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Title: The discovery and role of CD147 as a subunit of gamma-secretasecomplex.

Abstract

No abstract prepared.

Authors:
; ; ;
Publication Date:
Research Org.:
Ernest Orlando Lawrence Berkeley NationalLaboratory, Berkeley, CA (US)
Sponsoring Org.:
USDOE Director, Office of Science. Office of Biological andEnvironmental Research; National Institutes of Health (NIH)
OSTI Identifier:
901676
Report Number(s):
LBNL-59775
R&D Project: L0046; BnR: 400412000; TRN: US200715%%23
DOE Contract Number:
DE-AC02-05CH11231; NIH:R21 GM070511
Resource Type:
Journal Article
Resource Relation:
Journal Name: Drug News and Perspectives; Journal Volume: 19; Journal Issue: 3; Related Information: Journal Publication Date: 04/2006
Country of Publication:
United States
Language:
English
Subject:
59; ENZYMES; COMPLEXES; BIOLOGICAL FUNCTIONS

Citation Formats

Zhou, Shuxia, Zhou, Hua, Walian, Peter J., and Jap, Bing K. The discovery and role of CD147 as a subunit of gamma-secretasecomplex.. United States: N. p., 2006. Web. doi:10.1358/dnp.2006.19.3.985932.
Zhou, Shuxia, Zhou, Hua, Walian, Peter J., & Jap, Bing K. The discovery and role of CD147 as a subunit of gamma-secretasecomplex.. United States. doi:10.1358/dnp.2006.19.3.985932.
Zhou, Shuxia, Zhou, Hua, Walian, Peter J., and Jap, Bing K. Wed . "The discovery and role of CD147 as a subunit of gamma-secretasecomplex.". United States. doi:10.1358/dnp.2006.19.3.985932.
@article{osti_901676,
title = {The discovery and role of CD147 as a subunit of gamma-secretasecomplex.},
author = {Zhou, Shuxia and Zhou, Hua and Walian, Peter J. and Jap, Bing K.},
abstractNote = {No abstract prepared.},
doi = {10.1358/dnp.2006.19.3.985932},
journal = {Drug News and Perspectives},
number = 3,
volume = 19,
place = {United States},
year = {Wed Mar 01 00:00:00 EST 2006},
month = {Wed Mar 01 00:00:00 EST 2006}
}
  • {gamma}-secretase is a membrane protein complex that cleaves the {beta}-amyloid precursor protein (APP) within the transmembrane region, following prior processing by {beta}-secretase, producing amyloid {beta}-peptides (A{beta}{sub 40} and A{beta}{sub 42}). Errant production of A{beta}-peptides that substantially increases A{beta}{sub 42} production has been associated with the formation of amyloid plaques in Alzheimer's disease patients. Biophysical and genetic studies indicate that presenilin-1 (Psn-1), which contains the proteolytic active site, and three other membrane proteins, nicastrin (Nct), APH-1, and PEN-2 are required to form the core of the active {gamma}-secretase complex. Here, we report the purification of the native {gamma}-secretase complexes from HeLamore » cell membranes and the identification of an additional {gamma}-secretase complex subunit, CD147, a transmembrane glycoprotein with two immunoglobulin-like domains. The presence of this subunit as an integral part of the complex itself was confirmed through co-immunoprecipitation studies of the purified protein from HeLa cells and solubilized complexes from other cell lines such as neural cell HCN-1A and HEK293. Depletion of CD147 by RNA interference was found to increase the production of A{beta} peptides without changing the expression level of the other {gamma}-secretase components or APP substrates while CD147 overexpression had no statistically significant effect on amyloid {beta}-peptide production, other {gamma}-secretase components or APP substrates, indicating that the presence of the CD147 subunit within the {gamma}-secretase complex directly down-modulates the production of A{beta}-peptides. {gamma}-secretase was first recognized through its role in the production of the A{beta} peptides that are pathogenic in Alzheimer's disease (AD) (1). {gamma}-secretase is a membrane protein complex with unusual aspartyl protease activity that cleaves a variety of type I membrane proteins, such as APP, CD44, DCC, ErbB4, E-cadherin, LRP, N-cadherin, Nectin-1, and Notch, within their transmembranous regions (2-11); therefore, in addition to its role in AD, {gamma}-secretase has been found to participate in other important biological functions, such as intracellular signaling. {gamma}-secretase processing of APP requires prior removal of a major fragment of the APP extracellular domain (sAPP{sub {beta}}) by {beta}-secretase to yield a membrane bound fragment (APP CTF{sub {beta}}). Subsequent cleavage of this membrane bound fragment by {gamma}-secretase results in the release of the Alzheimer's disease (AD) associated amyloid {beta}-peptides (12). The proteolytic activity of {gamma}-secretase is found not to be critically dependent on the specific sequence, but instead on the size of the extracellular domain (13); such sequence independent characteristics of the substrate are reminiscent of those of the 26S proteasome complex that cleaves substrates in a non-sequence specific manner. {gamma}-secretase is present in almost all animal species, vertebrates and invertebrates; it is expressed in many human organs and tissues.« less
  • Alkylation of Torpedo californica purified nicotinic acetylcholine receptor (AChR) with N-phenylmaleimide (NPM) under nonreducing conditions led to ion flux inhibition without affecting ligand binding properties. The {gamma} subunit was shown to be preferentially labeled by ({sup 3}H)NPM with partial labeling of the {alpha} subunit at higher NPM concentrations. Alkylation occurs at cysteine residues as confirmed by amino acid analysis. Cyanogen bromide peptide mapping of the {gamma} subunit indicates that at least two residues corresponding to Cys-416, -420, or -451 are labeled. Residues 416 and 420 are part of the proposed amphipathic helix, and the functional role of these two cysteinesmore » is further investigated by site-directed mutagenesis of T. californica AChR cDNAs and expression of the mutants in Xenopus laevis oocytes following injection of SP6 transcripts. Several features of SP6 transcripts are shown to be important for efficient translation in vivo. Mutations Cys {yields} Ser{gamma}416,420 and Cys {yields} Phe{gamma}416 did not perturb either the receptor functional properties or its expression levels. The double mutant Cys {yields} Phe{gamma}416,420 displayed a 30% decrease of normalized AChR activity. The relatively small effect of large steric mutations in the amphipathic helix argues against its presence in the tightly packed transmembrane domain of the protein.« less
  • GABA{sub A} receptors are heterooligomeric ligand-gated ion channels that mediate the effect of the inhibitory neurotransmitter {gamma}-aminobutyric acid. The GABA{sub A} receptors consist of at least 15 different receptor subunits that can be classified into 5 subfamilies ({alpha},{beta},{gamma},{delta},{rho}) on the basis of sequence similarity. Chromosomal mapping studies have revealed that several of the GABA{sub A} receptor subunit genes appear to be organized as clusters. One such cluster, which consists of the GABA{sub A} receptor {beta}3 (GABRB3) and {alpha}5 (GABRA5) sub-unit genes, is located in chromosome 15q11-q13. It is shown here that the GABA{sub A} receptor {gamma}3 subunit gene (GABRG3) alsomore » maps to this region. Lambda and P1 phage clones surrounding both ends of GABRG3 were isolated; the clones derived from the 5{prime} end of GABRG3 were linked to an existing phage contig spanning the 3{prime} end of GABRA5. The two genes are located within 35 kb of each other and are transcribed in the same orientation. 39 refs., 4 figs.« less
  • The CD147 receptor plays an integral role in numerous diseases by stimulating the expression of several protein families and serving as the receptor for extracellular cyclophilins, however, neither CD147 nor its interactions with its cyclophilin ligands have been well characterized in solution. CD147 is a unique protein in that it can function both at the cell membrane and after being released from cells where it continues to retain activity. Thus, the CD147 receptor functions through at least two mechanisms that include both cyclophilin-independent and cyclophilin-dependent modes of action. In regard to CD147 cyclophilin-independent activity, CD147 homophilic interactions are thought tomore » underlie its activity. In regard to CD147 cyclophilin-dependent activity, cyclophilin/CD147 interactions may represent a novel means of signaling since cyclophilins are also peptidyl-prolyl isomerases.« less
  • CD147 is a type I transmembrane protein that is involved in inflammatory diseases, cancer progression, and multiple human pathogens utilize CD147 for efficient infection. In several cancers, CD147 expression is so high that it is now used as a prognostic marker. The two primary isoforms of CD147 that are related to cancer progression have been identified, differing in their number of immunoglobulin (Ig)-like domains. These include CD147 Ig1-Ig2 that is ubiquitously expressed in most tissues and CD147 Ig0-Ig1-Ig2 that is retinal specific and implicated in retinoblastoma. However, little is known in regard to the retinal specific CD147 Ig0 domain despitemore » its potential role in retinoblastoma. Thus, here we have extensively characterized the CD147 Ig0 domain by elucidating its three-dimensional structure through crystallography and its solution behavior through several biophysical methods that include nuclear magnetic resonance. Furthermore, we have utilized this data together with mutagenesis to probe the biological activity of CD147-containing proteins both with and without the CD147 Ig0 domain within several model cell lines. Our findings reveal that the CD147 Ig0 domain is a potent stimulator of interleukin-6, which is a well-known contributor to retinoblastoma and suggest that the CD147 Ig0 domain has its own receptor distinct from that of the other CD147 Ig-like domains, CD147 Ig1-Ig2. Furthermore, we show that the CD147 Ig0 dimer is the functional unit required for activity and can be disrupted by a single point mutation.« less