Identification of molecular targets of benzo(A)pyrene in vascular smooth muscle cells : implications in chemical atherogenesis /
The environmental carcinogen, benzo(a)pyrene (BaP), induces acquisition of highly proliferative (i.e. atherogenic) vascular smooth muscle cell (vSMC) phenotypes. The present studies were conducted to define the genetic basis of BaP-induced atherogenesis and to identify candidate target genes respon...
| Main Author: | |
|---|---|
| Format: | Thesis Book |
| Language: | English |
| Published: |
[Place of publication not identified] :
[publisher not identified] ;
2000.
|
| Subjects: | |
| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=731980911&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | The environmental carcinogen, benzo(a)pyrene (BaP), induces acquisition of highly proliferative (i.e. atherogenic) vascular smooth muscle cell (vSMC) phenotypes. The present studies were conducted to define the genetic basis of BaP-induced atherogenesis and to identify candidate target genes responsible for phenotypic control during chemical atherogenesis in rodent vSMCs. Candidate genes were identified in murine vSMCs by differential display polymerase chain reaction (DDPCR). Six target genes, human apoptosis inhibitor Aac11, aldose reductase, chaperonin containing TCP-1, GalNAc transferase, mitochondrial genes, and retrotransposon L1Md were differentially regulated in cultured mouse vSMCs acutely treated with 3 []M BaP for 8 hr, an in vitro atherogenic dosing regimen. L1Md was upregulated in BaP-treated cells, while the remainder genes were down regulated. Four additional target genes, ribosomal protein L31, developmentally regulated Zis, gas-5 growth arrest specific gene, and mitochondria ATPase 6 genes, were identified in proliferative vSMCs isolated from BaP-treated rats in vivo. Gas-5 and mitochondrial ATPase 6 genes were upregulated in proliferative cells, while ribosomal protein L31 and Zis were downregulated. Differential expression of these genes was confirmed with Northern hybridization, PCR and/or reverse Northern analysis. Subsequent studies were conducted to evaluate retrotransposon activation profiles in mouse vSMCs treated with BaP or its oxidative metabolites, and to screen for possible insertional mutation into p53 and retinoblastoma genes. Northern analysis revealed that BaP and its major precursor of reactive metabolite 7,8-diol metabolite (0.03-3 []M) activated L1Md in a concentration- and time-dependent manner. Two other metabolites, 3-OH and 3, 6-quinone (0.03-3[]M), as well as hydrogen peroxide (25-75[]M), also activated L1Md. No insertional mutations into either p53 or RB genes were observed, but expression of p53 was increased in vSMCs shortly after BaP challenge. Upregulation of p53 correlated with modest, but significant induction of DNA damage and inhibition of DNA repair in BaP-treated vSMCs during chemical atherogenesis. Based on these findings, we conclude that multiple genes participate in the regulation of phenotypic transition in vSMCs, with retrotransposons identified as primary targets of BaP in vSMCs. Genomic instability generated by translocation of retrotransposon within the cellular genome, coupled to apoptotic deficits, DNA damage, and inhibition of DNA repair may play key roles in the early stages of BaP atherogenesis. |
|---|---|
| Item Description: | Vita. "Major Subject: Toxicology". |
| Physical Description: | x, 151 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilm Inc. |
| Bibliography: | Includes bibliographical references (leaves 128-150). |