Hydrostatic pressure-dependent changes in cyclic AMP signaling in optic nerve head astrocytes from Caucasian and African American donors.
OBJECTIVE
Investigate the effect of hydrostatic pressure (HP) on 3', 5'-cyclic adenosine monophosphate (cAMP) levels and downstream signaling in cultures of normal optic nerve head (ONH) astrocytes from Caucasian American (CA) and African American (AA) donors.


METHODS
Intracellular cAMP levels were assayed after exposing ONH astrocytes to HP for varying times. Quantitative RT-PCR was used to determine the expression levels of selected cAMP pathway genes in human ONH astrocytes after HP treatment. Western blots were used to measure changes in the phosphorylation state of cAMP response element binding protein (CREB) in astrocytes subjected to HP, ATP, and phosphodiesterase or kinase inhibitors.


RESULTS
The basal intracellular cAMP level is similar among AA and CA astrocytes. After exposure to HP for 15 min and 30 min in the presence of a phosphodiesterase inhibitor a further increase of intracellular cAMP was observed in AA astrocytes, but not in CA astrocytes. Consistent with activation of the cAMP-dependent protein kinase pathway, CREB phosphorylation (Ser-133) was increased to a greater extent in AA than in CA astrocytes after 3 h of HP. Exposure to elevated HP for 3-6 h differentially altered the expression levels of selected cAMP pathway genes (ADCY3, ADCY9, PTHLH, PDE7B) in AA compared to CA astrocytes. Treatment with ATP increased more CREB phosphorylation in CA than in AA astrocytes, suggesting differential Ca(2+) signaling in these populations.


CONCLUSIONS
Activation of the cAMP-dependent signaling pathway by pressure may be an important contributor to increased susceptibility to elevated intraocular pressure and glaucoma in AA, a population at higher risk for the disease.
Chen
Lin
L
Department of Ophthalmology, Northwestern University, Feinberg School of Medicine, Chicago, IL 60611, USA.
Lukas
Thomas J
TJ
Hernandez
M Rosario
MR
D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000494:pharmacology; D000262:Adenylyl Cyclases / Q000235:genetics / Q000378:metabolism; D000328:Adult; D001741:Black or African American; D000368:Aged; D001253:Astrocytes / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects; D000242:Cyclic AMP / Q000378:metabolism*; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D054708:Cyclic Nucleotide Phosphodiesterases, Type 7 / Q000235:genetics / Q000378:metabolism; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D006874:Hydrostatic Pressure; D007546:Isoquinolines / Q000494:pharmacology; D008297:Male; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism; D008875:Middle Aged; D009898:Optic Disk / Q000166:cytology*; D044162:Parathyroid Hormone-Related Protein / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics; D013449:Sulfonamides / Q000494:pharmacology; D014019:Tissue Donors; D044465:White People
D048868:Adaptor Proteins, Signal Transducing; C484231:CAP2 protein, human; D017362:Cyclic AMP Response Element-Binding Protein; D007546:Isoquinolines; D008565:Membrane Proteins; C470121:PTHLH protein, human; D044162:Parathyroid Hormone-Related Protein; D012333:RNA, Messenger; D013449:Sulfonamides; D000255:Adenosine Triphosphate; D000242:Cyclic AMP; D054708:Cyclic Nucleotide Phosphodiesterases, Type 7; C517463:PDE7B protein, human; D000262:Adenylyl Cyclases; C063509:N-(2-(4-bromocinnamylamino)ethyl)-5-isoquinolinesulfonamide