabolism. Integrative analysis indicates that these disrupted Tanc2 systemic effects relate to interaction with Hippo developmental signalling pathway proteins and will increase the risk for comorbid somatic disease. This highlights how NDD gene pleiotropy can augment medical comorbidity susceptibility, underscoring the benefit of holistic NDD patient diagnosis and treatment for which large-scale preclinical functional genomics can provide complementary pleiotropic gene function information.

Summary: Disruption of mouse Tanc2 causes brain and liver abnormality, increasing psychiatric and somatic disease risk long term, highlighting the benefit of holistic diagnosis and treatment approaches for human neurodevelopmental disorder.

Truncating mutation in TANC2 in a Chinese boy associated with Lennox-Gastaut syndrome: a case report

Background

Lennox-Gastaut syndrome (LGS) is a severe epileptic encephalopathy that can be caused by brain malformations or genetic mutations. Recently, genome-wide association studies have led to the identification of novel mutations associated with LGS. The TANC2 gene, encodes a synaptic scaffolding protein that interacts with other proteins at the postsynaptic density to regulate dendritic spines and excitatory synapse formation. The TANC2 gene mutations were reported in neurodevelopmental disorders and epilepsy but not in LGS ever.

Case presentation

Here we describe the case of a boy with LGS who presented with multiple seizure patterns, such as myoclonic, atonic, atypical absence, generalized tonic-clonic, focal seizures, and notable cognitive and motor regression. The seizures were refractory to many antiepileptic drugs. He got seizure-free with ketogenic diet combined with antiepileptic drugs. A de novo nonsense mutation c.4321C > T(p.Gln1441Ter) in TANC2 gene was identified by the whole-exome sequencing and confirmed by Sanger sequencing.

Conclusion

We described the first Chinese case with LGS associated to a de novo nonsense mutation c.4321C > T(p.Gln1441Ter) in TANC2 gene, which would expand the clinical spectrum related to TANC2 mutations and contribute to better understanding of genotype-phenotype relationship to guide precision medicine.

Regulation of KIF1A-Driven Dense Core Vesicle Transport: Ca2+/CaM Controls DCV Binding and Liprin-α/TANC2 Recruits DCVs to Postsynaptic Sites

Tight regulation of neuronal transport allows for cargo binding and release at specific cellular locations. The mechanisms by which motor proteins are loaded on vesicles and how cargoes are captured at appropriate sites remain unclear. To better understand how KIF1A-driven dense core vesicle (DCV) transport is regulated, we identified the KIF1A interactome and focused on three binding partners, the calcium binding protein calmodulin (CaM) and two synaptic scaffolding proteins: liprin-α and TANC2. We showed that calcium, acting via CaM, enhances KIF1A binding to DCVs and increases vesicle motility. In contrast, liprin-α and TANC2 are not part of the KIF1A-cargo complex but capture DCVs at dendritic spines. Furthermore, we found that specific TANC2 mutations—reported in patients with different neuropsychiatric disorders—abolish the interaction with KIF1A. We propose a model in which Ca²⁺/CaM regulates cargo binding and liprin-α and TANC2 recruit KIF1A-transported vesicles.

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KIF1A directly interacts with CaM and with the scaffolds liprin-α and TANC2

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KIF1A is regulated by a Ca²⁺/CaM-dependent mechanism, which allows for DCV loading

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Liprin-α and TANC2 are static PSD proteins that are not part of the KIF1A-DCV complex

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KIF1A-driven DCVs are recruited to dendritic spines by liprin-α and TANC2