Nuclear Autophagy Protein WSTF Selectively Drives Chronic Inflammation
Scientists identify a nuclear autophagy mechanism that amplifies chronic—but not acute—inflammation, opening a new therapeutic window for common diseases.
Summary
Researchers at MGH and collaborating institutions discovered that WSTF, a chromatin remodeling protein, is selectively degraded via nuclear autophagy during chronic inflammation. When the autophagy protein GABARAP binds WSTF in the nucleus, WSTF is exported to the cytoplasm and destroyed by autophagosomes/lysosomes. Loss of WSTF opens chromatin over inflammatory genes, amplifying the inflammatory response. Crucially, this mechanism operates during chronic inflammation—such as cellular senescence, metabolic liver disease (MASH), and osteoarthritis—but not during acute inflammation. Cell-penetrating peptides blocking the WSTF-GABARAP interaction suppressed chronic inflammation in mouse models and patient samples without impairing acute immune responses, suggesting a targeted therapeutic strategy for chronic inflammatory diseases.
Detailed Summary
Chronic inflammation underlies some of the most prevalent and debilitating diseases of aging—including arthritis, metabolic dysfunction-associated steatohepatitis (MASH), autoimmune disorders, and cancer. Yet current anti-inflammatory therapies largely blunt both chronic and acute responses, limiting their safety and utility. This landmark study published in Nature identifies a molecular mechanism that specifically distinguishes chronic from acute inflammation, offering a potential path to targeted treatment.
The research team screened for substrates of nuclear autophagy—a process in which nuclear proteins are selectively exported and degraded by autophagosomes and lysosomes—using six ATG8 autophagy protein isoforms stably expressed in primary human fibroblasts. Co-immunoprecipitation coupled with tandem mass tag mass spectrometry of nuclear fractions revealed unexpected enrichment of chromatin remodeling proteins as ATG8 binding partners. Cross-referencing these findings with proteomics from senescent cells (induced by oncogene activation or DNA damage) identified WSTF (BAZ1B), a subunit of the ISWI chromatin remodeling complex, as a consistently downregulated target.
WSTF normally promotes nucleosome compaction, keeping chromatin in a 'closed,' transcriptionally repressive state over inflammatory gene loci. The study demonstrates that during chronic inflammation, the ATG8 family member GABARAP binds directly to WSTF in the nucleus, triggering its nuclear export and subsequent lysosomal degradation—a process dependent on autophagy genes ATG7, ATG13, and FIP200, and blocked by the lysosomal inhibitor bafilomycin A1 but not by proteasomal inhibitors. Loss of WSTF leads to chromatin opening over inflammatory genes, amplifying cytokine and chemokine expression. Importantly, this mechanism was active in senescence, MASH, and osteoarthritis but was absent during acute inflammatory stimulation (e.g., LPS treatment), explaining the selectivity for chronic conditions.
Therapeutically, the team developed cell-penetrating peptides that block the WSTF-ATG8 interaction. These peptides suppressed chronic inflammation in cellular senescence models and in mouse models of MASH and osteoarthritis, and showed concordant effects in human patient tissue samples—all without impairing acute inflammatory responses. This selectivity is a critical advantage over existing anti-inflammatory drugs.
The findings reframe nuclear autophagy as a chromatin-level regulator of inflammatory gene expression and establish WSTF as a molecular gatekeeper distinguishing chronic from acute inflammation. While the work is primarily mechanistic and the therapeutic peptides are at an early preclinical stage, the conceptual advance and proof-of-concept data are compelling. Future studies will need to address delivery, pharmacokinetics, and long-term safety of WSTF-targeting strategies in humans.
Key Findings
- WSTF chromatin remodeling protein is selectively degraded via nuclear autophagy during chronic but not acute inflammation.
- GABARAP (ATG8 family) binds WSTF in the nucleus, triggering its cytoplasmic export and lysosomal destruction.
- Loss of WSTF opens chromatin over inflammatory gene loci, amplifying cytokine and chemokine expression.
- Cell-penetrating peptides blocking WSTF-ATG8 interaction suppress MASH and osteoarthritis in mouse models and patient samples.
- Acute inflammation (e.g., LPS-induced) is unaffected by WSTF-targeting, demonstrating mechanistic selectivity.
Methodology
The study used co-IP with TMT-based mass spectrometry in nuclear fractions of human fibroblasts and GFP-LC3B transgenic mouse brains to map ATG8 nuclear interactomes. Senescence was induced by oncogene activation and DNA damage; autophagy dependence was confirmed by genetic knockdown (ATG7, ATG13, FIP200) and pharmacological inhibition. Therapeutic efficacy was tested using cell-penetrating peptides in mouse models of MASH and osteoarthritis, with validation in human patient tissue cohorts.
Study Limitations
The therapeutic peptides are at an early preclinical stage, and pharmacokinetics, bioavailability, and long-term safety in humans remain uncharacterized. The study focuses primarily on fibroblasts and hepatic/joint tissue; whether the WSTF nuclear autophagy axis operates similarly across all relevant immune and tissue cell types is not fully established. Causal directionality between WSTF loss and disease progression in humans requires further longitudinal and interventional evidence.
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