Cellular Recycling Pathway Emerges as Central Driver of Ageing and Disease

Deep inside every cell, a molecular delivery service runs around the clock, ferrying worn-out or no-longer-needed proteins to the lysosome, the cell’s digestive compartment, for destruction. This pathway, known as chaperone-mediated autophagy, or CMA, was first described more than three decades ago, yet it has spent much of that time in the shadow of its better-known cousin, macroautophagy, which engulfs bulk cytoplasm in membrane vesicles. A comprehensive new review by Susmita Kaushik and Ana Maria Cuervo of the Albert Einstein College of Medicine, published in Nature Reviews Molecular Cell Biology, argues that CMA deserves centre stage. Drawing on a wave of recent genetic, pharmacological and proteomic studies, the authors present CMA not merely as a cellular housekeeper but as a highly selective regulatory system whose failure reverberates through metabolism, immunity, the brain and the ageing process itself.

What sets CMA apart from all other degradative routes is the extraordinary way its cargo reaches the lysosomal interior. Instead of wrapping material in vesicles, CMA selects individual proteins one at a time. Cytosolic proteins carrying a specific pentapeptide targeting motif, first characterised by J. Fred Dice in 1990, are recognised by the heat-shock chaperone HSC70, which escorts them to the lysosomal membrane. There, the substrate docks onto LAMP2A, a single-pass membrane receptor that is unique among lysosomal proteins in doubling as a translocation machine. LAMP2A molecules multimerise into a proteinaceous pore, and the substrate, which must be unfolded before passage, threads through the membrane into the lumen, where a lysosomal form of HSC70 pulls it in for degradation. This one-by-one selectivity means CMA can remove a single protein from a crowded cytosol without disturbing its neighbours, a precision no bulk degradation pathway can match.

The past several years have dramatically expanded the known cast of CMA components and regulators. The review highlights a lysosome-associated signalling module built around mTORC2, the phosphatase PHLPP1 and the kinase AKT. Under basal conditions, mTORC2 and AKT sit on CMA-active lysosomes and hold the pathway in check: AKT phosphorylates GFAP at the lysosomal membrane, destabilising the LAMP2A translocation complex. When the cell faces oxidative stress, nutrient deprivation or DNA damage, the small GTPase RAC1 recruits PHLPP1 to the membrane, which dephosphorylates AKT and lifts the brake. Other layers of control include lipid microdomains in the lysosomal membrane that govern LAMP2A turnover, the protease cathepsin A, which cleaves the receptor, and trafficking regulators such as Rab11, Rab7 and cystinosin that reposition LAMP2A within the endolysosomal system. Transcription factors, notably the antioxidant regulator NRF2 and the lysosomal master regulator TFEB, tune the pathway from above, while endogenous peptides such as humanin can activate it.

Perhaps the most consequential conceptual shift documented in the review is that CMA is not simply a quality-control system for damaged proteins. Proteome-wide mapping of CMA targeting motifs and organ-specific analyses of the CMA subproteome have revealed that the pathway routinely degrades fully functional proteins, thereby terminating their physiological roles. In other words, CMA acts as a regulatory scalpel. When researchers blocked CMA in the livers of mice, the first consequence was not a toxic pile-up of misfolded proteins but widespread metabolic dysregulation, establishing the pathway as a key instrument of proteome remodelling. CMA degrades lipid droplet coat proteins to initiate lipolysis, removes signalling proteins and metabolic enzymes during adipocyte differentiation, and controls the stability of factors such as HIF-1α, PGC1α and PTEN that sit at the heart of cellular energy and stress responses.

Nowhere is this regulatory reach more striking than in stem cell biology. Work on embryonic stem cells showed that low CMA activity helps sustain pluripotency, whereas upregulating the pathway promotes differentiation by selectively eliminating metabolic enzymes and pluripotency factors. A parallel logic operates in the blood-forming system: CMA sustains haematopoietic stem-cell function, and it also clears negative regulators of T cell activation, sharpening immune responses. Conversely, restoring LAMP2A expression in old mice rejuvenates the T cell compartment and improves immune function. The pathway even participates in antigen presentation, with LAMP2A facilitating MHC class II display of cytoplasmic peptides, tying protein degradation directly to immunological surveillance.

The brain has become one of the most active frontiers of CMA research. A landmark 2021 study using mice lacking LAMP2A systemically or specifically in neurons demonstrated that CMA is essential for maintaining the solubility and function of the neuronal proteome, offering a unifying framework that connects CMA decline to a broad spectrum of neurodegenerative phenotypes. The connection to Parkinson’s disease runs deepest. In 2004, Cuervo and colleagues showed that pathogenic forms of α-synuclein bind the LAMP2A translocation complex at the lysosomal membrane and jam it, blocking degradation of other substrates and creating a vicious cycle in which the protein that CMA should clear disables the machinery meant to clear it. Mutant LRRK2, glucocerebrosidase deficiency and lysosomal lipid abnormalities all converge on the same bottleneck, while acetylated tau blocks the pathway and promotes tau pathology spread in mice. Encouragingly, boosting CMA in vivo mitigates α-synuclein-induced neurodegeneration, and recent work maps sex-specific, cell-type-specific remodelling of the synaptic proteome by the pathway.

Outside the nervous system, CMA dysfunction is emerging as a common thread in age-related disease. In the cardiovascular system, the pathway protects cardiomyocytes from hypoxic death, guards against atherosclerosis by managing macrophage lipid handling and inflammation, and its disruption has been linked to cardiac arrhythmias through degradation of sodium channel regulators. In the liver, CMA loss promotes fatty acid accumulation, steatohepatitis and bile acid abnormalities, and dietary lipids such as palmitic acid directly inhibit the pathway in hypothalamic neurons, suggesting a mechanism by which high-fat diets impair metabolic control. Recent studies extend the theme to skeletal muscle, where age-related CMA decline drives progressive myopathy and undermines muscle stem cell regeneration; to the retina, where defective CMA in the retinal pigment epithelium characterises age-related macular degeneration; and to bone, cartilage and the intervertebral disc, where the pathway balances senescence and tissue maintenance.

Cancer presents a genuinely double-edged picture. On one side, CMA can suppress tumorigenesis: it promotes degradation of the oncogene MYC, and a 2026 study identified the pathway as a tumour-suppressive mechanism in hepatocellular carcinoma. On the other side, many tumours exploit CMA for their own survival. LAMP2A is overexpressed in breast tumours, the pathway is required for tumour growth in mouse models, glioma stem cells depend on it, and glioblastoma co-opts pericyte CMA to blunt anti-tumour immunity. This duality has spurred the development of pharmacological tools that cut both ways. Retinoic acid derivatives and the CA family of compounds, which act as chemical glues stabilising the NCoR1–RARα interaction and thereby releasing CMA from nuclear receptor inhibition, can activate the pathway, while small molecules disrupting the HSC70–LAMP2A interaction offer a strategy to inhibit it in cancers addicted to CMA.

The link to ageing itself is now supported by an unusually rich evidence base. CMA activity declines with age in most tissues, and a systematic in vivo map published in 2025 revealed profound sex-specific and cell-type-specific patterns of that decline, positioning differential CMA vulnerability as a possible determinant of tissue-specific ageing trajectories. Restoring LAMP2A in aged liver improves cellular maintenance and hepatic function, and long-lived mouse models with reduced growth hormone signalling, including Snell dwarf mice that live 40 to 50 percent longer than normal, show constitutively elevated hepatic CMA. Calorie restriction and its mimetics activate the pathway, and a 2026 study found that CMA decline in ageing macrophages impairs the clearance of senescent cells, directly connecting the pathway to one of the canonical hallmarks of ageing. Intriguingly, CMA activity follows circadian rhythms in a tissue-specific manner, hinting that timing may matter for any future intervention.

The therapeutic horizon is widening accordingly. Metformin activates CMA and improves pathology in Alzheimer’s disease models, retinal degeneration has been protected by compounds that release the pathway from RARα-corepressor repression, and peptide-based inhibitors are being explored to normalise aberrant CMA in glioblastoma and lupus. The Cuervo laboratory has released computational resources, including a CMA score and the KFERQ Finder tool, to help researchers identify substrates and quantify pathway activity, while fluorescent reporter mice now allow CMA dynamics to be visualised in living tissues. The overall message of the review is that CMA has come of age: it is no longer a niche branch of autophagy but a master regulator of proteome composition whose selective, one-protein-at-a-time logic shapes everything from stem cell fate to immune memory, and whose restoration in old tissue may offer one of the most direct molecular levers yet identified for extending healthspan.

Subject of Research: Chaperone-mediated autophagy and its roles in physiological homeostasis, disease and ageing

Article Title: Chaperone-mediated autophagy in physiological homeostasis, disease and ageing

Article References: Kaushik, S., & Cuervo, A. M. (2026). Chaperone-mediated autophagy in physiological homeostasis, disease and ageing. Nature Reviews Molecular Cell Biology. https://doi.org/10.1038/s41580-026-01023-6

Image Credits: AI Generated

DOI: 10.1038/s41580-026-01023-6

Keywords: chaperone-mediated autophagy, CMA, LAMP2A, lysosome, ageing, proteostasis, neurodegeneration, Parkinson's disease, alpha-synuclein, metabolism, stem cells, cancer