A human PSMB11 variant affects thymoproteasome processing and CD8+ T cell production
Izumi Ohigashi, Yuki Ohte, Kazuya Setoh, Hiroshi Nakase, Akiko Maekawa, Hiroshi Kiyonari, Yoko Hamazaki, Miho Sekai, Tetsuo Sudo, Yasuharu Tabara, Hiromi Sawai, Yosuke Omae, Rika Yuliwulandari, Yasuhito Tanaka, Masashi Mizokami, Hiroshi Inoue, Masanori Kasahara, Nagahiro Minato, Katsushi Tokunaga, Keiji Tanaka, Fumihiko Matsuda, Shigeo Murata, Yousuke Takahama
Izumi Ohigashi, Yuki Ohte, Kazuya Setoh, Hiroshi Nakase, Akiko Maekawa, Hiroshi Kiyonari, Yoko Hamazaki, Miho Sekai, Tetsuo Sudo, Yasuharu Tabara, Hiromi Sawai, Yosuke Omae, Rika Yuliwulandari, Yasuhito Tanaka, Masashi Mizokami, Hiroshi Inoue, Masanori Kasahara, Nagahiro Minato, Katsushi Tokunaga, Keiji Tanaka, Fumihiko Matsuda, Shigeo Murata, Yousuke Takahama
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Research Article Genetics Immunology

A human PSMB11 variant affects thymoproteasome processing and CD8+ T cell production

Abstract

The Psmb11-encoded β5t subunit of the thymoproteasome, which is specifically expressed in cortical thymic epithelial cells (cTECs), is essential for the optimal positive selection of functionally competent CD8+ T cells in mice. Here, we report that a human genomic PSMB11 variation, which is detectable at an appreciable allele frequency in human populations, alters the β5t amino acid sequence that affects the processing of catalytically active β5t proteins. The introduction of this variation in the mouse genome revealed that the heterozygotes showed reduced β5t expression in cTECs and the homozygotes further exhibited reduction in the cellularity of CD8+ T cells. No severe health problems were noticed in many heterozygous and 5 homozygous human individuals. Long-term analysis of health status, particularly in the homozygotes, is expected to improve our understanding of the role of the thymoproteasome-dependent positive selection of CD8+ T cells in humans.

Authors

Izumi Ohigashi, Yuki Ohte, Kazuya Setoh, Hiroshi Nakase, Akiko Maekawa, Hiroshi Kiyonari, Yoko Hamazaki, Miho Sekai, Tetsuo Sudo, Yasuharu Tabara, Hiromi Sawai, Yosuke Omae, Rika Yuliwulandari, Yasuhito Tanaka, Masashi Mizokami, Hiroshi Inoue, Masanori Kasahara, Nagahiro Minato, Katsushi Tokunaga, Keiji Tanaka, Fumihiko Matsuda, Shigeo Murata, Yousuke Takahama

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Figure 2

Generation of β5t-G49S–knock-in mice.

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Generation of β5t-G49S–knock-in mice. (A) Schematic diagram of β5t genom...
(A) Schematic diagram of β5t genomic locus in mouse chromosome 14. The diagrams for targeting vector and targeted allele are also shown. Targeted mice were further crossed with CAG-Cre–transgenic mice to delete the PGK-Neo insertion. Arrowheads indicate the primers for genomic PCR. Probe for Southern blot analysis is also shown. DT-A, diphtheria toxin A; PGK-Neo, phosphoglycerate kinase I promoter–driven neomycin resistance gene. (B) Gel electrophoresis of PCR-amplified genomic DNA. Positions for primers are shown in A. Plasmid DNA containing the targeted fragment was used as positive control. (C) Southern blot analysis of XbaI-digested genomic DNA from targeted ES cells and control TT2 ES cells. Probe is shown in A. (D) The G-to-A 1 bp substitution at amino acid position 49 (Gly to Ser) of β5t in genomic DNA isolated from mouse tails in WT, heterozygous (hetero), and homozygous (homo) knock-in mice. See complete unedited blots in the supplemental material. Asterisks indicate nucleotides where 1-bp substitution is introduced.