IF a dual-transgene AAV8 vector encoding (i) the bowhead whale (Balaena mysticetus) duplicated LAMTOR1 paralog (bwLAMTOR1-dup) codon-optimized for Mus musculus expression under an hepatocyte-specific ApoE/hAAT promoter, and (ii) murine Atp6v1b2 (v-ATPase V1 domain B2 subunit, UniProt Q9Z1G3) under the same promoter — delivered as a single intravenous injection at 3×10¹¹ vg/kg to 22–24-month-old male and female C57BL/6J mice —

THEN lysosomal lumenal pH in hepatocytes will shift from the age-drifted alkaline range (~5.4–5.8) back toward the youthful acidic optimum (~4.6–5.0), lipofuscin autofluorescence area per hepatocyte will decrease by ≥30% relative to aged AAV-GFP controls at 12 weeks post-injection, and autophagic flux (LC3-II/LC3-I ratio under bafilomycin challenge) will increase ≥1.8-fold,

BECAUSE the following causal chain operates:

1. Age-related lysosomal alkalinization accumulates in post-mitotic hepatocytes over decades because v-ATPase pump efficiency declines and the Ragulator scaffold complex (LAMTOR1–5) loses membrane anchorage competence, disrupting the v-ATPase–Ragulator interaction required for both proton pumping and lysosomal surface mTORC1 recruitment. [Research Context — lysosomal pH drift and lipofuscin accumulation in aged hepatocytes]

2. Bowhead whale LAMTOR1 duplication (identified in comparative genomics of Balaena mysticetus, an animal exceeding 200 years of lifespan with minimal lipofuscin burden compared to shorter-lived cetaceans) represents a functional redundancy or neofunctionalization event that sustains lysosomal membrane tethering of the Ragulator–v-ATPase supercomplex under prolonged oxidative and lipotoxic stress — conditions that in shorter-lived mammals progressively oxidize the palmitoylated LAMTOR1 N-terminus, detaching it from the lysosomal membrane. [Research Context — bowhead LAMTOR1 duplication and longevity adaptation; SPECULATIVE: the duplicate copy may encode a paralog with altered palmitoylation motifs or an N-terminal domain resistant to lipid peroxidation-mediated uncoupling]

3. Exogenous bwLAMTOR1-dup expressed in aged hepatocytes re-establishes a stoichiometrically competent Ragulator complex at the lysosomal membrane, providing a fresh, non-oxidized scaffold for v-ATPase docking even in the presence of the endogenous, age-damaged murine LAMTOR1 (a dominant-supplement rather than a replacement strategy). [Research Context — LAMTOR1/Ragulator–v-ATPase interaction in mTORC1 nutrient sensing; SPECULATIVE: dominant supplementation of a more stable paralog overcomes the damaged endogenous pool]

4. Co-delivered Atp6v1b2 augments the catalytic B2 subunit pool at the lysosomal V1 domain; because B2 subunit availability is rate-limiting for V1 reassembly onto V0 (the canonical regulatory switch for lysosomal acidification), its overexpression in aged hepatocytes directly boosts proton pumping capacity and re-acidifies the lysosomal lumen. [Research Context — Atp6v1b2 ...

SENS category: GlycoSENS