Biology subjects

Herbine, K.

Publications and source records attributed to Herbine, K..

4 recordsLinked to original sources

bioRxiv2025

Structural Basis for Promoter Recognition and Transcription Factor Binding and Release in Human Mitochondria

Transcription in human mitochondria is driven by a core apparatus consisting of a Pol A family RNA polymerase (mtRNAP), the initiation factors TFAM and TFB2M, and the elongation factor TEFM. While earlier structures of initiation and elongation complexes provided valuable snapshots, they represent isolated stages of a highly dynamic and multistep process. Critical aspects of mitochondrial transcription--such as DNA recognition and melting, promoter escape, and the release of initiation factors--remain poorly understood. Here, we present a series of cryo-EM structures that capture the transcription complex as it transitions from the initial open promoter complex to the processive elongation complex through intermediate stages. Our data reveal new determinants of promoter specificity, the sequential disengagement of mtRNAP from TFAM and the promoter, the release of TFB2M, and the recruitment of TEFM. Together, these findings provide a detailed molecular mechanism underlying transcription in human mitochondria.

molecular biology↗

bioRxiv2018

Cell-intrinsic Wnt4 controls early cDC1 commitment and suppresses development of pathogen-specific Type 2 immunity

Whether conventional dendritic cell (cDC) precursors acquire lineage-specific identity under direction of regenerative secreted glycoproteins within bone marrow niches is entirely unknown. Herein, we demonstrate that Wnt4, a beta-catenin independent Wnt ligand, is both necessary and sufficient for necessary for the full extent of pre-cDC1 specification within bone marrow. Cell-intrinsic Wnt4 deficiency in CD11c+ cells reduced mature cDC1 numbers in BM, spleen, lung, and intestine and, reciprocally, rWnt4 treatment promoted pJNK activation and cDC1 expansion. Lack of cell-intrinsic Wnt4 in mice CD11cCreWnt4flox/flox impaired stabilization of IRF8/cJun complexes in BM and increased the basal frequency of both cDC2 and ILC2 populations in the periphery. Accordingly, CD11c-restricted Wnt4 augmented Type 2 immunity against the hookworm parasite Nippostrongylus brasiliensis accompanied by increased interleukin 5 production relative to CD11cCre controls. Collectively, these data show previously unappreciated role for Wnt4 in DC commitment and pathogen-specific immunity.

immunology↗

bioRxiv2018

LINGO3 interacts with Trefoil factor 2 to enforce mucosal barrier integrity and drive tissue repair during colitis

Mucosal epithelia are constantly exposed to damaging stimuli from mechanical, chemical, or biologic entities, and depend on rapid repair mechanisms to maintain tissue homeostasis and immunological quiescence. The reparative cytokine Trefoil factor 2 (TFF2) serves to enforce mucosal barrier integrity, but whether TFF2 receptor(s) exist is controversial. Herein, we demonstrate leucine rich repeat and immunoglobulin like domain containing nogo receptor interacting protein 3 (LINGO3) is a necessary transmembrane component for TFF2-mediated ERK signaling, proliferation, and recovery of trans-epithelial resistance of primary epithelia during wound healing. Human respiratory and intestinal epithelia express LINGO3 and mice lacking Lingo3 have impaired intestinal barrier function and fail to recover from DSS-induced colitis. Compared to wild-type controls, LINGO3 deficiency impairs both crypt regeneration and expression of the intestinal stem cell marker Lgr5. Importantly, Lingo3-/- mice display a phenotype similar to that previously reported for Tff2 deficiency, with increased paracellular permeability, and significant accumulation of mucosal CD4+ TH1 cells expressing IFN{gamma}+ TNF+ even under steady-state conditions. Combined, these data reveal a previously unrecognized role for LINGO3 as a putative TFF2 receptor that regulates mucosal barrier integrity and GI inflammation.\n\nSignificanceIntestinal epithelial cells (IEC) are necessary for maintenance of homeostasis, resistance to infectious organisms, and overall organismal health. When injured the IEC and the underlying stroma and progenitor cell pool undergo restitutive and regenerative processes driven by the reparative cytokine Trefoil factor 2 (TFF2). This report identifies a novel receptor component for TFF2 signaling expressed on both human and mouse epithelial cells that is necessary for barrier integrity at the steady state and during colitic disease. The discovery of a novel TFF2-LINGO3 axis sheds new light on the processes controlling tissue repair, restitution, and regeneration at the mucosal interface.

cell biology↗

bioRxiv2018

TFF3 is a ligand for LINGO2 that de-represses EGFR to control disease outcome during colitis and gastrointestinal nematode infection

Intestinal epithelial cells (IEC) comprise diverse lineages that serve distinct roles necessary for regulation of nutrient absorption, regeneration, immunity, and homeostasis1,2. Goblet cells secrete Trefoil factor 3 (TFF3) to maintain mucus viscosity and drive mucosal healing by inhibiting cell death and influencing tight junction protein expression3. However, whether TFF3 signaling relies upon conventional ligand-receptor interactions has been unclear for decades. This study demonstrates that the orphan transmembrane protein leucine rich repeat receptor and nogo-interacting protein 2 (LINGO2) immunoprecipitates with TFF3, that LINGO2 and TFF3 co-localize at the IEC cell surface, and that TFF3/LINGO2 interactions block IEC apoptosis. Loss of function studies show that TFF3-driven STAT3 and EGFR activation are both LINGO2 dependent. Importantly, we demonstrate that TFF3 disrupts LINGO2/EGFR interactions that normally restrict EGFR activity, resulting in enhanced EGFR signaling. Excessive EGFR activation in Lingo2 gene deficient mice exacerbates colitic disease and accelerates host resistance to parasitic nematodes, whereas TFF3 deficiency results in host susceptibility. Thus, our data demonstrating that TFF3 functions through a previously unrecognized ligand-receptor interaction with LINGO2 to de-repress LINGO2-dependent inhibition of EGFR activation provides a novel conceptual framework explaining how TFF3-mediates mucosal wound healing through enhanced activation of the EGFR pathway.

cell biology↗