Redox-stress response resistance (RRR) mediated by hyperoxidation of peroxiredoxin 2 in senescent cells.

Aging is closely related to redox regulation. In our previous work, we proposed a new concept, "redox-stress response capacity (RRC)," and found that the decline in RRC was a dynamic characteristic of aging. However, the mechanism of RRC decline during aging remains unknown. In this study, using the senescent human fibroblast cell model and Caenorhabditis elegans model, we identified that peroxiredoxin 2 (PRDX2), as a hydrogen peroxide (H2O2) sensor, was involved in mediating RRC. PRDX2 knockdown led to a decline of RRC and accelerated senescence in fibroblasts and prdx-2 mutant C. elegans also showed decreased RRC. The mechanism study showed that the decreased sensor activity of PRDX2 was related to the increase in hyperoxidation of PRDX2 in senescent cells. Moreover, the level of PRDX2 hyperoxidation also increased in old C. elegans. Simultaneous overexpression of both PRDX2 and sulfiredoxin (SRX) rescued the reduced RRC and delayed senescence. The increase in PRDX2 hyperoxidation in senescent cells led to a decrease in its sensor activity, resulting in the decreased cellular response to H2O2, which is similar to the mechanism of insulin resistance due to the lower insulin receptor sensitivity. Treatment of young cells with a high level of H2O2 to induce a higher level of PRDX2-SO3 resulted in mimicking the RRC decline in senescent cells, which is also similar to a model of insulin resistance induced by high levels of insulin. All these results thrillingly indicate that there is an insulin-resistance-like phenomenon in senescent cells, we named it redox-stress response resistance, RRR. RRR in senescent cells is an important new discovery that explains RRC decline during aging and reveals the internal relationship between redox regulation and aging from a new perspective.

[Characteristics, dynamics and niche of insect community in plum orchard].

The insect community in plum orchard was investigated on organization level and temporal-spatial niche. The results showed that the insect community was abundant, which included 6 orders, 23 families. The individuals of species, diversity indices, and evenness increased with time. Myzus persicae and Asiaarposina sasokii had the widest spatial niche breadth, while Didesmococcus koreauus borchs had the widest temporal niche breadth. Among the natural enemies, Chilocorus rubidus had the widest both temporal and spatial niche breadth. The niche of Chicocorus rubidus and Didesmococcus koreauus overlapped larger than that of the others, which indicated their synchrony in temporal dimension and their similarity in spatial dimension. As the dominant natural enemies, the two populations should be protected and utilized to control plum pest.