KONG, L. | Search bioRxiv

bioRxiv2025

Dual Transcriptional Drivers of Immune Suppression in SACC: NOTCH1 for Cellular and MYB for Humoral Immunity

As a classic immune-"cold" tumor, salivary adenoid cystic carcinoma (SACC) represents a significant clinical challenge. Through sequencing analyses, we identify profound systemic immune dysregulation in SACC, characterized by suppressed hematopoiesis, T-cell exhaustion, compensatory myelopoiesis, and an expanded immature B-cell compartment. While lung metastases exhibit a relatively immune-engaged microenvironment enriched in tissue-resident T cells, these sites remain dominated by immature B cells. Mechanistically, this hematopoietic dysfunction originates from direct disruption of tumor-derived signaling entering the circulation, supported by detection of the SACC-signature MYB-NFIB fusion gene in peripheral plasma and blood cells. At the molecular level, we discover that IL17RB/OLIG1/NOTCH1 signaling pathways engage in multicellular crosstalk via IL33 or TP53 to suppress T-cell activation in primary tumors. Moreover, at lung metastatic sites, the MYB/MYBL2-NOTCH1-CXCL13-CXCR5 axis is blocked through CD24 or IL17RB, thereby inhibiting B-cell maturation. Single-cell transcriptomic profiling further identifies cancer stem cells (CSCs) exhibiting dual characteristics of cell-cycle activity and immune progenitor features, a finding that clarifies the fundamental mechanism by which these cells evade immune surveillance. In conclusion, we propose that stem cell camouflage constitutes the core mechanism underlying bone marrow hematopoietic dysfunction and drives immune evasion in SACC. These findings highlight the IL17RB-NOTCH1 signaling axis as a promising therapeutic target, offering potential to overcome the long-standing challenges associated with NOTCH1-targeted therapies in this malignancy. SignificanceOur novel transcriptomic analysis revealed a key G2M/CLP dual-progenitor state in SACC immunocold tumors. Tracing its origin to hematopoietic differentiation, we uncovered a NOTCH1-mediated dual-hit mechanism: restricting antigen presentation to silence T cells while partnering with MYB to block B-cell maturation. This finding pinpoints a root cause of immune evasion and establishes this pathway as a central therapeutic target. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=107 SRC="FIGDIR/small/688163v2_ufig1.gif" ALT="Figure 1"> View larger version (36K): org.highwire.dtl.DTLVardef@18c22a2org.highwire.dtl.DTLVardef@135e381org.highwire.dtl.DTLVardef@eb4eadorg.highwire.dtl.DTLVardef@7a51c4_HPS_FORMAT_FIGEXP M_FIG C_FIG Dichotomous gene mapping and single-cell interactome reveal the microenvironmental specificity of NOTCH1/MYB regulation of T/B-cell differentiation and its distinct signaling flows.

immunology↗

bioRxiv2024

The Alexander Disease Protein GFAP Drives Mitochondrial Fission

Mitochondrial plasticity, coordinated by fission and fusion, is crucial to ensure cellular functions. Mitochondrial fission is mediated by the GTPase Drp1 at the constriction site, which is proposed to be driven by the actin-myosin contractile force. However, the mechanism that propels constriction remains unclear, and the potential involvement of additional mechanisms in this process remains an open question. Here, using structured illumination microscopy and electron microscopy, we show that the type-III intermediate filament glial fibrillary acidic protein (GFAP) closely surrounds mitochondria fission sites and associates with accumulated Drp1 molecules. Remarkably, loss of GFAP results in hyperfused mitochondria under physiological condition and even Ca2+-induced mitochondrial fission. Additionally, mutations of GFAP, the cause of Alexander disease, result in an elevated recruitment of Drp1 to GFAP, leading to significantly increased mitochondrial fissions. Taking together, these findings suggest a novel mechanism of mitochondrial division mediated by type-III intermediate filaments.

cell biology↗

bioRxiv2019

Overcoming tissue scattering in wide-field deep imaging by extended detection and computational reconstruction

Compared to the golden technique of point-scanning multiphoton microscopy, line-scanning temporal focusing microscopy (LTFM) is competitive in high imaging speed while maintaining tight axial confinement. However, considering its wide-field detection mode, LTFM suffers from shallow penetration depth as a result of crosstalk induced by tissue scattering. In contrast to the spatial filtering based on confocal slit detection, we propose the extended detection LTFM (ED-LTFM), the first technique to extract signals from scattered photons and thus effectively extend the imaging depth. By recording a succession of line-shape excited signals in 2D and reconstructing signals under Hessian regularization, we can push the depth limitation in scattering tissue imaging. We valid the concept with numerical simulations, and demonstrate the performance of enhanced imaging depth in in vivo imaging of mouse brains.

neuroscience↗