Interleukin-6 mediates PSAT1 expression and serine metabolism in TSC2-deficient cells

Wang, J.; Filippakis, H.; Hougard, T.; Du, H.; Ye, C.; Liu, H.-J.; Zhang, L.; Hindi, K.; Bagwe, S.; Nijmeh, J.; Asara, J. M.; Shi, W.; El-Chemaly, S. Y.; Henske, E. P.; Lam, H. C.

doi:10.1101/2021.05.17.444471

bioRxiv · 10.1101/2021.05.17.444471

Interleukin-6 mediates PSAT1 expression and serine metabolism in TSC2-deficient cells

Wang, J.·Filippakis, H.·Hougard, T.·Du, H.·Ye, C.·Liu, H.-J.·Zhang, L.·Hindi, K.·Bagwe, S.·Nijmeh, J.·Asara, J. M.·Shi, W.·El-Chemaly, S. Y.·Henske, E. P.·Lam, H. C.

View original source ↗Export metadata ↓

Abstract

Tuberous sclerosis complex (TSC) and lymphangioleiomyomatosis (LAM) are caused by aberrant mechanistic Target of Rapamycin Complex 1 (mTORC1) activation due to loss of either TSC1 or TSC2. Cytokine profiling of TSC2-deficient LAM patient-derived cells revealed striking upregulation of Interleukin-6 (IL-6). LAM patient plasma contained increased circulating IL-6 compared with healthy controls, and TSC2-deficient cells showed upregulation of IL-6 transcription and secretion compared to wildtype cells. IL-6 blockade repressed the proliferation and migration of TSC2-deficient cells and reduced oxygen consumption and extracellular acidification. U-13C glucose tracing revealed that IL-6 knockout reduced 3-phosphoserine and serine production in TSC2-deficient cells, implicating IL-6 in de novo serine metabolism. IL-6 knockout reduced expression of phosphoserine aminotransferase 1 (PSAT1), an essential enzyme in serine biosynthesis. Importantly, recombinant IL-6 treatment rescued PSAT1 expression in the TSC2-deficient, IL-6 knockout clones selectively and had no effect on wildtype cells. Treatment with anti-IL-6 (aIL-6) antibody similarly reduced cell proliferation and migration and reduced renal tumors in Tsc2+/- mice, while reducing PSAT1 expression. These data reveal a novel mechanism through which IL-6 regulates serine biosynthesis, with potential relevance to the therapy of tumors with mTORC1 hyperactivity. ClassificationMajor category: Biological Sciences Minor category: Cell Biology

Source connections

Published article ↗

Explore related subjects

pathology Preprint

Keep this discovery

Explore connections, maps & timelines

BibTeX RIS

Wang, J., Filippakis, H., Hougard, T., Du, H., Ye, C., Liu, H.-J., Zhang, L., Hindi, K., Bagwe, S., Nijmeh, J., Asara, J. M., Shi, W., El-Chemaly, S. Y., Henske, E. P., Lam, H. C.. 2021-05-17. Interleukin-6 mediates PSAT1 expression and serine metabolism in TSC2-deficient cells. https://doi.org/10.1101/2021.05.17.444471

Cite the original work for its findings. Save a collection to share your selection of sources.

KEEP EXPLORING

Related preprints

bioRxiv2026

SilencioM: silencing connected interfering oligonucleotides against MAPT as a potential disease modifying therapeutic for tauopathies

Tauopathies are a diverse group of neurodegenerative diseases whose pathogenesis involves brain accumulation of misfolded, pathological tau (Microtubule Associated Protein Tau, MAPT). More than twenty tauopathies have been identified thus far that collectively impact millions of people worldwide, of which the most common is Alzheimer's disease (AD). Despite substantial efforts to develop drugs for tauopathies, no effective treatments currently exist, highlighting the urgent need for therapeutics to combat these prevalent and ruinous neurodegenerative diseases. Strategies that target tau are likely to have the greatest impact since tau is the proximal cause of their pathogenesis. Small interfering RNAs (siRNAs) have emerged as a powerful class of precision therapeutics that silence disease-causing genes through RNA interference with favorable safety profiles. Delivery challenges are rapidly being addressed, and siRNA-based approaches are poised to transform the therapeutic landscape of neurological diseases. In this study, we describe SilencioM (Silencing connected interfering oligonucleotides against MAPT) and show its efficacy in markedly reducing tau pathology after a single intracerebroventricular injection in PS19 mice, a mouse model of severe tauopathy. SilencioM targets human, primate, rat and mouse ortholog genes; thus, the same compound can proceed from efficacy studies to Investigational New Drug Application (IND)-enabling studies. SilencioM is simple to manufacture and is administered without encapsulation in lipid nanoparticles and without requirements for lipophilic conjugation, making it a promising candidate for further development as a novel therapeutic for tauopathies, including AD.

pathology↗

bioRxiv2026

SilencioMA: A single compound that targets both MAPT and APP as a potential disease modifying therapeutic for Alzheimer's Disease

Alzheimer's Disease (AD) is the most common age-related neurodegenerative disease and the leading cause of dementia worldwide. AD pathogenesis involves aggregation of amyloid-beta (A{beta}), produced from amyloidogenic proteolytic processing of Amyloid Precursor Protein (APP), and accumulation of misfolded, pathological tau (Microtubule Associated Protein Tau, MAPT). Current efforts focus on developing disease modifying therapeutics (DMTs) against single targets: A{beta} or tau. However, DMTs that concurrently target both tau and A{beta} are likely to have the greatest impact since they target both culprits of AD pathogenesis. Here we describe the development of SilencioMA, a single compound that targets both MAPT and APP messenger RNAs (mRNAs) based on silencing connected interfering oligonucleotides against MAPT and APP. Cerebrospinal fluid (CSF) administration of SilencioMA reduces A{beta} and tau and pathology after a single intracerebroventricular injection in 5XFAD/PS19 mice, an animal model of severe amyloidosis and tauopathy. SilencioMA does not rely on lipid nanoparticles or lipophilic conjugates for CSF administration. At the same time its modular design permits conjugation of ligands that facilitate transcytosis through the blood brain barrier, allowing systemic administration. Our findings provide proof-of-concept for a strategy that targets the dual A{beta} and tau pathologies of AD, and establishes a compelling foundation for further development of SilencioMA as a next-generation DMT for AD.

pathology↗

bioRxiv2026

TREM2-stimulated, PDGF-dependent macrophage-fibroblast crosstalk induces beneficial plaque remodeling in clonal hematopoiesis

Background: In Jak2V617F clonal hematopoiesis, inflammatory signaling suppresses macrophage TREM2 and promotes features of plaque instability, while therapeutic TREM2 agonism reverses plaque instability by increasing fibroblasts and fibrous cap formation. We tested whether macrophage-derived PDGFB and stromal cell PDGFR? signaling mediate this response. Methods: Low allele burden (LAB) Jak2V617F atherosclerosis models were combined with inducible Pdgfb deletion in CX3CR1-lineage monocytes/macrophages or Pdgfra deletion in Col1a2-lineage fibroblast-enriched stromal cells. Mice were treated with the TREM2 agonist 4D9. Plaque composition, macrophage-fibroblast interactions, and aortic stromal cell populations were analyzed. Human WT and JAK2V617F iPSC-derived macrophages were used for validation. Results: TREM2 activation with 4D9 increased macrophage PDGFB production and promoted fibrous cap formation in LAB Jak2V617F atherosclerosis. Deletion of Pdgfb in CX3CR1-lineage cells markedly attenuated the 4D9-mediated increase in fibrous cap area and lesional PDGFR?+ cells, establishing macrophage-derived PDGFB as a key signal for the stromal response. Consistently, Col1a2-lineage Pdgfra deletion abolished the 4D9-induced fibrous cap response without significantly altering lesion or necrotic core area. Single cell RNA-seq identified increased Fmod+ and CD26/Dpp4+ fibroblast populations associated with 4D9 treatment. Fmod+ fibroblasts represented an abundant matrix-associated population, whereas CD26+ fibroblasts showed greatest enrichment, prominent extracellular matrix, collagen organization, and matrix-remodeling programs that were enhanced by 4D9 and attenuated by Pdgfra deletion. The stromal response was also associated with reduced macrophage migration-related programs and predicted chemokine communication from CD26+ fibroblasts to macrophages which was verified by macrophage migration studies. Moreover, stromal Pdgfra deletion increased lesional CCR2+ and CCR5+ macrophages. Conclusions: In a CH model of inflammatory atherosclerosis, TREM2 activation promotes a macrophage PDGFB-stromal PDGFR? pathway that expands Fmod+ and CD26+ fibroblast populations and increases fibrous cap matrix formation. CD26+ fibroblasts impair macrophage chemotaxis in a DPP4-dependent manner, suggesting reciprocal macrophage-fibroblast communication that coordinates matrix remodeling and inflammatory cell trafficking in the plaque.

pathology↗