TY - JOUR
T1 - Increased myogenic repressor Id mRNA and protein levels in hindlimb muscles of aged rats
AU - Alway, Stephen E.
AU - Degens, Hans
AU - Lowe, Dawn A.
AU - Krishnamurthy, Gururaj
PY - 2002
Y1 - 2002
N2 - The objective of this study was to determine if levels of repressors to myogenic regulatory factors (MRFs) differ between muscles from young adult and aged animals. Total RNA from plantaris, gastrocnemius, and soleus muscles of Fischer 344 × Brown Norway rats aged 9 mo (young adult, n = 10) and 37 mo (aged, n = 10) was reverse transcribed and then amplified by PCR. To obtain a semiquantitative measure of the mRNA levels, PCR signals were normalized to cyclophilin or 18S signals from the corresponding reverse transcription product. Normalization to cyclophilin and 18S gave similar results. The mRNA levels of MyoD and myogenin were ∼275-650% (P < 0.001) and ∼500-1,100% (P < 0.001) greater, respectively, in muscles from aged compared with young adults. In contrast, the protein levels were lower in plantaris and gastrocnemius muscles and similar in the soleus muscle of aged vs. young adult rats. Id repressor mRNA levels were ∼300-900% greater in fast and slow muscles of aged animals (P ≤ 0.02), and Mist 1 mRNA was ∼50% greater in the plantaris and gastrocnemius muscles (P < 0.01). The mRNA level of Twist mRNA was not significantly affected by aging. Id-1, Id-2, and Id-3 protein levels were ∼17-740% greater (P < 0.05) in hindlimb muscles of aged rats compared with young adult rats. The elevated levels of Id mRNA and protein suggest that MRF repressors may play a role in gene regulation of fast and slow muscles in aged rats.
AB - The objective of this study was to determine if levels of repressors to myogenic regulatory factors (MRFs) differ between muscles from young adult and aged animals. Total RNA from plantaris, gastrocnemius, and soleus muscles of Fischer 344 × Brown Norway rats aged 9 mo (young adult, n = 10) and 37 mo (aged, n = 10) was reverse transcribed and then amplified by PCR. To obtain a semiquantitative measure of the mRNA levels, PCR signals were normalized to cyclophilin or 18S signals from the corresponding reverse transcription product. Normalization to cyclophilin and 18S gave similar results. The mRNA levels of MyoD and myogenin were ∼275-650% (P < 0.001) and ∼500-1,100% (P < 0.001) greater, respectively, in muscles from aged compared with young adults. In contrast, the protein levels were lower in plantaris and gastrocnemius muscles and similar in the soleus muscle of aged vs. young adult rats. Id repressor mRNA levels were ∼300-900% greater in fast and slow muscles of aged animals (P ≤ 0.02), and Mist 1 mRNA was ∼50% greater in the plantaris and gastrocnemius muscles (P < 0.01). The mRNA level of Twist mRNA was not significantly affected by aging. Id-1, Id-2, and Id-3 protein levels were ∼17-740% greater (P < 0.05) in hindlimb muscles of aged rats compared with young adult rats. The elevated levels of Id mRNA and protein suggest that MRF repressors may play a role in gene regulation of fast and slow muscles in aged rats.
KW - E proteins
KW - Muscle atrophy
KW - Repressors of transcription
KW - Sarcopenia
KW - Transcription factors
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U2 - 10.1152/ajpregu.00332.2001
DO - 10.1152/ajpregu.00332.2001
M3 - Article
C2 - 11792650
AN - SCOPUS:0036081474
SN - 0363-6119
VL - 282
SP - R411-R422
JO - American Journal of Physiology - Regulatory Integrative and Comparative Physiology
JF - American Journal of Physiology - Regulatory Integrative and Comparative Physiology
IS - 2 51-2
ER -