Rho GTPase signaling regulates tight junction assembly and protects tight junctions during ATP depletion.
Tight junctions control paracellular permeability and cell polarity. Rho GTPase regulates tight junction assembly, and ATP depletion of Madin-Darby canine kidney (MDCK) cells (an in vitro model of renal ischemia) disrupts tight junctions. The relationship between Rho GTPase signaling and ATP depletion was examined. Rho inhibition resulted in decreased localization of zonula occludens-1 (ZO-1) and occludin at cell junctions; conversely, constitutive Rho signaling caused an accumulation of ZO-1 and occludin at cell junctions. Inhibiting Rho before ATP depletion resulted in more extensive loss of junctional components between transfected cells than control junctions, whereas cells expressing activated Rho better maintained junctions during ATP depletion than control cells. ATP depletion and Rho signaling altered phosphorylation signaling mechanisms. ZO-1 and occludin exhibited rapid decreases in phosphoamino acid content following ATP depletion, which was restored on recovery. Expression of Rho mutant proteins in MDCK cells also altered levels of occludin serine/threonine phosphorylation, indicating that occludin is a target for Rho signaling. We conclude that Rho GTPase signaling induces posttranslational effects on tight junction components. Our data also demonstrate that activating Rho signaling protects tight junctions from damage during ATP depletion.
Gopalakrishnan
S
S
Department of Medicine, Division of Nephrology, Indiana University Medical Center, Indianapolis, Indiana 46202-5116, USA.
Raman
N
N
Atkinson
S J
SJ
Marrs
J A
JA
D000255:Adenosine Triphosphate / Q000378:metabolism*; D000596:Amino Acids / Q000378:metabolism; D000818:Animals; D002460:Cell Line; D004285:Dogs; D020558:GTP Phosphohydrolases / Q000378:metabolism; D020690:GTPase-Activating Proteins; D007511:Ischemia; D007668:Kidney; D007700:Kinetics; D008565:Membrane Proteins / Q000032:analysis / Q000096:biosynthesis*; D008954:Models, Biological; D062793:Occludin; D010766:Phosphorylation; D011506:Proteins / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism; D012079:Renal Circulation; D015398:Signal Transduction / Q000502:physiology*; D019108:Tight Junctions / Q000502:physiology*; D014162:Transfection
D000596:Amino Acids; D020690:GTPase-Activating Proteins; D008565:Membrane Proteins; D062793:Occludin; D011506:Proteins; D011994:Recombinant Proteins; D000255:Adenosine Triphosphate; D020558:GTP Phosphohydrolases