Sequestration of CAPNS1 into Polyglycine Aggregates in a Cellular Model of NOTCH2NLC Repeat Expansion
Abstract
Neuronal Intranuclear Inclusion Disease (NIID) is caused by GGC repeat expansions in the 5' untranslated region of the notch 2 N-terminal like C (NOTCH2NLC) gene. An upstream open reading frame within the mutant transcript produces the NOTCH2NLC upstream open reading frame-derived polyglycine protein (uN2CpolyG) containing expanded polyglycine (polyG), which forms intranuclear inclusions. Although uN2CpolyG is thought to play a critical role in disease pathogenesis, the mechanisms underlying its toxicity and inclusion formation remain incompletely understood. In this study, we first expressed a pure GGC repeat encoding polyG in Neuro2a cells and identified aggregate-associated proteins by mass spectrometry. We then confirmed the formation of intracellular aggregates using both transient expression and drug-inducible expression systems for uN2CpolyG. Among the proteins identified by mass spectrometry, Calpain small subunit 1 (Capns1), the regulatory subunit of calpain, was found to be sequestered into uN2CpolyG aggregates. Notably, the N-terminus of Capns1 contains a glycine-rich sequence, which mediated its co-aggregation with uN2CpolyG. Furthermore, knockdown of Capns1 appeared to reduce the accumulation of uN2CpolyG aggregates. Collectively, these findings identify Capns1 as a potential modifier of NIID pathology.
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BibTeX
@article{kubokawa2026sequestration,
title = {{Sequestration of CAPNS1 into Polyglycine Aggregates in a Cellular Model of NOTCH2NLC Repeat Expansion}},
author = {Arisa Kubokawa and Ai Ohki and Risa Ono and Makoto Araki and Motoaki Yanaizu and Yoshihiro Kino},
journal = {Biological and Pharmaceutical Bulletin},
year = {2026},
month = sep,
doi = {10.1248/bpb.b26-00313},
url = {https://www.jstage.jst.go.jp/article/bpb/49/9/49_b26-00313/_article},
note = {CC BY-NC},
}
RIS
TY - JOUR
TI - Sequestration of CAPNS1 into Polyglycine Aggregates in a Cellular Model of NOTCH2NLC Repeat Expansion
AU - Arisa Kubokawa
AU - Ai Ohki
AU - Risa Ono
AU - Makoto Araki
AU - Motoaki Yanaizu
AU - Yoshihiro Kino
PY - 2026
DA - 2026/09/01
JO - Biological and Pharmaceutical Bulletin
DO - 10.1248/bpb.b26-00313
UR - https://www.jstage.jst.go.jp/article/bpb/49/9/49_b26-00313/_article
AB - Neuronal Intranuclear Inclusion Disease (NIID) is caused by GGC repeat expansions in the 5' untranslated region of the notch 2 N-terminal like C (NOTCH2NLC) gene. An upstream open reading frame within the mutant transcript produces the NOTCH2NLC upstream open reading frame-derived polyglycine protein (uN2CpolyG) containing expanded polyglycine (polyG), which forms intranuclear inclusions. Although uN2CpolyG is thought to play a critical role in disease pathogenesis, the mechanisms underlying its toxicity and inclusion formation remain incompletely understood. In this study, we first expressed a pure GGC repeat encoding polyG in Neuro2a cells and identified aggregate-associated proteins by mass spectrometry. We then confirmed the formation of intracellular aggregates using both transient expression and drug-inducible expression systems for uN2CpolyG. Among the proteins identified by mass spectrometry, Calpain small subunit 1 (Capns1), the regulatory subunit of calpain, was found to be sequestered into uN2CpolyG aggregates. Notably, the N-terminus of Capns1 contains a glycine-rich sequence, which mediated its co-aggregation with uN2CpolyG. Furthermore, knockdown of Capns1 appeared to reduce the accumulation of uN2CpolyG aggregates. Collectively, these findings identify Capns1 as a potential modifier of NIID pathology.
SN - 1347-5215
SN - 0918-6158
ER -