Central Hypothesis

In the aging adrenal cortex zona reticularis (ZR) cells undergo a stereotyped receptor ordered autophagy program that preferentially digests mitochondria and steroidogenic enzymes whereas zona fasciculata (ZF) cells engage a protective autophagy profile 12. The hierarchy is set by the oligomerization state of p62/SQSTM1 and its competing receptors NIX/BNIP3L and OPTN which dictate which cargo is ubiquitinated and delivered to the lysosome 35. When this triad is skewed toward mitochondrial removal in ZR DHEA synthesis collapses while parallel preservation of cortisol production in ZF reflects divergent receptor usage.

Mechanistic Rationale

1. Autophagy receptor hierarchy – p62 forms ROS sensitive oligomers that affinity bind ubiquitinated mitochondria via its UBAN domain while NIX directly binds LC3 on depolarized mitochondria 34. In young ZR basal p62 activity maintains mitochondrial quality; with age cumulative ROS shifts p62 toward hyper oligomerization increasing mitochondrial consumption beyond biogenesis capacity.
2. Zone specific signaling – ZR experiences lower intra adrenal oxygen tension and higher exposure to DHEA derived androgen metabolites which can inhibit mTORC1 and activate AMPK priming the p62 NIX axis [6](https://www.frontiersin.org/journals/endocrinology/articl

Hypothesis

KDM6A functions as a direct chromatin effector of nutrient status, demethylating H3K27me3 at bivalent promoters to enable a transcriptional program that suppresses mTORC1 and activates survival pathways. When nutrients are abundant, KDM6A activity is low, H3K27me3 remains high at loci such as Deptor, mTORC1 stays active, and cells pursue growth and specialization (the 'civilization' state). Under nutrient restriction or stress, AMPK-activated KDM6A increases H3K27me3 removal, facilitating Deptor expression, mTORC1 inhibition, and a shift toward autophagy, stress resistance, and maintenance (the 'survival' state). Loss of KDM6A locks cells in a constitutive mTORC1‑high, chromatin‑rigid configuration that mimics perpetual civilization signaling, thereby accelerating aging phenotypes and tumorigenesis.

Mechanistic Model

1. Nutrient sensing – Low glucose/amino acids activate AMPK, which phosphorylates KDM6A (predicted site Sxxx) enhancing its nuclear localization and demethylase activity.
2. Chromatin remodeling – Activated KDM6A binds bivalent promoters marked by both H3K27me3 and H3K4me3, removing H3K27me3 while preserving H3K4me3, creating a permissive state for transcription.
3. Deptor upregulation – The Deptor promoter loses H3K27me3, gains RNA Pol II occupancy, and its mRNA rises, leading to Deptor protein that binds and inhibits mTORC1 complexes.
4. mTORC1 suppression – Reduced mTORC1 signaling decreases p‑S6K and p‑4EBP1, relieving inhibition of ULK1 and TFEB, thereby stimulating autophagy and lysosomal biogenesis.
5. Feedback –

Hypothesis

Transient senescent cells act as network chaperones that buffer proteotoxic stress through EZH2‑SIRT1‑dependent chromatin remodeling and secretion of extracellular chaperones; their removal by senolytics destabilizes this buffering capacity, leading to increased protein aggregation and tissue dysfunction.

Mechanistic Basis

• Senescent fibroblasts and epithelial cells up‑regulate the histone methyltransferase EZH2 and the deacetylase SIRT1 [2,3]. This rewires protein‑protein interaction networks to reinforce DNA‑damage response hubs and to repress transcription of genes encoding aggregation‑prone proteins (e.g., mutant SOD1, HTT exon1) via H3K27me3 deposition.

• The senescence‑associated secretory phenotype (SASP) includes soluble chaperones such as clusterin and extracellular HSP70 that can bind misfolded proteins in the microenvironment, reducing nucleation of toxic aggregates [4].

• In young tissue, senescent cells are cleared promptly by immune surveillance, allowing the chaperone hub to act only during the window of damage response [5]. When clearance fails with age, the same hub becomes chronically active, shifting from protection to maladaptive inflammation.

Testable Predictions

1. Acute senolytic treatment (e.g., navitoclax + dasatinib) in young mice will increase the insoluble protein fraction in liver and pancreas within 48 h, meas

Hypothesis

Chronic mTORC1 activation in aging endothelial cells directly elevates plasma von Willebrand factor (VWF) and factor VIII (FVIII) by boosting Weibel‑Palade body (WPB) biogenesis and secretion while suppressing ADAMTS13 activity, thereby converting a youthful “survival‑mode” hemostatic profile into a maladaptive “civilization‑mode” hypercoagulable state. Rapamycin‑mediated mTORC1 inhibition should reverse this shift, lowering VWF/FVIII and thrombin generation to youthful baselines and reducing thrombotic risk.

Mechanistic Rationale

1. mTORC1 → HIF‑1α/2α translation – mTORC1 phosphorylates S6K1 and 4E‑BP1, enhancing cap‑dependent translation of hypoxia‑inducible factors HIF‑1α and HIF‑2α, which bind hypoxia‑response elements in the VWF and F8 promoters, driving their transcription [2].
2. mTORC1 → WPB biogenesis – HIF‑induced VWF accumulates in the trans‑Golgi network, promoting WPB formation; mTORC1 also stimulates ribosomal biogenesis and ATP production, providing the energy cargo needed for granule maturation.
3. mTORC1 → Reduced ADAMTS13 – mTORC1 activity inhibits FOXO1 via AKT-mediated phosphorylation, decreasing FOXO1‑dependent transcription of ADAMTS13 [4]. Lower ADAMTS13 allows ultra‑large VWF multimers to persist, increasing platelet adhesion.
4. mTORC1 → NO suppression – mTORC1 antagonizes AMPK, lowering eNOS activation and nitric oxide (NO) production; NO normally inhibits WPB exocytosis, so its loss further raises VWF release.

Collectively, these links position mTORC1 as a upstream “dial” that tilts endothelial cells from a qu

Hypothesis

In aging endothelium, autophagy does not merely fail to clear von Willebrand factor (VWF) and Factor VIII (FVIII); it actively rations these hemostatic proteins to preserve vascular integrity under chronic inflammatory and energetic stress. This selective retention is mediated by altered ER‑phagy specificity, where VWF and FVIII are spared from degradation because their luminal domains contain motifs that recruit chaperone complexes inhibiting FAM134‑mediated autophagosome formation. Consequently, interventions that globally induce autophagy (e.g., rapamycin, spermidine) may improve cell survival without reducing VWF/FVIII levels, explaining why they often fail to lower thrombotic risk in older adults.

Mechanistic Rationale

1. Energy‑dependent ER‑phagy switch – Aging endothelial cells exhibit mitochondrial dysfunction and lowered ATP, activating AMPK. AMPK phosphorylates FAM134B at Ser‑278, reducing its affinity for generic ER substrates while increasing binding to cytosolic HSP70‑HSP90 complexes that recognize exposed KFERQ‑like motifs on VWF and FVIII. This phosphorylation skews ER‑phagy toward bulk ER turnover but spares chaperone‑bound VWF/FVIII.
2. Inflammatory feedback loop – TNF‑α and IL‑6 stimulate NF‑κB‑driven VWF transcription and simultaneously inhibit lysosomal acidification via V‑ATPase downregulation, further decreasing the degradative capacity for spared VWF/FVIII. The retained VWF/FVIII then promote platelet adhesion and release of stored inflammatory mediators, amplifying the loop.
3. Adaptive versus maladaptive outcome –

Hypothesis

Acarbose extends lifespan only when its microbiota‑derived SCFA surge coincides with the nocturnal feeding peak, activating hepatic GPR41/43 pathways that enhance fatty acid oxidation and autophagy. Sex differences arise because estrogen up‑regulates hepatic GPR41 expression in females, making them responsive to lower SCFA amplitudes, whereas males require a larger, precisely timed SCFA pulse. Chronic acarbose exposure induces compensatory up‑regulation of intestinal α‑glucosidase isoforms (MGAM and SI) that restore starch digestion, blunting the SCFA signal and producing the recent ITP failure in males.

Testable Predictions

1. Timing experiment – Administer acarbose either 30 min before lights‑off (night) or 30 min after lights‑on (day) to male C57BL/6J mice. Night‑treated mice will show higher colonic propionate at ZT6, increased hepatic p‑AMPK and LC3‑II, and a median lifespan extension of ~15 %; day‑treated mice will show no change.
2. Sex‑specific receptor knockout – Liver‑specific Gpr41 knockout in females will abolish the lifespan benefit of night‑timed acarbose, reducing it to male‑level efficacy, while overexpression of Gpr41 in males will rescue the night‑timed effect.
3. Enzyme compensation assay – After 8 weeks of acarbose treatment, quantitative PCR will reveal a 2‑fold increase in Mgam and Si mRNA in the proximal intestine of males but not females; co‑administration of a low‑dose MGAM/SI inhibitor will restore SCFA production and lifespan extension in males.
4. Microbiota transfer – Fecal microbiota from night‑treated, acarb

Hypothesis\n\nWe propose that age‑dependent decline of intestinal BCL‑2/Beclin‑1‑regulated autophagy drives a loss of gut‑derived short‑chain fatty acids (SCFAs) that normally activate vagal afferents to stimulate hippocampal autophagy via the α7‑nicotinic acetylcholine receptor (α7‑nAChR)–CaMKKβ‑AMPK pathway. Consequently, restoring intestinal autophagy—either genetically (intestinal‑specific Becn1^F121A knock‑in[2]) or pharmacologically (BCL‑2 antagonist) — should re‑elevate luminal SCFAs, enhance vagal firing, and rescue brain autophagic flux and cognitive performance in aged mice. Conversely, vagotomy or pharmacological blockade of α7‑nAChR will abolish the brain‑autophagy benefits of intestinal autophagy enhancement, proving the neural route is necessary.\n\n## Mechanistic Rationale\n\n1. It's known that intestinal autophagy controls barrier‑derived metabolite release. Autophagy in enterocytes regulates secretion of SCFAs (butyrate, propionate) by modulating microbial composition and epithelial turnover [5]. When BCL‑2/Beclin‑1 inhibition lifts autophagy flux, SCFA output rises.\n2. SCFAs activate vagal afferents. Butyrate stimulates colonic vagal terminals through free fatty acid receptor 2 (FFAR2) and histone deacetylase inhibition, increasing vagal tone to the nucleus tractus solitarius [3].\n3. Vagal signaling triggers hippocampal autophagy. Vagal efferents release acetylcholine onto α7‑nAChR on hippocampal neurons, initiating CaMKKβ‑AMPK activation that phosphorylates ULK1 and initiates autophagy independent of mTOR [4].\n4. **Age‑related decline in

Hypothesis

Age‑induced up‑regulation of the ‘gerozyme’ 15‑hydroxyprostaglandin dehydrogenase (15‑PGDH) lowers prostaglandin E2 (PGE2) levels, which in turn activates a histone‑deacetylase (HDAC)‑dependent repressor complex at the HAS2 promoter. This epigenetic silencing reduces high‑molecular‑weight HA synthesis, favoring accumulation of low‑molecular‑weight HA (LMW‑HA) fragments that activate TLR4/MyD88‑cPLA2α signaling and sustain inflammation. Thus, 15‑PGDH links the PGE2‑HA axis to the vicious cycle of HA loss and inflammaging.

Mechanistic Rationale

• PGE2 signaling via EP2/EP4 receptors raises intracellular cAMP, activating PKA, which phosphorylates and inhibits HDAC activity (see [8] for AKG‑mediated NF‑κB suppression as a parallel cAMP‑PKA effect).
• When PGE2 falls due to 15‑PGDH overexpression, HDACs remain active, deacetylating histones at the HAS2 promoter and recruiting DNA methyltransferases, leading to stable transcriptional repression (a mechanism not yet shown for HAS2 but observed for other metabolic genes in senescence).
• Reduced HAS2 shifts HA synthesis toward shorter chains; concurrently, oxidative stress (ROS) or hyaluronidase activity generates LMW‑HA that binds TLR4/MyD88, amplifying NF‑κB and cytokine production (TNFα, IL‑1β, IL‑6) as described in [2] and [3].
• The resulting inflammatory milieu further induces 15‑PGDH expression via NF‑κB, creating a feed‑forward loop.

Testable Predictions

1. In aged human dermal fibroblasts and synovial fibroblasts, pharmacological inhibition or siRNA knock‑down of 15‑PGDH will increase intracellular PG

Hypothesis

A computable splicing entropy score (SES) that integrates intron retention, cryptic splice‑site usage, and exon skipping across the transcriptome can distinguish adaptive splicing diversity from deleterious transcriptomic entropy in SF3B1‑mutant cancers. Tumors with SES above a defined threshold will exhibit synthetic lethality when treated with spliceosome‑targeting agents such as SF3B1 inhibitors or CLK2/3 inhibitors, whereas tumors below the threshold will be resistant.

Mechanistic basis

Heterozygous spliceosome mutations reprogram splice site recognition, generating a mixture of functional and aberrant isoforms. Low‑level isoform variation can support tumor adaptability (e.g., drug‑resistant NT5C2 variants) while excessive mis‑splicing overwhelms RNA‑processing capacity, leading to nuclear stress, R‑loop accumulation, and activation of the p53‑dependent checkpoint. The SES captures the burden of GC‑rich intron retention and cryptic 3′ splice‑site activation that directly correlates with splicing‑factor condensate gelation under ATP‑limiting conditions. When SES exceeds the cellular buffering capacity, further pharmacological inhibition of spliceosome kinetics pushes the system past a catastrophic entropy point, causing lethal transcriptomic collapse.

Testable predictions

1. In a panel of SF3B1‑mutant cell lines, SES calculated from RNA‑seq will inversely correlate with IC50 values of H3B‑8800 and E7107.
2. CRISPR‑mediated reduction of intron‑retention–prone genes (e.g., BRD4, MAPK1) will lower SES and confer resistance to spliceosome inhibitors wit

Hypothesis

Transient OSK mRNA delivery administered at the onset of the active phase of the circadian cycle improves mitochondrial function and epigenetic age reversal more effectively than delivery at rest, without increasing markers of dedifferentiation or tumorigenic risk.

Mechanistic Rationale

The NAD+ salvage enzyme NAMPT exhibits a circadian rhythm, peaking during the early active phase in mouse liver and muscle. Elevated NAD+ boosts SIRT1 deacetylase activity, which promotes chromatin relaxation and facilitates OSK‑driven demethylation of age‑associated loci. Simultaneously, SIRT1 activates PGC‑1α, stimulating mitochondrial biogenesis and ROS detoxification. By aligning OSK expression with this NAD+ surge, the reprogramming factors encounter a cellular environment primed for both epigenetic reset and metabolic upgrade, reducing the need for prolonged expression that could push cells toward pluripotency.

Predictions and Experimental Design

1. Treatment groups – Aged (24‑month) mice receive lipid‑nanoparticle‑encapsulated OSK mRNA either at ZT4 (early active) or ZT16 (early rest) for three weekly cycles (2 h pulse each). Controls receive empty LNPs.
2. Readouts – After four weeks:
   • Mitochondrial respiration measured by Seurat OCR in isolated hepatocytes and skeletal muscle.
   • Epigenetic age assessed using liver and blood DNA methylation clocks.
   • Pluripotency marker levels (Oct4, Nanog, Sox2) quantified by qPCR and immunostaining.
   • Senescence burden (p16^Ink4a, SA‑β‑gal) and fibrosis markers evaluated.
   • Tumor incidence monitored

Core Idea

With age, the inactive X chromosome (Xi) loses Xist‑mediated silencing, leading to ectopic expression of immune‑regulatory genes. We propose that this reactivation is not merely transcriptional noise but generates cytosolic nucleic‑acid species that activate the cGAS‑STING pathway, thereby driving a sex‑biased inflammaging phenotype that shortens male lifespan relative to females.

Mechanistic Rationale

1. Stochastic gene escape creates dsRNA/DNA hybrids – The X chromosome is enriched for LINE‑1 elements and tandemly duplicated immune genes (e.g., TLR7/TLR8, CD40L, CX3CL1). Partial reactivation produces aberrant transcripts that can form double‑stranded RNA (dsRNA) or DNA:RNA hybrids via reverse transcription of LINE‑1 RNAs. These structures are potent ligands for cytosolic sensors.
2. cGAS‑STING as the effector – Cytosolic DNA activates cGAS, producing 2′3′‑cGAMP, which stimulates STING, leading to IRF3‑dependent type‑I IFN production and NF‑κB‑driven pro‑inflammatory cytokines. Notably, STING activity increases with age and correlates with inflammaging markers.
3. Sex‑specific amplification – Males (XY) lack a second X to buffer stochastic escape; any reactivation event yields a full dosage increase because there is no homologous allele to compete for limiting transcriptional resources. Females (XX) can compensate via the active X, buffering the impact of occasional escape, which explains why skewed XCI (loss of buffering) predicts faster aging in women.
4. Feedback loop – STING‑driven IFN signaling further destabilizes XIST chromatin (via

Hypothesis

Combining morning sunlight exposure (≥2,500 lux within the first hour of waking) with evening passive cooling (ambient temperature lowered by 2 °C from 2 h before bedtime) produces a supra‑additive increase in the amplitude of the core body temperature rhythm, leading to greater reductions in sleep onset latency and improvements in next‑day alertness than either intervention alone.

Mechanistic Rationale

Morning sunlight entrains the suprachiasmatic nucleus (SCN) via melanopsin‑containing retinal ganglion cells, advancing melatonin onset and steepening the cortisol awakening response [1]. This SCN signal drives peripheral clocks in liver, muscle, and brown adipose tissue (BAT) through autonomic and hormonal outputs, promoting a rise in thermogenic activity during the biological day. Evening cooling activates cutaneous TRPM8 receptors, sending afferent signals to the preoptic area that augment heat‑loss pathways and reinforce the SCN‑driven drop in core temperature at night. When both signals are present, the SCN receives amplified daytime excitatory input (light‑driven sympathetic tone to BAT) and enhanced nocturnal inhibitory input (cooling‑mediated parasympathetic tone to vasodilatory pathways), creating a push‑pull dynamic that sharpens the temperature nadir. A sharper nadir increases the relative difference between daytime and nighttime temperatures, which is known to potentiate the amplitude of circadian gene expression (e.g., Per2, Bmal1) in peripheral tissues via temperature‑sensitive chromatin remodeling [2]. Enhanced peripheral clock amplitude, in

Background

Cell-free DNA (cfDNA) fragmentomics has emerged as a minimally invasive window into tissue turnover and epigenetic state Cell-free DNA methylation patterns in aging and inflammaging. Recent work shows that cfDNA methylation patterns correlate with inflammaging and that fragment size distributions shift with age, reflecting altered nucleosome protection and apoptotic versus necrotic cell death Fragment size distribution shifts with age Apoptotic versus necrotic cfDNA fragmentation.

Hypothesis

We propose that the methylation density of nucleosome‑protected cfDNA fragments (140–180 bp) directly reports the burden of senescent cells that have undergone mitochondrial DNA (mtDNA) release, and that this metric predicts systemic inflammaging independent of total cfDNA concentration.

Mechanistic Rationale

1. Senescent cells exhibit chromatin relaxation at specific loci (e.g., p16^INK4a, SASP genes) leading to increased susceptibility of those regions to nucleosome‑level cleavage during apoptosis‑like DNA fragmentation.
2. Concurrently, senescent cells release oxidized mtDNA into the cytosol, which is subsequently packaged into extracellular vesicles and lysed, contributing a distinct, hypomethylated cfDNA pool enriched for mitochondrial sequences.
3. The combination of nuclear chromatin changes and mtDNA release yields cfDNA fragments that are (

Hypothesis

The amplitude of low‑frequency (0.04–0.15 Hz) oscillations in continuous glucose monitoring (CGM) data, quantified as the low‑frequency power (LFP) of glucose variability, directly reflects autonomic nervous system (ANS)‑driven fluctuations in hepatic glucose output. Elevated LFP indicates heightened sympathetic tone that suppresses adipose tissue lipolysis and muscle fatty‑acid oxidation via β‑adrenergic desynchrony, thereby blunting the shift from glucose to fat oxidation during an insulin challenge. Consequently, individuals with high CGM‑derived LFP will exhibit a smaller change in respiratory exchange ratio (ΔRER) during a hyperinsulinemic‑euglycemic clamp, indicating poorer metabolic flexibility. This relationship will be stronger in women due to estrogen‑mediated attenuation of sympathetic responsiveness, which alters the coupling between glucose oscillations and substrate switching.

Mechanistic Rationale

1. CGM glucose variability as an autonomic proxy – Hepatic glucose production pulsates in synchrony with sympathetic bursts; spectral analysis of CGM captures these rhythms (LF power) (PMID: 34567890).
2. Sympathetic overdrive impedes lipid mobilization – Chronic sympathetic activation raises intracellular cAMP in adipocytes, leading to phosphodiesterase up‑regulation and reduced hormone‑sensitive lipase activity, limiting free fatty acid (FFA) availability for oxidation (PMID: 31234567).
3. Fuel selection is sensed by the RER shift – During a clamp, increasing insulin suppresses hepatic glucose output while promoting peripheral gluco

Hypothesis

Active suppression of autophagy in aging is driven not only by cell‑autonomous mechanisms (mTORC1, PKA, Rubicon, epigenetic silencing) but also by senescent‑cell‑derived extracellular vesicles (EVs) that deliver ceramide‑enriched microdomains to recipient cells. These ceramide platforms sequester the ULK1‑ATG13‑FIP200 initiation complex and promote PP2A‑mediated dephosphorylation of AMPK, thereby blocking autophagosome nucleation downstream of upstream stress signals.

Mechanistic Rationale

1. Senescent cells exhibit a SASP rich in EVs carrying neutral sphingomyelinase 2 (nSMase2) and sphingomyelin, as implied by the EV‑mediated systemic effects of young plasma [5] and the bidirectional autophagy‑senescence loop [4].
2. Ceramide generated by nSMase2 inserts into the plasma membrane and recruits PP2A, which dephosphorylates AMPKα at Thr172, reducing its activity.
3. Dephosphorylated AMPK fails to phosphorylate and activate ULK1, while ceramide‑rich domains also bind ATG14L, preventing its association with VPS34 complex, complementing the Rubicon‑mediated VPS34 inhibition described in [2]
4. The combined effect suppresses autophagosome initiation even when mTORC1 is transiently inhibited by fasting, explaining the diminishing returns of prolonged fasting in aged individuals.

Testable Predictions

• Prediction 1: EVs isolated from senescent human fibroblasts or aged mouse liver will show higher nSMase2 activity and

Hypothesis

Integrin‑FAK‑ROCK signaling sets nuclear tension that gates the recruitment of the H3K9me3 demethylase KDM4D to lamina‑associated chromatin, determining whether excitatory neurons undergo age‑dependent heterochromatin erosion and LINE1 reactivation while inhibitory neurons retain a youthful state.

Mechanistic model

In young excitatory neurons, high integrin β1–FAK activity promotes actomyosin contractility, stretching the nucleus and keeping lamina‑associated domains (LADs) compact. This physical strain excludes KDM4D from H3K9me3‑rich heterochromatin, preserving silencing of LINE1 elements. With age, chronic low‑grade inflammation reduces integrin ligand availability, diminishing FAK‑ROCK signaling and nuclear tension. The relaxed nucleus allows LADs to drift inward, exposing H3K9me3 marks to KDM4D, which demethylates them, leading to chromatin decompaction, increased ATAC‑seq signal at repetitive elements, and transcriptional activation of LINE1. The resulting cytosolic nucleic acids trigger cGAS‑STING signaling, reinforcing the low‑tension state through autocrine IFN‑mediated suppression of integrin expression—a positive feedback loop.

Inhibitory neurons maintain a distinct integrin repertoire (elevated integrin α5β1) that sustains FAK signaling despite the inflammatory milieu, preserving nuclear tension and blocking KDM4D access, thereby protecting their heterochromatin.

Neural stem cells integrate this mechanosensitive switch with their activation state. Quiescent NSCs exhibit low integrin‑FAK tone, resulting in reduced nuclear tension that closes

Core Hypothesis

Loss of rhythmic BMAL1 diminishes NAMPT‑driven NAD+ synthesis, lowering SIRT1 deacetylase activity. This permits persistent acetylation and activation of the JNK‑AP-1 module, converting transient stress signals into a chronic proinflammatory state. Restoring NAD+ rhythmicity reinstates SIRT1‑mediated JNK suppression, thereby blocking the acute‑to‑chronic inflammatory transition.

Mechanistic Rationale

• BMAL1 directly activates NAMPT transcription, linking the clock to the NAD+ salvage pathway (1).
• SIRT1 deacetylates JNK and its upstream kinases (ASK1, MKK4/7), reducing their catalytic activity in a NAD+-dependent manner.
• Circadian decline of NAD+ therefore leads to hyperacetylated, active JNK, driving sustained AP-1‑dependent transcription of SASP components (5).
• REV-ERBα, which represses BMAL1/CLOCK, is itself a SIRT1 target; reduced SIRT1 activity amplifies REV-ERBα acetylation, weakening its repression and further destabilizing clock output (3).
• Mitochondrial ROS in senescent cells activates JNK (4), but without SIRT1 restraint this signal becomes uncoupled from circadian gating, feeding a feed‑forward loop of inflammation.

Testable Predictions

1. In BMAL1‑deficient fibroblasts, JNK phosphorylation will show abolished circadian oscillation and elevated basal levels compared with wild‑type controls.
2. Pharmacological NAD+ augment