Altered Tau Isoform Ratio Caused by Loss of FUS and SFPQ Function Leads to FTLD-like Phenotypes

Publication date: 31 January 2017
Source:Cell Reports, Volume 18, Issue 5
Author(s): Shinsuke Ishigaki, Yusuke Fujioka, Yohei Okada, Yuichi Riku, Tsuyoshi Udagawa, Daiyu Honda, Satoshi Yokoi, Kuniyuki Endo, Kensuke Ikenaka, Shinnosuke Takagi, Yohei Iguchi, Naruhiko Sahara, Akihiko Takashima, Hideyuki Okano, Mari Yoshida, Hitoshi Warita, Masashi Aoki, Hirohisa Watanabe, Haruo Okado, Masahisa Katsuno, Gen Sobue
Fused in sarcoma (FUS) and splicing factor, proline- and glutamine-rich (SFPQ) are RNA binding proteins that regulate RNA metabolism. We found that alternative splicing of the Mapt gene at exon 10, which generates 4-repeat tau (4R-T) and 3-repeat tau (3R-T), is regulated by interactions between FUS and SFPQ in the nuclei of neurons. Hippocampus-specific FUS- or SFPQ-knockdown mice exhibit frontotemporal lobar degeneration (FTLD)-like behaviors, reduced adult neurogenesis, accumulation of phosphorylated tau, and hippocampal atrophy with neuronal loss through an increased 4R-T/3R-T ratio. Normalization of this increased ratio by 4R-T-specific silencing results in recovery of the normal phenotype. These findings suggest a biological link among FUS/SFPQ, tau isoform alteration, and phenotypic expression, which may function in the early pathomechanism of FTLD.

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Ishigaki et al. investigate the functions of Fused in sarcoma (FUS) and its binding partner proline- and glutamine-rich (SFPQ) in regulation of Mapt splicing. The authors show how loss of interaction between FUS and SFPQ causes altered expression ratio of tau isoforms and leads to a neurodegenerative phenotype similar to FTLD. Normalization of this ratio can reduce phenotypic abnormalities in the mouse model of disease.


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