Cross-species genetic screens identify transglutaminase 5 as a regulator of polyglutamine-expanded ataxin-1
Won-Seok Lee, … , Juan Botas, Huda Y. Zoghbi
Won-Seok Lee, … , Juan Botas, Huda Y. Zoghbi
Published May 2, 2022
Citation Information: J Clin Invest. 2022;132(9):e156616. https://doi.org/10.1172/JCI156616.
View: Text | PDF
Research Article Genetics Neuroscience

Cross-species genetic screens identify transglutaminase 5 as a regulator of polyglutamine-expanded ataxin-1

Abstract

Many neurodegenerative disorders are caused by abnormal accumulation of misfolded proteins. In spinocerebellar ataxia type 1 (SCA1), accumulation of polyglutamine-expanded (polyQ-expanded) ataxin-1 (ATXN1) causes neuronal toxicity. Lowering total ATXN1, especially the polyQ-expanded form, alleviates disease phenotypes in mice, but the molecular mechanism by which the mutant ATXN1 is specifically modulated is not understood. Here, we identified 22 mutant ATXN1 regulators by performing a cross-species screen of 7787 and 2144 genes in human cells and Drosophila eyes, respectively. Among them, transglutaminase 5 (TG5) preferentially regulated mutant ATXN1 over the WT protein. TG enzymes catalyzed cross-linking of ATXN1 in a polyQ-length–dependent manner, thereby preferentially modulating mutant ATXN1 stability and oligomerization. Perturbing Tg in Drosophila SCA1 models modulated mutant ATXN1 toxicity. Moreover, TG5 was enriched in the nuclei of SCA1-affected neurons and colocalized with nuclear ATXN1 inclusions in brain tissue from patients with SCA1. Our work provides a molecular insight into SCA1 pathogenesis and an opportunity for allele-specific targeting for neurodegenerative disorders.

Authors

Won-Seok Lee, Ismael Al-Ramahi, Hyun-Hwan Jeong, Youjin Jang, Tao Lin, Carolyn J. Adamski, Laura A. Lavery, Smruti Rath, Ronald Richman, Vitaliy V. Bondar, Elizabeth Alcala, Jean-Pierre Revelli, Harry T. Orr, Zhandong Liu, Juan Botas, Huda Y. Zoghbi

×

Figure 2

Validation of ATXN1 regulators in Daoy cells and iPSC-derived neurons from patients with SCA1.

Options: View larger image (or click on image) Download as PowerPoint
Validation of ATXN1 regulators in Daoy cells and iPSC-derived neurons fr...
(A) Representative Western blot analysis of endogenous ATXN1 and qRT-PCR results of target genes after knockdown of 93 genes for 9 days in WT Daoy cells. ATXN1 shRNA was used as positive control. Data shown as mean ± SD, *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001, 1-way ANOVA, post hoc Dunnett’s test for left graphs; Tukey’s test for right graphs. Blue-colored genes selected for further validation. (B) Culturing scheme of patient iPSC-derived neurons. iPSCs were first differentiated into NPCs, and then differentiated into neurons by incubating NPCs in NIM and NDM. (C) Immunofluorescent (IF) image of MAP2, VGLUT1, and GABA in the iPSC-derived neurons from patients with SCA1 after 3 weeks of differentiation. Scale bar: 50 μm. (D) Representative Western blot analysis of mutant and WT ATXN1, and qRT-PCR results of target genes and ATXN1 after knockdown of ATXN1 regulators for 9 days in iPSC-derived neurons from patients with SCA1. Blue-colored genes are validated ATXN1 regulators. Data shown as mean ± SD, *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001, 1-way ANOVA, post hoc Dunnett’s test for the left and right graphs; Tukey’s test for the middle graphs.