Sir2 is a NAD+-dependent histone deacetylase that controls gene silencing, cell cycle, DNA
damage repair, and life span. Prompted by the observation that the [NAD+]/[NADH] ratio is
subjected to dynamic fluctuations in skeletal muscle, we have tested whether Sir2 regulates
muscle gene expression and differentiation. Sir2 forms a complex with the acetyltransferase
PCAF and MyoD and, when overexpressed, retards muscle differentiation. Conversely, cells
with decreased Sir2 differentiate prematurely. To inhibit myogenesis, Sir2 requires its NAD+ …

(Molecular Cell 12, 51–62; July 2003) The detailed protocol for biochemical evaluation of
the redox state was inadvertently omitted from the Supplemental Data for this article. The
information has now been added to the Molecular Cell website and is available at
http://www. molecule. org/cgi/content/full/12/1/51/DC1/by following the link titled ''Protocol for
Biochemical Evaluation of the Redox State.''