Fig 2: Integrating significant plasma proteins on human longevity outcomes. It integrates MR results after meta‐analysis with colocalization evidence of the causal effect of plasma proteins on human longevity outcomes. (A) The funnel plot indicates our steps for the filtration. First, we excluded any candidate proteins with pleiotropy and heterogeneity from the original results (IVW/Wald ratio p < 0.05). Second, we performed the meta‐analysis based on a random‐effect model and selected proteins with FDR q < 0.05. Third, proteins with colocalization PP.H4 > 70% remained. Finally, the remaining proteins validated by MR‐PRESSO, using both cis‐ and trans‐pQTLs, and being replicated in the DECODE cohort were included. (B) The Manhattan plot shows the distribution of significant individual proteins related to each outcome. (C) Seven plasma cis‐acting proteins with FDR‐corrected significant MR results and colocalized evidence (PP.H4 > 70%) on parental lifespan. (D) Plasma cis‐acting proteins with FDR‐corrected significant MR results and colocalized evidence (PP.H4 > 70%) on top 1% (CTSB, GRN, SCARF2, ROBO1, TMEM106B) and top 10% (CTSF, AMY1A) extreme longevity. AGER, Advanced Glycosylation End‐Product Receptor; AMY1A, Alpha‐amylase 1; ANGPTL4, Angiopoietin‐like 4; CTSB, Cathepsin B; CTSF, Cathepsin F; DNAJA4, Heat Shock Protein Family (Hsp40) Member A4; GRN, Granulin; LPA, Lipoprotein (a); LRP8, LDL receptor related protein 8; NPPB, Brain natriuretic peptide; PDAP1, Platelet‐derived growth factor subunit A‐associated protein 1; PP.H4, Posterior probability of hypothesis 4; ROBO1, Roundabout homolog 1; SCARF2, Scavenger receptor class F member 2; SE, Standard error; TMEM106B, Transmembrane protein 106B.

Fig 3: Functional investigation of plasma proteins and focus on the novel PDAP1 on longevity. (A) The moloc plot (PDAP1 gene, ±500 kb) links genetic expression in whole blood, plasma protein level of PDAP1 to the human lifespan outcome following the central dogma: Both eQTL/pQTL (regardless of cis‐ or trans‐acting ones) of PDAP1 showed a significant effect on lifespan with high colocalization evidence. The variant rs10243678 was located as a coloc variant for eQTL, pQTL, and longevity outcome. (B) The effect of both gene transcripts and plasma protein of PDAP1 on mediators in relation to the outcome of lifespan. Mediators beneficial to lifespan are shown in green (SHBG and usual walking pace), and harmful to lifespan are shown in purple (other mediators). (C) The effect of both gene transcripts and plasma protein of PDAP1 on the acceleration of the aging process (PhenoAge and GrimAge). (D) The association between per unit level increased plasma PDAP1 level and the risk of all‐cause mortality. Model 1 adjusted for age and sex. Model 2 was further adjusted for diabetes status, smoking status, and body mass index. Model 3 further adjusted for systolic blood pressure, diastolic blood pressure, total cholesterol, triglycerides, high‐density lipoprotein cholesterol, and low‐density lipoprotein cholesterol. Model 4 was further adjusted for protein Lp (a) and DNAJA4 levels. (E) The all‐cause mortality influenced by plasma PDAP1. Plasma PDAP1 level was categorized into low, middle, and high levels based on tertile value. (F) Years of life lost associated with middle and high‐level PDAP1 when compared to the low PDAP1 group. PDAP1 level was categorized into low, middle, and high levels based on tertile value. The reference group is the low‐tertile group. SHBG, Sex‐hormone binding globulin.

Fig 4: PDAP1 is upregulated under senescence and exogenous PDAP1 stimulation accelerates cellular senescence. (A) Representative immunoblotting images showing PDAP1 protein levels in MRC‐5 cells collected at different population doublings (PDs). Quantification was from four independent experiments. (B) Real‐time quantitative reverse transcription polymerase chain reaction analysis comparing PDAP1 mRNA expression in MRC‐5 cells at different PDs. (C and D) Real‐time quantitative reverse transcription polymerase chain reaction analysis comparing PDAP1 mRNA expression in MRC‐5 cells treated by UVA (C) or doxorubicin (D) and control groups. (E) Representative images showing the senescence‐associated β‐galactosidase in MRC‐5 cells at different concentrations of exogenous PDAP protein. Quantification was the percentage of cells positive for senescence‐associated β‐galactosidase. (F and G) Real‐time quantitative reverse transcription polymerase chain reaction analysis comparing p16 (F) and p21 (G) mRNA expression in MRC‐5 cells at different concentrations of exogenous PDAP protein. (H) Representative images showing the EdU in MRC‐5 cells at different concentrations of exogenous PDAP protein. Quantification was the percentage of cells positive for EdU. The mean ± SD of biological replicates is shown. Statistical analyses were performed using the Kruskal‐Wallis test (*p < 0.05; **p < 0.01; ***p < 0.001; *****p < 0.0001).