Identification and characterization of a positive regulatory region for activation induced cytidine deaminase mediated gene conversion in chicken B cells

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dc.contributor.advisor Tian , Ming , Ph . D .
dc.contributor.committeeMember Tucker , Philip W .
dc.contributor.committeeMember Paull , Tanya T .
dc.contributor.committeeMember Iyer , Vishwanath
dc.contributor.committeeMember Yin , Whitney
dc.creator Kim , Yonghwan , 1975 -
dc.date.accessioned 2010 -08 -23T20 :33 :22Z
dc.date.accessioned 2010 -08 -23T20 :33 :28Z
dc.date.accessioned 2014 -02 -19T22 :39 :19Z
dc.date.available 2010 -08 -23T20 :33 :22Z
dc.date.available 2010 -08 -23T20 :33 :28Z
dc.date.available 2014 -02 -19T22 :39 :19Z
dc.date.created 2009 -12 *
dc.date.issued 2010 -08 -23
dc.date.submitted December 2009
dc.identifier.uri http : / /hdl .handle .net /2152 /ETD -UT -2009 -12 -674
dc.description.abstract B cells have unique machinery to make up a large pool of antibody repertoire . After V (D )J recombination in early B cell development , the rearranged immunoglobulin genes are further diversified by somatic hypermutation (SHM ) , gene conversion (GC ) and class switch recombination (CSR ) . Acitvation induced cytidine deaminase (AID ) is a key initiating factor for SHM , GC and CSR . A majority of research data supports the model that AID modifies Ig genes at the DNA level by deaminating cytosines to uracils . The mutagenic activity of AID is largely restricted to Ig genes to avoid genomic instability in general . The specificity cannot be attributed to the primary sequence of the Ig genes since unrelated DNA is mutated by AID in the context of Ig genes . A clue to this problem is that AID function is dependent on transcription . Since not all transcribed genes are mutated by AID , there must be something special about the transcription of Ig genes , and the reasoning has prompted extensive analysis of Ig promoters and enhancers . We addressed this question in chicken B cell line DT40 . We identified a 2 .4 -kilobase regulatory region which is important for AID function both within and outside of Ig locus . This regulatory region contains binding sites for multiple transcription factors . Mutation of these binding sites impairs AID mediated gene conversion . In addition , ablation of NF -κB family member , c -Rel and p50 , reduces the AID targeting function of this regulatory region . Since the implicated transcription factors have been reported to associate with histone acetylases , the regulatory region may function by facilitating the access of AID to target DNA . To test this hypothesis , we used the I -SceI endonuclease and dam methylase as probes for chromatin structure . We found that the regulatory region does not increase chromatin accessibility to these probes . In fact , the regulatory region appears to interfere with the cleavage of target DNA by I -SceI . Another possible role of the regulatory region could be direct recruitment of AID to Ig genes . To test this hypothesis , we utilized Dam identification method . Surprisingly , we found that the regulatory region facilitates AID targeting to the Igλ locus .
dc.format.mimetype application /pdf
dc.language.iso eng
dc.subject Antibody diversification
dc.subject Gene conversion
dc.subject DNA repair
dc.subject B cells
dc.subject Transcription
dc.title Identification and characterization of a positive regulatory region for activation induced cytidine deaminase mediated gene conversion in chicken B cells
dc.type.genre thesis *
dc.type.material text *
thesis.degree.name Doctor of Philosophy
thesis.degree.level Doctoral
thesis.degree.discipline Microbiology
thesis.degree.grantor The University of Texas at Austin
thesis.degree.department Microbiology
dc.date.updated 2010 -08 -23T20 :33 :29Z

Citation

Identification and characterization of a positive regulatory region for activation induced cytidine deaminase mediated gene conversion in chicken B cells. Doctoral dissertation, The University of Texas at Austin. Available electronically from http : / /hdl .handle .net /2152 /ETD -UT -2009 -12 -674 .

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