Activation of cyclic AMP Signaling in Ae2-deficient mouse fibroblasts.
Anion exchanger 2 (AE2, SLC4A2) is a ubiquitously expressed membrane solute carrier that regulates intracellular pH (pH(i)) by exchanging cytosolic bicarbonate for extracellular chloride. We used fibroblasts from Ae2-deficient (Ae2(a,b)(-/-)) mice to study the effects of an alkaline shift in resting intracellular pH (pH(i)) on the activation of cAMP signaling and gene expression. Ae2(a,b)(-/-) fibroblasts show increased pH(i) (by 0.22 +/- 0.03 unit) compared with wild type cells at extracellular pH (pH(o)) 7.4 and 37 degrees C. This shift in resting pH(i) is associated with an up-regulation of bicarbonate-activated soluble adenylyl cyclase expression, increased cAMP production, Creb phosphorylation, inducible cAMP early repressor 1 mRNA expression, and impaired activation of c-Fos transcription by forskolin. These results highlight the importance of bicarbonate transport via Ae2 in maintaining pH(i) homeostasis in cultured mouse fibroblasts and unveil the role of cAMP in the cellular response to chronic alkalization, which putatively includes an inducible cAMP early repressor 1-mediated attenuation of phosphorylated Creb activity.
Mardones
Pablo
P
Academic Medical Center Liver Center, Academic Medical Center, University of Amsterdam, 1105 BK, Amsterdam, The Netherlands.
Medina
Juan F
JF
Elferink
Ronald P J Oude
RP
D000262:Adenylyl Cyclases / Q000096:biosynthesis / Q000235:genetics; D000818:Animals; D027321:Anion Transport Proteins / Q000172:deficiency* / Q000378:metabolism; D017920:Antiporters / Q000172:deficiency* / Q000378:metabolism; D027963:Chloride-Bicarbonate Antiporters; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000096:biosynthesis / Q000378:metabolism*; D051786:Cyclic AMP Response Element Modulator / Q000235:genetics / Q000378:metabolism; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D004790:Enzyme Induction / Q000187:drug effects; D005347:Fibroblasts / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000187:drug effects; D006863:Hydrogen-Ion Concentration / Q000187:drug effects; D007700:Kinetics; D008297:Male; D051379:Mice; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D064606:SLC4A Proteins; D015398:Signal Transduction / Q000187:drug effects; D012995:Solubility / Q000187:drug effects
D027321:Anion Transport Proteins; D017920:Antiporters; D027963:Chloride-Bicarbonate Antiporters; D017362:Cyclic AMP Response Element-Binding Protein; D010750:Phosphoproteins; D016760:Proto-Oncogene Proteins c-fos; D012333:RNA, Messenger; D064606:SLC4A Proteins; C579495:Slc4a2 protein, mouse; D051786:Cyclic AMP Response Element Modulator; D005576:Colforsin; D000242:Cyclic AMP; D000262:Adenylyl Cyclases