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Ciliary neurotrophic factor stimulates tyrosine hydroxylase activity
Author(s) -
Shi Xiao,
Woodward William R.,
Habecker Beth A.
Publication year - 2012
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.2012.07712.x
Subject(s) - tyrosine hydroxylase , ciliary neurotrophic factor , phosphorylation , glycoprotein 130 , tyrosine 3 monooxygenase , medicine , endocrinology , tyrosine , neurotrophic factors , enzyme assay , norepinephrine , enzyme , chemistry , biology , microbiology and biotechnology , dopamine , biochemistry , stat3 , receptor
J. Neurochem. (2012) 121 , 700–704. Abstract Tyrosine hydroxylase (TH) is the rate‐limiting enzyme in norepinephrine synthesis, and its expression and activity are regulated by many factors in sympathetic neurons. Cytokines that act through gp130, such as ciliary neurotrophic factor (CNTF) decrease norepinephrine production in sympathetic neurons by suppressing TH mRNA and stimulating degradation of TH protein, leading to the loss of enzyme. Their effect on the activity of TH is unclear, but recent in vivo observations suggest that cytokines may stimulate TH activity. We investigated this issue by quantifying TH protein levels and activity in cultured sympathetic neurons. We also examined the state of TH phosphorylation on serine 31 and 40, sites known to affect TH activity and degradation. We found that CNTF, acting through gp130, stimulated the rate of l ‐3,4‐dihydroxyphenylalanine production while at the same time decreasing TH enzyme levels, thereby increasing the specific activity of the enzyme. We also found that phosphorylation of TH on Ser31 was increased, and phosphorylation on Ser40 was decreased, after four days of CNTF exposure. Our data are consistent with previous findings that Ser31 phosphorylation stimulates TH activity, whereas Ser40 phosphorylation can target TH for proteasomal degradation.