Mesenchymal Drift Module

Aging Module mesenchymal_drift 3 disorders Pathograph 7

A conserved mechanism module for the age-associated loss of cell identity termed mesenchymal drift: differentiated cells of many lineages (epithelial, endothelial, neural and glial) progressively lose their lineage identity programs while up-regulating mesenchymal (fibroblast-like) genes. The chain is erosion of the epigenetic control that maintains lineage identity -> sustained TGF-beta pro-mesenchymal signaling -> mesenchymal drift (loss of lineage identity with mesenchymal gene up-regulation) -> loss of tissue homeostasis with fibrotic remodeling -> age-related organ decline, disease progression and mortality. The key conformance target is "mesenchymal_drift#Mesenchymal Drift of Differentiated Cells". Drug-target pattern, both experimental: Yamanaka-factor partial reprogramming INHIBITS the central node, reducing the mesenchymal signature before dedifferentiation, and TGF-beta type I receptor (ALK5) inhibitors such as RepSox INHIBIT the TGF-beta signaling node. Complementary to, not overlapping with, its siblings: `epigenetic_alterations` models the upstream drift of the epigenome itself (methylation clocks) and ends in a generic "cellular decline" node, whereas this module models what that drift does to cell identity and in which direction identity is lost; `fibrotic_response` models wound-healing activation of resident mesenchymal cells (fibroblasts, stellate cells) into myofibroblasts, whereas here the cells acquiring mesenchymal features are non-mesenchymal cells; and classical epithelial-to-mesenchymal transition is a coordinated, switch-like program, whereas mesenchymal drift is low-grade, stochastic and mosaic.

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Pathophysiology Nodes

5 shared nodes are defined in this module.

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Cell Types

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Biological Processes

epigenetic maintenance of lineage identity GO:0040029 ⚠ ABNORMAL TGF-beta receptor signaling GO:0007179 ↑ INCREASED mesenchymal drift (aberrant acquisition of mesenchymal identity) GO:0048762 ⚠ ABNORMAL excessive extracellular matrix deposition GO:0030198 ⚠ ABNORMAL

Notes

This is a mechanism module, not a specific disease. Disorder entries reference individual nodes via conforms_to (e.g. "mesenchymal_drift#Mesenchymal Drift of Differentiated Cells"), substituting the drifting cell type (alveolar or renal tubular epithelium, vascular endothelium, astrocytes, oligodendrocytes, pericytes) and the organ-specific outcome. Do not create a "Mesenchymal Drift" Disease entry; it is a process that recurs across age-related diseases. Worked conformers, each attaching at the central node: Idiopathic Pulmonary Fibrosis (epithelial and endothelial drift, with a lavage drift score tracking survival), Chronic Kidney Disease (tubular and podocyte drift, with mouse partial-EMT genetics cited for the functional consequence and the edge to interstitial fibrosis), and Alzheimer Disease (astrocyte, oligodendrocyte and pericyte drift, signature-level only and deliberately left without downstream edges). The human disease-level evidence for all three reaches the KB through reviews that restate Lu et al. 2025, whose abstract does not itemize diseases. Two cautions a conformer must carry. First, the defining evidence is transcriptomic: a mesenchymal gene signature rising in bulk and single-cell expression data. As the Alzheimer's disease review cited on the central node stresses, a drifting transcriptome does not by itself establish a physiological change, and new single-cell clusters may reflect blurred lineages or technical artifact. A conforming node should cite disease-specific evidence that the identity loss has functional consequences, not only the signature. Second, the framework is recent (2025) and the claim that it integrates the other hallmarks of aging is a proposal from the same group, so this module is deliberately not added to a hallmarks-of-aging collection. Ontology choices. GO has no term for loss of cell identity or for mesenchymal drift; "epithelial to mesenchymal transition" (GO:0001837) names the coordinated program the sources distinguish MD from and is deliberately not bound. The central node instead binds "mesenchymal cell differentiation" (GO:0048762) with modifier ABNORMAL, carrying the specificity in preferred_term. That term covers only the gain of mesenchymal traits; the other half of the drift, loss of the original lineage identity, is unbound. An OLS search of GO for "cell identity" returned only "maintenance of meristem identity" (GO:0010074, a plant term) and lineage-specific fate-commitment terms, so GO has no general term for maintaining or losing differentiated cell identity. A Nature 2026 perspective by Yucel, Moliere and Gladyshev (DOI 10.1038/s41586-026-10955-0) framing identity loss as erosion of PRC2-maintained chromatin architecture is relevant to the trigger node but is not cited, because the reference fetch returned no abstract or full text to quote.

Discussions and Knowledge Gaps

Does mesenchymal drift cause age-related tissue decline, or is the mesenchymal transcriptional signature a readout of underlying epigenetic instability that has no functional effect of its own?

KNOWLEDGE GAP OPEN mesenchymal_drift_cause_or_marker

Attached to: Mesenchymal Drift of Differentiated Cells Age-Related Organ Decline and Mortality

The evidence for the central node is transcriptomic, and the link to outcome is a correlation with survival and mortality. Reversal by partial reprogramming does not settle direction, because reprogramming also resets the upstream epigenome. In Alzheimer's disease the signature itself has been shown in only a few cell types, and the authors who apply the framework there call for in vivo functional and morphological validation before treating identity shifts as causal.

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Used By Disorder Entries

Alzheimer Disease via Glial and Pericyte Mesenchymal Drift → Mesenchymal Drift of Differentiated Cells

Chronic Kidney Disease via Tubular and Podocyte Mesenchymal Drift → Mesenchymal Drift of Differentiated Cells

Idiopathic Pulmonary Fibrosis via Epithelial and endothelial mesenchymal drift → Mesenchymal Drift of Differentiated Cells

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Pathograph

Use the checkboxes to hide or show graph categories. Hover nodes for evidence-backed metadata.

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Pathophysiology

Erosion of Epigenetic Maintenance of Lineage Identity

trigger

Differentiated cell identity is held in place by epigenetic and transcriptional controls laid down during development. With age and chronic stress this control loosens, epigenetic noise increases, and lineage programs are no longer stably maintained. This is the point at which the upstream epigenetic drift of the epigenetic_alterations module acquires a cell-identity consequence.

epigenetic maintenance of lineage identity GO:0040029 ⚠ ABNORMAL

Downstream

Mesenchymal Drift of Differentiated Cells Loss of stable epigenetic maintenance lets lineage programs decay and mesenchymal programs rise.

Show evidence (2 references)

PMID:42680479 SUPPORT REVIEW SYNTHESIS Other

"Cellular identity is maintained by precise epigenetic regulation, but chronic stress and aging can disrupt this control, leading to mesenchymal drift (MD)."

States that lineage identity depends on epigenetic regulation and that aging and chronic stress disrupt it as the origin of mesenchymal drift. Evidence source is OTHER because this is a review.

PMID:41322283 SUPPORT REVIEW SYNTHESIS Other

"Mechanistically, it converges with epigenetic erosion, chronic inflammation, and extracellular matrix stiffening to establish self-reinforcing loops of dysfunction."

Places epigenetic erosion upstream of, and converging with, mesenchymal drift. Evidence source is OTHER because this is a review.

Sustained TGF-beta Pro-Mesenchymal Signaling

amplifier

Persistent TGF-beta/SMAD signaling pushes drifting cells toward mesenchymal gene expression and forms a feedback loop with the drift itself. The sources name two parallel inputs alongside it, chronic inflammatory cytokines (IL-1 beta, IL-6/STAT3) and extracellular matrix stiffening with YAP/TAZ activation. This node models only the TGF-beta arm, which is the one bound and the one with a pharmacological handle; the inflammatory arm is modeled by inflammaging#Chronic Low-Grade Sterile Inflammation, and matrix stiffening has no node here.

TGF-beta receptor signaling GO:0007179 ↑ INCREASED

Downstream

Mesenchymal Drift of Differentiated Cells Pro-mesenchymal signals drive mesenchymal gene programs in cells whose lineage identity is already weakened.

Show evidence (1 reference)

PMID:41322283 SUPPORT REVIEW SYNTHESIS Other

"Mechanistically, MD aligns with sustained TGF- β signaling, chronic inflammation, and matrix stiffening, forming feedback loops that erode lineage fidelity."

Names sustained TGF-beta signaling, chronic inflammation and matrix stiffening as the signals that drive and reinforce mesenchymal drift. Evidence source is OTHER because this is a review.

Mesenchymal Drift of Differentiated Cells

central effector

Cells that should maintain epithelial, endothelial, neural or glial programs progressively lose lineage markers (EPCAM, CDH1, claudins; PECAM1, CDH5 in endothelium) and up-regulate mesenchymal genes (VIM, FN1, COL1A1, COL3A1), with an altered composition of stromal cell populations. Analysis of expression data from over 40 human tissues and 20 diseases found the signature rising with age across most tissues. Unlike the coordinated epithelial-to-mesenchymal transition of development and cancer, the drift is low-grade, stochastic and mosaic within cells and populations. It is partially reversible: suppressing key drift transcription factors, or brief Yamanaka-factor partial reprogramming, reduces it. This is the key conformance target.

epithelial cell CL:0000066 endothelial cell CL:0000115

mesenchymal drift (aberrant acquisition of mesenchymal identity) GO:0048762 ⚠ ABNORMAL

Used by disorders

Alzheimer Disease as Glial and Pericyte Mesenchymal Drift

Chronic Kidney Disease as Tubular and Podocyte Mesenchymal Drift

Idiopathic Pulmonary Fibrosis as Epithelial and endothelial mesenchymal drift

Downstream

Loss of Tissue Homeostasis and Fibrotic Remodeling Cells that have lost lineage identity no longer sustain specialized organ functions and add profibrotic programs to the tissue.

Show evidence (3 references)

PMID:40816266 SUPPORT PRIMARY RESULT Human Clinical

"Our analysis of gene expression data from over 40 human tissues and 20 diseases reveals a pervasive upregulation of mesenchymal genes across multiple cell types, along with an altered composition of stromal cell populations, denoting a "mesenchymal drift" (MD)."

The defining observation: mesenchymal genes rise across many human tissues and cell types with age and in disease. Graded HUMAN_CLINICAL because the data are human tissue expression profiles; the result is an analysis of those data rather than a wet-lab experiment.

PMID:42208498 SUPPORT REVIEW SYNTHESIS Other

"We propose mesenchymal drift, a process in which cells progressively lose lineage identity and adopt mesenchymal features, as a convergent framework that integrates the hallmarks of aging."

Defines the central node as the coupled loss of lineage identity and gain of mesenchymal features. Evidence source is OTHER because this is a perspective; its claim that the drift integrates the other hallmarks is a proposal, not a result.

PMID:42680479 SUPPORT REVIEW SYNTHESIS Other

"Unlike the coordinated process of epithelial-mesenchymal transition (EMT), MD is a stochastic, lineage-independent phenomenon marked by increased epigenetic noise and the widespread activation of profibrotic gene programs."

Distinguishes the drift from classical EMT, which is why this node does not bind the GO epithelial-to-mesenchymal transition term. Evidence source is OTHER because this is a review.

Loss of Tissue Homeostasis and Fibrotic Remodeling

effector

Drifting cells lose barrier and specialized functions and acquire motility, contractility and extracellular matrix deposition, disrupting organ integrity and promoting fibrosis in lung, liver, kidney, heart and brain.

excessive extracellular matrix deposition GO:0030198 ⚠ ABNORMAL

Downstream

Age-Related Organ Decline and Mortality Loss of tissue homeostasis accumulates into organ decline and disease progression.

Show evidence (1 reference)

PMID:41322283 SUPPORT REVIEW SYNTHESIS Other

"By eroding lineage identity and promoting fibrosis, MD disrupts organ integrity in the lung, liver, kidney, heart, and brain."

Links loss of lineage identity to fibrosis and disrupted organ integrity across several organs. Evidence source is OTHER because this is a review.

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Treatments

Partial Epigenetic Reprogramming (Experimental)

Platform: Gene therapy

Brief, transient expression of the Yamanaka factors (OCT4, SOX2, KLF4, with or without MYC) resets epigenetic and transcriptional age without driving cells to pluripotency. It is an experimental intervention with no approved clinical use; it is recorded here as the drug-target pattern for this module, because it reduces the mesenchymal-drift signature before cells dedifferentiate.

Mechanism target:

INHIBITS Mesenchymal Drift of Differentiated Cells — Partial reprogramming lowers the mesenchymal signature and rejuvenates the aging transcriptome while the cells keep their identity.

Evidence: 1

TGF-beta Receptor (ALK5) Inhibition (Experimental)

Pharmacotherapy NCIT:C15986

Platform: Small molecule

Small-molecule inhibitors of the TGF-beta type I receptor ALK5 (and ALK2), such as RepSox, are proposed as a pharmacological substitute for partial reprogramming that suppresses mesenchymal drift without dedifferentiation. The evidence is from mice and cells; there is no approved use for this indication.

Mechanism target:

INHIBITS Sustained TGF-beta Pro-Mesenchymal Signaling — Blocking the TGF-beta type I receptor removes the sustained signal that drives cells toward a mesenchymal state.

Evidence: 2