Biology subjects

Qiang, L.

Publications and source records attributed to Qiang, L..

14 recordsLinked to original sources

bioRxiv2026

De novo design of protease-activatable cytokine prodrugs

Cytokines can elicit potent antitumor immunity, but their clinical use is often limited by systemic immune activation and dose-limiting toxicity. Protease-responsive masking offers a way to improve selectivity by linking cytokine activity to disease-associated protease cleavage, but current approaches have faced several challenges. Here we describe a de novo protein design strategy for generating protease-activatable cytokine prodrugs that overcomes these challenges. We use this strategy to design and characterize cytokine prodrugs and well-behaved AND-gated split systems that require both target-dependent colocalization and proteolytic unmasking to generate active cytokines. In challenging syngeneic tumor models, our IL-21 prodrugs reduced treatment-associated toxicity while maintaining antitumor efficacy.

bioengineering↗

bioRxiv2026

Long-term Connectivity between Spinal Cord Tissue Transplants and the Injured Phrenic Motor Network

Restoring vital motor functions after spinal cord injury (SCI) remains a central challenge in neuroscience and regenerative medicine. Cervical SCI can cause life-threatening respiratory deficits by damaging the phrenic motor network that controls the diaphragm. Cellular transplantation offers a viable means to improve function by providing new neurons that can relay supraspinal drive to denervated spinal phrenic networks, yet the long-term stability of transplants is poorly defined. Here, we examine donor-host neuronal synaptic connectivity in a respiratory model of cervical SCI, 1-year post-transplantation in adult rats. Embryonically-derived spinal cord tissue was transplanted into the lesion cavity one-week post-SCI, and transplant integration and diaphragm function were assessed at 1-month and 1-year post-transplantation. At 1-month, transplant-recipients exhibited significantly greater diaphragm output than injured, vehicle control animals. The extent of recovery at 1-year, however, was significantly less, coinciding with anatomical changes in graft neuronal density and donor-host connectivity, revealed by transneuronal tracing (pseudorabies virus). These results demonstrate that embryonic spinal cord transplants can improve phrenic motor activity after cervical SCI, but that long-term efficacy may be limited by reduced donor-host connectivity. Significance StatementCell transplantation can repair injured spinal cord circuits, but whether donor-host connections persist long term remains unclear. Using a rat model of cervical spinal cord injury, we show that embryonic spinal cord transplants improve diaphragm activity and integrate with the injured phrenic motor network at early time points, but these benefits decline by 1 year after transplantation. This loss of functional recovery is accompanied by reduced transneuronal labeling of donor neurons and changes in graft tissue composition. These results provide important proof of principle that transplant-host connectivity can be evaluated over extended survival times and identify long-term stability of donor-host integration as a critical challenge for achieving durable respiratory repair after spinal cord injury.

neuroscience↗

bioRxiv2026

IgG Propels Atherosclerosis by Noncanonically Activating Macrophages

Despite being a central component of adaptive immunity and a highly abundant serum protein, the contribution of IgG to the milieu of atherosclerosis remains unappreciated. Here, we identify a pro-atherogenic role for IgG as it activates an innate immune cascade, independent of its classical antigen-neutralizing function. Analyses of human coronary artery plaques reveal a positive correlation between IgG and cardiovascular and cerebrovascular disease severity. Integrated single-cell plaque analyses localize IgG, coinciding with its recycling receptor FcRn, to pro-inflammatory and foamy macrophages. Genetic ablation of FcRn in myeloid cells prevents IgG from accumulating in mouse atherosclerotic lesions, diminishing plaque size and inflammation. Mechanistically, IgG acts as an endogenous ligand for TLR4, triggering NF-{kappa}B-NLRP3 inflammasome signaling without requiring its antigen-binding domain. Additionally, IgG accelerates macrophage foam cell formation through upregulation of downstream effector LCN2. Our work uncovers a role for previously overlooked adaptive immune molecules in the pathogenesis of atherosclerosis through a noncanonical mechanism linked with innate immunity.

immunology↗

bioRxiv2025

Small molecule inhibitor of PPARγ acetylation promotes insulin sensitization and browning of white adipose tissue with improved safety

The nuclear receptor PPAR{gamma} is a primary therapeutic target for insulin resistance and type 2 diabetes (T2D); however, its thiazolidinedione (TZD) class of PPAR{gamma} agonists have substantial safety concerns in clinical utilization. Genetic inhibition of PPAR{gamma} acetylation at K268 and K293 dissociates the major adverse effects of TZDs from insulin sensitization and other metabolic improvements. We therefore posit that chemical inhibition of PPAR{gamma} acetylation would elicit insulin sensitization with improved safety. Here we describe the identification of a synthetic thiopyrimidine derivative (TPMD) that acts as a small molecule inhibitor of PPAR{gamma} acetylation. TPMD improves insulin sensitivity, promotes brown remodeling of white adipose tissue (WAT), increases energy expenditure, and decreases adiposity in dietary and genetic mouse models of T2D. Importantly, TPMD is deprived of the major side effects of TZDs, including weight gain, fluid retention, cardiac hypertrophy, bone marrow adiposity, and bone loss. X-ray crystallography at 2.0 [A] resolution reveals a unique binding mode of TPMD molecules to the PPAR{gamma} ligand-binding domain and provides structural and molecular basis for the acetylation inhibitory activity of TPMD together with site-directed mutagenesis studies. These findings identify TPMD as a first-in-class compound that specifically targets PPAR{gamma} acetylation and possesses the potential of developing into a safe insulin sensitizer to treat and prevent T2D and obesity.

cell biology↗

bioRxiv2025

Genotype-Phenotype Distinctions in Spastic Paraplegia 4 Reveal HDAC6 as a Therapeutic Target

Spastic Paraplegia 4 (SPG4) is the most prevalent form of Hereditary Spastic Paraplegia (HSP), a neurodegenerative disorder characterized by progressive lower limb spasticity and debilitating gait impairment, primarily driven by axonal degeneration of corticospinal motor neurons (CSMNs). Caused by mutations in the SPAST gene encoding spastin, an AAA-ATPase involved in microtubule severing and intracellular organelle function, SPG4 accounts for 40-50% of autosomal dominant HSP cases, yet without effective treatments. Although reduced microtubule acetylation has emerged as a key pathological mechanism, whether and how distinct mutations lead to microtubule deacetylation and subsequent neurodegeneration remains unclear. To address this, we generated isogenic human induced pluripotent stem cell (hiPSC) lines with two distinct heterozygous SPAST mutations - SPASTWT/C448Y (missense) and SPASTWT/S245X (truncation). Employing an innovative differentiation protocol, we created human motor cortical organoids enriched in CSMNs, providing a robust platform to study SPG4 pathophysiology. These organoids revealed striking genotype-phenotype distinctions, with mutation-specific variations in CSMN loss, axonal degeneration and neuronal activities, mirroring clinical heterogeneity. Mechanistic studies identified aberrant activation of histone deacetylase 6 (HDAC6), a major neuronal microtubule deacetylase, as a key driver of SPG4 pathology. This dysregulation was specifically attributed to mutant M1-spastin, the longer isoform of spastin. Remarkably, pharmacological inhibition of HDAC6 with Tubastatin A restored microtubule acetylation status and mitigated axonal degeneration in both SPAST-mutant organoids, with corresponding improvements in corticospinal tract integrity and gait deficits validated in SPG4-transgenic mice. Collectively, our study establishes isogenic hiPSC-derived motor cortical organoids as a robust human model for corticospinal motor neuron degeneration and identifies HDAC6 hyperactivation as a central pathogenic mechanism and viable therapeutic target in SPG4.

neuroscience↗

bioRxiv2024

SMAC mimetics induce human macrophages to phagocytose live cancer cells

Macrophages engulf apoptotic bodies and cellular debris as part of homeostasis, but they can also phagocytose live cells such as aged red blood cells. Pharmacologic reprogramming with the SMAC mimetic LCL161 in combination with T cell-derived cytokines can induce macrophages to phagocytose live cancer cells in mouse models. Here we extend these findings to encompass a wide range of monovalent and bivalent SMAC mimetic compounds, demonstrating that live cell phagocytosis is a class effect of these agents. We demonstrate robust phagocytosis of live pancreatic and breast cancer cells by primary human macrophages across a range of healthy donors. Unlike mouse macrophages where combination of SMAC mimetics with lymphotoxin enhanced phagocytosis, human macrophages were more efficiently polarized to phagocytose live cells by the combination of SMAC mimetics and IFN{psi}. We profiled phagocytic macrophages by transcriptional and proteomic methodologies, uncovering a positive feedback loop of autocrine TNF production.

immunology↗

bioRxiv2024

Peptide-MHC-targeted retroviruses enable in vivo expansion and gene delivery to tumor-specific T cells

Tumor-infiltrating-lymphocyte (TIL) therapy has demonstrated that endogenous T cells can be harnessed to initiate an effective anti-tumor response. Despite clinical promise, current TIL production protocols involve weeks-long ex vivo expansions which can affect treatment efficacy. Therefore, additional tools are needed to engineer endogenous tumor-specific T cells to have increased potency while mitigating challenges of manufacturing. Here, we present a strategy for pseudotyping retroviral vectors with peptide-major histocompatibility complexes (pMHC) for antigen-specific gene delivery to CD8 T cells and examine the efficacy of these transduced cells in immunocompetent mouse models. We demonstrate that pMHC-targeted viruses are able to specifically deliver function-enhancing cargoes while simultaneously activating and expanding anti-tumor T cells. The specificity of these viral vectors enables in vivo engineering of tumor-specific T cells, circumventing ex vivo manufacturing processes and improving overall survival in B16F10-bearing mice. Altogether, we have established that pMHC-targeted viruses are efficient vectors for reprogramming and expanding tumor-specific populations of T cells directly in vivo, with the potential to substantially streamline engineered cell therapy production for a variety of applications.

immunology↗

bioRxiv2024

Challenges and Efficacy of Astrocyte-to-Neuron Reprogramming in Spinal Cord Injury: In Vitro Insights and In Vivo Outcomes

Traumatic spinal cord injury (SCI) leads to the disruption of neural pathways, causing loss of neural cells, with subsequent reactive gliosis and tissue scarring that limit endogenous repair. One potential therapeutic strategy to address this is to target reactive scar-forming astrocytes with direct cellular reprogramming to convert them into neurons, by overexpression of neurogenic transcription factors. Here we used lentiviral constructs to overexpress Ascl1 or a combination of microRNAs (miRs) miR124, miR9/9*and NeuroD1 transfected into cultured and in vivo astrocytes. In vitro experiments revealed cortically-derived astrocytes display a higher efficiency (70%) of reprogramming to neurons than spinal cord-derived astrocytes. In a rat cervical SCI model, the same strategy induced only limited reprogramming of astrocytes. Delivery of reprogramming factors did not significantly affect patterns of breathing under baseline and hypoxic conditions, but significant differences in average diaphragm amplitude were seen in the reprogrammed groups during eupneic breathing, hypoxic, and hypercapnic challenges. These results show that while cellular reprogramming can be readily achieved in carefully controlled in vitro conditions, achieving a similar degree of successful reprogramming in vivo is challenging and may require additional steps.

neuroscience↗

bioRxiv2024

Antagonistic Roles of Tau and MAP6 in Regulating Neuronal Development

Association of tau with microtubules causes them to be labile while association of MAP6 with microtubules causes them to be stable. As axons differentiate and grow long, tau and MAP6 segregate from one another on individual microtubules, resulting in the formation of stable and labile domains. The functional significance of the yin/yang relationship between tau and MAP6 remained speculative in those studies, with one idea being that such a relationship assists in balancing morphological stability with plasticity. Here, using primary rodent neuronal cultures, we show that depletion of tau has opposite effects compared to depletion of MAP6 on the rate of neuronal development, the efficiency of growth cone turning, and the number of processes and axonal branches. Opposite effects to those of tau depletion were also observed on the rate of neuronal migration, in an in vivo assay, when we depleted MAP6. When tau and MAP6 were depleted together in the cell culture assays, the morphological phenotypes negated one another. Tau and MAP6 are multifunctional proteins, but the present results suggest that the observed effects of their depletion on neuronal development are likely due to their opposite roles in regulating microtubule dynamics. SummaryTau and MAP6 play antagonistic roles in regulating multiple aspects of neuronal development, presumably via their antagonistic effects on microtubule dynamics.

cell biology↗

bioRxiv2023

Autophagy regulates tumor growth and metastasis

The role of autophagy in tumorigenesis and tumor metastasis remains poorly understood. Here we show that inhibition of autophagy stabilizes the transcription factor Twist1 through Sequestosome-1 (SQSTM1, also known as p62) and thus increases cell proliferation, migration, and epithelial-mesenchymal transition (EMT) in tumor development and metastasis. Inhibition of autophagy or p62 overexpression blocks Twist1 protein degradation in the proteasomes, while p62 inhibition enhances it. SQSTM1/p62 interacts with Twist1 via the UBA domain of p62, in a Twist1-ubiquitination-dependent manner. Lysine 175 in Twist1 is critical for Twist1 ubiquitination, degradation, and SQSTM1/p62 interaction. For squamous skin cancer and melanoma cells that express Twist1, SQSTM1/p62 increases tumor growth and metastasis in mice. Together, our results identified Twist1 as a key downstream protein for autophagy and suggest a critical role of the autophagy/p62/Twist1 axis in cancer development and metastasis.

cancer biology↗

bioRxiv2022

Alveolar regeneration following viral infection is independent of tuft cells

Severe injuries following viral infection cause lung epithelial destruction with the presence of ectopic basal progenitor cells (EBCs), although the exact function of EBCs remains controversial. We and others previously showed the presence of ectopic tuft cells in the disrupted alveolar region following severe influenza infection. Here, we further revealed that the ectopic tuft cells are derived from EBCs. This process is amplified by Wnt signaling inhibition but suppressed by Notch inhibition. Further analysis revealed that p63-CreER labeled population de novo arising during regeneration includes alveolar epithelial cells when Tamoxifen was administrated after viral infection. The generation of the p63-CreER labeled alveolar cells is independent of tuft cells, demonstrating segregated differentiation paths of EBCs in lung repair. EBCs and ectopic tuft cells can also be found in the lung parenchyma post SARS-CoV-2 infection, suggesting a similar response to severe injuries in humans.

cell biology↗

bioRxiv2021

Adipsin promotes bone marrow adiposity by priming mesenchymal stem cells

BackgroundBone marrow (BM) adipose tissue (BMAT) has been shown to be vital for regulating metabolism and maintaining skeletal homeostasis in the marrow niche. As a reflection of BM remodeling, BMAT is highly responsive to nutrient fluctuations, hormonal changes and metabolic disturbances such as obesity and diabetes mellitus. Expansion of BMAT has also been strongly associated with bone loss in mice and humans. However, the regulation of BM plasticity remains poorly understood, as does the mechanism that links changes in marrow adiposity with bone remodeling. MethodsUsing C57BL/6 mice as a model, we employed the bone-protected PPAR{gamma} constitutive deacetylation (2KR), Adipsin, and its downstream effector, C3, knockout mice. These mice were challenged to thiazolidinedione treatment, calorie restriction, or aging in order to induce bone loss and MAT expansion. Analysis of bone density and marrow adiposity was performed using a CT scanner and by RNA analysis to assess adipocyte and osteoblast markers. For in vitro studies, primary bone marrow stromal cells (BMSCs) were isolated and subjected to osteoblastogenic or adipogenic differentiation or chemical treatment followed by morphological and molecular analyses. Clinical data was obtained from samples of a previous clinical trial of fasting and high calorie diet in healthy human volunteers. ResultsWe have shown that Adipsin is the most up-regulated adipokine during BMAT expansion in mice and humans, in a PPAR{gamma} acetylation-dependent manner. Ablation of Adipsin in mice specifically inhibited BMAT expansion but not peripheral adipose depots, and improved bone mass during calorie restriction, thiazolidinedione treatment, and aging. These effects were mediated through its downstream effector, complement component C3, to prime common progenitor cells toward adipogenesis rather than osteoblastogenesis through inhibiting Wnt/{beta}- catenin signaling. ConclusionsAdipsin promotes new adipocyte formation and affects skeletal remodeling in the BM niche. Our study reveals a novel mechanism whereby the BM sustains its own plasticity through paracrine and endocrine actions of a unique adipokine. FundingThis work was supported by the National Institutes of Health T32DK007328 (NA), F31DK124926 (NA), R01DK121140 (JCL), R01AR068970 (BZ), R01AR071463 (BZ), R01DK112943 (LQ), and P01HL087123 (LQ).

molecular biology↗

bioRxiv2020

A Mycobacterium tuberculosis effector protein attacks host innate immunity by acting as an unusual ubiquitinating enzyme

Protein kinase G (PknG), a eukaryotic type serine-threonine protein kinase (STPK) in Mycobacterium tuberculosis (Mtb), is secreted into the cytosol of infected macrophages to promote intracellular survival of mycobacteria and has been considered as a promising therapeutic target for tuberculosis (TB) treatment. However, the molecular details of Mtb PknG-host intracellular interactions remain obscure. Here, we demonstrate that PknG serves as both the ubiquitin-activating enzyme (E1) and the ubiquitin ligase (E3) to promote ubiquitination and degradation of tumor necrosis factor receptor-associated factor 2 (TRAF2) and TGF-{beta}-activated kinase 1 (TAK1), and thus inhibits the NF-{kappa}B-mediated host innate immune responses. Surprisingly, PknG promotes the attachment of ubiquitin (Ub) to ubiquitin-conjugating enzyme (E2) UbcH7 via an isopeptide bond (UbcH7 K82-Ub), instead of a usual C86-Ub thiol-ester bond, and then promotes the discharge of Ub from UbcH7 by acting as an isopeptidase before attaching Ub to its substrates TRAF2 and TAK1. These results demonstrate that Mtb PknG promotes ubiquitination of the key components of the host innate immunity by acting as an unusual ubiquitinating enzyme to suppress innate immunity. Our findings provide a potential TB treatment via targeting unconventional ubiquitinating activities of PknG. SignificanceMycobacterium tuberculosis (Mtb) protein kinase G (PknG), which is critical for Mtb intracellular survival, is a promising target for tuberculosis (TB) treatment. However, the molecular mechanisms underlying PknG-host interactions remain largely unclear. Here we demonstrate that PknG serves as both the ubiquitin-activating enzyme and the ubiquitin ligase to promote the ubiquitination and degradation of tumor necrosis factor receptor-associated factor 2 (TRAF2) and TGF-{beta}-activated kinase 1 (TAK1), thus inhibiting NF-{kappa}B signaling activation. PknG promotes the attachment of ubiquitin to ubiquitin-conjugating enzyme UbcH7 via an isopeptide bond, instead of a usual thiol-ester bond, and releases the ubiquitin from UbcH7 by acting as an isopeptidase. These findings provide important information for rational development of TB treatment via targeting unconventional ubiquitinating activity of PknG.

microbiology↗

bioRxiv2020

KALRN Mutations Promote Anti-tumor Immunity and Immunotherapy Response in Cancer

BackgroundKALRN (kalirin RhoGEF kinase) is mutated in a wide range of cancers. Nevertheless, the association between KALRN mutations and the pathogenesis of cancer remains unexplored. The identification of biomarkers for cancer immunotherapy response is important considering that immunotherapies show beneficial effects only in a subset of cancer patients. MethodsWe explored the correlation between KALRN mutations and anti-tumor immunity in 10 cancer cohorts from The Cancer Genome Atlas (TCGA) program by the bioinformatics approach. Moreover, we verified the findings from bioinformatics analysis by in vitro experiments. Furthermore, we explored the correlation between KALRN mutations and immunotherapy response in four cancer cohorts receiving immune checkpoint blockade therapy. ResultsWe found that anti-tumor immune signatures were stronger in KALRN-mutated than in KALRN-wildtype cancers. Moreover, KALRN mutations correlated with increased tumor mutation burden and the microsatellite instability or DNA damage repair deficiency genomic properties which may explain the elevated anti-tumor immunity in KALRN-mutated cancers. Furthermore, we found that PD-L1 expression was significantly upregulated in KALRN-mutated versus KALRN-wildtype cancers. The enhanced anti-tumor immune signatures and PD-L1 expression in KALRN-mutated cancers may favor the response to immune checkpoint blockade therapy in this cancer subtype, as evidenced in four cancer cohorts receiving anti-PD-1/PD-L1/CTLA-4 immunotherapy. We further revealed that the significant association between KALRN mutations and increased anti-tumor immunity was attributed to that KALRN mutations compromised the function of KALRN target Rho GTPases on regulating DNA damage repair pathways. ConclusionsThe KALRN mutation is a useful biomarker for predicting the response to immunotherapy in cancer patients.

immunology↗