Chapter 44 Cellular and molecular models of neuron-matrix adhesion in nerve fiber growth

Journal of Neurochemistry

Pearson

et al. 2002

Neuroserpin is a serine protease inhibitor widely expressed in the developing and adult nervous systems and implicated in the regulation of proteases involved in processes such as synaptic plasticity, neuronal migration and axogenesis. We have analysed the effect of neuroserpin on growth factorinduced neurite outgrowth in PC12 cells. We show that small changes in neuroserpin expression result in changes to the number of cells extending neurites and total neurite length following NGF treatment. Increased expression of neuroserpin resulted in a decrease in the number of cells extending neurites and a reduction in total free neurite length whereas reduced levels of neuroserpin led to a small increase in the number of neurite extending cells and a significant increase in total free neurite length compared to the parent cell line. Neuroserpin also altered the response of PC12 cells to bFGF and EGF treatment. Neuroserpin was localised to dense cored secretory vesicles in PC12 cells but was unable to complex with its likely enzyme target, tissue plasminogen activator at the acidic pH found in these vesicles. These data suggest that modulation of neuroserpin levels at the extending neurite growth cone may play an important role in regulating axonal growth.

“…tPA has been shown to degrade extracellular matrix proteins involved in neurite outgrowth (Carbonetto et al . 1983; Carbonetto et al . 1988; Alexander and Werb 1989; Seeds et al .…”

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Neuroserpin regulates neurite outgrowth in nerve growth factor‐treated PC12 cells

Journal of Neurochemistry

Pearson

et al. 2002

“…Neurite extension is likely to involve either direct or indirect modulation of the interaction between the extending growth cone and the extracellular matrix. Laminin and other extracellular matrix proteins are involved in neurite outgrowth 46–49. tPA, which is inhibited by neuroserpin in vitro , has been shown to degrade extracellular matrix proteins,50,51 suggesting that increased neurite outgrowth in AtT20 cell lines overexpressing neuroserpin could be a response to reduced extracellular matrix degradation mediated by reduced tPA enzymatic activity.…”

Section: Overexpression Of Neuroserpin In An Anterior Pituitary Cortimentioning

confidence: 99%

Expression and Functional Characterization of the Serine Protease Inhibitor Neuroserpin in Endocrine Cells

Hill

Annals of the New York Academy of Sciences

et al. 2002

Serine proteases play essential roles in a wide variety of cellular processes in endocrine cells. There is a growing interest in the roles of serine protease inhibitors, or serpins, as key regulators of their activity. We have cloned two neuroserpin cDNAs from a rat pituitary cDNA library and confirmed tissue plasminogen activator as a potential target for this inhibitor. We show that neuroserpin transcripts are expressed by endocrine cells in the adrenal and pituitary glands and that immunoreactive neuroserpin is stored in densely cored secretory granules in these cells. Overexpression of neuroserpin in an anterior pituitary corticotroph cell line results in the extension of neurite-like processes, suggesting that neuroserpin may play a role in cell communication, cell adhesion, and/or cell migration.

“…Presumably it involves either direct or indirect modulation of the interaction between the extending growth cone and the extracellular matrix. Laminin and other extracellular-matrix proteins have been shown to be involved directly in neurite outgrowth [29][30][31][32]. tPA, a serine protease that is inhibited by neuroserpin in itro [17,33], has been shown to degrade extracellular-matrix proteins [34,35].…”

Section: Figure 6 Measurement Of Tpa Levels In Att-20 and Nsat-2 Cell Lines By Zymographymentioning

confidence: 99%

Neuroserpin is expressed in the pituitary and adrenal glands and induces the extension of neurite-like processes in AtT-20 cells

Hill

et al. 2000

Biochemical Journal

Two cDNAs encoding the serine protease inhibitor (serpin) neuroserpin were cloned from a rat pituitary cDNA library (rNS-1, 2922 bp; rNS-2, 1599 bp). In situ hybridization histochemistry showed neuroserpin transcripts in the intermediate, anterior and posterior lobes of the pituitary gland and medullary cells in the adrenal gland. Expression of rNS-1 mRNA was restricted to selected cells in the pituitary gland. Analysis of purified secretory-granule fractions from pituitary and adrenal tissues indicated that neuroserpin was found in dense-cored secretory granules. This result suggested that endocrine neuroserpin may regulate intragranular proteases or inhibit enzymes following regulated secretion. To investigate the function of neuroserpin in endocrine tissues we established stable anterior pituitary AtT-20 cell lines expressing neuroserpin. Cells with increased levels of neuroserpin responded by extending neurite-like processes. Extracellular proteolysis by serine protease plasminogen activators has been suggested to regulate neurite outgrowth. As neuroserpin inhibits tissue plasminogen activator (tPA) in vitro, we measured plasminogen-activator levels. Zymographic analysis indicated that AtT-20 cells synthesized and secreted a plasminogen activator identical in size to tPA. A higher-molecular-mass tPA-neuroserpin complex was also observed in AtT-20-cell conditioned culture medium. tPA levels were similar in parent AtT-20 cells and a stable cell line with increased levels of neuroserpin. There was no accumulation of a tPA-neuroserpin complex. Together these results identify endocrine cells as an important source of neuroserpin. Moreover they suggest that neuroserpin is released from dense-cored secretory granules to regulate cell-extracellular matrix interactions through a mechanism that may not directly involve tPA.