Involvement of Matrix Metalloproteinase-Mediated Proteolysis of Neural Cell Adhesion Molecule in the Development of Cerebral Ischemic Neuronal Damage

Abstract

Neural cell adhesion molecule (NCAM) is a membrane protein abundantly expressed in the central nervous system. Recently, it has been reported that dysfunction of NCAM is linked to human brain disorders. Furthermore, NCAM is one of the proteolysis targets of matrix metalloproteinase (MMP), whose activation is implicated in neuronal damage. The aim of this study was to elucidate the involvement of MMP-mediated proteolysis of NCAM in the development of ischemic neuronal damage. Male ddY and MMP-9 knockout (KO) C57BL/6J mice were subjected to 2 h of middle cerebral artery occlusion (MCAO). In MCAO model mice, development of infarction and behavioral abnormality were clearly observed on days 1 and 3 after MCAO. Protein levels of MMP-2 and MMP-9 were significantly increased on days 1 and 3 after MCAO. In addition, full-length NCAM (180 kDa) was significantly decreased, but its metabolite levels increased on day 1 by ischemic stress per se. NCAM small interfering RNA significantly increased the neuronal damage induced by MCAO. MMP inhibition or MMP-9 gene KO attenuated the infarction, behavioral abnormalities, and decrease of NCAM (180 kDa) observed after MCAO in mice. The present findings clearly suggest that MMP-2/MMP-9-mediated NCAM proteolysis is implicated in the exacerbation of ischemic neuronal damage.

Prolyl endopeptidase is involved in the degradation of neural cell adhesion molecules in vitro

“…Decreased full-length NCAM180 has been described in mice 1 day after middle cerebral artery occlusion (Shichi et al, 2011). Moreover, it has been shown that in the processes of demyelinating neuroinflammation resulting from the autoimmune encephalomyelitis, the level of MMP-2 was significantly increased in hippocampus, which was accompanied by reduced levels of NCAM (Jovanova-Nesic and Shoenfeld, 2006).…”

“…Previous studies have demonstrated that several metalloproteases, such as MMP-2 and MMP-9, as well as the ADAM family of metalloproteases, target NCAM (Brennaman et al, 2014;Hinkle et al, 2006;Hübschmann et al, 2005;Shichi et al, 2011). It has also been shown that inhibition of MMP-2 and MMP-9 prevents NCAM shedding, indicating the roles of these MMPs in NCAM cleavage (Hübschmann et al, 2005;Shichi et al, 2011). Moreover, ADAM-10-dependent shedding of NCAM has been extensively studied, and the second fibronectin-type III domain of NCAM has been shown to be a target for ADAM-10 cleavage (Brennaman et al, 2014).…”

“…In addition to the aforementioned fragments cleaved by ADAMs, a 65 kDa degradation product of NCAM has been demonstrated to result from the action of MMP-9 and/or MMP-2 after cerebral ischemic neuronal damage and the appearance of this fragment was reduced when MMPs were suppressed (Shichi et al, 2011). The precise cleavage site through which these smaller fragments are produced is not known; however, it might be proposed that the origin of the fragment found in cell culture medium might represent an N-terminal domain of NCAM.…”

“…Therefore, it seemed unlikely that PREP itself is able to degrade NCAM. It has been demonstrated previously that NCAM molecule degradation might be mediated by the matrix metalloproteases (MMPs) (Brennaman et al, 2014;Hinkle et al, 2006;Hübschmann et al, 2005;Shichi et al, 2011). Therefore, to test whether increased expression and activity of PREP might be involved in the activation of MMPs, we measured the expression levels and activity of MMP-9.…”

TRPM7, the cytoskeleton and neuronal death

“…In this regard, recent reports have revealed the breakdown of Neural Cell Adhesion Molecule (NCAM) as a functional consequence of injury caused by middle cerebral artery occlusion. 135,136 A noteworthy finding in the N1E-115 neuroblastoma cell line was the involvement of TRPM7 in the development of podosomes. While these actin-based protrusions have been suggested to contribute toward tissue invasiveness during malignancy, 137 they are also thought to be mediators of cell adhesion.…”