The muscle damage that will weaken you at 60 may begin decades earlier.<\/p>\n
Not as soreness or fatigue, but as a microscopic cascade you cannot feel: damaged proteins piling up, calcium pumps seizing, the molecular machinery of muscle contraction slowly breaking down \u2014 all while you go about your day, unaware.<\/p>\n
Two companion studies recently published in Nature Metabolism<\/em> have traced this invisible timeline, revealing that sarcopenia \u2014 the progressive muscle wasting that accelerates after 60 \u2014 doesn\u2019t start when weakness appears. It starts years earlier, when a cellular cleanup system called chaperone-mediated autophagy (CMA) begins to fail.<\/p>\n \u201cBy midlife, you start losing CMA in the muscle,\u201d said Ana Maria Cuervo, MD, PhD, distinguished professor of developmental and molecular biology at the Albert Einstein College of Medicine in Bronx, New York. She led the studies with collaborators at New York University, the National Institute on Aging, the Reynolds Oklahoma Center on Aging, and the Altos Labs San Diego Institute of Science.<\/p>\n These studies encourage reevaluation of the processes of sarcopenia and muscle aging because they also reveal something unexpected: a potential pathway to stalling and even reversing this decline.<\/p>\n Cuervo has spent more than three decades building the story of CMA, one organ at a time. From the liver she moved to the brain, linking the pathway\u2019s failure to protein tangles in Alzheimer\u2019s disease and alpha-synuclein aggregates in Parkinson\u2019s disease, and showing how the pathway\u2019s activation protects against retinal degeneration.<\/p>\n Each study added another tile to a mosaic of age-related decline, all tracing back to the same system.<\/p>\n Muscle was an unexplored frontier. When a postdoc with muscle expertise \u2014 Olaya Santiago-Fern\u00e1ndez, PhD \u2014 joined Cuervo\u2019s lab at the Albert Einstein College of Medicine to continue research started by Luisa Coletto, PhD, on the effects of CMA in muscle, the work intensified.<\/p>\n \u201cI inherited this project from [Luisa],\u201d Santiago-Fern\u00e1ndez said. \u201cI thought it had a lot of possibilities because the lab had already seen that when you block CMA specifically in skeletal muscle, you start to see muscle damage.\u201d With her background in muscle biology, Santiago-Fern\u00e1ndez was positioned to dig deeper into what that damage meant.<\/p>\n As the lead of one of the two companion studies, she and the team genetically engineered mice to lack CMA in their muscles. During strength tests, the mice showed a weak grip, and their endurance flagged on treadmill exercises. When the team dissected their muscles, the real story emerged.<\/p>\n \u201cOne of the main characteristics of muscle damage is that the cells\u2019 nuclei, which are normally in the periphery of the fibers, relocate to the center,\u201d Santiago-Fern\u00e1ndez explained. In healthy muscles, nuclei hug the edges, leaving the interior packed with contractile machinery. But when they drift inward, it\u2019s a sign that machinery has broken down.<\/p>\n \u201cWe also saw necrotic [dying tissue] areas, and that\u2019s where we started to see this phenotype,\u201d she said. \u201cFrom there, we moved on to electron microscopy and saw more alterations.\u201d<\/p>\n When CMA fails, damaged proteins accumulate and gum up the machinery of movement. But how does CMA work? Unlike bulk autophagy, which engulfs large swaths of cellular material wholesale to clean out debris and repurpose them into raw materials, CMA targets specific proteins bearing a particular molecular tag that marks them for disposal.<\/p>\n Chaperone proteins recognize this tag, escort the damaged protein to the lysosome, the cell\u2019s recycling center, and thread it through a receptor called LAMP2A for degradation, hence the term \u201cchaperone-mediated autophagy.\u201d<\/p>\n But CMA doesn\u2019t just eliminate garbage. The amino acids from the disposed proteins are released and become raw materials for building new, functional proteins. It\u2019s a cleanup crew and supply chain in one.<\/p>\n Cuervo often explains the system with an analogy: \u201cImagine you go up a mountain in the cold because you have a house there, but the heat is not working. You see that you have a fireplace. You\u2019re going to look around and say, \u2018What do I have here that is old and that I can burn for fuel?\u2019 Cells do the same.\u201d<\/p>\n When electron microscopy images of the damaged muscle in CMA-deficient mice came back, Cuervo was astonished by what she saw.<\/p>\n \u201cYou have all these beautiful muscle fibers, with everything aligned [in normal muscle],\u201d Cuervo said, describing what healthy muscle looks like under an electron microscope.<\/p>\n There are dark bands called Z-lines on the ends of sarcomeres, the basic functional unit of muscle fibers responsible for contraction. Z-lines anchor the more central contractile machinery in the sarcomere as they stack in precise parallel rows like rungs on a ladder.<\/p>\n \u201cBut you look at these other muscles [in mice with CMA removed], and all this alignment [in the sarcomere] is lost.\u201d<\/p>\n In the CMA-deficient mice, the Z-lines were distorted and scattered, with the orderly architecture of contraction in disarray. Even the mitochondria had swollen into dysfunctional-looking balloons. The membrane network responsible for calcium storage, the sarcoplasmic reticulum (SR), was also severely disrupted.<\/p>\n \u201cThat was the aha moment,\u201d Cuervo said. \u201cI kept showing that image to all the collaborators to convince them, and they said, \u2018We\u2019ve never seen damage like this so severe.\u2019\u201d<\/p>\n Susmita Kaushik, PhD, co-author of the studies, describes the chills she experienced viewing those images. \u201cI have goosebumps just speaking about it. It was a night and day difference. [I thought] How are these mice even functional?\u2019\u201d<\/p>\n When researchers measured which proteins were accumulating in the damaged muscle, one stood out: the sarcoplasmic and endoplasmic reticulum Ca\u00b2\u207a ATPase, or SERCA, a calcium pump critical for muscle contraction and relaxation.<\/p>\n During muscle contraction, calcium floods into the cell, activating receptors on the SR, which then releases most of the calcium needed for contraction. SERCA\u2019s job is to rapidly pump most of it back into the SR, allowing the muscle to relax.<\/p>\n But SERCA bunched up into misfolded aggregates in mice without CMA.<\/p>\n \u201cWe first saw that SERCA levels were elevated in mice [without CMA],\u201d Santiago-Fern\u00e1ndez explained. \u201cSERCA started to accumulate in a misfolded fashion, creating these big, toxic accumulations.\u201d<\/p>\n \u201cIf SERCA is aggregating, calcium levels can\u2019t go down,\u201d Cuervo added. \u201cCalcium levels increase, you contract the muscle, but then the cell has to put it away in storage. That\u2019s what SERCA does.\u201d<\/p>\n To validate the findings in people, Santiago-Fern\u00e1ndez collaborated with geriatrician Luigi Ferrucci, MD, PhD, at the National Institute on Aging, who has access to large datasets of muscle samples from young and old human populations.<\/p>\n Even among healthy older adults without overt frailty, CMA was already declining. And in patients with sarcopenia, the decrease was dramatic. The molecular changes preceded functional decline, suggesting reduced CMA in muscle could serve as an early warning marker.<\/p>\n The muscle findings fit into Cuervo\u2019s larger vision of aging as a systemic failure of cellular maintenance.<\/p>\n \u201cYou don\u2019t only age in one organ,\u201d Cuervo said. \u201cCMA is required in all the cells of your body. In the brain, as CMA declines, you will experience problems with memory and motor coordination. In the skeletal muscle, you have problems with force and movement. In the liver, you have problems with detoxification. In the retina, you have problems with sight.\u201d<\/p>\n This systemic perspective shapes her therapeutic ambitions. The small molecules her lab has developed can even cross the blood-brain barrier, meaning they reach multiple organ systems. \u201cBy restoring CMA in many of the organs, you will have a more functional overall organism.\u201d<\/p>\n A companion study \u2014 conducted in collaboration with muscle stem cell expert Pura Mu\u00f1oz-C\u00e1noves, PhD, principal investigator at the Altos Labs San Diego Institute of Science \u2014 revealed an equally troubling finding about muscle regeneration.<\/p>\n Skeletal muscle fibers can\u2019t divide to repair themselves. Instead, the body relies on satellite cells, a population of stem cells that sit dormant at the edges of muscle fibers. When injury occurs these stem cells activate, proliferate, and differentiate to rebuild damaged tissue. It\u2019s a regenerative capacity that tissues such as the heart and brain largely lack.<\/p>\n In the study, mice lacking CMA in these stem cells couldn\u2019t regenerate muscle. The researchers identified 723 proteins that CMA normally clears in these cells \u2014 all of which accumulate when the pathway fails. Glycolytic enzymes piled up in inactive forms, creating an energy crisis. And a protein called ARPC1B, which helps control the internal scaffolding that stem cells need to divide and move, accumulated abnormally.<\/p>\n The critical finding: Aged muscle stem cells \u2014 from both old mice and elderly humans \u2014 displayed the same defects as genetically CMA-deficient young cells. The pathway that fails with experimental deletion is the same one that fails naturally with aging.<\/p>\n \u201cIt\u2019s not only that you can\u2019t maintain your muscle,\u201d Cuervo said, \u201cbut if you need to regenerate it because of damage, you can\u2019t because now those cells are compromised.\u201d<\/p>\n This creates what she calls a \u201cdouble hit\u201d \u2014 aging simultaneously undermines both the maintenance of existing muscle and the capacity to repair damage.<\/p>\n The therapeutic implications emerged from rescue experiments in both studies.<\/p>\n In the fiber study, researchers engineered mice to maintain LAMP2A expression throughout life and prevent the age-related decline because the loss of LAMP2A is the primary bottleneck in aging cells; by keeping this \u201centry gate\u201d open, they allowed the continuous flow of cellular waste into the lysosome for degradation.<\/p>\n These animals preserved grip strength and muscle structure into extreme old age, which is the mouse equivalent of 95 human years.<\/p>\n In the stem cell study, pharmacologic activation proved equally effective. A small-molecule compound, which boosts CMA activity by inhibiting a natural CMA suppressor, restored the proliferative capacity of aged muscle stem cells.<\/p>\n Perhaps most intriguing was a metabolic workaround. Supplementing cells with pyruvate \u2014 a fuel that feeds into the cell\u2019s energy machinery at a later stage, bypassing the broken enzymes \u2014 rescued proliferation even without fixing CMA itself.<\/p>\n Old human muscle cells responded similarly. Myoblasts from elderly donors, which showed impaired motility characteristic of CMA decline, regained their ability to move following CMA activation.<\/p>\n \u201cJust a little bit of an increase [in CMA] is more than enough to boost the system for healthy aging,\u201d Kaushik said.<\/p>\n Cuervo\u2019s lab has spent 7 years developing CMA-activating compounds in collaboration with Evripidis Gavathiotis, PhD, medicinal chemist at Albert Einstein College of Medicine. \u201cWe gave them as pills,\u201d she noted. \u201cWe don\u2019t even have to inject the animals.\u201d Einstein holds patents on these molecules, and licensing discussions with pharmaceutical companies are underway.<\/p>\n The studies also revealed that everyday choices influence CMA activity. Aerobic exercise such as running on the treadmill significantly activated CMA in mice skeletal muscle, and moderate exercise 30 minutes a day should be enough to activate it at least once daily.<\/p>\n Fasting works through similar logic: When dietary amino acids aren\u2019t available, cells must recycle existing proteins to build new ones.<\/p>\n Cuervo envisions a future where CMA is monitored as routinely as cholesterol, where markers for CMA can be measured like any other test. Catch the decline early, intervene before the damage accumulates, and perhaps the weakness that seems inevitable in old age won\u2019t be inevitable at all.<\/p>\n But significant questions remain. Mouse models don\u2019t perfectly replicate human aging. And the long-term effects of pharmacologically boosting CMA in humans are unknown. Though they\u2019ve found that falling LAMP2A levels in aging mice trigger muscle decline, her lab is still working to find if additional factors contribute to CMA decline in humans.<\/p>\n But for the millions of older adults who have watched their strength slip away, who have struggled to rise from a chair or recover from a fall, these studies offer something that wasn\u2019t there before: a target. Not just an explanation for why the body fails, but a mechanism that might be repaired.<\/p>\n The cleanup crew, it turns out, can be called back to work.<\/p>\n Cuervo was a co-founder and scientific advisor for the autophagy program at Life Biosciences during part of this project. Financial support was not provided for this work, and no data were shared with Life Biosciences, CalciMedica, or Altos Labs.<\/em><\/p>\n<\/div>\n The muscle damage that will weaken you at 60 may begin decades earlier. Not as soreness or fatigue, but as a microscopic cascade you cannot feel: damaged proteins piling up, calcium pumps seizing, the molecular machinery of muscle contraction slowly breaking down \u2014 all while you go about your day, unaware. Two companion studies recently […]<\/p>\n","protected":false},"author":1,"featured_media":11788,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_daextam_enable_autolinks":"","jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2}},"categories":[2],"tags":[],"class_list":["post-11787","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-health"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"https:\/\/diyhaven858.wasmer.app\/wp-content\/uploads\/2026\/01\/gty-260126-chest-muscle-800x450.jpg","jetpack_sharing_enabled":true,"jetpack-related-posts":[],"_links":{"self":[{"href":"https:\/\/diyhaven858.wasmer.app\/index.php\/wp-json\/wp\/v2\/posts\/11787","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/diyhaven858.wasmer.app\/index.php\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/diyhaven858.wasmer.app\/index.php\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/diyhaven858.wasmer.app\/index.php\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/diyhaven858.wasmer.app\/index.php\/wp-json\/wp\/v2\/comments?post=11787"}],"version-history":[{"count":0,"href":"https:\/\/diyhaven858.wasmer.app\/index.php\/wp-json\/wp\/v2\/posts\/11787\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/diyhaven858.wasmer.app\/index.php\/wp-json\/wp\/v2\/media\/11788"}],"wp:attachment":[{"href":"https:\/\/diyhaven858.wasmer.app\/index.php\/wp-json\/wp\/v2\/media?parent=11787"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/diyhaven858.wasmer.app\/index.php\/wp-json\/wp\/v2\/categories?post=11787"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/diyhaven858.wasmer.app\/index.php\/wp-json\/wp\/v2\/tags?post=11787"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}![\"photo](\"https:\/\/img.medscapestatic.com\/vim\/live\/professional_assets\/medscape\/images\/thumbnail_library\/ht-260126-ana-maria-cuervo120x156.jpg\")
The First Clues<\/h2>\n
![\"photo](\"https:\/\/img.medscapestatic.com\/vim\/live\/professional_assets\/medscape\/images\/thumbnail_library\/ht-260126-olaya-santiago-120x156.jpg\")
Seeing the Damage<\/h2>\n
![\"photo](\"https:\/\/img.medscapestatic.com\/vim\/live\/professional_assets\/medscape\/images\/thumbnail_library\/ou-260126-sarcomeres-comparisons-689x402.jpg\")
![\"photo](\"https:\/\/img.medscapestatic.com\/vim\/live\/professional_assets\/medscape\/images\/thumbnail_library\/ht-260126-susmita-kaushik-120x156.jpg\")
Tracking the Damage to Its Source<\/h2>\n
What They Saw in Humans<\/h2>\n
The Double Hit: When Repair Fails Too<\/h2>\n
Reversal and Rescue<\/h2>\n
Monitoring Healthy Aging as We Get Older<\/h2>\n
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<<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"