Biology subjects

Spruce, L. A.

Publications and source records attributed to Spruce, L. A..

6 recordsLinked to original sources

bioRxiv2026

Short-Term Combined Tat-Beclin1 and Endurance Training Improves Age-Related Decline in Physical Function in Male Mice

Autophagy is a hallmark of aging, but autophagy-related proteins have not been exclusively targeted to attenuate the progressive decline in physical function associated with aging. Here, we combined Tat-Beclin1, an autophagy agonist, and endurance training to determine whether Tat-Beclin1 enhances exercise adaptation in old male mice. Tat-Beclin1 was administered intraperitoneally (TB group, 15 mg/kg, 2x/week) as a standalone therapy, or in combination with endurance training (TB+Exe group, 70% of maximal running speed 3x/week) for 1 month in 23-month-old male C57BL/6J mice. Control groups were age-matched cage controls and exercise-only groups. Animals were assessed for grip strength, endurance capacity on a treadmill, and balance and coordination on a rotarod. Gastrocnemius/plantaris (G/P) and tibialis anterior muscles were harvested for western blotting, myofiber typing, and proteomic profiling (G/P only). TB+Exe led to significant increases in grip strength, endurance capacity, and balance and coordination performance beyond those observed in the TB and Exe groups alone. Autophagy markers, including Beclin1, the LC3B-II/I ratio, and p62, did not differ among groups. A proteomic analysis of the G/P muscle revealed that TB upregulated biological processes involved in muscle contraction and adaptation, whereas TB+Exe increased mitochondrial bioenergetic processes and, surprisingly, upregulated acute inflammatory responses, including proteins such as haptoglobin and orosomucoid-1. We conclude that combining Tat-Beclin1 and endurance training may represent a new approach to attenuate aging-related decline in physical function. New & NoteworthyWe show evidence that combining Tat-Beclin1 and endurance training (TB+Exe) resulted in greater improvements in physical function in 24-month-old male mice than either standalone therapy. We also show that TB+Exe upregulates traditional exercise-like biological processes and unexpectedly upregulates acute-inflammatory proteins (e.g., orosomucoid-1), which are thought to improve physical function in preclinical studies. Our study suggests that TB may be a new drug enhancing physical function, especially when combined with endurance training in old male mice.

physiology↗

bioRxiv2025

Biosynthetic plasticity enables CD8+ T cell functional resilience under nutrient stress

Summary / AbstractTo maintain lineage-specific functions, cells must acquire and allocate nutrients across diverse cellular processes, even in metabolically-dysregulated environments. The mechanisms allowing CD8+ T cells to maintain immune function in perturbed environments are poorly understood. We find that CD8+ T cells adapt to nutrient stresses over time, reconfiguring gene-regulatory and metabolic networks to license functional recovery. Under acute stress, T cells reorient translational programming, limiting nutrient demand while prioritizing stress-sensitive metabolic and transcriptional responses. Within these responses, the transcription factors ATF4 and CEBPG jointly establish an adaptive metabolic program, promoting amino acid synthesis and uptake while maintaining mitochondrial anaplerosis. Despite diminished energetic capacity under environmental stress, this program prevents failure of central carbon metabolism, mitigating stress amplification and cellular dysfunction to potentiate anti-tumor immunity. Altogether, we demonstrate that biosynthetic plasticity via translational and metabolic reprioritization confers functional resilience to immune cells in unfavorable environments, offering novel strategies to enhance immunotherapies.

immunology↗

bioRxiv2023

Quantitative label free mass spectrometry reveals content and signaling differences between neonatal and adult platelets

Background and ObjectiveRecent clinical studies have shown that transfusions of adult platelets increase morbidity and mortality in preterm infants. Neonatal platelets are hyporesponsive to agonist stimulation, and emerging evidence suggests developmental differences in platelet immune functions. This study was designed to compare the proteome and phosphoproteome of resting adult and neonatal platelets. MethodsWe isolated resting umbilical cord blood-derived platelets from healthy full term neonates (n=9) and resting blood platelets from healthy adults (n=7), and compared protein and phosphoprotein contents using data independent acquisition mass spectrometry. ResultsWe identified 4745 platelet proteins with high confidence across all samples. Adult and neonatal platelets clustered separately by principal component analysis. Adult platelets were significantly enriched for immunomodulatory proteins, including {beta}2 microglobulin and CXCL12, whereas neonatal platelets were enriched for ribosomal components and proteins involved in metabolic activities. Adult platelets were enriched for phosphorylated GTPase regulatory enzymes and proteins participating in trafficking, which may help prime them for activation and degranulation. Neonatal platelets were enriched for phosphorylated proteins involved in insulin growth factor signaling. ConclusionsUsing state-of-the-art mass spectrometry, our findings expanded the known neonatal platelet proteome and identified important differences in protein content and phosphorylation compared with adult platelets. These developmental differences suggested enhanced immune functions for adult platelets and presence of a molecular machinery related to platelet activation. These findings are important to understanding mechanisms underlying key platelet functions as well as the harmful effects of adult platelet transfusions given to preterm infants.

cell biology↗

bioRxiv2022

A Coxiella burnetii effector interacts with the host PAF1 complex and suppresses the innate immune response

Intracellular bacteria such as the pathogen Coxiella burnetii inject effector proteins into the host cell that promote productive infection. One common strategy of pathogen effectors is to suppress host immune responses to enable pathogen replication. The C. burnetii type IV secretion system translocates a large number of effectors into host cells that collectively promote intracellular bacterial replication, but the individual functions of most of these effectors are poorly understood. In this study, we describe a C. burnetii effector, CBU1314, that localizes to the nucleus and inhibits NF-{kappa}B-, MAPK-, and type I IFN-dependent gene expression. Mechanistically, we find that CBU1314 interacts with the PAF1 complex (PAF1C), a central host transcriptional complex that regulates expression of inflammatory genes in innate immune cells. Notably, we find that PAF1 promotes immune gene expression in response to various immune agonists and C. burnetii infection. Moreover, we find that PAF1 is critical for restricting intracellular C. burnetii replication. Overall, our findings uncover PAF1C as a host target of a C. burnetii effector and reveal new insight into how intracellular bacterial pathogens subvert cell- intrinsic innate defenses. SignificanceIntracellular bacteria often employ secreted effector proteins to modulate cellular processes and survive intracellularly. The study of these effectors can provide valuable insight into microbial pathogenesis and host biology. Here, we describe a Coxiella burnetii effector that inhibits multiple host signaling pathways and modulates the innate immune response. This effector interacts with the host PAF1 complex (PAF1C), a central regulator of transcription. Furthermore, we show that PAF1 is necessary for maximal gene expression downstream of various innate immune receptors and restricts bacterial replication during infection. Overall, our study elucidates the function of a C. burnetii effector in evading the immune response and provides insight into the role of PAF1C in cell-intrinsic defense against bacterial pathogens.

microbiology↗

bioRxiv2022

FBXW7β isoform drives transcriptional activation of a proinflammatory TNF cluster in normal and malignant pro-B cells

Non-canonical exon usage plays many important roles in cellular phenotypes, but its contribution to human B-cell development remains sketchily understood. To fill this gap, we collected various B-cell fractions from bone marrow and tonsil donors, performed RNA-seq, and examined transcript variants. We identified 150 genes that harbor local splicing variations in all pairwise comparisons. One of them encodes FBXW7, an E3 ubiquitin ligase implicated as a cancer driver in several blood cancers. Surprisingly, we discovered that in normal human pro-B cells, the predominant transcript utilized an alternative first exon to produce the poorly characterized FBXW7{beta} isoform, previously thought to be restricted to neural tissues. The FBXW7{beta} transcript was also abundant in cell lines and primary samples of pediatric B-cell acute lymphoblastic leukemia (B-ALL), which originates in the bone marrow. When overexpressed in a heterologous cell system, this transcript yielded the expected protein product, as judged by anti-FLAG immunoblotting and mass spectrometry. Furthermore, in REH B-ALL cells, FBXW7{beta} mRNA was the only FBXW7 isoform enriched in the polyribosome fraction. To shed light on possible functions of FBXW7{beta}, we utilized gain- and loss-of-function approaches and identified an FBXW7{beta}-dependent inflammatory gene signature, apparent in a subset of B-ALL with high FBXW7{beta} expression. This signature contained several members of the TNF superfamily, including those comprising the HLA Class III cluster (LTB, LST1, NCR3, LTA, and NFKBIL1). Our findings suggest that FBXW7{beta} expression drives proinflammatory responses, which could contribute to normal B-cell development, leukemogenesis and responses to anti-cancer therapies. Key pointsO_LIPreviously thought to be restricted to neural tissues, FBXW7{beta} is the predominant FBXW7 isoform in normal and malignant human pro-B cells. C_LIO_LIFBXW7{beta} promotes transcriptional activation of a proinflammatory gene cluster that contains TNF superfamily members. C_LI

cell biology↗

bioRxiv2019

PIKfyve deficiency in myeloid cells impairs lysosomal homeostasis in macrophages and promotes systemic inflammation in mice

Macrophages are professional phagocytes that are essential for host defense and tissue homeostasis. Proper membrane trafficking and degradative functions of the endolysosomal system is known to be critical for the function of these cells. We have found that PIKfyve, the kinase that synthesizes the endosomal phosphoinositide PI(3,5)P2, is an essential regulator of lysosomal biogenesis and degradative functions in macrophages. Genetically engineered mice lacking PIKfyve in their myeloid cells (PIKfyvefl/fl LysM-Cre) develop diffuse tissue infiltration of foamy macrophages, hepatosplenomegaly, and systemic inflammation. PIKfyve loss in macrophages causes enlarged endolysosomal compartments and impairs the lysosomal degradative function. Moreover, PIKfyve deficiency increases the cellular levels of lysosomal proteins. Although PIKfyve deficiency reduced the activation of mTORC1 pathway and was associated with increased cleavage of TFEB proteins, this does not translate into transcriptional activation of lysosomal genes, suggesting that PIKfyve modulates the abundance of lysosomal proteins by affecting the degradation of these proteins. Taken together, our study shows that PIKfyve modulation of lysosomal degradative activity and protein expression is essential to maintain lysosomal homeostasis in macrophages.

cell biology↗