INPP5D modulates TREM2 loss-of-function phenotypes in a β-amyloidosis mouse model

Akihiro Iguchi; Sho Takatori; Shingo Kimura; Hiroki Muneto; Kai Wang; Hayato Etani; Genta Ito; Haruaki Sato; Yukiko Hori; Junko Sasaki; Takashi Saito; Takaomi C Saido; Tsuneya Ikezu; Toshiyuki Takai; Takehiko Sasaki; Taisuke Tomita

doi:10.1016/j.isci.2023.106375

INPP5D modulates TREM2 loss-of-function phenotypes in a β-amyloidosis mouse model

iScience. 2023 Mar 13;26(4):106375. doi: 10.1016/j.isci.2023.106375. eCollection 2023 Apr 21.

Authors

Akihiro Iguchi¹, Sho Takatori¹, Shingo Kimura¹, Hiroki Muneto¹, Kai Wang¹, Hayato Etani¹, Genta Ito², Haruaki Sato¹, Yukiko Hori¹, Junko Sasaki³, Takashi Saito^{4

5}, Takaomi C Saido⁴, Tsuneya Ikezu⁶, Toshiyuki Takai⁷, Takehiko Sasaki³, Taisuke Tomita¹

Affiliations

¹ Laboratory of Neuropathology and Neuroscience, Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
² Department of Biomolecular Chemistry, Faculty of Pharma-Science, Teikyo University, 2-11-1 Kaga, Itabashi-ku, Tokyo 173-8605, Japan.
³ Department of Lipid Biology, Medical Research Institute, Tokyo Medical and Dental University, 1-5-45 Yushima, Bunkyo-ku, Tokyo 113-8510, Japan.
⁴ Laboratory for Proteolytic Neuroscience, RIKEN Center for Brain Science, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan.
⁵ Department of Neurocognitive Science, Institute of Brain Science, Nagoya City University Graduate School of Medical Science, 1 Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya, Aichi 467-8601, Japan.
⁶ Department of Neuroscience, Mayo Clinic Florida, Jacksonville, FL 32224, USA.
⁷ Department of Experimental Immunology, Institute of Development, Aging and Cancer, Tohoku University, 4-1 Seiryo, Sendai 980-8575, Japan.

Abstract

The genetic associations of TREM2 loss-of-function variants with Alzheimer disease (AD) indicate the protective roles of microglia in AD pathogenesis. Functional deficiencies of TREM2 disrupt microglial clustering around amyloid β (Aβ) plaques, impair their transcriptional response to Aβ, and worsen neuritic dystrophy. However, the molecular mechanism underlying these phenotypes remains unclear. In this study, we investigated the pathological role of another AD risk gene, INPP5D, encoding a phosphoinositide PI(3,4,5)P₃ phosphatase expressed in microglia. In a Tyrobp-deficient TREM2 loss-of-function mouse model, Inpp5d haplodeficiency restored the association of microglia with Aβ plaques, partially restored plaque compaction, and astrogliosis, and reduced phosphorylated tau⁺ dystrophic neurites. Mechanistic analyses suggest that TREM2/TYROBP and INPP5D exert opposing effects on PI(3,4,5)P₃ signaling pathways as well as on phosphoproteins involved in the actin assembly. Our results suggest that INPP5D acts downstream of TREM2/TYROBP to regulate the microglial barrier against Aβ toxicity, thereby modulates Aβ-dependent pathological conversion of tau.

Keywords: Biological sciences; Immune response; Immune system; Immunity; Immunology; Molecular neuroscience; Neuroscience; Omics; Transcriptomics.

Abstract

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