Head-to-head debate between Richard Miller and Paul Hasty/Jan Vijg. Aging Cell Vol. 3, Issue 2 (2004)

Epigenetic hereditary transcription profiles II, aging revisited

Background

Previously, we have shown that deviations from the average transcription profile of a group of functionally related genes can be epigenetically transmitted to daughter cells, thereby implicating nuclear programming as the cause. As a first step in further characterizing this phenomenon it was necessary to determine to what extent such deviations occur in non-tumorigenic tissues derived from normal individuals. To this end, a microarray database derived from 90 human donors aged between 22 to 87 years was used to study deviations from the average transcription profile of the proteasome genes.

Results

Increase in donor age was found to correlate with a decrease in deviations from the general transcription profile with this decline being gender-specific. The age-related index declined at a faster rate for males although it started from a higher level. Additionally, transcription profiles from similar tissues were more alike than those from different tissues, indicating that deviations arise during differentiation.

Conclusion

These findings suggest that aging and differentiation are related to epigenetic changes that alter the transcription profile of proteasomal genes. Since alterations in the structure and function of the proteasome are unlikely, such changes appear to occur without concomitant change in gene function.

These findings, if confirmed, may have a significant impact on our understanding of the aging process.

Open peer review

This article was reviewed by Nathan Bowen (nominated by I. King Jordan), Timothy E. Reddy (nominated by Charles DeLisi) and by Martijn Huynen. For the full reviews, please go to the Reviewers'comments section.

Progeria of stem cells: stem cell exhaustion in Hutchinson-Gilford progeria syndrome

Hutchinson-Gilford progeria syndrome (HGPS) is a rare, fatal genetic disorder that is characterized by segmental accelerated aging. The major causal mutation associated with HGPS triggers abnormal messenger RNA splicing of the lamin A gene leading to changes in the nuclear architecture. To date, two models have been proposed to explain how mutations in the lamin A gene could lead to HGPS, structural fragility and altered gene expression. We favor a compatible model that links HGPS to stem cell-driven tissue regeneration. In this model, nuclear fragility of lamin A-deficient cells increases apoptotic cell death to levels that exhaust tissues' ability for stem cell-driven regeneration. Tissue-specific differences in cell death or regenerative potential, or both, result in the tissue-specific segmental aging pattern seen in HGPS. We propose that the pattern of aging-related conditions present or absent in HGPS can provide insight into the genetic and environmental factors that contribute to normal aging.