pnas00316-0192 - Proc.Natl.Acad Sci USA Vol 83,pp 4292-4296...

Info iconThis preview shows pages 1–2. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Proc.Natl.Acad. Sci. USA Vol. 83,pp. 4292-4296, June 1986 CellBiology Selectiveregulationoftrypsin gene expressionby calciumandby glucosestarvationinaratexocrinepancreascellline (AR4-2Jcelis/A23187/phorbol12-myristate13-acetate/acetyltransferaseassay) CHRISTIAN STRATOWA AND WILLIAM J.RUTTER Hormone ResearchInstituteandDepartmentsofBiochemistryandBiophysics,UniversityofCalifornia,San Francisco,CA 94143 Contributedby WilliamJ.Rutter,January2,1986 ABSTRACT Treatment ofthe ratpancreatic acinar cell line AR4-2J with the calcium ionophore A23187 selectively increases,withinafewhours,thesteady-stateleveloftrypsin mRNA. Addition of the tumor-promoting phorbol ester phorbol 12-myristate 13-acetate potentiates the calcium-in- duced increase.The mRNA leveloftheothertestedexocrine pancreaticgenesdecreases. These resultswere confrmed by DNA transfectionexperiments,usingthe5'flankingregionof the trypsin and chymotrypsin genes linked to the coding sequenceoftheacetyltransferase(CAT)gene. In calcium-induced cells transfected with the trypsin con- structs,anincreaseinCAT activitywasobserved,whereasthe chymotrypsinconstructs revealed a decreased CAT activity. GlucosestarvationofAR4-2Jcellssimilarlyelicitedaselective increaseintrypsinmRNA. Thisselectiveregulationoftrypsin may reflectitsroleasthekeyactivatoroftheotherzymogen species. Calcium isa majorintracellularmessenger stimulatingen- zymereleasefrompancreaticacinarcells(forreview,seeref. 1). It is unknown whether calcium is also involved in regulationoftheexpressionoftheexocrinepancreaticgenes. Could there be a correlation between Ca-induced enzyme secretionandCa-regulatedexpressionofthegenesforthose pancreatic enzymeswhose secretionistriggeredbycalcium? Early studiesrevealed a secretagogue-induced effluxof Ca2" inpancreaticfragments.More compellingevidencefor theimportanceof Ca2" insecretionwasprovidedbystudies inwhichanincreaseinintracellularfree Ca2+wasproduced by calcium ionophores, such as A23187 (1).The Ca iono- phoresstimulateamylase secretionfrompancreaticacini(2, 3).Furthermore,thetumor-promotingphorbolesterphorbol 12-myristate 13-acetate (PMA) has a synergistic effecton amylaserelease(4).SimilarexperimentsshowedthatA23187 and PMA in combination simulate the biphasicpattern of glucose-inducedinsulinsecretionfrompancreaticislets(5). These experimentssuggestthatthecalcium-activatedphos- pholipid-dependentproteinkinaseC(6)isalsoinvolvedinthe activationofsecretion. We have used theratpancreaticacinarcelllineAR4-2J, which displays a relatively high level of expression for severalexocrinegeneproducts(7),tostudytheinfluenceof calcium on the expression of these genes. Our studies revealed a selective induction oftrypsin by A23187 treat- ment, which is further potentiated by PMA. Using gene chimeras composed ofthe5'flankingregionsofthetrypsin orchymotrypsingeneslinkedtothecodingsequenceofthe bacterialacetyltransferase(CAT) gene(8), we demonstratedthatsequencesupstreamofthesegenesare...
View Full Document

This note was uploaded on 07/28/2011 for the course VET 4335 taught by Professor Sakomura during the Spring '11 term at University of the South Pacific, Fiji.

Page1 / 5

pnas00316-0192 - Proc.Natl.Acad Sci USA Vol 83,pp 4292-4296...

This preview shows document pages 1 - 2. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online