TP53/TAU axis regulates microtubule bundling to control alveolar stem cell–mediated regeneration
Satoshi Konishi, Khaliun Enkhbayar, Shuyu Liu, Naoya Miyashita, Yoshihiko Kobayashi, Vera Hutchison, Ashna Sai, Pankaj Agarwal, Jonathan Witonsky, Nathan D. Jackson, Max A. Seibold, Jichao Chen, Aleksandra Tata, Purushothama Rao Tata
Satoshi Konishi, Khaliun Enkhbayar, Shuyu Liu, Naoya Miyashita, Yoshihiko Kobayashi, Vera Hutchison, Ashna Sai, Pankaj Agarwal, Jonathan Witonsky, Nathan D. Jackson, Max A. Seibold, Jichao Chen, Aleksandra Tata, Purushothama Rao Tata
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Research Article Cell biology Pulmonology

TP53/TAU axis regulates microtubule bundling to control alveolar stem cell–mediated regeneration

Abstract

Cells exhibit diverse sizes and shapes, tailored for functional needs of tissues. Lung alveoli are lined by large, extremely thin epithelial alveolar type 1 cells (AT1s). Their characteristic morphology is essential for lung function and must be restored after injury. The mechanisms underlying small, cuboidal alveolar type 2 cell (AT2) differentiation into thin AT1s remain elusive. Here, we demonstrated that AT2s undergo a stepwise morphological transformation characterized by the development of a unique thick microtubule (MT) bundle organization, critical for AT1 morphology. Using AT2 cultures and in vivo genetic loss-of-function models, we found that MT bundling occurred in a transitional cell state during AT2 differentiation and was regulated by the TP53/TAU (encoded by the microtubule-associated protein tau [MAPT] gene) signaling axis. Notably, TAU underwent a linear clustering process, forming beads-on-a-string-like pattern that preceded thick MT bundle formation. Genetic gain or loss of function of TAU in mouse or human models prevented the formation of thick MT bundles, highlighting the critical role of precise TAU levels in generating ultrathin AT1s. This defect was associated with increased tissue fibrosis following bleomycin-induced injury in vivo. GWAS analysis revealed risk variants in the MAPT locus in lung diseases. Moreover, TP53 controlled TAU expression and its loss phenocopied TAU deficiency. This work revealed an unexpected role for TAU in organizing MT bundles during AT2 differentiation.

Authors

Satoshi Konishi, Khaliun Enkhbayar, Shuyu Liu, Naoya Miyashita, Yoshihiko Kobayashi, Vera Hutchison, Ashna Sai, Pankaj Agarwal, Jonathan Witonsky, Nathan D. Jackson, Max A. Seibold, Jichao Chen, Aleksandra Tata, Purushothama Rao Tata

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Figure 3

TAU regulates the formation of thick MT bundles.

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TAU regulates the formation of thick MT bundles. (A) Experimental design...
(A) Experimental design for AT2 isolation from H11-Cas9 mice followed by AT2 culture and AAV6-gRNA-GFP infection to knock out Mapt ex vivo. (B) Staining for GFP (green, infected cells) and TAU (red) in NTC and Mapt-KO cells. Scale bars: 20 μm. (C) Staining for GFP (green) and TUBA1B (gray) in control and Mapt-KO cells. Scale bars: 20 μm. (D) Staining for TUBA1B (gray) and Ac-TUB (red) in infected GFP+ (green) control and Mapt-deleted cells. Scale bars: 20 μm (low magnification); 5 μm (high magnification). Yellow box indicates region of single-channel images. (E) Quantification of cells exhibiting thick MT bundles and cell thickness in control and Mapt-deleted cells. **P = 0.0049, ***P = 0.0005, unpaired 2-tailed t test. n = 3 biological replicates. (F) Schematic of ex vivo–cultured AT2s infected with mouse Mapt or human MAPT and analyses at indicated time point. (G) Staining for TAU (red) and TUBA1B (gray) in control and TAU-overexpressed (-OE) cells (green). Scale bars: 20 μm. Yellow box indicates region of single-channel images. DAPI stains nuclei (blue). (H) Staining for TUBA1A (green), TUBA1B (gray), and Ac-TUB (red) in TAU-OE and control cells. Yellow box indicates region of single-channel images. Scale bars: 20 μm. (I) Quantification of cell area, cell thickness, and the percentage of infected cells exhibiting thick MT bundles. *P = 0.05, Mann-Whitney U statistical test. **P < 0.005, unpaired 2-tailed t test. n = 3 biological replicates. Data in E and I are presented as mean ± SEM.