Purification and characterization of NCAD90, a Soluble endogenous form of N‐cadherin, which is generated by proteolysis during retinal development and retains adhesive and neurite‐promoting function

Abstract

The cadherins are calcium-dependent cell adhesion molecules which regulate cell-cell interactions during morphogenesis. During development, cadherin expression is subject to dynamic patterns of regulation. We have previously demonstrated that expression of N-cadherin, the predominant cadherin of neural tissues, is sharply down-regulated during development of the retina and brain during later stages of histogenesis (Lagunowich and Grunwald, Dev Biol 135:158-171, 1989; Lagunowich et al., J Neurosci Res 32:202-208, 1992), and that this down-regulation is due to multiple factors, including decreased mRNA levels and turnover apparently mediated by endogenous metalloproteolytic activity (Roark et al., Development 114:973-984, 1992). In the present study, we describe metabolic studies which provide direct biochemical evidence for turnover of 130-kDa N-cadherin in embryonic retina tissues, yielding a soluble 90-kDa N-terminal fragment. We demonstrate that this form of N-cadherin, which we refer to as NCAD90, accumulates in vivo during development. We further demonstrate that purified NCAD90, obtained from embryonic vitreous humor, retains biological function and promotes cell adhesion and neurite growth in a dose-dependent fashion among chick embryo neural retina cells when present in a substrate-bound form. The morphology of retinal cells and neurites grown on a substrate of NCAD90 differs strikingly from that seen on a laminin substrate, in a manner similar to that described for intact 130-kDa N-cadherin. We conclude that proteolysis of N-cadherin at the cell surface during embryonic retinal histogenesis is an endogenous mechanism for regulating N-cadherin expression which generates a novel and functional form of the protein. The results further indicate that an intact cytoplasmic domain is not essential for all cadherin functions.

Soluble N-cadherin fragment promotes angiogenesis

“…Different proteases have already been described which are able to cleave N-cadherin extracellularly, like MMP [23] and ADAM10 (protein with a disintegrin and a metalloprotease domain) [40], giving rise to a 90-kDa sN-CAD fragment. Other proteases like presenilin/c-secretase [41] and caspase-3 [42] are able to cleave N-cadherin intracellularly.…”

“…Similar soluble fragments are released from cells expressing N-cadherin (sN-CAD), and they also exert regulatory functions, such as during neurite outgrowth in the retina of the chick embryo [23]. The aim of the present study was to identify a possible effect of sN-CAD on angiogenesis.…”

Role of tissue stroma in cancer cell invasion

“…Fulllength N-cadherin (130 kDa) might be proteolytically cleaved into a 40 kDa membrane-associated fragment and a 90 kDa amino-terminal fragment (soluble N-cadherin = sN-CAD) that is released in the ECM. Purified sN-CAD coated on plastic promotes neurite outgrowth [166], indicating that sN-CAD may conserve its activity as an adhesive ligand when attached to the ECM. A chimeric molecule consisting of sN-CAD fused to the Fc fragment of human IgG promotes neurite outgrowth in a fibroblast growth factor receptor [167].…”

Extracellular Cleavage of Cadherin-11 by ADAM Metalloproteases Is Essential forXenopusCranial Neural Crest Cell Migration

“…For example, although the extracellular fragment of E-cadherin was shown to decrease cell-cell adhesion in vitro, the extracellular fragment of N-cadherin promotes neural cell-cell adhesion in chick embryos (Paradies and Grunwald, 1993;Noe et al, 2001). Thus, the expression of specific cadherins along with the generation of their cleavage fragments seems to play an active role in mediating a specific cellular response, such as cell migration.…”