Proteolytic cleavage of human acid-sensing ion channel 1 by the serine protease matriptase.
Acid-sensing ion channel 1 (ASIC1) is a H(+)-gated channel of the amiloride-sensitive epithelial Na(+) channel (ENaC)/degenerin family. ASIC1 is expressed mostly in the central and peripheral nervous system neurons. ENaC and ASIC function is regulated by several serine proteases. The type II transmembrane serine protease matriptase activates the prototypical alphabetagammaENaC channel, but we found that matriptase is expressed in glioma cells and its expression is higher in glioma compared with normal astrocytes. Therefore, the goal of this study was to test the hypothesis that matriptase regulates ASIC1 function. Matriptase decreased the acid-activated ASIC1 current as measured by two-electrode voltage clamp in Xenopus oocytes and cleaved ASIC1 expressed in oocytes or CHO K1 cells. Inactive S805A matriptase had no effect on either the current or the cleavage of ASIC1. The effect of matriptase on ASIC1 was specific, because it did not affect the function of ASIC2 and no matriptase-specific ASIC2 fragments were detected in oocytes or in CHO cells. Three matriptase recognition sites were identified in ASIC1 (Arg-145, Lys-185, and Lys-384). Site-directed mutagenesis of these sites prevented matriptase cleavage of ASIC1. Our results show that matriptase is expressed in glioma cells and that matriptase specifically cleaves ASIC1 in heterologous expression systems.
Clark
Edlira B
EB
Department of Physiology and Biophysics, University of Alabama at Birmingham, Birmingham, Alabama 35294.
Jovov
Biljana
B
Department of Medicine, University of North Carolina, Chapel Hill, North Carolina 27599.
Rooj
Arun K
AK
Department of Physiology and Biophysics, University of Alabama at Birmingham, Birmingham, Alabama 35294.
Fuller
Catherine M
CM
Department of Physiology and Biophysics, University of Alabama at Birmingham, Birmingham, Alabama 35294.
Benos
Dale J
DJ
Department of Physiology and Biophysics, University of Alabama at Birmingham, Birmingham, Alabama 35294. Electronic address: benos@uab.edu.
D062565:Acid Sensing Ion Channels; D000818:Animals; D001253:Astrocytes / Q000378:metabolism; D016466:CHO Cells; D045744:Cell Line, Tumor; D006224:Cricetinae; D003412:Cricetulus; D053503:Epithelial Sodium Channels / Q000235:genetics / Q000378:metabolism; D005910:Glioma / Q000235:genetics / Q000378:metabolism; D006801:Humans; D016297:Mutagenesis, Site-Directed; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D009474:Neurons / Q000378:metabolism*; D009865:Oocytes; D017933:Peripheral Nervous System / Q000378:metabolism*; D012697:Serine Endopeptidases / Q000235:genetics / Q000378:metabolism*; D015222:Sodium Channels / Q000235:genetics / Q000378:metabolism*; D014981:Xenopus
C568266:ASIC1 protein, human; D062565:Acid Sensing Ion Channels; D053503:Epithelial Sodium Channels; D009419:Nerve Tissue Proteins; D015222:Sodium Channels; D012697:Serine Endopeptidases; C485596:ST14 protein, human