Essential Regulator Research Articles

Essential Role of Cortactin in Myogenic Differentiation: Regulating Actin Dynamics and Myocardin-Related Transcription Factor A-Serum Response Factor (MRTFA-SRF) Signaling

Cortactin (CTTN) is an actin-binding protein regulating actin polymerization and stabilization, which are vital processes for maintaining skeletal muscle homeostasis. Despite the established function of CTTN in actin cytoskeletal dynamics, its role in the myogenic differentiation of progenitor cells remains largely unexplored. In this study, we investigated the role of CTTN in the myogenic differentiation of C2C12 myoblasts by analyzing its effects on actin cytoskeletal remodeling, myocardin-related transcription factor A (MRTFA) nuclear translocation, serum response factor (SRF) activation, expression of myogenic transcription factors, and myotube formation. CTTN expression declined during myogenic differentiation, paralleling the reduction in MyoD, suggesting a potential role in the early stages of myogenesis. We also found that CTTN knockdown in C2C12 myoblasts reduced filamentous actin, enhanced globular actin levels, and inhibited the nuclear translocation of MRTFA, resulting in suppressed SRF activity. This led to the subsequent downregulation of myogenic regulatory factors, such as MyoD and MyoG. Furthermore, CTTN knockdown reduced the nuclear localization of YAP1, a mechanosensitive transcription factor, further supporting its regulatory roles in cell cycle and proliferation. Consequently, CTTN depletion impeded proliferation, differentiation, and myotube formation in C2C12 myoblasts, highlighting its dual role in the coordination of cell cycle regulation and myogenic differentiation of progenitor cells during myogenesis. This study identifies CTTN as an essential regulator of myogenic differentiation via affecting the actin remodeling-MRTFA-SRF signaling axis and cell proliferation.

Meis transcription factors regulate cardiac conduction system development and adult function.

The Cardiac Conduction System (CCS) is progressively specified during development by interactions among a discrete number of Transcriptions Factors that ensure its proper patterning and the emergence of its functional properties. Meis genes encode homeodomain transcription factors (TFs) with multiple roles in mammalian development. In humans, Meis genes associate with congenital cardiac malformations and alterations of cardiac electrical activity, however the basis for these alterations has not been established. Here we studied the role of Meis transcription factors in cardiomyocyte development and function during mouse development and adult life. We studied Meis1 and Meis2 conditional deletion mouse models that allowed cardiomyocyte-specific elimination of Meis function during development and inducible elimination of Meis function in cardiomyocytes of the adult CCS. We studied cardiac anatomy, contractility and conduction. We report that Meis factors are global regulators of cardiac conduction, with a predominant role in the CCS. While constitutive Meis deletion in cardiomyocytes led to congenital malformations of the arterial pole and atria, as well as defects in ventricular conduction, Meis elimination in cardiomyocytes of the adult CCS produced sinus node dysfunction and delayed atrio-ventricular conduction. Molecular analyses unraveled Meis-controlled molecular pathways associated with these defects. Finally, we studied in transgenic mice the activity of a Meis1 human enhancer related to an SNP associated by GWAS to PR elongation and found that the transgene drives expression in components of the atrio-ventricular conduction system. Our study identifies Meis TFs as essential regulators of the establishment of cardiac conduction function during development and its maintenance during adult life. In addition, we generated animal models and identified molecular alterations that will ease the study of Meis-associated conduction defects and congenital malformations in humans.

Regulatory T cells promote decidual vascular remodeling and modulate uterine NK cells in pregnant mice.

Regulatory T (Treg) cells are essential for maternal immune tolerance of the fetus and placenta. In preeclampsia, aberrant Treg cell tolerance is implicated, but whether and how Treg cells affect the uterine vascular dysfunction thought to precede placental impairment and maternal vasculopathy is unclear. We utilized Foxp3DTR mice to test the hypothesis that Treg cells are essential regulators of decidual spiral artery adaptation to pregnancy. Transient Treg cell depletion during early placental morphogenesis caused impaired remodeling of decidual spiral arteries, altered uterine artery function and led to fewer DBA+ uterine natural killer (uNK) cells, resulting in late gestation fetal loss and fetal growth restriction. Replacing the Treg cells by transfer from wild-type donors mitigated the impact on uNK cells, vascular remodeling, and fetal loss. RNA sequencing of decidua revealed genes associated with NK cell function and placental extravillous trophoblasts were dysregulated after Treg cell depletion, and normalized by Treg cell replacement. These data implicate Treg cells as essential upstream drivers of uterine vascular adaptation to pregnancy, through a mechanism likely involving phenotypic regulation of uNK cells and trophoblast invasion. The findings provide insight into mechanisms linking impaired adaptive immune tolerance and altered spiral artery remodeling, two hallmark features of preeclampsia.

Identification of potential methyltransferase NSD2 enzymatic inhibitors through a multi-step structure-based drug design.

Reversing aberrant protein methylation levels is widely recognized as a key focus in cancer therapy. As an essential lysine methylation regulator, NSD2 (Nuclear receptor-binding SET Domain 2, also known as WHSC1/MMSET) regulates chromatin structural sparsity and DNA repair processes. Abnormal enhancement of NSD2 methylation activity (caused by NSD2 overexpression and point mutations) has been closely related to the initiation and development of various cancers and diseases. However, the lack of selective inhibitors hinders further therapeutic intervention and limits the exploration of its biological mechanism. Therefore, this study developed an integrated approach that includes binding feature pharmacophore modeling, gradient database screening of 120 million compounds, flexible docking, and molecular dynamic simulation. This approach was used to identify hit compounds targeting the substrate/coenzyme binding site of NSD2. Subsequently, 20 lead compounds were retrieved by using molecular docking analysis and ADMET prediction. Finally, MD simulations were performed to validate the binding stability of selected drug candidates. The findings indicated that these newly obtained compounds might be potent NSD2 inhibitors. We hope the integrated virtual screening approach will provide a valuable idea for discovering novel H3K36 methyltransferase inhibitors.

LINC01614 Accelerates CRC Progression via STAT1/LINC01614/miR-4443/PFKFB3-Mediated Aerobic Glycolysis.

Colorectal cancer (CRC) is an aggressive malignancy among malignant tumours, with a high incidence globally. LINC01614, a long non-coding RNA, has been identified as an essential regulator in multiple cancer types. However, its biological functions and underlying molecular mechanisms in CRC remain largely unknown. In this study, we employed RT-qPCR to assess the expression levels of LINC01614 in CRC samples. In vitro, glucose metabolism experiments were conducted to evaluate glucose metabolism in cells. The binding relationship between miR-4443, PFKFB3, and LINC01614 was confirmed through fluorescence reporter gene detection. The subcellular localization of LINC01614 in CRC cells was determined using FISH and subcellular fractionation experiments. Additionally, a mouse subcutaneous tumor model was established for in vivo experiments. Our findings reveal that LINC01614 is upregulated in CRC tissues. Silencing of LINC01614 suppresses the malignant behaviors of CRC cells, including cell proliferation, invasion, migration, and aerobic glycolysis. Furthermore, we discovered that LINC01614 promotes the expression of PFKFB3. Additional experiments demonstrated that LINC01614 binds to miR-4443, leading to the upregulation of PFKFB3 expression. Further experiments confirmed that the LINC01614/miR-4443/PFKFB3 axis promotes CRC cell malignancy by enhancing aerobic glycolysis. Additionally, we found that STAT1 promotes the transcription of LINC01614. These findings uncover a novel regulatory pathway wherein STAT1-induced LINC01614 enhances PFKFB3 expression by sponging miR-4443, thereby accelerating CRC development. This understanding may lead to novel therapeutic strategies for CRC treatment.

Group 2 innate lymphoid cells are a non-redundant source of interleukin-5 required for development and function of murine B1 cells

Tissue-resident immune cells, such as innate lymphoid cells, mediate protective or detrimental immune responses at barrier surfaces. Upon activation by stromal or epithelial cell-derived alarmins, group 2 innate lymphoid cells (ILC2s) are a rapid source of type 2 cytokines, such as IL-5. However, due to the overlap in effector functions, it remains unresolved whether ILC2s are an essential component of the type 2 response or whether their function can be compensated by other cells, such as T cells. Here we show a non-redundant role of ILC2s in supporting the development and function of B1 cells. We demonstrate that B1 cells fail to develop properly in the absence of ILC2s and identify the IL-33 receptor on ILC2s as an essential cell-intrinsic regulator of IL-5 production. Further, conditional deletion of Il5 in ILC2s results in defective B1 cell development and immunoglobulin production. Consequently, B1 cells with phosphatidylcholine specific B cell receptor rearrangements are diminished in ILC2-deficient mice. Thus, our data establish an essential function of ILC2s in supporting B1 cells and antibody production at barrier surfaces.

TFAP2C is a key regulator of intrauterine trophoblast cell invasion and deep hemochorial placentation.

Transcription factor AP-2 gamma (TFAP2C) has been identified as a key regulator of the trophoblast cell lineage and hemochorial placentation. The rat possesses deep placentation characterized by extensive intrauterine trophoblast cell invasion, which resembles human placentation. Tfap2c is expressed in multiple trophoblast cell lineages, including invasive trophoblast cells situated within the uterine-placental interface of the rat placentation site. Global genome-editing was used to explore the biology of Tfap2c in rat placenta development. Homozygous global disruption of Tfap2c resulted in prenatal lethality. Heterozygous global disruption of Tfap2c was associated with diminished invasive trophoblast cell infiltration into the uterus. The role of TFAP2C in the invasive trophoblast cell lineage was explored using Cre-lox conditional mutagenesis. Invasive trophoblast cell-specific disruption of Tfap2c resulted in inhibition of intrauterine trophoblast cell invasion and intrauterine and postnatal growth restriction. The invasive trophoblast cell lineage was not impaired following conditional monoallelic disruption of Tfap2c. In summary, TFAP2C contributes to the progression of distinct stages of placental development. TFAP2C is a driver of early events in trophoblast cell development and reappears later in gestation as an essential regulator of the invasive trophoblast cell lineage. A subset of TFAP2C actions on trophoblast cells are dependent on gene dosage.

Comparative analysis of amino acid sequence level in plant GATA transcription factors

Transcription factors (TFs) are essential regulators of gene expression, influencing numerous biological processes such as development, growth, and cellular responses in plants. Among these, GATA TFs are distinguished by their highly conserved DNA-binding domain, characterized by a class IV zinc finger motif (CX2CX18-20CX2C). This study investigates the amino acid sequence patterns of 5,335 GATA TFs across 165 plant species sourced from the PlantTFDB database (http://planttfdb.gao-lab.org/), encompassing diverse taxonomic groups. Through comparative sequence analysis, I identify conserved domains and structural features that enhance the understanding functional roles, evolutionary conservation, and lineage-specific adaptations of GATA TFs. These findings provide valuable insights into the diversification and functional specialization of GATA TFs, with implications for improving stress tolerance and adaptability in crops. This study contributes to the broader knowledge of transcriptional regulation in plant biology.

The Hox protein Antennapedia orchestrates Drosophila adult flight muscle development.

Muscle development and diversity require a large number of spatially and temporally regulated events controlled by transcription factors (TFs). Drosophila has long stood as a model to study myogenesis due to the highly conserved key TFs involved at all stages of muscle development. While many studies focused on the diversification of Drosophila larval musculature, how distinct adult muscle types are generated is much less characterized. Here, we identify an essential regulator of Drosophila thoracic flight muscle development, the Hox TF Antennapedia (Antp). Correcting a long-standing belief that flight muscle development occurs without the input of Hox TFs, we show that Antp intervenes at several stages of flight muscle development, from the establishment of the progenitor pool in the embryo to myoblast differentiation in the early pupa. Furthermore, the precisely regulated clearance of Hox in the developing flight muscle fibers is required to allow for fibrillar muscle fate diversification, setting these muscles apart from all other adult tubular muscle types.

Adrenochrome formation during photochemical decomposition of "caged" epinephrine derivatives.

Control of biological activity with light is a fascinating idea. "Caged" compounds, molecules modified with photolabile protecting group, are one of the instruments for this purpose. Adrenergic receptors are essential regulators of neuronal, endocrine, cardiovascular, vegetative, and metabolic functions. These receptors are largely used as pharmacologic targets. Photolabile "caged" analogs of adrenergic receptor agonists has been reported more than 30years ago. We report that the photolysis of epinephrine analogs, apart from liberation of the epinephrine, is accompanied by a formation of significant amount of adrenochrome, a compound with neuro- and cardiotoxic effect.

Sevuparin strongly reduces hepcidin expression in cells, mice, and healthy human volunteers.

Hepcidin is an essential regulator of systemic iron availability mediating both iron uptake from the diet and its release from body stores. Abnormally high hepcidin levels resulting from inflammation in chronic diseases cause iron restriction with the onset of anemia. Restoring physiological levels of hepcidin could contribute to ameliorating anemia in these patients. Heparin derivatives are known to suppress hepcidin expression acting on the BMP/SMAD pathway. The novel heparin derivative sevuparin, modified to markedly reduce its anticoagulant activity, is proposed as a promising hepcidin antagonizing strategy. Sevuparin was tested for its anti-hepcidin properties in vitro in HepG2 cells, in vivo in mice, and in healthy volunteers. Sevuparin strongly suppressed basal, BMP6-, and IL6-dependent hepcidin expression in HepG2 cells in a dose- and time-dependent manner, modulating the essential BMP6/SMAD cascade. These effects were evident in C57BL/6J mice after intravenous injection of a single dose of sevuparin (20 mg/kg) with a 70% reduction of hepcidin mRNA. Remarkably, similar effects were observed in healthy volunteers following single subcutaneous doses at 3, 6, and 9 mg/kg with 40%-50% suppression at 3 and 6 mg/kg and 72% at 9 mg/kg. Moreover, sevuparin was able to reduce hepcidin upregulation in a mouse model of acute inflammation induced by LPS, also showing an amelioration of the inflammatory markers. Combined with its excellent safety profile, these data suggest a role for sevuparin in treating high-hepcidin disorders.

β’-COP mediated loading of PPARγ into trophoblast-derived extracellular vesicles

Fetal growth restriction (FGR) is characterized by impaired fetal growth and dysregulated lipid metabolism. Extracellular vesicles (EVs) have been proved playing a crucial role in transporting biomolecules from the mother to the fetus. However, the mechanisms underlying cargo sorting and loading into trophoblastic EVs remain elusive. This study focuses on examining how the essential fatty acid regulator, peroxisome proliferator-activated receptor gamma (PPARγ), is sorted and loaded into EVs originating from trophoblasts. We conducted proteomic analysis on placenta-derived EVs from normal and FGR pregnancies. Interactions between PPARγ and coat protein complex I (COPI) subunit were evaluated using co-immunoprecipitation and bioinformatics simulation. Molecular dynamics simulations were conducted to identify critical binding sites between β’-coat protein complex I (β’-COP), a subunit of COPI, and PPARγ. lentivirus-mediated knockout and overexpression techniques were employed to elucidate the role of β’-COP in PPARγ loading into EVs. Our findings demonstrate that PPARγ protein levels are significantly decreased in EVs from FGR placentas. β’-COP subunit directly interacts with PPARγ in trophoblasts, mediating its sorting into early endosomes and multivesicular bodies for EVs incorporation. Knockout of β’-COP impaired PPARγ loading into EVs. Molecular dynamics simulations identified critical binding sites for the interaction between β’-COP and PPARγ. Mutation of these sites significantly weakened the β’-COP-PPARγ interaction and reduced PPARγ levels in trophoblastic EVs. In conclusion, β’-COP mediates sorting and loading of PPARγ into trophoblastic EVs. This study provides insights into regulating EVs cargo loading and potential strategies for targeted cargo delivery from the maternal to the fetal circulation.

Adapt or Perish: Efficient Selenocysteine Insertion is Critical for Metastasizing Cancer Cells.

During metastasis, cancer cells detach from the primary tumor, circulate through the bloodstream, and establish themselves at distant sites, facing increased levels of reactive oxygen species (ROS) that act as significant barriers to metastatic progression. Adapting to and surviving in these high-ROS environments is thus crucial for successful metastasis. A recent study by Nease and colleagues identified FTSJ1 as the methyltransferase responsible for methylation of the U34 position wobble uridine modification of selenocysteine (Sec) tRNA. This methylation enables efficient Sec insertion, leading to increased translation of a subset of stress-responsive selenoproteins that combat the oxidative stress encountered during the metastatic process. This study establishes FTSJ1 as an essential redox regulator during metastasis through its role in enhancing Sec insertion efficiency, and introduces a potential therapeutic strategy against metastasis.

Comparative lipidome and transcriptome provide novel insights into zero-valent iron nanoparticle-treated Fremyella diplosiphon.

Understanding the intricate interplay between nanoparticle-mediated cyanobacterial interactions is pivotal in elucidating their impact on the transcriptome and lipidome. In the present study, total fatty acid methyl esters (FAMEs) in the wild-type (B481-WT) and transformant (B481-SD) Fremyella diplosiphon strains treated with nanoscale zero-valent iron nanoparticles (nZVIs) were characterized, and transcriptome changes analyzed. Comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry revealed a 20-25% higher percentage of FAMEs in nZVI-treated F. diplosiphon strain B481-SD compared to B481-WT. Accumulation of alkanes was significantly higher (> 1.4 times) in both strains treated with 25.6 mg L-1 nZVIs compared to the untreated control. In addition, we observed significantly higher levels of monounsaturated FAMEs (11%) in B481-WT in 3.2 (11.34%) and 25.6 mg L-1 (11.22%) nZVI-treated cells when compared to the untreated control (7%). Analysis of the F. diplosiphon transcriptome treated with 3.2mg L-1 revealed a total of 1811 and 1651 genes that were differentially expressed in B481-SD and B481-WT respectively. While the expression of iron uptake and ion channel genes was downregulated, genes coding for photosynthesis, pigment, and antioxidant enzymes were significantly (p < 0.05) upregulated in B481-SD treated with 3.2 mg L-1 nZVIs compared to the untreated control. This study on essential FAMEs and regulation of genes in nZVI-treated F. diplosiphon strains provides a molecular framework for optimization of metabolic pathways in this model species.

Chromatin Helicase CHD6 Establishes Pro-inflammatory Enhancers and is a Synthetic Lethal Target in FH-Deficient Renal Cell Carcinoma.

Fumarate hydratase (FH) deficiency causes hereditary leiomyomatosis and renal cell carcinoma (RCC). FH-deficient tumors lack effective therapeutic options. Here, we utilized an epigenetic-focused single-guide RNA library to elucidate potential drug targets in FH-deficient tumors. The screen identified chromodomain helicase DNA binding protein 6 (CHD6) as an essential regulator of the growth of FH-mutated RCC. Mechanically, FH loss induced fumarate-mediated succinylation and inactivation of KEAP1, blocking subsequent ubiquitin-proteasome degradation of CHD6. Stabilized CHD6 formed a complex with p65 to establish pro-inflammatory enhancers and thereby regulate NF-κB-mediated transcription. Moreover, CHD6 recruited mSWI/SNF ATPases to maintain chromatin accessibility at CHD6-bound enhancers. The PROTAC degrader of SMARCA2/4 AU-15330 effectively abolished structures of cis-regulatory elements bound by CHD6 and suppressed the growth of FH-mutated, but not FH-intact, RCC in vivo. Collectively, these data indicate that CHD6 is a molecular bridge between FH deficiency and pro-inflammatory enhancers assembly that endows FH-deficient tumors with epigenetic vulnerabilities.

Early disruption of the CREB pathway drives dendritic morphological alterations in FTD/ALS cortical neurons

Synaptic loss and dendritic degeneration are common pathologies in several neurodegenerative diseases characterized by progressive cognitive and/or motor decline, such as Alzheimer's disease (AD) and frontotemporal dementia/amyotrophic lateral sclerosis (FTD/ALS). An essential regulator of neuronal health, the cAMP-dependent transcription factor CREB positively regulates synaptic growth, learning, and memory. Phosphorylation of CREB by protein kinase A (PKA) and other cellular kinases promotes neuronal survival and maturation via transcriptional activation of a wide range of downstream target genes. CREB pathway dysfunction has been strongly implicated in AD pathogenesis, and recent data suggest that impaired CREB activation may contribute to disease phenotypes in FTD/ALS as well. However, the mechanisms behind reduced CREB activity in FTD/ALS pathology are not clear. In this study, we found that cortical-like neurons derived from iPSC lines carrying the hexanucleotide repeat expansion in the C9ORF72 gene, a common genetic cause of FTD/ALS, displayed a diminished activation of CREB, resulting in decreased dendritic and synaptic health. Importantly, we determined such impairments to be mechanistically linked to an imbalance in the ratio of regulatory and catalytic subunits of the CREB activator PKA and to be conserved in C9-ALS patient's postmortem tissue. Modulation of cAMP upstream of this impairment allowed for a rescue of CREB activity and an amelioration of dendritic morphology and synaptic protein levels. Our data elucidate the mechanism behind early CREB pathway dysfunction and discern a feasible therapeutic target for the treatment of FTD/ALS and possibly other neurodegenerative diseases.

Mutations in unfolded protein response regulator ATF6 cause hearing and vision loss syndrome.

Activating transcription factor 6 (Atf6) is a key regulator of the unfolded protein response (UPR) and is important for endoplasmic reticulum (ER) function and protein homeostasis in metazoan cells. Patients carrying loss-of-function ATF6 disease alleles develop the cone dysfunction disorder, achromatopsia. The impact of loss of ATF6 function on other cell types, organs, and diseases in people remains unclear. Here, we reported that progressive sensorineural hearing loss was a notable complaint in some patients carrying ATF6 disease alleles and that Atf6-/- mice also showed progressive auditory deficits affecting both genders. In mice with hearing deficits, we found disorganized stereocilia on hair cells and focal loss of outer hair cells. Transcriptomic analysis of Atf6-/- cochleae revealed marked induction of UPR, especially through the PERK arm. These findings identify ATF6 as an essential regulator of cochlear health and function. Furthermore, they supported that ATF6 inactivation in people causes progressive sensorineural hearing loss as part of a blindness-deafness genetic syndrome targeting hair cells and cone photoreceptors. Lastly, our genetic findings support ER stress as an important pathomechanism underlying cochlear damage and hearing loss with clinical implications for patient lifestyle modifications that minimize environmental/physiologic sources of ER stress to the ear.

A theoretical systems chronopharmacology approach for COVID-19: Modeling circadian regulation of lung infection and potential precision therapies.

The COVID-19 pandemic, caused by SARS-CoV-2, has underscored the urgent need for innovative therapeutic approaches. Recent studies have revealed a complex interplay between the circadian clock and SARS-CoV-2 infection in lung cells, opening new avenues for targeted interventions. This systems pharmacology study investigates this intricate relationship, focusing on the circadian protein BMAL1. BMAL1 plays a dual role in viral dynamics, driving the expression of the viral entry receptor ACE2 while suppressing interferon-stimulated antiviral genes. Its critical position at the host-pathogen interface suggests potential as a therapeutic target, albeit requiring a nuanced approach to avoid disrupting essential circadian regulation. To enable precise tuning of potential interventions, we constructed a computational model integrating the lung cellular clock with viral infection components. We validated this model against literature data to establish a platform for drug administration simulation studies using the REV-ERB agonist SR9009. Our simulations of optimized SR9009 dosing reveal circadian-based strategies that potentially suppress viral infection while minimizing clock disruption. This quantitative framework offers insights into the viral-circadian interface, aiming to guide the development of chronotherapy-based antivirals. More broadly, it underscores the importance of understanding the connections between circadian timing, respiratory viral infections, and therapeutic responses for advancing precision medicine. Such approaches are vital for responding effectively to the rapid spread of coronaviruses like SARS-CoV-2.

FZD5 controls intestinal crypt homeostasis and colonic Wnt surrogate agonist response.

The rapidly regenerating intestinal epithelium requires crypt intestinal stem cells (ISCs). Wnt/β-catenin signaling maintains crypt homeostasis and Lgr5+ ISCs, and WNT ligands bind Frizzled receptors (FZD1-10). Identifying specific FZD(s) essential for intestinal homeostasis has been elusive; however, bioengineered antagonists blocking Wnt binding to FZD5 and FZD8 deplete the gut epithelium invivo, highlighting potential roles. Here, an epithelial-specific Fzd5 knockout (KO) elicited lethal pan-intestinal crypt and villus loss, whereas an Lgr5+ ISC-specific Fzd5 KO depleted Lgr5+ ISCs via premature differentiation and repressed Wnt target genes. Fzd5-null phenotypes were rescued by constitutive β-catenin activation invivo and in both mouse and human enteroids. KO of Fzd5, not Fzd8, in enteroids ablated responsiveness to dual-specificity FZD5/FZD8-selective Wnt surrogate agonists, which ameliorated DSS-induced colitis in wild-type and Fzd8 KO mice. Overall, FZD5 is a dominant and essential regulator of crypt homeostasis, Lgr5+ ISCs, and intestinal response to Wnt surrogate agonists, with implications for therapeutic mucosal repair.

Divergent roles of RIPK3 and MLKL in high-fat diet-induced obesity and MAFLD in mice.

Cell death frequently occurs in the pathogenesis of obesity and metabolic dysfunction-associated fatty liver disease (MAFLD). However, the exact contribution of core cell death machinery to disease manifestations remains ill-defined. Here, we show via the direct comparison of mice genetically deficient in the essential necroptotic regulators, receptor-interacting protein kinase-3 (RIPK3) and mixed lineage kinase domain-like (MLKL), as well as mice lacking apoptotic caspase-8 in myeloid cells combined with RIPK3 loss, that RIPK3/caspase-8 signaling regulates macrophage inflammatory responses and drives adipose tissue inflammation and MAFLD upon high-fat diet feeding. In contrast, MLKL, divergent to RIPK3, contributes to both obesity and MAFLD in a manner largely independent of inflammation. We also uncover that MLKL regulates the expression of molecules involved in lipid uptake, transport, and metabolism, and congruent with this, we discover a shift in the hepatic lipidome upon MLKL deletion. Collectively, these findings highlight MLKL as an attractive therapeutic target to combat the growing obesity pandemic and metabolic disease.