TBK1-Zyxin signaling controls tumor-associated macrophage recruitment to mitigate antitumor immunity.

Mechanical control is fundamental for cellular localization within a tissue, including for tumor-associated macrophages (TAMs). While the innate immune sensing pathways cGAS-STING and RLR-MAVS impact the pathogenesis and therapeutics of malignant diseases, their effects on cell residency and motility remain incompletely understood. Here, we uncovered that TBK1 kinase, activated by cGAS-STING or RLR-MAVS signaling in macrophages, directly phosphorylates and mobilizes Zyxin, a key regulator of actin dynamics.

Starvation-induced phosphorylation activates gasdermin A to initiate pyroptosis.

Pyroptosis, a pro-inflammatory form of programmed cell death, is crucial for host defense against pathogens and danger signals. Proteolytic cleavage of gasdermin proteins B-E (GSDMB-GSDME) is well established as a trigger for pyroptosis, but the intracellular activation mechanism of GSDMA remains elusive. Here, we demonstrate that severe starvation induces pyroptosis through phosphorylation-induced activation of GSDMA.

The RNF214-TEAD-YAP signaling axis promotes hepatocellular carcinoma progression via TEAD ubiquitylation.

RNF214 is an understudied ubiquitin ligase with little knowledge of its biological functions or protein substrates. Here we show that the TEAD transcription factors in the Hippo pathway are substrates of RNF214. RNF214 induces non-proteolytic ubiquitylation at a conserved lysine residue of TEADs, enhances interactions between TEADs and YAP, and promotes transactivation of the downstream genes of the Hippo signaling.

New progress in roles of TGF-β signaling crosstalks in cellular functions, immunity and diseases.

The family of secreted dimeric proteins known as the Transforming Growth Factor-β (TGF-β) family plays a critical role in facilitating intercellular communication within multicellular animals. A recent symposium on TGF-β Biology - Signaling, Development, and Diseases, held on December 19-21, 2023, in Hangzhou, China, showcased some latest advances in our understanding TGF-β biology and also served as an important forum for scientific collaboration and exchange of ideas. More than twenty presentations and discussions at the symposium delved into the intricate mechanisms of TGF-β superfamily signaling pathways, their roles in normal development and immunity, and the pathological conditions associated with pathway dysregulation.

Nuclear KRT19 is a transcriptional corepressor promoting histone deacetylation and liver tumorigenesis.

Background And Aims: Epigenetic reprogramming and escape from terminal differentiation are poorly understood enabling characteristics of liver cancer. Keratin 19 (KRT19), classically known to form the intermediate filament cytoskeleton, is a marker of stemness and worse prognosis in liver cancer. This study aimed to address the functional roles of KRT19 in liver tumorigenesis and to elucidate the underlying mechanisms.

IRF3 activates RB to authorize cGAS-STING-induced senescence and mitigate liver fibrosis.

Cytosolic double-stranded DNA surveillance by cyclic GMP-AMP synthase (cGAS)-Stimulator of Interferon Genes (STING) signaling triggers cellular senescence, autophagy, biased mRNA translation, and interferon-mediated immune responses. However, detailed mechanisms and physiological relevance of STING-induced senescence are not fully understood. Here, we unexpectedly found that interferon regulatory factor 3 (IRF3), activated during innate DNA sensing, forms substantial endogenous complexes in the nucleus with retinoblastoma (RB), a key cell cycle regulator.

Loss of ZNRF3/RNF43 Unleashes EGFR in Cancer.

ZNRF3 and RNF43 are closely related transmembrane E3 ubiquitin ligases with significant roles in development and cancer. Conventionally, their biological functions have been associated with regulating WNT signaling receptor ubiquitination and degradation. However, our proteogenomic studies have revealed EGFR as the most negatively correlated protein with mRNA levels in multiple human cancers.

Innate immune sensing of lysosomal dysfunction drives multiple lysosomal storage disorders.

Lysosomal storage disorders (LSDs), which are characterized by genetic and metabolic lysosomal dysfunctions, constitute over 60 degenerative diseases with considerable health and economic burdens. However, the mechanisms driving the progressive death of functional cells due to lysosomal defects remain incompletely understood, and broad-spectrum therapeutics against LSDs are lacking. Here, we found that various gene abnormalities that cause LSDs, including Hexb, Gla, Npc1, Ctsd and Gba, all shared mutual properties to robustly autoactivate neuron-intrinsic cGAS-STING signalling, driving neuronal death and disease progression.

A chaperone-like function of FUS ensures TAZ condensate dynamics and transcriptional activation.

The Hippo pathway has important roles in organ development, tissue homeostasis and tumour growth. Its downstream effector TAZ is a transcriptional coactivator that promotes target gene expression through the formation of biomolecular condensates. However, the mechanisms that regulate the biophysical properties of TAZ condensates to enable Hippo signalling are not well understood.

Smad4 sequestered in SFPQ condensates prevents TGF-β tumor-suppressive signaling.

Loss of TGF-β growth-inhibitory responses is a hallmark of human cancer. However, the molecular mechanisms underlying the TGF-β resistance of cancer cells remain to be fully elucidated. Splicing factor proline- and glutamine-rich (SFPQ) is a prion-like RNA-binding protein that is frequently upregulated in human cancers.

Computational design and genetic incorporation of lipidation mimics in living cells.

Protein lipidation, which regulates numerous biological pathways and plays crucial roles in the pharmaceutical industry, is not encoded by the genetic code but synthesized post-translationally. In the present study, we report a computational approach for designing lipidation mimics that fully recapitulate the biochemical properties of natural lipidation in membrane association and albumin binding. Furthermore, we establish an engineered system for co-translational incorporation of these lipidation mimics into virtually any desired position of proteins in Escherichia coli and mammalian cells.

High-sensitivity profiling of SARS-CoV-2 noncoding region-host protein interactome reveals the potential regulatory role of negative-sense viral RNA.

A deep understanding of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-host interactions is crucial to developing effective therapeutics and addressing the threat of emerging coronaviruses. The role of noncoding regions of viral RNA (ncrRNAs) has yet to be systematically scrutinized. We developed a method using MS2 affinity purification coupled with liquid chromatography-mass spectrometry and designed a diverse set of bait ncrRNAs to systematically map the interactome of SARS-CoV-2 ncrRNA in Calu-3, Huh7, and HEK293T cells.

Imatinib blocks tyrosine phosphorylation of Smad4 and restores TGF-β growth-suppressive signaling in BCR-ABL1-positive leukemia.

Loss of TGF-β-mediated growth suppression is a major contributor to the development of cancers, best exemplified by loss-of-function mutations in genes encoding components of the TGF-β signaling pathway in colorectal and pancreatic cancers. Alternatively, gain-of-function oncogene mutations can also disrupt antiproliferative TGF-β signaling. However, the molecular mechanisms underlying oncogene-induced modulation of TGF-β signaling have not been extensively investigated.

Protein phosphatase PPM1A inhibition attenuates osteoarthritis via regulating TGF-β/Smad2 signaling in chondrocytes.

TGF-β signaling is crucial for modulating osteoarthritis (OA), and protein phosphatase magnesium-dependent 1A (PPM1A) has been reported as a phosphatase of SMAD2 and regulates TGF-β signaling, while the role of PPM1A in cartilage homeostasis and OA development remains largely unexplored. In this study, we found increased PPM1A expression in OA chondrocytes and confirmed the interaction between PPM1A and phospho-SMAD2 (p-SMAD2). Importantly, our data show that PPM1A KO substantially protected mice treated with destabilization of medial meniscus (DMM) surgery against cartilage degeneration and subchondral sclerosis.

Protein tyrosine phosphatase PTPN2 regulates TGF-β signaling through Smad4 dephosphorylation.

Transforming Growth Factor beta (TGF-β) is a multifunctional cytokine that regulates cell proliferation, differentiation, and apoptosis. Dysregulation of the TGF-β signaling is one of the major mechanisms underlying tumor progression. We have previously reported that anaplastic lymphoma kinase (ALK) phosphorylates Smad4 at Tyr95, which compromises the DNA-binding ability of Smad4 and thus renders ALK-positive cancer cells resistant to TGF-β tumor-suppressive action.

HERC3 promotes YAP/TAZ stability and tumorigenesis independently of its ubiquitin ligase activity.

YAP/TAZ transcriptional co-activators play pivotal roles in tumorigenesis. In the Hippo pathway, diverse signals activate the MST-LATS kinase cascade that leads to YAP/TAZ phosphorylation, and subsequent ubiquitination and proteasomal degradation by SCF . When the MST-LATS kinase cascade is inactive, unphosphorylated or dephosphorylated YAP/TAZ translocate into the nucleus to mediate TEAD-dependent gene transcription.

Targeting proteostasis of the HEV replicase to combat infection in preclinical models.

Background & Aims: Appropriate treatment options are lacking for hepatitis E virus (HEV)-infected pregnant women and immunocompromised individuals. Thus, we aimed to identify efficient anti-HEV drugs through high-throughput screening, validate them in vitro and in vivo (in a preclinical animal study), and elucidate their underlying antiviral mechanism of action.

Methods: Using appropriate cellular and rodent HEV infection models, we studied a critical pathway for host-HEV interactions and performed a preclinical study of the corresponding antivirals, which target proteostasis of the HEV replicase.

AMPK directly phosphorylates TBK1 to integrate glucose sensing into innate immunity.

Nutrient sensing and damage sensing are two fundamental processes in living organisms. While hyperglycemia is frequently linked to diabetes-related vulnerability to microbial infection, how body glucose levels affect innate immune responses to microbial invasion is not fully understood. Here, we surprisingly found that viral infection led to a rapid and dramatic decrease in blood glucose levels in rodents, leading to robust AMPK activation.

Energy sensor AMPK gamma regulates translation via phosphatase PPP6C independent of AMPK alpha.

Maintenance of energy level to drive movements and material exchange with the environment is a basic principle of life. AMP-activated protein kinase (AMPK) senses energy level and is a major regulator of cellular energy responses. The gamma subunit of AMPK senses elevated ratio of AMP to ATP and allosterically activates the alpha catalytic subunit to phosphorylate downstream effectors.

To Ub or not to Ub: a regulatory question in TGF-β signaling.

The transforming growth factor β (TGF-β) superfamily controls a wide spectrum of biological processes in metazoans, including cell proliferation, apoptosis, differentiation, cell-fate determination, and embryonic development. Deregulation of TGF-β-Smad signaling contributes to developmental anomalies and a variety of disorders and diseases such as tumorigenesis, fibrotic disorders, and immune diseases. In cancer, TGF-β has dual effects through its antiproliferative and prometastatic actions.

Liver cancer heterogeneity modeled by in situ genome editing of hepatocytes.

Mechanistic study and precision treatment of primary liver cancer (PLC) are hindered by marked heterogeneity, which is challenging to recapitulate in any given liver cancer mouse model. Here, we report the generation of 25 mouse models of PLC by in situ genome editing of hepatocytes recapitulating 25 single or combinations of human cancer driver genes. These mouse tumors represent major histopathological types of human PLCs and could be divided into three human-matched molecular subtypes based on transcriptomic and proteomic profiles.

FUNDC2 promotes liver tumorigenesis by inhibiting MFN1-mediated mitochondrial fusion.

Mitochondria generate ATP and play regulatory roles in various cellular activities. Cancer cells often exhibit fragmented mitochondria. However, the underlying mechanism remains elusive.

A non-canonical cGAS-STING-PERK pathway facilitates the translational program critical for senescence and organ fibrosis.

Innate DNA sensing via the cyclic GMP-AMP synthase-stimulator of interferon genes (cGAS-STING) mechanism surveys microbial invasion and cellular damage and thus participates in various human infectious diseases, autoimmune diseases and cancers. However, how DNA sensing rapidly and adaptively shapes cellular physiology is incompletely known. Here we identify the STING-PKR-like endoplasmic reticulum kinase (PERK)-eIF2α pathway, a previously unknown cGAS-STING mechanism, enabling an innate immunity control of cap-dependent messenger RNA translation.