A Signaling Role for the Uncleaved Form of α6 Integrin in Differentiating Lens Fiber Cells

Developmental Biology

Janice L. Walker¹  A.Sue Menko¹  Liping Zhang¹ 

[1] Department of Pathology, Anatomy and Cell Biology, Thomas Jefferson University, 571 Jefferson Alumni Hall, 1020 Locust Street, Philadelphia, Pennsylvania, 19107

关键词: integrin;    glycosylation;    endoproteolytic cleavage;    Shc;    Grb2;    lens;   

DOI  :  10.1006/dbio.2002.0823

学科分类：生物科学（综合）

来源: Academic Press

【 摘 要 】

Manyαintegrinsubunitsarecleavedduringtheirprocessingtoyieldheavyandlightchains,whichremainassociatedbydisulfidebonds.Whileuncleavedαintegrinsubunitscanformfunctionalreceptorsthatsometimeshavedistinctsignalingrolesfromtheirbetter-characterizedendoproteolyticallycleavedcounterparts,theirexpressionatthecellsurfaceandtheirassociationwithsignalingcomplexeshaveyettobedeterminedinvivo.Inthisstudy,wedemonstratethat,indifferentiatinglensfibercells,theuncleavedformofα6integrinwasexpressedatthecellsurface.Thisformofα6integrincoimmunoprecipitatedwithboththesignalingadaptormoleculeShcanditsdownstreameffectorGrb2,suggestingthat,inlensfibercells,uncleavedα6integrinwasassociatedwithaShc-mediatedsignalingcomplex.Weshowthatexpressionofthecleavedformofα6integrinprogressivelydecreasedrelativetouncleavedα6integrinasthestateoflenscelldifferentiationincreased,resultinginthepredominanceofuncleavedα6integrininthelensfibercellzones.Interestingly,wepreviouslyhaveshownthatα6integrinislocalizedprincipallyalongtheextensivecell–cellinterfacesoftheselensfibercells,intheabsenceofitsextracellularmatrixligandlaminin.Whilewefoundthatthecleavedformofα6integrincontainedbothhighmannoseandcomplexsugars,theuncleavedformofα6integrincontainedonlyhighmannosesugars.Thesepropertiessuggestthattheuncleavedformofα6integrinmayhaveauniqueroleintheembryoniclens.ItshighassociationwithShcandGrb2inthedifferentiatingcorticalfibercellzoneindicatesthatα6integrinmayprovideacellsurvivalsignalinthepresenceoftheapoptotic-likeprocessesthatareinitiatedinthisregionoftheembryoniclenstoclearthelenscellsoftheirorganelles.

【 授权许可】

Unknown