AP-1 transcription factor binding activity in rat adrenal medulla and hypothalamus with age and cold exposure.
The AP-1 regulatory element has been implicated in the cold-induced expression of tyrosine hydroxylase in the adrenal medulla. Since in this tissue, the cold-induced increase in tyrosine hydroxylase expression is impaired with age and in other tissues, there is some evidence that AP-1 transcription factor binding is diminished with age, we examined the cold-stimulated AP-1 transcription factor binding to an oligonucleotide with the consensus sequence of the AP-1 response element in nuclear extracts from adrenal medulla and hypothalamus of young and senescent rats. AP-1 transcription factor binding activity diminished by 38% with age in unstimulated adrenal medulla. Following cold stimulation, the AP-1 binding activity increased by 21-25% in the adrenal medulla of both young and senescent rats. However, the level of AP-1 binding in cold-stimulated senescent rats was still less than in cold-stimulated younger rats. There were no changes in AP-3 binding activity with either age or cold exposure in the adrenal medulla. Similarly, in the hypothalamus, there was a 25% decrease with age and a 25% increase following cold stimulation in the level of AP-1 binding. There was a 62% age-related increase in AP-3 binding activity but no change with cold exposure. These data indicate that there is reduced AP-1 binding activity in senescent control rats. Moreover, the demonstration that cold stimulus evokes similar increases in AP-1 binding activity in both young and old rats suggests that the stimulation pathway that increases AP-1 transcription factor is maintained in the senescent animal.
Tümer
N
N
Geriatric Research, Education and Clinical Center, Department of Veterans Affairs Medical Center, Gainesville, Florida 32608-1197, U.S.A.
Scarpace
P J
PJ
Baker
H V
HV
Larochelle
J S
JS
D000313:Adrenal Medulla / Q000378:metabolism*; D000375:Aging / Q000502:physiology*; D000818:Animals; D003080:Cold Temperature; D004268:DNA-Binding Proteins / Q000378:metabolism*; D007031:Hypothalamus / Q000378:metabolism*; D008297:Male; D051381:Rats; D011916:Rats, Inbred F344; D018808:Transcription Factor AP-1 / Q000378:metabolism*
D004268:DNA-Binding Proteins; D018808:Transcription Factor AP-1