Search bioRxiv⌕ Search

Biology subjects

Berisa, M.

Publications and source records attributed to Berisa, M..

5 recordsLinked to original sources

Tetherin enforces an immunometabolic checkpoint that coordinates glycolytic and interferon signaling in adipocytes

Coordination between innate immune signaling and glucose metabolism is fundamental to organismal homeostasis, yet despite decades of study linking immunity and metabolism, the mechanisms by which metabolic cells restrain antiviral innate signaling while preserving glycolytic competence during overnutrition remain poorly defined. Here we identify Tetherin (BST2) as a unique cell-intrinsic immunometabolic checkpoint that couples restraint of type I interferon (IFN-I) signaling to preservation of glycolytic capacity in adipocytes. Tetherin localizes to endoplasmic reticulum and organizes an interactome enriched for antiviral sensing regulators and glycolytic control nodes in adipocytes. Mechanistically, Tetherin directly engages the ubiquitin-dependent degradation machinery NDFIP1 and RNF128 to terminate IRF3 activation, thereby limiting pro-inflammatory, anti-glycolytic signaling and protecting adipocytes from metabolic dysfunction. In parallel, multiomics integration reveals that Tetherin also acts as a scaffold that binds and spatially organizes and activates PFKFB3 to increase glycolytic capacity and restrain MAVS-IRF3 innate immune signalling. In vivo, adipocyte-specific loss of Tetherin amplifies high sucrose diet and high-fat-diet-induced glucose intolerance and liver steatosis, whereas overexpression of human Tetherin in adipocyte suppresses obesity-driven interferon signaling, restores glycolytic pathway, and improves metabolic homeostasis. Orthogonal perturbations in cancer and insulinoma cells further confirm an immunometabolic role for Tetherin. Together, these findings define Tetherin as a dual node immunometabolic checkpoint that couples restraint of antiviral innate inflammatory signaling to maintenance of glycolytic competence, thereby safeguarding adipocyte metabolic homeostasis.

cell biology↗

Coordinated synthesis of double-stranded DNA by a dual reverse transcriptase immune system

Defense-associated reverse transcriptase (DRT) systems mediate antiviral immunity through distinct modes of cDNA synthesis: Class 1 DRTs catalyze untemplated synthesis, whereas Class 2 DRTs polymerize noncoding RNA-templated products. However, how these distinct modes drive defense remains unclear. Here, we report that DRT3 immunity arises when Class 1 and Class 2 RT activities cooperate to produce self-complementary double-stranded DNA (dsDNA). DRT3a uses a 5'-ACACAC-3' RNA template to synthesize poly-(dTdG) repeats, whereas DRT3b synthesizes poly-(dCdA) repeats without any nucleic acid template. Cryo-electron microscopy reveals that DRT3b forms a hexamer and uses active-site-adjacent residues as deoxyadenosine and deoxycytidine gates to enforce alternating nucleotide addition, representing a unique example of amino acid-templated DNA polymerization. DRT3 is toxic in cells lacking RecBCD, implicating host recombination machinery in limiting dsDNA accumulation, and the phage-encoded RecBCD inhibitor Gam triggers DRT3-mediated abortive infection. These findings reveal how two polymerases with distinct templating strategies generate complementary DNA for defense.

microbiology↗

ATM functions as a rheostat of metabolic stress in small-cell lung cancer

ATM is best known as a guardian of genomic stability, yet its contributions to oncogenic signaling in aggressive malignancies like small-cell lung cancer (SCLC) remain poorly understood. Despite ATM being an established clinical vulnerability in SCLC, its influence on dysregulated tumorigenic circuits remains unclear. We demonstrate that inhibition of ATM disrupts the AKT-mTORC1-4EBP1 signaling axis, leading to attenuation of the master regulator of stress, ATF4. ATF4 and MYC appear to co-regulate one another in a feedback loop critical for redox homeostasis. ATM inhibition perturbs both the expression and function of MYC and ATF4, leading to increased intracellular reactive oxygen species, impaired glutathione recycling, and ferroptotic cell death, thereby exposing a crucial dependency of SCLC on stress-adaptive signaling. We uncover previously unrecognized metabolic vulnerability in SCLC, nominating ATM as a regulator of adaptive stress, expanding its role beyond canonical DNA damage repair (DDR) and highlighting therapeutically exploitable opportunities in aggressive tumors. Statement of SignificanceThe metabolic landscape of SCLC remains poorly characterized, particularly its interaction with dysregulated signaling networks, limiting the development of effective strategies to overcome therapeutic resistance. Our work reveals an expanded role for ATM beyond DNA repair, positioning it as a key regulator of metabolic rewiring and highlighting new therapeutic opportunities for SCLC.

cancer biology↗

Protein-primed DNA homopolymer synthesis by an antiviral reverse transcriptase

Bacteria defend themselves from viral predation using diverse immune systems, many of which sense and target foreign DNA for degradation1. Defense-associated reverse transcriptase (DRT) systems provide an intriguing counterpoint to this strategy by leveraging DNA synthesis instead2,3. We and others recently showed that DRT2 systems use an RNA template to assemble a de novo gene, leading to expression of an antiviral effector protein, Neo4,5. It remains unknown whether similar mechanisms of defense are employed by other DRT families. Focusing on DRT9, here we uncover an unprecedented mechanism of DNA homopolymer synthesis, in which viral infection triggers polydeoxyadenylate (poly-dA) accumulation in the cell to drive abortive infection and population-level immunity. Cryo-EM structures reveal how a conserved noncoding RNA serves as both a structural scaffold and reverse transcription template to direct hexameric complex assembly and RNA-templated poly-dA synthesis. Remarkably, biochemical and functional experiments identify conserved tyrosine residues within the reverse transcriptase itself that prime DNA synthesis, leading to the formation of high-molecular weight protein-DNA covalent adducts. Synthesis of poly-dA in vivo is regulated by the competing activities of phage-encoded triggers and host-encoded silencers of DRT9. Collectively, our work unveils a novel nucleic acid-driven defense system that expands the paradigm of bacterial immunity and broadens the known functions of reverse transcriptases.

molecular biology↗

Ontogeny Dictates Oncogenic Potential, Lineage Hierarchy, and Therapy Response in Pediatric Leukemia

Accumulating evidence links pediatric cancers to prenatal transformation events, yet the influence of the developmental stage on oncogenesis remains elusive. We investigated how hematopoietic stem cell developmental stages affect leukemic transformation, disease progression, and therapy response using a novel, humanized model of NUP98::NSD1-driven pediatric acute myeloid leukemia, that is particularly aggressive with WT1 co-mutations. Fetal-derived hematopoietic stem cells readily transform into leukemia, and WT1 mutations further enhance stemness and alter lineage hierarchy. In contrast, stem cells from later developmental stages become progressively resistant to transformation. Single-cell analyses revealed that fetal-origin leukemia stem cells exhibit greater quiescence and reliance on oxidative phosphorylation than their postnatal counterparts. These differences drive distinct therapeutic responses, despite identical oncogenic mutations. In patients, onco-fetal transcriptional programs correlate with worse outcomes. By targeting key vulnerabilities of fetal-origin leukemia cells, we identified combination therapies that significantly reduce aggressiveness, highlighting the critical role of ontogeny in pediatric cancer treatment.

cancer biology↗