Neuroserpin, a Brain-associated Inhibitor of Tissue Plasminogen Activator Is Localized Primarily in Neurons

Abstract

A cDNA clone for the serine proteinase inhibitor (serpin), neuroserpin, was isolated from a human whole brain cDNA library, and recombinant protein was expressed in insect cells. The purified protein is an efficient inhibitor of tissue type plasminogen activator (tPA), having an apparent second-order rate constant of 6.2 ؋ 10 5 M ؊1 s ؊1 for the two-chain form. However, unlike other known plasminogen activator inhibitors, neuroserpin is a more effective inactivator of tPA than of urokinase-type plasminogen activator. Neuroserpin also effectively inhibited trypsin and nerve growth factor-␥ but reacted only slowly with plasmin and thrombin. Northern blot analysis showed a 1.8 kilobase messenger RNA expressed predominantly in adult human brain and spinal cord, and immunohistochemical studies of normal mouse tissue detected strong staining primarily in neuronal cells with occasionally positive microglial cells. Staining was most prominent in the ependymal cells of the choroid plexus, Purkinje cells of the cerebellum, select neurons of the hypothalamus and hippocampus, and in the myelinated axons of the commissura. Expression of tPA within these regions is reported to be high and has previously been correlated with both motor learning and neuronal survival. Taken together, these data suggest that neuroserpin is likely to be a critical regulator of tPA activity in the central nervous system, and as such may play an important role in neuronal plasticity and/or maintenance.

Gene Expression of Metabolic Enzymes and a Protease Inhibitor in the Prefrontal Cortex Are Decreased in Schizophrenia

“…We evaluated the mRNA levels of these candidate genes by Q-PCR and found greater than 2.5-fold reductions for all three genes in the DLPFC of male patients with schizophrenia compared to controls, whereas the reductions were not found in females with schizophrenia. Interestingly, these genes appear to be highly expressed in neurons in the DLPFC, HINT1 by our ISH study, and MDH1 and neuroserpin by other ISH studies (6,18). Whether these three genes are coexpressed or co-dysregulated in the same neurons requires further study in specific neuronal populations.…”

“…There are reports of MDH1 and neuroserpin showing neuronal localization (6,18). HINT1 signal intensity on BioMax film was robust in DLPFC sections, indicating high brain expression in adult cortex.…”

Chronic relapsing experimental allergic encephalomyelitis (CREAE) in plasminogen activator inhibitor‐1 knockout mice: the effect of fibrinolysis during neuroinflammation

“…Furthermore, other PA inhibitors, such as macrophage-derived PAI-2, could compensate for loss of PAI-1 [49,50]. Neuroserpin, the CNS-specific tPA inhibitor [51,52], was not up-regulated during CREAE, although levels of this protein did significantly decrease during remission (30-40 dpi) in PAI-1 -/-mice, possibly representing complex formation with tPA during the chronic stages of disease.…”

Localization and Regulation of the Tissue Plasminogen Activator–Plasmin System in the Hippocampus

“…Protease expression is balanced by proteolytic inhibitors (Festoff et al, 1996;Osterwalder et al, 1996;Hastings et al, 1997;Jaworski and Fager, 2000;Hino et al, 2001;Kato et al, 2001). Given the neuronal roles of extracellular proteases and their inhibitors (Shiosaka and Yoshida, 2000), knowledge of their expression and regulation is critical to an understanding of neuronal communication, learning and memory, and certain instances of neuronal death.…”