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. 2022 Oct 27;5:1141. doi: 10.1038/s42003-022-04097-y

Fig. 3. Nrf1 mediates mTORC1-stimulated proteasome biogenesis.

Fig. 3

a localization of Nfe2l1 mRNA within muscle fibers using RNA in situ hybridization coupled to antibody-based immunofluorescence. b mRNA and c protein expression of Nrf1 (encoded by the Nfe2l1 gene), Nrf1 regulators, 26S proteasome subunits and the 20S activator PSME4 in tibialis anterior (TA) muscle with representative Western blots (left). Nrf1 FL, CL, and β refer to the full length, cleaved and alternatively spliced versions of Nrf1, respectively. Muscles were collected 2 weeks after transfection of a plasmid expressing either a scrambled (Scr) or Nfe2l1-targeting (Nrf1-kd) shRNA into TA/extensor digitorum longus (EDL) muscles of control and TSCmKO mice. d Luciferase-based peptidase activity of 20S proteasome catalytic enzymes in EDL muscle and e TA muscle mass 2 weeks after transfection. Des was used as the reference gene and α-actinin as the protein loading control. For all experiments n = 6 per group, except for control in b where n = 5. Data are presented as mean ± SEM. Two-way ANOVAs with Sidak post hoc tests were used to compare the data. *, **, and *** denote a significant difference between groups of P < 0.05, P < 0.01, and P < 0.001, respectively. For trends, where 0.05 < P < 0.10, p values are reported.