SAMP1/TMEM201 protects alveolar type 2 cells from DNA damage-associated senescence and restrains pulmonary fibrosis

SAMP1/TMEM201 protects alveolar type 2 cells from DNA damage–associated senescence, and its loss worsens bleomycin-induced pulmonary fibrosis by day 21.

• Why it matters: IPF involves repeated alveolar epithelial injury and AT2 senescence that sustain myofibroblast activation and matrix deposition, but the role of inner nuclear membrane DNA-damage surveillance in this process is unclear.
• What they did: The study identified SAMP1/TMEM201 as an inner nuclear membrane protein binding lamin A/C, emerin, and LINC-complex components, then tested AT2-specific Samp1 deletion (Sftpc-CreERT2; Samp1flox/flox) and AAV6-CAG-Samp1 delivery before bleomycin, plus baseline AT2 analyses for 53BP1, gammaH2AX, p16INK4a, and PAI-1.
• The result: AT2 Samp1 deletion increased Ashcroft scores and pulmonary Tnfa and Acta2 expression at day 21, while AAV6-CAG-Samp1 attenuated histological fibrosis and these transcriptional responses; in freshly isolated AT2 cells, SAMP1 loss reduced 53BP1, left gammaH2AX comparable, and increased p16INK4a and PAI-1, linking SAMP1 to a senescence–fibrogenesis axis.

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