title: Dietary Calorie Restriction from Adulthood Through Old Age in Rats: Improved DNA Polymerase β and DNA Gap Repair Activity in Cortical Neurons.
abstract: It is well established now that dietary calorie restriction (CR) leads to extension of life span in many species, although the exact mechanism of this effect is still eluding. In the present study, we examined the effect of 40 % CR imposed during a prolonged period of life span (from 6 to 30 months) of rats on the activity of DNA polymerase β (pol β) in view of its role in short gap base excision DNA repair and template driven primer extension. DNA pol β activity is very low at this late age. However, cortical neuronal extracts prepared from CR rats of 30 months age showed significantly higher pol β protein levels and activity when compared to control 30 month old rats. Yet, one-nucleotide gap repair in old control neurons and an improved efficiency in CR neurons could be visualized only after supplementation of the extracts with T4 DNA ligase indicating the lack of CR affect on ligase activity. No impressive primer extension activity is seen either in the CR or old control neurons. These results are taken to convey that extended CR through adult life leads to improved pol β activity and therefore, pol β dependent DNA gap repair activity.
authors.affiliation: Department of Biochemistry, School of Life Sciences, University of Hyderabad, Hyderabad, 500 046, India.
authors.forename: Umakanta
authors.initials: U
authors.lastname: Swain
authors.affiliation: Department of Biochemistry, School of Life Sciences, University of Hyderabad, Hyderabad, 500 046, India.
authors.forename: V N
authors.initials: VN
authors.lastname: Vyjayanti
authors.affiliation: Department of Biochemistry, School of Life Sciences, University of Hyderabad, Hyderabad, 500 046, India.
authors.forename: T
authors.initials: T
authors.lastname: Harikrishna
authors.affiliation: Department of Biochemistry, School of Life Sciences, University of Hyderabad, Hyderabad, 500 046, India.
authors.forename: S
authors.initials: S
authors.lastname: Mahipal
authors.affiliation: Department of Biochemistry, School of Life Sciences, University of Hyderabad, Hyderabad, 500 046, India. ksrsl@yahoo.com.|School of Medical Sciences, University of Hyderabad, Hyderabad, 500 046, India. ksrsl@yahoo.com.
authors.forename: Kalluri Subba
authors.initials: KS
authors.lastname: Rao
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D031204:Caloric Restriction; D002540:Cerebral Cortex / Q000166:cytology / Q000201:enzymology / Q000378:metabolism*; D011088:DNA Ligases / Q000378:metabolism; D019951:DNA Polymerase beta / Q000378:metabolism*; D004260:DNA Repair; D004032:Diet; D009474:Neurons / Q000201:enzymology / Q000378:metabolism*; D051381:Rats
chemical_list: D000255:Adenosine Triphosphate; D019951:DNA Polymerase beta; D011088:DNA Ligases
keywords: Base excision repair; Dietary calorie restriction; Gap repair; Neurons; pol β