Control of antioxidant defenses during cellular aging and the effect of antioxidant augmentation on gene expression.

Format:

Book

Thesis/Dissertation

Author/Creator:

Keogh, Bartholomew P.

Contributor:

Cristofalo, Vincent J., 1933- advisor.

University of Pennsylvania.

Language:

English

Subjects (All):

Cytology.

Molecular biology.

0307.

0379.

Penn dissertations--Pathology.

Pathology--Penn dissertations.

Local Subjects:

Penn dissertations--Pathology.

Pathology--Penn dissertations.

0307.

0379.

Physical Description:

240 pages

Contained In:

Dissertation Abstracts International 59-07B.

System Details:

Mode of access: World Wide Web.

text file

Summary:

The Free Radical Theory of aging postulates that the cumulative effect of oxidants on cellular metabolism and gene expression is the basis for aging. The studies described here have examined antioxidant defenses in both in vivo, 29 skin fibroblast lines established from fetal (12-20 weeks), young (17-34 years) and old (78-94 years) adult donors, and in vitro, early and late passage WI-38 lung fibroblasts, models of aging. Increased activity and protein for manganese-superoxide dismutase (SOD-2), copper/zinc-superoxide dismutase (SOD-1) and catalase (CAT) was observed in each postnatal compared with the fetal group. SOD-2 and CAT messenger RNA (mRNA) abundances were also higher in each postnatal relative to the fetal group. Measurement of SOD-1, SOD-2 and CAT transcription by nuclear run-on (NRO) assay revealed higher SOD-2 and CAT transcription in postnatal, compared to fetal lines. There were no significant differences in any parameter measured between the postnatal groups or during in vitro senescence.

To test the hypothesis that the level of antioxidant defense may alter gene expression, we examined the effect of treatment with N-acetylcysteine (NAC), Trolox C and nordihydroguaiaretic acid (NGA) on c-fos gene expression. c-fos mRNA increased in response to cellular reduction by these compounds reaching a maximum at 30-60 minutes. NRO assay demonstrated a substantial increase in c-fos gene transcription. Pretreatment with phorbol 12-myristate 13-acetate (PMA) prevented subsequent induction of c-fos mRNA by NGA. In contrast, c-fos induction by NAC and Trolox was uninhibited. The induction of c-fos mRNA by NGA, NAC and trolox was not associated with translocation of PKC-$\alpha$ from the cytosol to the membrane. Treatment of in vitro aged cells with NGA and NAC revealed a decrease in responsiveness to NGA, but not NAC, with proliferative age. However, this was not associated with a decrease in the absolute amount of immunoreactive PKC or members of the MAP kinase pathway.

These data indicate that there are significant, coordinate, increases in enzymatic antioxidant defenses associated with in vivo development, but not in vivo or in vitro aging. Further, during in vitro senescence WI-38 cells lose responsiveness to some, but not all, perturbations of cellular redox state.

Notes:

Thesis (Ph.D. in Pathology) -- University of Pennsylvania, 1998.

Source: Dissertation Abstracts International, Volume: 59-07, Section: B, page: 3243.

Adviser: Vincent J. Cristofalo.

Local Notes:

School code: 0175.

ISBN:

9780591940909

Access Restriction:

Restricted for use by site license.