Fig. 3

Deletion of HDAC9 contributes to degeneration of IVD during aging. A Schematic diagram of the HDAC9 knockout design showing partial mouse HDAC9 gene (top), sequences of two gRNAs used for deletion of exon 3 to 6 (middle), and the truncated DNA was confirmed by sequencing validation (bottom). B MRI scan of the lumbar spine and IVDs of HDAC9^WT mice and HDAC9^KO mice at 1, 3, and 6 months. C, D Coronal sections of disc compartments stained and analyzed by safranin-O/fast green. Scale bar: black, 500 μm; yellow, 200 μm. Quantification of area ratios of NP cell band/IVD (E) and NP/IVD (F). G Body weight of WT mice and HDAC9^KO mice at 1, 3, and 6 months. H Fluorescence staining of HDAC9 in NP compartment. Scale bar: 25 μm. I Apoptotic cells in the NP compartment were detected by TUNEL staining. Scale bar: 25 μm. Data are represented as mean ± SD (n = 6). A p value of less than 0.05 was considered significant using an unpaired Student’s t-test. NS, not significant