biostudies-literatureBasello DAGrantov Agentura, Univerzita KarlovaAkademie Věd České RepublikyMinisterstvoAkademie Vʃd ɨesk RepublikyMinisterstvo Školství, Mládeže a TělovýchovyNational Institutes of HealthGrantová Agentura, Univerzita KarlovaNIGMS NIH HHSjcs259587https://www.ebi.ac.uk/biostudies/studies/S-EPMC9080554biostudies-literatureUnknown135(8)Coilin is a conserved protein essential for integrity of nuclear membrane-less inclusions called Cajal bodies. Here, we report an amino acid substitution (p.K496E) found in a widely-used human EGFP-coilin construct that has a dominant-negative effect on Cajal body formation. We show that this coilin-K496E variant fails to rescue Cajal bodies in cells lacking endogenous coilin, whereas the wild-type construct restores Cajal bodies in mouse and human coilin-knockout cells. In cells containing endogenous coilin, both the wild-type and K496E variant proteins accumulate in Cajal bodies. However, high-level overexpression of coilin-K496E causes Cajal body disintegration. Thus, a mutation in the C-terminal region of human coilin can disrupt Cajal body assembly. Caution should be used when interprJournal of cell scienceA point mutation in human coilin prevents Cajal body formation.PMC90805541650218RVO68378050-KAV-NPUIRVO68378050R35 GM136435R35-GM136435LTAUSA18103Stanek DMatera AGBasello DAfalseA point mutation in human coilin prevents Cajal body formation.Coilin is a conserved protein essential for integrity of nuclear membrane-less inclusions called Cajal bodies. Here, we report an amino acid substitution (p.K496E) found in a widely-used human EGFP-coilin construct that has a dominant-negative effect on Cajal body formation. We show that this coilin-K496E variant fails to rescue Cajal bodies in cells lacking endogenous coilin, whereas the wild-type construct restores Cajal bodies in mouse and human coilin-knockout cells. In cells containing endogenous coilin, both the wild-type and K496E variant proteins accumulate in Cajal bodies. However, high-level overexpression of coilin-K496E causes Cajal body disintegration. Thus, a mutation in the C-terminal region of human coilin can disrupt Cajal body assembly. Caution should be used when interpr2022-01-01T00:00:00Z2022 Apr2026-05-09T19:47:05.461Z2025-02-19T04:16:13.296ZS-EPMC90805543535698810.1242/jcs.259587