The FEBS Journal

High-protein diets increase hepatic sulfur amino acid metabolism, but the underlying transcriptional mechanisms remain unclear. This study investigated whether Kruppel-like factor 15 (KLF15) directly regulates cystathionine {gamma}-lyase (CTH), a key enzyme linking methionine transsulfuration to hydrogen sulfide (H2S) and taurine production. Promoter-reporter assays, electrophoretic mobility shift assays, and chromatin immunoprecipitation identified two functional KLF15-binding elements, designated 1-1 and 2-2, within the proximal Cth promoter. Mutation of either element attenuated KLF15-dependent promoter activation, whereas mutation of both largely abolished it. In vivo luciferase imaging further demonstrated that these elements were required for the hepatic transcriptional response to a high-protein diet. KLF15 loss of function reduced high-protein-diet-induced Cth expression and altered the hepatic sulfur amino acid profile. Methionine, cystathionine, and cystine accumulated, whereas taurine production and the high-protein-diet-induced increase in hepatic H2S were attenuated. Gene expression analyses further indicated that KLF15 selectively regulates components of methionine, taurine, and H2S metabolism rather than controlling the entire sulfur metabolic program. Collectively, these findings establish the high-protein diet-KLF15-CTH axis as a physiologically relevant transcriptional pathway that amplifies hepatic sulfur amino acid disposal and directs sulfur toward H2S and taurine production.

BACH1 is a heme-regulated basic-leucine-zipper containing transcriptional repressor that binds its DNA recognition elements as a heterodimer with MAFK. Heme-binding is thought to be mediated by several Cys-Proline (CP) motifs and this results in dissociation of the heterodimer from DNA. The mechanism of heme-binding and heme-mediated DNA dissociation remains unresolved. We have used UV-visible spectroscopy, 2D-NMR and DNA-binding assays to explore both heme-binding and DNA dissociation of a minimal BACH1 construct containing 2 CP motifs (C492(CP5) and C646(CP6)) flanking the DNA-binding domain. We find that heme is able to bind to both CP motifs, but also to other non-CP cysteines and histidines in the construct. Using NMR spectroscopy, we identify a structured binding pocket in which heme interacts with both C646(CP6) and Cys621. However, DNA-binding assays show that C646(CP6) is not required for heme-mediated DNA dissociation of the BACH1:MAFK heterodimer. Using UV-visible spectroscopy we show that C492(CP5) also recruits heme with a second ligand, a conserved histidine, His559, in the BACH1 DNA-recognition helix. Mutation of C492(CP5) reduces but does not abolish heme-mediated dissociation from DNA. Our findings suggest a mechanism for heme-binding to BACH1 and heme-mediated dissociation from DNA.

Quorum sensing in Gram-positive bacteria commonly relies on posttranslationally modified peptide pheromones. In Bacillus subtilis, the prenyltransferase ComQ catalyzes tryptophan prenylation of the quorum-sensing peptide ComX, but the structural basis of this unique peptide modification has remained unclear. Here we identified a previously uncharacterized ComQ homolog, StheQ, and its cognate peptide substrate, StheX, from Sphaerobacter thermophilus and investigated their structural and functional relationship. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis demonstrated that StheQ catalyzes prenylation of the tryptophan residue located second from the C-terminus of StheX. Crystal structures of apo StheQ and its complexes with a farnesyl pyrophosphate analog revealed that StheQ adopts the all--helical fold of the trans-isoprenyl diphosphate synthase (IPPS) superfamily while possessing an active-site architecture adapted for peptide-based indole prenylation. The structures identified a single Mg2+-binding site associated with the first aspartic acid-rich motif and showed no evidence for metal coordination at the pseudo-second aspartic acid-rich motif. Site-directed mutagenesis, complex formation assays, and docking analyses identified a peptide-binding pocket adjacent to the active site and suggested that N215 contributes to productive positioning of the acceptor tryptophan. These findings establish the structural basis for peptide prenylation by a ComQ-family enzyme, providing insight into the evolution of peptide-based indole prenylation within the IPPS superfamily, and support the view that ComQ-family enzymes constitute a distinct functional branch specialized for peptide modification.

Zinc is an essential micronutrient at low concentrations, yet it becomes toxic at slightly higher ones. This is exploited by plants as an effective defensive strategy. However, the molecular components that are involved zinc-mediated immunity remain poorly defined. Here, we show that mixed-linked {beta}-1,3/1,4-glucans naturally occurring in microbial and grass cell walls and used as an agrobiological solution, trigger zinc accumulation in the Arabidopsis apoplast and upregulate the expression of the zinc transporters HMA2 and HMA4. This response occurs independently of salicylic acid, jasmonic acid and ethylene-mediated signalling pathways, but it requires the LysM receptor kinases CERK1, LYK4 and LYK5, indicating a specific pattern triggered immunity-associated mechanism. We further demonstrate that hma2hma4 mutants display constitutive activation of a broad set of defence-related genes, yet this transcriptional reprogramming is insufficient to confer resistance against the necrotrophic fungus Plectosphaerella cucumerina BMM. Moreover, metabolomic profiling highlights the contribution of specialized metabolites to this defective defence output. Altogether, our findings reveal that zinc-mediated toxicity constitutes a defence mechanism integrated into the immune response triggered by specific microbial or damage associated molecular patterns.

Lysophosphatidic acid (LPA) is widely recognized as an extracellular lipid mediator; however, the functional significance of intracellularly produced LPA remains poorly understood. Here, we investigated the regulatory mechanism and functional role of a LPA-producing lysophospholipase D GDE4, also known as GDPD1, in prostate cancer cells. GDE4 expression is induced under ER stress conditions in a PERK-dependent manner and requires the transcription factor ATF3. Disruption of GDE4 expression resulted in altered intracellular levels of LPA and LPA precursor lysophosphatidylethanolamine, accompanied by reduced cell proliferation. RNA sequencing and subsequent validation identified a set of genes downregulated in GDE4-depleted cells. Pharmacological inhibition experiments indicated that peroxisome proliferator-activated receptor and {gamma} (PPAR and PPAR{gamma}) signaling pathways contribute to the regulation of these GDE4-dependent genes. Collectively, our findings suggest that GDE4-dependent lipid remodeling is associated with PPAR/{gamma}-mediated transcriptional regulation under ER stress conditions. These results provide a potential framework for understanding the link between intracellular lipid metabolism and stress-responsive gene regulation.

THAP9 is a transposable element-derived gene which encodes a protein that is homologous to the active Drosophila P-element transposase (DmTNP). Both THAP9 and DmTNP possess a C-terminal domain (CTD) which is functionally uncharacterized. Sequence and structural analysis suggest that the THAP9-CTD has a novel fold which is only found in THAP9 homologs. To explore the evolutionary history and characteristics of this novel domain, exhaustive phylogenetic analysis (using MSA, structure prediction, MSTA-based clustering) was performed. THAP9-CTD homologs were more widely distributed throughout the animal kingdom in comparison to DmTNP-CTD homologs which were restricted to arthropods. Moreover, the THAP9-CTD homologs were more conserved, especially among mammals and birds and their average length increased in a class-specific manner. Comparison with the DmTNP-CTD homologs demonstrates that although their respective CTDs may have evolved independently, they both surprisingly share similar secondary structure elements consisting of three conserved helical regions made of hydrophobic residues that are predicted to make up a conserved core. The role of the respective CTDs were further investigated by creating truncation mutants lacking the CTD. Interestingly both THAP9 and DmTNP truncation mutants are still capable of DNA excision and integration suggesting that their respective CTDs are not essential for DNA transposition. Moreover, CTD truncation favours DNA integration in THAP9: this suggests that CTD acquisition during evolution may have led to THAP9 domestication as observed in other transposable element-derived genes like Rag1 and piggybac, which have similar terminal regulatory domains.

Mutations in the E3 Ubiquitin (Ub) ligase RNF216 cause Gordon Holmes syndrome (GHS), a neurodegenerative disorder accompanied by neuroendocrine disruption. We developed an orthogonal ubiquitin transfer (OUT) platform to capture RNF216 substrates in neuronal cells and identified OTUD4, a deubiquitinating enzyme (DUB) mutated in GHS, and FMRP, a neuronal-enriched translational repressor. RNF216 predominantly synthesizes K6-linked Ub chains on OTUD4 to induce its degradation, forming donut-shaped structures in neurons. In return, OTUD4 removes the ubiquitination of RNF216 and FMRP. Analysis of RNF216 substrates revealed biological functions regulating protein synthesis, a shared function of the OTUD4-RNF216 substrate interaction network. Indeed, RNF216 expression increased protein synthesis rates in different cell types while Rnf216 deletion decreased dendritic development in neurons. Overall, our findings show that RNF216 and OTUD4 balance rates of protein synthesis and degradation and suggest GHS-related mutations in RNF216 or OTUD4 may offset this balance, triggering neurodegeneration.

Nuclear pore complexes (NPCs) are nuclear envelope (NE)-embedded protein assemblies that mediate nucleocytoplasmic exchange and interact with the genome, including binding of an NPC component Nup93 to Polycomb chromatin domains. Here, we investigated the in vivo relevance of this relationship in Drosophila, which unusually contains two distinct paralogs of Nup93. Interestingly, we identified a Nup93-2-specific tumorigenic phenotype in larval wings, where depletion of Nup93-2, but not Nup93-1, led to tumor-like overgrowth, reminiscent of Polycomb mutations. Consistently, our transcriptomic analysis revealed a wide-spread loss of gene silencing in Nup93-2-depleted wings, particularly in a Nup93-bound Polycomb domain spanning genes for activators of JAK/STAT signaling. Nup93 paralogs were not found to differ in their effect on NPC biogenesis but strikingly, showed differences in subnuclear localization patterns. While Nup93-1 co-localized exclusively with fully assembled NPCs, Nup93-2 exhibited only partial co-localization and was found at additional NE locations in a tissue-specific manner. Together, our results identify an in vivo silencing role of a Nup93 paralog and suggest that Nup93-2 may form a unique NE-associated complex that targets a subset of Polycomb domains containing growth-promoting genes.

The binding affinities of a chimeric analog of a riboflavin derivative linked to biotin, (6- (7,8-dimethyl-2,4-dioxo-3,4-dihydrobenzo[g]pteridin-10(2H)-yl)hexyl 5-((3aS,4S,6aR)-2- oxohexahydro-1H-thieno[3,4-d]imidazol-4-yl)pentanoate), referred to as C6-Rf-biotin-tag, to the riboflavin binding retain or streptavidin are in the M range, 1.29 {+/-} 0.277 and 3.00 {+/-} 0.459, respectively. These values suggest that C6-Rf-biotin-tag has potential applications in diagnostic assay and labelling target flavin binding proteins. The C6-Rf-biotin-tag which was characterized with respect to physical and biochemical properties retains UV/Vis spectroscopic and fluorescence behavior similar to riboflavin.

The cluster of differentiation 36 (CD36) is a membrane protein with broad physiological roles in health and disease, and its function is regulated in part by phosphorylation. Experimental evidence shows that phosphorylation of Thr92 reduces CD36 affinity for thrombospondin-1 (TSP-1), binding of which initiates antiangiogenic signaling, whereas phosphorylation of Ser237 decreases CD36-mediated fatty acid uptake, with implications for energy metabolism. However, the only available crystal structure of CD36 lacks phosphorylation, and the molecular mechanisms by which phosphorylation regulates CD36 function remain largely unknown. This study provides an atomically detailed computational characterization of CD36 in unphosphorylated and dual phosphorylated states, using molecular dynamics simulations with a total sampling time of 30 microseconds in combination with Markov state models. We present, to our knowledge, the first evidence of a cryptic pocket on CD36 surface that is formed by phosphorylation. This cryptic surface pocket and a loop spanning residues 121-131 form a high affinity binding site for TSP-1 derived ligands, shifting their binding away from the canonical site. We propose that this altered binding provides a molecular basis for the disruption of antiangiogenic signaling upon CD36 phosphorylation. Additionally, our data indicate that, phosphorylation increases helicity and compaction within the helix-loop region spanning residues 296-331, narrowing one of the entrances to the internal cavity and reducing its overall volume. These conformational changes provide a potential mechanistic explanation for the decrease in fatty acid uptake upon CD36 phosphorylation. Our findings provide structural insights that may inform the future design of CD36 modulators and emphasize the importance of targeting phosphorylation induced CD36 conformations in angiogenic and metabolic diseases.

Nuclear bile acid (BA) signaling plays a central role in liver homeostasis and represents a major therapeutic axis in fibrotic liver diseases. The farnesoid X receptor (FXR), a master nuclear effector of BA signaling, is expressed in several liver-resident cell types, suggesting that it may regulate distinct biological programs beyond the hepatocyte (HC) compartment. Using complementary pharmacological, genetic, and computational approaches across in vitro, ex vivo, and in vivo models of mouse and human origin, we investigated the role of hepatic stellate cell (HSC) FXR (FXRHSC) in both unchallenged and injured livers, which has remained controversial. FXR is robustly expressed in both HCs and HSCs with distinct isoform distributions, and these isoforms exhibited differential capacities to activate gene expression in an HSC context. We found that the potent selective FXR agonist tropifexor triggers a transcriptional program reminiscent of that observed after partial hepatectomy and associated with HC proliferation. This cell cycle-related response was also observed in HSCs and did not require intestinal FXR expression. An HSC-specific response to tropifexor was observed for several genes, including members of the glutathione-S-transferase (GST) family or Scube1. FXRHSC was sufficient to observe the anti-fibrotic effects of tropifexor in precision-cut liver slices, an ex-vivo model of fibrosis. Finally, we identified the regulation of the chemerin-encoding gene Rarres2 as a relevant example of FXRHSC-dependent control of hepatic intercellular communication. Together, these findings identify FXRHSC as an important contributor to hepatic adaptation and therapeutic response to BA analogs and confirmed HSCs as a significant site of nuclear bile acid signaling in liver biology.

Human cytochrome P450 2C9 (CYP2C9) is a hepatic microsomal enzyme involved in the oxidative metabolism of clinically important drugs, but the structural organization of its oligomeric assemblies outside crystallographic packing environments remains poorly understood. Here, we report the cryo-EM structure of human CYP2C9 determined under aqueous, membrane-free conditions at 3.31 Angstrom resolution. The structure reveals a C2-symmetric hexameric assembly organized as a dimer of trimers. Individual protomers retain the conserved P450 fold and heme-binding architecture observed in previously reported crystal structures, indicating that assembly formation does not substantially perturb the catalytic core. The hexamer is stabilized by defined intra-trimer interfaces involving the N-terminal region and residues around Trp212 and Phe482, together with inter-trimer interfaces involving Leu71 and the 220-227 loop. These interfaces are distinct from the crystal packing contacts observed in CYP2C9 crystal structures, demonstrating that the assembly is not a simple recapitulation of crystallographic packing. Notably, the inter-trimer interface is located near the FG-loop-containing surface previously implicated in membrane association. This suggests that the observed hexamer may represent a membrane-free association of two trimers through membrane-related surfaces, whereas the trimeric arrangement itself may be compatible with membrane-associated organization. The structure therefore provides a framework for investigating how trimer formation, membrane interaction and local conformational changes in the FG-loop region may influence CYP2C9 function.

Transcription factor Ets2 coalesce with the NF-{kappa}B pathway to regulate gene expression in specific signaling contexts. IKK2/{beta}-mediated phosphorylation events critically regulate the NF-{kappa}B pathway. However, any link between Ets2 and IKK2 remains elusive. Here we report Ets2 as a direct substrate of IKK2. In-vitro kinase assays using deletion constructs, high resolution MS-MS and site directed mutagenesis identified S295 as a prominent phosphorylation site distal to the DNA binding domain, substitution of which to phosphor-mimetic Glutamate triggers further phosphorylation of Ets2. MD simulations clearly indicate conformational constriction of the otherwise disordered N-terminal region and inhibition of DNA binding activity upon phosphorylation, which was further confirmed by Electrophoretic mobility shift assays. Our results uncover a phosphoregulatory connection between Ets2 and IKK2.

Cyclic oligosaccharides possess industrial advantages, including molecular encapsulation capability and high physicochemical stability, owing to the absence of a reducing end. Recently, a novel cyclic tetrasaccharide, cycloisomaltotetraose (CI4), consisting of four -1,6-linked glucose units, and the enzymes responsible for its synthesis, cycloisomaltotetraose glucanotransferases (CI4Tases), were discovered. Unlike known cycloisomaltooligosaccharide glucanotransferases (CITases) that yield a wide distribution of cyclic products with a degree of polymerization (DP) of 7 or higher, CI4Tases strictly produce CI4. To elucidate the molecular mechanism underlying this strict DP4 specificity, we determined the crystal structures of CI4Tase from Agreia sp. D1110, in its ligand-free form, as well as in complex with the linear hydrolysis product isomaltotetraose (IG4) and with CI4. Structural comparisons revealed that a loop (M247 to R251) blocks the region corresponding to the -5 subsite of typical CITases, narrowing the substrate-binding pocket. This "molecular ruler" mechanism ensures that only a glycan chain of exactly four glucose units is accommodated for cyclization. Among mutants of the residue positioned at the center of bound CI4, the formation of by-products other than CI4 was significantly suppressed in F245L, F245A, and F245W. While the cyclization activity of all F245 mutants decreased, the CI4 hydrolysis activity of these three mutants was also significantly reduced, resulting in an increased specificity for cyclic sugar production. These findings elucidate the strict size-control mechanism of CI4Tase and provide a structural foundation for engineering cycloisomaltooligosaccharide-producing enzymes with optimized transglycosylation efficiency and specificity for industrial applications.

Viral infections have long been proposed as environmental contributors to neurodegenerative diseases, including Parkinson's disease (PD), yet the molecular mechanisms linking infection and neurodegeneration are not well defined. Neuroinflammation and disruption of central nervous system (CNS) homeostasis have emerged as potential mediators. In this study, we used severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the causative agent of COVID-19, as a model pathogen to investigate convergent molecular pathways between viral infection and PD. Single-nucleus RNA sequencing (snRNA-seq) was performed on post-mortem striatal tissue from 14 individuals stratified into four groups: COVID-19 only (COVID-19), PD only (PD), comorbid PD with COVID-19 (PD/COVID-19), and controls (Control). The PD/COVID-19 group exhibited an expanded astrocytic population and a pronounced interferon-associated molecular signature characterized by increased expression of canonical interferon-stimulated genes, including IFI44L (average log2FC= 3.9; adjusted p=2.3 x 10-373), IFI44 (average log2FC=2.9; adjusted p=8.0 x 10-266), ISG15 (average log2FC=3.1; adjusted p=1.2 x 10-197), and RSAD2 (average log2FC= 3.5; adjusted p=8.6 x 10-111). Pathway analyses demonstrated activation of innate immune and antiviral signaling pathways, particularly within microglia and astrocytes, including interferon signaling, pattern-recognition receptor pathways, and complement-associated responses. In parallel, genes involved in lipid metabolism, cholesterol homeostasis, synaptic maintenance, and neuronal signaling were reduced across disease groups. Proteomic analyses independently confirmed enrichment of antiviral and interferon-associated pathways and identified convergent suppression of sterol, cholesterol, and lipid metabolic processes. Our findings identify a convergent molecular signature linking PD and COVID-19, pronounced in comorbid individuals and characterized by interferon-driven innate immune activation, glial inflammatory responses, and dysregulation of lipid metabolic homeostasis. Collectively, the data support a model in which severe viral infection amplifies biological pathways already implicated in PD pathogenesis.

Developmental regression is a severe but poorly understood complication of several neurodevelopmental disorders. In Kleefstra syndrome (KLEFS1), caused by EHMT1 haploinsufficiency, regression often emerges during adolescence or early adulthood and is frequently preceded by marked sleep disturbance. Experimental work implicating EHMT1/G9a in metabolic regulation and stress responses raises the possibility that impaired metabolic resilience contributes to this vulnerability. Here, we aimed to investigate whether altered glucose metabolism is a feature of KLEFS1 and whether it relates to clinical variability, including regression. Through [18F]FDG-PET/CT, individuals with KLEFS1 who had experienced regression (n=4) exhibited a hypometabolic brain profile, whereas one individual who had not experienced regression showed globally elevated metabolic activity. In parallel, G9a mutant flies exhibited increased baseline metabolic rate and neuronal ATP levels together with sleep fragmentation resembling the clinical phenotype. Providing flies with oxidative stress to model KLEFS1 regression further exacerbated sleep disruption and was associated with a reduction in metabolic output. Importantly, adult high sugar feeding in flies prevented oxidative stress-induced worsening of sleep and maintained metabolic stability under challenge. Together, these findings suggest that regression in KLEFS1 and associated sleep disturbances are linked to underlying metabolic vulnerability and impaired maintenance of energy homeostasis under stress.

We present the solution structures of HIV-1 proteins NC(p7)1-55 corresponding to the full-length NC(p7) and mature p6. The studies were carried in water and, to mimic the membrane, in micellar DPC (Dodecylphosphocholine) conditions. Our results unravel for the first time the structure adopted by the N-terminal amino acids of the free NC(p7)1-55, with the formation of a small helix spanning residues F6 to R10. Our NMR and Fluorescence Anisotropy data disclose an interaction between NC(p7)1-55 and p6 both in water and DPC, with respective Kd of 2.5mM and 370 mM at 23{degrees}C. The interaction is thus strengthened in lipidic conditions. Protein p6 stabilizes the N-terminus of NC(p7)1-55 while increasing at the same time the dynamic of the first zinc finger. Although the entire p6 sequence is involved in the interaction, we show that its C-terminal region is particularly sensitive to the presence of NC(p7)1-55, with a propensity of forming a a helix ranging from amino acids S111 to F116. This study brings experimental evidence of a direct protein-protein interaction between p6 and the N-terminal region of NC(p7)1-55. We further show that such interaction is readily accommodated within the NC(p15) framework and hypothesize that it may facilitate the selective assembly of assembly of the viral genomic RNA (gRNA) in the cell.

Plasmodium falciparum heat shock protein 90 (PfHsp90) is a promising antimalarial target, but the molecular pathways influenced by its inhibition remain poorly understood. Herein, we leveraged chemoproteomic profiling employing geldanamycin and XL888 Hsp90 inhibitors to investigate proteins and pathways dependent on the chaperone during the Plasmodium blood stage. This study revealed 131 proteins reduced in abundance after inhibition, of which 40% co-immunoprecipitated with PfHsp90. Bioinformatic analyses identified DNA replication as the most enriched pathway. This link was investigated in phenotypic studies demonstrating reduced parasite DNA content after PfHsp90 inhibition. To assess nascent DNA synthesis, we utilized a 7-deaza-7-ethynyl-2'-deoxyadenosine (EdA) assay, yielding dual-stage attenuation of nucleoside incorporation following Hsp90 inhibition. We further show that parasite co-treatment with Hsp90 and DNA replication inhibitors produces synergistic interactions, highlighting the therapeutic potential of the discovered link. Overall, these findings expand our understanding of PfHsp90 function and uncover novel PfHsp90-dependent pathways.

The navigational prowess of migratory birds is thought to arise from light-dependent radical-pair chemistry in cryptochrome 4 (CRY4), yet the slow structural transitions that couple photochemistry to signaling remain elusive. Here, we combine temperature-controlled steady-state UV-visible spectroscopy and hydrogen-deuterium exchange mass spectrometry (HDX-MS) to elucidate the photochemical and conformational dynamics of pigeon CRY4 (ClCRY4). Steady-state measurements at 5-25 {degrees}C reveal that lower temperatures slow FAD photoreduction and prolong the FAD neutral semiquinone signaling state. This occurs without a solvent kinetic isotope effect, implicating a conformational change rather than proton transfer as the rate determining step in FAD neutral semiquinone formation. Simultaneous HDX-MS under blue-light exposure identifies protection near the FAD-binding site and C-terminal region. To enhance sensitivity, we developed a pump-probe HDX-MS approach at 10 {degrees}C. This reveals eight peptides (within the phosphate-binding loop, protrusion motif, electron-transfer-chain loops and C-terminal tail) that exhibit rapid ([≤]10 s) and sustained light-induced protection, delineating early conformational rearrangements as a prerequisite for FAD neutral semiquinone accumulation. The findings of slower onset HDX protection as well as a bimodal pattern of deuterium uptake in the phosphate-binding loop further identify a local redistribution of conformational substates on the time scale of the accumulation of the signaling species. Site specific mutagenesis within the CTT supports the findings, which lead to a model in which blue light triggers rapid clamping down of protein near the two regions of spin pair separation, followed by a rate limiting closure of a surface loop. The resolution of time-dependent structural transitions that follow photoactivation of CRY4 resolves the interface between quantum radical-pair formation and classical conformational changes, while providing an enhanced structural framework for the molecular events that underlie avian magnetoreception.

Orthodontic tooth movement relies on a tightly regulated pro-inflammatory and pro resorptive mechanoresponse of local periodontal ligament fibroblasts (PdLFs). Dysregulation is linked to complications such as root resorption and tooth loss. Hyperlipidemic conditions promote excessive PdL mechanoresponses, with growth differentiation factor 15 (GDF15) acting as potential regulator. This study examined the contribution of the inflammasome/pyroptosis pathway as underlying mechanism for dysregulated mechanoresponses. Human PdLFs were treated with palmitic acid (PA) or oleic acid (OA) for six days before 24 hours of compressive loading. PA increased CASP1, CASP4, and CASP3 activity, secretion of IL-1{beta}, IL-18, and HMGB1, and LDH release. Pharmacological blockade and siRNA-mediated knockdown of inflammasome- and pyroptosis-related targets revealed that NLRP3, CASP1, CASP4, and GSDMD partially contributed to monocyte and osteoclast overactivation. Silencing PA-increased GDF15, partially normalized the phenotype, at least in part by inflammasome/pyroptosis regulation. GDF15 acted through extracellular, and a nuclear signaling route, each accounting partially to this phenotype. Together, GDF15 partially regulates the PA-induced, pyroptosis-associated overactivated mechanoresponse alongside pyroptosis-independent mechanisms suggesting it as an interesting target for potential clinical interventions.