@article{3097004e346742afac96a8e1939da9b8,
title = "Calreticulin is transcriptionally upregulated by heat shock, calcium and heavy metals",
abstract = "Calreticulin is a new human rheumatic disease-associated autoantigen that plays a multifaceted role in cell biology. In earlier studies, this protein was shown to share an intimate relationship with the Ro/SS-A autoantigen complex, although the nature of this association continues to be debated. Since modulation of the Ro/SS-A autoantigen in epidermal keratinocytes has been implicated in the pathogenesis of subacute cutaneous lupus erythematosus and neonatal lupus erythematosus, we have begun to examine the transcriptional regulation of calreticulin. A 504 bp calreticulin promoter fragment was subcloned into a reporter gene plasmid containing firefly luciferase. Calcium ionophore, heat shock, and heavy metals such as zinc and cadmium were consistently found to increase calreticulin transcriptional activities in A431 cells (a human epidermoid squamous carcinoma cell line) under transient transfection conditions. These studies suggest that (a) calreticulin is regulated at the transcriptional level, and (b) calreticulin, like some other LE-related autoantigens, appears to function as a heat shock/stress-response gene.",
keywords = "Heat shock protein, calreticulin, keratinocyte, luciferase, transcriptional regulation",
author = "Nguyen, {Tho Q.} and Capra, {J. Donald} and Sontheimer, {Richard D.}",
note = "Funding Information: moter fragmentu sed in our experimentsT. hese MREs et al., 1992;L ieu and Sontheimer,1 995)( datareviewed have been shown to confer heavy metal-dependent in Sontheimeert al., 1995)R. OSS-A antibodiesa ref ound expressionto metallothionein(sS earlee t al., 1984S; tuart in high prevalencein SCLE and NLE, and are thought et al., 1985).C R transcriptionala ctivity is upregulated to play a major role in thep athogenesiosf thes kinlesions by zinc, and cadmium.H owever,i t doesn ot respondt o in thesed iseasebs y virtue of the fact that skin lesionsi n copper.M etallothioneinsa re thoughtt o play an impor-infants with NLE often resolvea t the samet ime that tant role in protectingc ellsa gainstm etalt oxicity and in these maternally-deriveda ntibodiesare cleared from zinc and copper homeostasis(H amer, 1986).C R might their circulation.M oreover, therei s evidences uggestive play a similar role as metallothioneinsin metal detox-of thei nvolvemenot f thesea ntibodiesw ith thec ongenital ification. CR has not beens hown to bind heavym etals heart block found in thesei nfants (reviewedi n Zappi othert hanz inc. However,m obilferrin,a CR homologue, and Sontheimer1, 993)E. lsewherew, e haves hownt hata has been reportedt o bind cobalt, lead, iron, as well as subpopulationo f cytoplasmicC R is associatedw ith hY zinc (Conrad and Umbreit, 1993)I.t is thereforep ossible RNA and that it is this subpopulationo f CR molecules that CR may have similar affinitiesf or thesem etalsa s that are bound by ROSS-A antibodies( Lieu and Son-well. theimer,1 995)O. ne would wonder how thesem olecules Recently, Conway et al. (1995) demonstratedt he aree xposedt o the immunes ystema nd ultimatelyl eadt o induciblee ffecto f heats hocko n the expressiono f CR at cell or antibody-mediatedc ytotoxicity. Several inves-the mRNA level.I n our studies,w e showedf urther that tigatorsh aved emonstratetdh ats tresss ucha su ltraviolet-CR respondst o a variety of heat shock inducers( heat, B (UV-B) irradiation can induce the displacemenot f heavy metals,a nd calcium).S ince heavy metalsi nduce intracellular ROSS-A antigens to the cell surface CR transcriptional activities similarly to heat in a (LeFebere t al., 1984F; urukawae t al., 1990J;o nes, 1992; reporterg enes ystemi n term of stimulationi ndex, it is Golan et al., 1992)a nd thereforea llow ROSS-A anti-likely that one would seea n increasein CR mRNA level bodiesa ccesst o thesea utoantigensR. ecently,C asciola-with heavym etalsa s well. Likewise,c alciumw ould also Rosen et al. (1994)h ave shown that UV-B irradiation induceC R mRNA but at a lower level. induces apoptosis in cultured keratinocytesa nd that The CR promoter sharesh omology with other pro-ROSS-A antigensa rec lustereda longw ith someE R com-moters of ER proteins such as BiP (GRP78), GRP94, ponent(s)in cludingC R in the surfaceb lebso f apoptotic and proteind isulfidei somerase(M cCauliffe et al., 1992). cells (Casciola-Rosene t al., 1994;R osen et al., 1994). Theseg lucose-responsivper oteins( GRP) like HSP70 are This mightb e anotherm echanismb y whicht hen ormally stressp roteinsa nd are thoughtt o play a role in protein sequestereRdO SS-A antigens( and CR) are exposedt o transport,f olding and/or assembly( Sorgera nd Pelham, the immunes ystem.S everalg roupsh avef ound that the 1987;R othman, 1989)L. ikewise,C R hasb eens uggested expressiono f CR on the cell surfacec an be inducedb y to play a chaperoner ole (Guan et al., 1991;D upuis et UV-B irradiation (Casciola-Rosene t al., 1994;K awa-al., 1993).I dentifying CR as a stressr esponseg ene is shima et al., 1994; Newkirk and Tsoukas, 1992). consistenwt ith its functiona s a chaperoneC. R mighta ct However, to date, we have been unablet o consistently similarlyt o HSPs to protectc ellsf rom adversec onditions induceC R transcriptionaal ctivity in responset o UV-B by binding to and facilitating the destruction of with the 504 bp promoter fragmentu sedi n this study. denaturedp roteins. We are currently isolatinga longer promoter fragment Another interestinga spectr egardingH SPs is that they to investigatet he possibility of the existenceo f a UV have been suggestedto have a close relationshipw ith a responsiver egion further upstreamo f the cap site. Prenumber of autoimmuned iseasesT. here is evidencet o vious work has indicatedt hat UV-B exposurec an acti-suggestth at immuner esponsesa gainstt he HSPs of cer-vatet hee xpressiono f classich eats hockp roteins( Brunet tain pathogensa rec rossr eactivew ith highlyh omologous and Giacomoni, 1989;M aytin, 1992)O. ur studiesw ould humanH SPs and may lead to the developmenot f auto-suggesth, owever,t hat the heat responsivee lementc on-immuned iseasesth rough molecularm imicry (reviewed tainedw ithin the 504b p CR promoter fragmente xam-in Kaufmann, 1994). CR which is transcriptionally inedi n thiss tudyd oesn ot respondt o UV-B. Nonetheless, responsivet o heat shock is a newly identified human CR, a humana utoantigena, ppearst o function as a heat autoantigen.A ntibodies to CR have been detectedi n shock genes incei ts promotera ctivity is upregulatedb y a number of rheumatologicacl onditions such as SLE, experimentaclo nditionsk nown to inducea classicahl eat Sjogren{\textquoteright}s syndrome, rheumatoida rthritis, and mixed shock response(M orimoto et al., 1992). connectivet issued isease(B oehme t al., 1994;R outsiase t al., 1993)W. hile it is uncleara t this time whethert hese antibodies play a role in the pathogenesiso f these Acknowledgements-This work was supportedb y grants diseasesi,t is possiblet hat certainc onditionsk nown to of Health and by the resources of the U.T. Southwestern Skin AR19101. A112127,a nd AR07341 from the National Institute generatea heat shock responsem ight induce over-Disease Research Core Center (AR41940). Dr Capra holds expressiono f CR which in turn might exacerbateth ese the Edwin L. Cox Distinguished Chair in Immunology and diseasetsh roughh umorala utoimmunity. Genetics. We would like to thank Dr Richard J. Baer (Depart- In earlier studies,w e have presentedd ata suggesting ment of Microbiology at U.T. Southwestern Medical Center) an associationo f CR with hY RNA and Ro/SS-A RNP for providing pGL2-Basic, Dr Kiyoshi Ariizumi (Department particles( McCauliffe et al., 1990;L ieu et al., 1988;L ux of Dermatology at U.T. Southwestern Medical Center) for pro-",
year = "1996",
doi = "10.1016/0161-5890(95)00149-2",
language = "English (US)",
volume = "33",
pages = "379--386",
journal = "Molecular Immunology",
issn = "0161-5890",
publisher = "Elsevier Limited",
number = "4-5",
}