Nuclear α1-adrenergic receptors signal activated ERK localization to caveolae in adult cardiac myocytes

Casey D. Wright, Quanhai Chen, Nichole L. Baye, Yuan Huang, Chastity L Healy, Sivakanthan Kasinathan, Timothy D. O'Connell

Research output: Contribution to journalArticlepeer-review

72 Scopus citations


We previously identified an α1-AR-ERK (α1A-adrenergic receptor-extracellular signal-regulated kinase) survival signaling pathway in adult cardiac myocytes. Here, we investigated localization of α1-AR subtypes (α1A and α1B) and how their localization influences α1-AR signaling in cardiac myocytes. Using binding assays on myocyte subcellular fractions or a fluorescent α1-AR antagonist, we localized endogenous α1-ARs to the nucleus in wild-type adult cardiac myocytes. To clarify α1 subtype localization, we reconstituted α1 signaling in cultured α1A- and α1B-AR double knockout cardiac myocytes using α1-AR-green fluorescent protein (GFP) fusion proteins. Similar to endogenous α1-ARs and α1A- and α1B-GFP colocalized with LAP2 at the nuclear membrane. α1-AR nuclear localization was confirmed in vivo using α1-AR-GFP transgenic mice. The α1-signaling partners Gαq and phospholipase Cβ1 also colocalized with α1-ARs only at the nuclear membrane. Furthermore, we observed rapid catecholamine uptake mediated by norepinephrine-uptake-2 and found that α1-mediated activation of ERK was not inhibited by a membrane impermeant α1-blocker, suggesting α1 signaling is initiated at the nucleus. Contrary to prior studies, we did not observe α1-AR localization to caveolae, but we found that α1-AR signaling initiated at the nucleus led to activated ERK localized to caveolae. In summary, our results show that nuclear α1-ARs transduce signals to caveolae at the plasma membrane in cardiac myocytes.

Original languageEnglish (US)
Pages (from-to)992-1000
Number of pages9
JournalCirculation research
Issue number9
StatePublished - Oct 24 2008
Externally publishedYes


  • Cardiac myocytes
  • ERK
  • α1-adrenergic receptors


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