TITLE:
The effects of aging on muscle loss and tissue-specific levels of NF-κB and SIRT6 proteins in rats
AUTHORS:
Tiev C. LaGuire, Corinne R. Kohlen, Susan N. Hawk, Scott K. Reaves
KEYWORDS:
Rat; NF-κB; SIRT6; Muscle Atrophy; Proteolysis
JOURNAL NAME:
Advances in Aging Research,
Vol.2 No.1,
February
19,
2013
ABSTRACT: The objective of this
study was to examine the influence of aging on food intake, tissue and organ
mass and NF-κB and SIRT6 levels in various
tissues. The transcription factor, Nuclear Factor Kappa-B (NF-κB), is associated with both catabolic
and anabolic pathways of muscle metabolism and may be involved in age-related
muscle loss. SIRT6 is a member of the sirtuin family of proteins that function
as protein lysine deacetylases and are associated with longevity in a number of
organisms. Male Sprague-Dawley rats, aged 6 months (Adult) and 21 months (Old)
were fed a commercially available diet for 10-17 days. Old rats consumed less
food per body weight (BW) each day than Adult rats (1.45% g diet/g BW vs. 2.4%
g diet/g BW). However, when intake data were expressed as g/diet per day there
was no significant difference between groups. For skeletal muscle tissue, the
average mass of gastrocnemius and soleus (g muscle/g BW) was significantly
lower in Old rats. Levels of NF-κB
(p65/RelA) and SIRT6 were measured by Western blot analysis in gastrocnemius,
tibialis anterior, quadriceps, soleus, lung, heart, kidney and liver. NF-κB levels were higher in gastroc- nemius
of Old rats compared to Adult rats. No significant age-specific differences in
SIRT6 protein levels were noted in the tissues examined. Interestingly, when
examined independent of age, levels of SIRT6 were significantly different
between certain tissues. Data from this study suggest that aging affects muscle
loss and NF-κB in a tissue-specific
manner. Furthermore, these findings indicate tissue-specific but not
age-specific differences in SIRT6 protein levels.