Figure - PMC

Skip to main content

An official website of the United States government

Here's how you know

Here's how you know

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

View full-text article in PMC

. 2007 Jun 4;177(5):769–779. doi: 10.1083/jcb.200608122

Search in PMC
Search in PubMed
View in NLM Catalog
Add to search

Copyright © 2007, The Rockefeller University Press

This article is distributed under the terms of an Attribution–Noncommercial–Share Alike–No Mirror Sites license for the first six months after the publication date (see http://www.rupress.org/terms). After six months it is available under a Creative Commons License (Attribution–Noncommercial–Share Alike 4.0 Unported license, as described at http://creativecommons.org/licenses/by-nc-sa/4.0/).

PMC Copyright notice

Figure 4. — Myogenin negatively regulates Pax7 expression. (A, left) Western blots from C3H10T1/2 cell lysates expressing MyoD, myogenin, and Pax7 reveal reduction of both myogenin and Pax7 levels upon coexpression. (middle) Quantification of lanes 2–4 for myogenin (top) and Pax7 (bottom) abundance, respectively. (right) Proteasome inhibition increases levels of myogenin and Pax7 affected by coexpression. (B) Analysis of Pax7 and myogenin expression in mitotically synchronized MM14 myoblasts during commitment to terminal differentiation (schematic). At the indicated times, cells expressing either Pax7 (white bars) or myogenin (black bars) were independently scored and plotted as a percentage of the total population. Cells coexpressing both Pax7 and myogenin (gray bars) are plotted as the percentage of Pax7⁺ cells in the myogenin⁺ subpopulation. (C) Ectopic expression of myogenin down-regulates Pax7 (96.6 ± 1.3% of transfected cells are Pax7⁻; yellow arrowheads) in MM14 myoblasts under growth conditions. Data are representative of three experiments. (D, left) Endogenous myogenin induction in C3H10T1/2 cells (by MyoD forced expression) is efficiently down-regulated by RNAi, as monitored by Western blot. (right) Quantification of myogenin abundance in the presence of specific or control (ctrl) siRNAs. Inset shows that MyoD protein levels are unaffected. (E) RNAi-mediated down-regulation of myogenin (no detectable myogenin in 60 ± 12.7% of transfected cells; middle and bottom) results in retention of Pax7 expression in differentiating cells (high Pax7 expression in 64.3 ± 18.7% of total transfected cells; bottom, white arrowheads). Control siRNA has no effect on myogenin (high myogenin expression in >80% of transfected cells; top, white arrowheads) or Pax7 expression (not depicted). β-Gal expression was used to identify transfected cells. Bar, 10 μm. (F) Pax7 protein stability is regulated during commitment to terminal differentiation. Mitotically synchronized MM14 cells were induced to differentiate for 15 h and treated with MG132 for 6 h before fixation. In control conditions (DMSO), myogenin (88.9 ± 5.8%) and Pax7 (16.1 ± 6%) are expressed in a mutually exclusive pattern (top and middle, white arrows). Upon MG132 treatment, 77.5 ± 10.1% of the cells are myogenin⁺, yet 57.2 ± 13% of the cells are also Pax7⁺ (bottom, white arrows). Bar, 10 μm.