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Identification and characterization of senescence-associated microRNAs in a mouse model of the XFE Progeroid Syndrome

Nidadavolu, Lolita S. (2013) Identification and characterization of senescence-associated microRNAs in a mouse model of the XFE Progeroid Syndrome. Doctoral Dissertation, University of Pittsburgh. (Unpublished)

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XFE progeroid syndrome, a disease of accelerated aging caused by deficiency in the DNA repair endonuclease XPF-ERCC1, is modeled by Ercc1 knockout and hypomorphic mice. Tissues and primary cells from these mice senesce prematurely, offering a unique opportunity to identify factors that regulate senescence and aging. We compared microRNA (miRNA) expression in Ercc1-/- primary mouse embryonic fibroblasts (MEFs) and wild-type (WT) MEFs in different oxygen growth conditions and at different passages to identify miRNAs that possibly drive cellular senescence. Microarray analysis showed three differentially expressed miRNAs in senescent passage 7 (P7) Ercc1-/- MEFs grown at 20% O2 compared to less senescent Ercc1-/- MEFs grown at 3% O2. Thirty-six differentially expressed miRNAs were identified in Ercc1-/- MEFs at P7 compared to early passage (P3) in 3% O2. Eight of these miRNAs (miR-449a, miR-455*, miR-128, miR-497, miR-543, miR-450b-3p, miR-872 and miR-10b) were similarly downregulated in the liver of progeroid Ercc1-/Δ and old WT mice compared to adult WT mice, a tissue that demonstrates increased senescence with aging. Three miRNAs (miR-449a, miR-455* and miR-128) were also downregulated in Ercc1-/Δ and WT old mice kidneys compared to young WT mice. We also discovered that the miRNA expression regulator Dicer is significantly downregulated in tissues of old mice and late passage cells compared to young controls. Collectively these results support the conclusion that the miRNAs identified may play an important role in staving off cellular senescence and their altered expression could be indicative of aging.
We also identified IL-6 as a possible target for miR-128, one of the senescence- and DNA damage-associated miRNAs from our microarray analysis of MEFs. IL-6 mRNA levels were reduced significantly when miR-128 was overexpressed and IL-6 mRNA was increased when miR-128 was knocked down by 80%. Furthermore, miR-128 knock-down resulted in increases to the known senescence markers p16 and miR-146a. MiR-128 overexpression resulted in significant IL-6 mRNA reduction, with accompanying reduction in miR-146a.
Based on these studies, we have shown that progeroid models can be a useful method to identify miRNAs that are dysregulated in normal aging processes. We have also identified IL-6 as a possible target for miR-128, a senescence- and DNA-damage associated miRNA that is downregulated in senescent fibroblasts and aged livers and kidney tissues.


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Item Type: University of Pittsburgh ETD
Status: Unpublished
CreatorsEmailPitt UsernameORCID
Nidadavolu, Lolita S.lsn4@pitt.eduLSN4
ETD Committee:
TitleMemberEmail AddressPitt UsernameORCID
Thesis AdvisorKhan, Saleemkhan@pitt.eduKHAN
Committee Memberde Vallejo, AbbeAbbe.Vallejo@chp.eduANDV26
Committee MemberGalbiati, Ferrucciofeg5@pitt.eduFEG5
Committee MemberNiedernhofer,
Committee MemberRobbins,
Date: 1 August 2013
Date Type: Publication
Defense Date: 19 July 2013
Approval Date: 1 August 2013
Submission Date: 31 July 2013
Access Restriction: 5 year -- Restrict access to University of Pittsburgh for a period of 5 years.
Number of Pages: 127
Institution: University of Pittsburgh
Schools and Programs: School of Medicine > Biochemistry and Molecular Genetics
Degree: PhD - Doctor of Philosophy
Thesis Type: Doctoral Dissertation
Refereed: Yes
Uncontrolled Keywords: microRNA; aging; cellular senescence; DNA damage; IL-6; mouse embryonic fibroblasts
Date Deposited: 01 Aug 2013 19:42
Last Modified: 01 Aug 2018 05:15


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