Matrix Metalloproteinase (MMP) Proteolysis of the Extracellular Loop of Voltage-gated Sodium Channels and Potential Alterations in Pain Signaling.
Congenital insensitivity to pain (CIP) or congenital analgesia is a rare monogenic hereditary condition. This disorder is characterized by the inability to perceive any form of pain. Nonsense mutations in Nav.1.7, the main pain signaling voltage-gated sodium channel, lead to its truncations and, consequently, to the inactivation of the channel functionality. However, a non-truncating homozygously inherited missense mutation in a Bedouin family with CIP (Nav1.7-R907Q) has also been reported. Based on our currently acquired in-depth knowledge of matrix metalloproteinase (MMP) cleavage preferences, we developed the specialized software that predicts the presence of the MMP cleavage sites in the peptide sequences. According to our in silico predictions, the peptide sequence of the exposed extracellular unstructured region linking the S5-S6 transmembrane segments in the DII domain of the human Nav1.7 sodium channel is highly sensitive to MMP-9 proteolysis. Intriguingly, the CIP R907Q mutation overlaps with the predicted MMP-9 cleavage site sequence. Using MMP-9 proteolysis of the wild-type, CIP, and control peptides followed by mass spectrometry of the digests, we demonstrated that the mutant sequence is severalfold more sensitive to MMP-9 proteolysis relative to the wild type. Because of the substantial level of sequence homology among sodium channels, our data also implicate MMP proteolysis in regulating the cell surface levels of the Nav1.7, Nav1.6, and Nav1.8 channels, but not Nav1.9. It is likely that the aberrantly accelerated MMP-9 proteolysis during neurogenesis is a biochemical rational for the functional inactivation in Nav1.7 and that the enhanced cleavage of the Nav1.7-R907Q mutant is a cause of CIP in the Bedouin family.
From the Sanford-Burnham Medical Research Institute, La Jolla, California 92037.
Albert G
AG
Remacle
From the Sanford-Burnham Medical Research Institute, La Jolla, California 92037.
Sonu
S
Kumar
From the Sanford-Burnham Medical Research Institute, La Jolla, California 92037.
Khatereh
K
Motamedchaboki
From the Sanford-Burnham Medical Research Institute, La Jolla, California 92037.
Piotr
P
Cieplak
the Department of Anesthesiology, University of California San Diego, La Jolla, California 92093, and the Veterans Affairs San Diego Healthcare System, La Jolla, California 92037.
Swathi
S
Hullugundi
the Department of Anesthesiology, University of California San Diego, La Jolla, California 92093, and the Veterans Affairs San Diego Healthcare System, La Jolla, California 92037.
Jennifer
J
Dolkas
the Department of Anesthesiology, University of California San Diego, La Jolla, California 92093, and the Veterans Affairs San Diego Healthcare System, La Jolla, California 92037.
Veronica I
VI
Shubayev
From the Sanford-Burnham Medical Research Institute, La Jolla, California 92037, strongin@sanfordburnham.org.
Alex Y
AY
Strongin
D019943:Amino Acid Substitution; D006801:Humans; D020780:Matrix Metalloproteinase 9 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D020125:Mutation, Missense; D010146:Pain / Q000235:genetics / Q000378:metabolism*; D000699:Pain Insensitivity, Congenital / Q000235:genetics / Q000378:metabolism*; D017433:Protein Structure, Secondary; D059748:Proteolysis; D015398:Signal Transduction; D061566:Voltage-Gated Sodium Channels / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
D061566:Voltage-Gated Sodium Channels; C579270:MMP9 protein, human; D020780:Matrix Metalloproteinase 9
MMP-9; Nav1.7; matrix metalloproteinase (MMP); missense mutations; mutant; pain; pain signaling; protease; proteolysis; sodium channel; voltage-gated sodium channels