Drosophila melanogaster p53 has developmental stage-specific and sex-specific effects on adult life span indicative of sexual antagonistic pleiotropy

Abstract

Truncated and mutant forms ofp53 affect life span in Drosophila, nematodes and mice, however the role of wild-type p53 in aging remains unclear. Here conditional over-expression of both wild-type and mutant p53 transgenes indicated that, in adult flies, p53 limits life span in females but favors life span in males. In contrast, during larval development, moderate over-expression of p53 produced both male and female adults with increased life span. Mutations of the endogenous p53 gene also had sex-specific effects on life span under control and stress conditions: null mutation of p53 increased life span in females, and had smaller, more variable effects in males. These developmental stage-specific and sex-specific effects of p53 on adult life span are consistent with a sexual antagonistic pleiotropy model.

Keywords: Geneswitch; aging; maternal effects; sexual conflict; tumor suppressor.

Figure 1.. Summaryof Drosophila p53 locus, mutations, transgenes and life span effects.

(A) Diagram of p53 locus and major protein product Dmp53. The p53 gene is indicated in blue, including the two promoters, indicated by black arrows. The internal intron/exon structure of p53 is omitted here for clarity, but is shown below in (B). The pink arrows in indicate the genes that flank p53 on the 5' and 3' side, genes CG17119 and CG17121, respectively. The orange arrow indicates the gustatory receptor gene Gr94a, located in the p53 intron. The 385 aa Dmp53 protein is diagrammed using black and gray boxes, including the N-terminal transcriptional activation domain, the central DNA binding domain, and the C-terminal oligomerization domain and basic region. (B) Diagram of endogenous p53 transcripts and mutations. The intron/exon structure of the A and B variant transcripts is indicated. The Gr94a gene is indicated in orange with an arrow indicating orientation. The location of insertion of the P element P{EPgy2}p53^EY14108 in the second exon of the B isoform is indicated by a triangle, with an arrow indicating the orientation of the insert. The lower black bracket indicates the breakpoints of the 3.3kb deletion in the p53[5A-1-4] mutation. (C) Diagram of transgenic p53 constructs. (D) Summary of p53 effects on adult life span. The effect on adult life span of p53 wild type (A variant) over-expression during larval development and in adults is diagrammed: Bars represent negative effects of p53 wild-type on adult life span, while arrows represent positive effects on adult life span; thickness of the lines indicates relative strength of the effect. "Sum effect of p53" is the expected summation of effects of p53 on adult life span, which is consistent with the life span phenotype of p53 null mutation (p53-/-), as indicated.

Figure 2.. Conditional over-expression of wild-type p53 trans-genes using Geneswitch system.

All flies were the progeny of either Oregon R control (A) or p53-WT transgenic strain (B, C) crossed to the tissue-general Geneswitch driver Act-GS-255B. The flies were cultured in the presence and absence of drug, as larvae or adults, as indicated: M = males, F = females, + indicates culture in presence of drug, - indicates culture in absence of drug. The number of flies in each group are indicated in parentheses. (A, B) Blue diamonds indicate male adults plus drug, pink squares indicate male adults minus drug, orange triangles indicate female adult plus drug, turquoise x indicates female adults minus drug. (A) Control flies, progeny of Oregon R wild-type and Act-GS-255B. (B) p53 wild-type transgene over-expression. Note male larvae plus drug produced no adult flies, whereas female larvae plus drug produced only three escapers. (C) Titration of p53 wild-type over-expression during female larval development and effect on subsequent adult life span. EtOH indicates the ethanol solvent for the drug alone (vector control, indi-cated with light blue diamonds). Repeats of the titration experiments, including data for males are presented in Supplementary Figure 1.

Figure 3.. Effect of p53 mutations on life span.

Cumulative survival curves for L cohort. A key of p53 genotypes is presented below the graphs. Males are indicated with solid symbols and females are indicated with open symbols. (A) Females. (B) Males.

Figure 4.. Survival curves for the indicated genotypes under stress conditions.

(A) Ionizing radiation. (B) 100% oxygen survival. A key of p53 genotypes is presented below the graphs. Males are indicated with solid symbols and females are indicated with open symbols. Survival curves for replicate experiments (cohort 2) are presented in Supplementary Figure 5. Survival statistics for these and replicate experiments are summarized in Supplementary Table 9.