Rectal epithelial expression of protein kinase A phosphorylation of cystic fibrosis transmembrane conductance regulator

Mrinalini C. Rao, Grace B. Bissonnette, Teresa Mahaffey, William B Guggino, Jay L. Goldstein

Research output: Contribution to journalArticle

Abstract

Background/Aims: Human rectal epithelium in cystic fibrosis (CF) shows impaired ion transport in response to theophylline or bethanechol, although it possesses regulatory subunits of adenosine cyclic 3′,5′-monophosphate (cAMP)-dependent protein kinase (protein kinase A). Protein kinase A-specific phosphorylation of CF transmembrane conductance regulator (CFTR) in rectal tissues of control and CF volunteers was examined in this study. Methods: CFTR was evaluated using a polyclonal antiserum (pre-NBF) raised against a peptide corresponding to residues 415-427 of CFTR. Microsomal membranes from normal and CF rectal mucosa and from T-84 cells were incubated with [γ32P]-adenosine triphosphate ± protein kinase A and subjected to immunoblotting with pre-NBF and autoradiography. Results: Pre-NBF recognized a single band of 180 kilodaltons. Protein kinase A altered phosphorylation of this 180-kilodalton band 1.4-, 2.2- and 0.9-fold in T-84, normal, and CF rectal membranes, respectively. Catalytic activities of protein kinase A, Ca2+ calmodulin protein kinase, or protein kinase C in control and CF tissues were similar. Conclusions: cAMP and Ca2+-signaling pathways are normal up to the kinases in CF rectal mucosa. Our results suggest differences in CFTR phosphorylation in normal and CF rectal mucosal membranes.

Original languageEnglish (US)
Pages (from-to)890-898
Number of pages9
JournalGastroenterology
Volume106
Issue number4
StatePublished - 1994

    Fingerprint

ASJC Scopus subject areas

  • Gastroenterology

Cite this