Biology subjects

Kim, H.-J.

Publications and source records attributed to Kim, H.-J..

At least 19 recordsLinked to original sources

bioRxiv2026

LoGoPPI enables fast and accurate protein protein interaction mapping at scale

Graph-based protein function analysis is powerful, but protein-protein interaction (PPI) networks exist for only a small fraction of animal and plant genomes. We present LoGoPPI, which infers PPIs from sequence by combining bi-encoder global protein representation with local residue-level late interaction. LoGoPPI matches or exceeds state-of-the-art PLM-based cross-encoders while achieving orders-of-magnitude faster inference, up to ~1,500-fold, and its local branch provides residue-level signals associated with interaction interfaces and structurally flexible regions. This efficiency enables practical proteome-wide PPI reconstruction at scales prohibitive for cross-encoder models, potentially extending interactome mapping to tens of thousands of animal and plant species. LoGoPPI thus provides a scalable framework for comparative and functional analysis of protein networks across diverse taxa.

bioinformatics↗

bioRxiv2026

Targeting Tumor-derived Sphingosine Kinase 2 Unleashes Antitumor Immunity and Improves Survival of Mice with Group 3 Medulloblastoma

Group 3 medulloblastomas (G3MB) carry the worst prognosis among medulloblastoma subtypes, yet molecularly targeted therapies remain elusive. Standard treatments cause severe long-term morbidity in survivors. Here, we identify tumor-derived sphingosine kinase 2 (SPHK2) as an essential driver of G3MB initiation and progression. SPHK2 exacerbates local immunosuppression by suppressing cytotoxic T-cell and NK-cell activity while promoting regulatory T-cell infiltration. Genetic or pharmacologic SPHK2 inhibition using Opaganib attenuates pro-survival tumor signaling and restores anti-tumor immunity, significantly improving survival in syngeneic G3MB mouse models. Combining Opaganib with fractionated low-dose radiation (f-LDRT) further enhances antigen presentation and reprograms tumor-associated myeloid cells toward an anti-tumor phenotype. This combination therapy markedly prolongs survival without inducing significant toxicity. Overall, our study establishes SPHK2 as a previously unrecognized therapeutic target and presents a safe, effective, microenvironment-reprogramming regimen for G3MB. One Sentence SummaryDirect inhibition of tumor-derived SPHK2 overcomes local immunosuppression and downregulates pro-survival signaling in Group 3 medulloblastoma, while combination with fractionated low-dose radiation further enhances anti-tumor immunity and significantly improves survival.

cancer biology↗

bioRxiv2026

Embryo-scale Visual Cell Sorting reveals a conserved transcriptomic signature of nucleolar size linked to proteostasis

Nucleoli, nuclear speckles and other compartments regulate transcription, RNA processing, and chromatin organization within the nucleus, yet the relationship of their morphology to developmental gene expression programs in vivo is poorly understood. Here, we develop a high-throughput Visual Cell Sorting (VCS) workflow for fixed cells and nuclei that combines antibody-based photoconversion; GPU-accelerated, real-time image analysis; and three-level single-cell combinatorial indexing RNA-seq (sci-RNA-seq3) to link nuclear compartment morphology to single-nucleus transcriptomes at embryo scale. We use VCS to analyze and sort over 1 million mouse embryo-derived nuclei by nucleolar, nuclear speckle, or nuclear size and construct a transcriptional atlas annotated with nuclear compartment phenotypes. Nuclear compartment size varies both between and within lineages and is shaped by proliferation and differentiation. In extracellular matrix protein-producing cell types such as fibroblasts, chondrocytes, and osteoblasts, nucleolar enlargement is uncoupled from cell cycle, and in erythroid cells exhibit a sharp nucleolar contraction preceding cell-cycle exit. We identify a 41-gene transcriptional signature whose expression tracks nucleolar size, enriched for ribosome biogenesis, mitochondrial metabolism, unfolded protein response, stress granule, and ubiquitin-proteasome pathway components. We used this nucleolar transcriptional signature to annotate mouse, zebrafish and human developmental atlases with nucleolar size information, revealing a conserved coupling between nucleolar activity and proteostasis programs. Our work establishes Visual Cell Sorting as a scalable platform for mapping image-based phenotypes to molecular programs; details the relationship between nuclear compartment phenotypes and development; and provides a transcriptional signature to estimate nucleolar size from existing single-cell datasets.

genomics↗

bioRxiv2026

Linking live-cell behavior to transcriptional responses across perturbations using dynamic caging

Single-cell technologies, encompassing molecular, morphological, and functional assays, have emerged as cornerstones of modern biological research and discovery. However, current experimental methods often fail to explicitly link these omic modalities, especially in live cells or longitudinally through time, impeding the study of multi-scale interactions and mechanisms of regulation. CellCage Enclosure (CCE) technology overcomes these limitations by dynamically compartmentalizing cells, allowing for scalable, live-cell, longitudinal exploration and simultaneous analysis of transcriptomic, proteomic, and morphological profiles. Using this novel technology, we generate previously inaccessible insights across various in vitro cellular systems under a diverse set of perturbations, including the discovery of morphological and proteomic features linked to immune suppressive gene set expression in human primary regulatory T cells (Tregs), as well as direct association of morphological and proteomic features with inflammatory gene modules in human colonic fibroblasts. We then develop a novel pooled CRISPR genetic screening technology using CCEs, PERTURB-LINK (PERTURBational LINKage of transcriptomics and imaging in single cells via enclosure-based screening) and apply this approach in murine bone marrow derived macrophages (BMDMs), enabling multiomic dissection of NF-{kappa}B pathway regulation in response to lipopolysaccharide (LPS) stimulation. Together, these findings demonstrate the broad impact that advancements in live-cell, paired multimodal technologies, especially upon perturbation, may offer in deepening our understanding of cellular biology.

cell biology↗

bioRxiv2026

Deep Plasma Proteomics Coupled with Functional Genomics Reveals Drivers of Parkinson's Disease Progression and Levodopa Response

Parkinsons disease (PD) is a progressive neurodegenerative disorder lacking disease-modifying therapies, and its clinical management is limited by the absence of accessible biomarkers for tracking disease progression and treatment response. To map these complex disease trajectories, we implemented an ultra-deep plasma proteomics workflow integrating Mag-Net extracellular vesicle enrichment with Orbitrap Astral mass spectrometry to profile longitudinal samples from PD patients. This approach quantified 6,481 plasma proteins at unprecedented depth in PD studies, revealing distinct signatures directly associated with disease duration and dopaminergic therapy exposure. Candidate biomarkers were subsequently validated in an independent cohort using ELISA, demonstrating robust predictive utility in AI-driven prediction models. To uncover the mechanistic drivers underlying these systemic changes, we intersected our proteomic data with novel proteome-wide gene overexpression perturbation screens designed to identify regulators of alpha-synuclein pre-formed fibril (PFF) uptake and PFF-induced neuronal toxicity. Finally, an integrative network analysis combining three independent proteome-wide assays revealed that key pathological hubs, such as CD14, IFNG, and PLAT, are targets of currently approved pharmacological agents. Collectively, these findings provide a comprehensive, systems-level map for PD biomarker discovery and highlight druggable pathways to advance precision medicine strategies.

neuroscience↗

bioRxiv2025

Structural studies of mycobacterial HptG reveal a silent state and offer insights into TLR4 activation

HtpG of Mycobacterium tuberculosis (HtpGMtb) is an ATP-dependent chaperone that assists the correct folding of nascent and stress-accumulated misfolded proteins, in concert with other chaperones. Beside playing a role in stress response, it is able to elicit an immune response against M. tuberculosis infection by activating Dendritic Cells in a TLR4-mediated manner. However, we lack a full understanding of the molecular determinants of HtpGMtb catalytic activity and TLR4 activation, due to the lack of structural and biophysical data. Here, we report the first crystal structure of HtpGMtb, in complex with the non-hydrolysable form of ATP, AMPPNP. The crystal structure reveals that the HtpGMtb dimer adopts a conformationally silent structure, that precludes the dimerisation of the chaperone catalytic domains needed for ATP hydrolysis. Also, binding studies show that HtpGMtb directly interacts with TLR4 with a nanomolar affinity, and that this interaction allows HtpGMtb dimer to engage two TLR4 molecules. This finding suggests that activation of TLR4 by HtpGMtb is due to its ability to induce intra-cellular receptor dimerisation in an LPS-like mode.

biophysics↗

bioRxiv2025

Cas9-enriched nanopore sequencing enables comprehensive and multiplexed detection of repeat expansions

Short tandem repeat (STR) expansion is a major genetic mechanism underlying numerous neurogenetic disorders. However, traditional PCR amplification and short-read next-generation sequencing (NGS)-based methods often fail to detect complex and large expansions including methylation information. Here, we modified an amplification-free nanopore Cas9-targeted sequencing (nCATS) platform and developed a dedicated analysis algorithm, STRiker, for the simultaneous assessment of all currently defined STR loci (56 sites) using a single test with genomic DNA from patient-derived blood cells. We ultimately identified pathogenic repeat expansions in 12 of 37 patients (32.4%) with cerebellar ataxia who remained genetically undiagnosed despite extensive prior genetic testing, in FGF14 (n=4), ATXN8OS, NOP56, RFC1 (n=2 each), and PRNP and NOTCH2NLC (n=1 each). Additionally, family-based cascade screening revealed six relatives with repeat expansions in five families. These results demonstrated a broader diversity of pathogenic repeat structures, particularly in FGF14, and illustrated that CpG methylation can mitigate the pathogenic effects of repeat expansions. This approach offers a powerful strategy for improving the diagnosis of STR-related neurogenetic diseases, for cerebellar ataxia and other STR-related diseases in the future. One Sentence SummaryImproved nanopore Cas9-targeted sequencing with STRiker enhances diagnosis of STR- related neurogenetic diseases and offers broader molecular insights.

bioengineering↗

bioRxiv2025

Trophic transfer of nanoplastics reduces larval survival of marine fish more than waterborne exposure

Microplastics (MPs) and nanoplastics (NPs) are widespread contaminants in marine environments and pose significant risks to aquatic organisms. However, physiological effects and survival consequences of different MP and NP exposure pathways during early developmental stages of marine fish remain poorly understood. We investigated effects of direct and indirect consumption of MPs and NPs by larvae of red sea bream (Pagrus major) using a controlled laboratory system. Larvae were exposed to fluorescently labeled polystyrene particles (3 {micro}m and 0.2 {micro}m) either directly from the water or indirectly via contaminated zooplankton prey. MPs and NPs were detected in digestive tracts of all exposed individuals, regardless of the exposure route. However, survival was significantly reduced in larvae that consumed NPs via rotifer predation, suggesting that ingestion of contaminated prey organisms may represent a greater hazard than direct uptake from water. In both groups, antioxidant enzymes, superoxide dismutase (SOD) and catalase (CAT) were elevated, suggesting induction of oxidative stress. Relative gene expression revealed greater upregulation of several stress and immune-related genes in larvae exposed to MPs via rotifer predation than via direct consumption. Our findings provide clear evidence that both MPs and NPs can alter physiological and molecular responses in marine fish larvae, especially via rotifer predation. This study suggests the importance of considering trophic interactions in ecotoxicological assessments of plastic pollution to address plastic bioavailability and toxicity during early life stages. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=114 SRC="FIGDIR/small/675286v1_ufig1.gif" ALT="Figure 1"> View larger version (24K): org.highwire.dtl.DTLVardef@1de4a22org.highwire.dtl.DTLVardef@d53060org.highwire.dtl.DTLVardef@5b13fborg.highwire.dtl.DTLVardef@17cd662_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LILarval survival was significantly reduced by nanoplastics via trophic transfer C_LIO_LIGrowth of larvae was not affected by micro-and nanoplastics C_LIO_LIMicro- and nanoplastics cause oxidative stress by both exposure routes C_LIO_LIUp-regulated gene expression revealed that larvae undergo various stresses C_LI

developmental biology↗

bioRxiv2025

Disulfide Crosslinking Induces Rapid Degradation of Arc/Arg3.1 via Hsp70-Mediated Ubiquitin Ligase Pathway

Activity-regulated cytoskeleton-associated protein (Arc/Arg3.1) is an immediate-early gene (IEG) induced by stress and synaptic activity, characterized by transient expression and rapid degradation. However, the mechanisms governing its degradation remain unclear. In this study, we identify a novel degradation pathway for Arc/Arg3.1, driven by its structural features. We demonstrate that the proteasomal degradation of Arc/Arg3.1 is modulated by the Hsp70-CHIP complex, with ubiquitination being impaired in HSF1 knockout cells. The formation of a Cys34-Cys159 disulfide bond crosslinks Arc/Arg3.1 into high-molecular-weight oligomers, altering its ubiquitination pattern and degradation kinetics compared to the C159A mutant. Hydrogen-deuterium exchange mass spectrometry (HDX-MS) revealed that wild-type (WT) Arc/Arg3.1 adopts a more compact structure than the C159A mutant. Notably, the C159A mutant fails to interact with HSF1, resulting in Hsp70 induction upon heat shock. Our findings propose a feedback loop in which disulfide crosslinking of Arc/Arg3.1 induces rapid degradation through Hsp70-mediated ubiquitination, which in turn modulates the heat shock response by inhibiting HSF1 function.

biochemistry↗

bioRxiv2025

Image-based, pooled phenotyping reveals multidimensional, disease-specific variant effects

Genetic variants often produce complex phenotypic effects that confound current assays and predictive models. We developed Variant in situ sequencing (VIS-seq), a pooled, image-based method that measures variant effects on molecular and cellular phenotypes in diverse cell types. Applying VIS-seq to [~]3,000 LMNA and PTEN variants yielded high-dimensional morphological profiles that captured variant-driven changes in protein abundance, localization, activity and cell architecture. We identified gain-of-function LMNA variants that reshape the nucleus and autism-associated PTEN variants that mislocalize. Morphological profiles predicted variant pathogenicity with near-perfect accuracy and distinguished autism-linked from tumor syndrome-linked PTEN variants. Most variants impacted a multidimensional continuum of phenotypes not recapitulated by any single functional readout. By linking protein variation to cell images at scale, we illuminate how variant effects cascade from molecular to subcellular to cell morphological phenotypes, providing a framework for resolving the complexity of variant function.

genomics↗

bioRxiv2025

Electrochemical Metabolic Profiling Reveals Mitochondrial Hyperactivation and Enhanced Neural Progenitor Proliferation in MLC1-Mutant Human Cortical Organoids

Mitochondrial function is critical for neural progenitor regulation, yet its dysregulation during early human brain development remains poorly defined. Megalencephalic leukoencephalopathy with subcortical cysts (MLC) is a neurodevelopmental disorder caused by MLC1 mutations, previously attributed to postnatal astrocyte dysfunction. Using patient-derived human cortical organoids, we show that MLC1 is expressed in early neuroepithelial cells. To assess mitochondrial state in live organoids, we developed the MAGO (Matrigel-coated gold nanostructure) platform for real-time, label-free detection of redox activity. MLC1 mutant organoids showed mitochondrial hyperactivation, increased ATP and ROS, reduced membrane potential, and altered fusion protein expression. These changes were accompanied by enhanced BrdU incorporation and expansion of PAX6/SOX2 progenitors. To assess the causal role of MLC1 mutation, we generated isogenic organoids using CRISPR prime editing, which recapitulated redox hyperactivation and increased proliferation. Our findings redefine MLC as a disorder of early mitochondrial and progenitor dysregulation and establish a tractable platform to study metabolic mechanisms in neurodevelopmental disease.

neuroscience↗

bioRxiv2025

Mechanical environment afforded by engineered polymer hydrogel critically regulates survival of neural stem cells transplanted in the injured spinal cord via Piezo1-mediated mechanotransduction

Neural stem cell (NSC) transplantation is a promising therapeutic approach for spinal cord repair, but poor graft survival remains a critical challenge. Here, we demonstrate that the mechanical properties of the transplantation microenvironment play a crucial role in NSC survival in the injured spinal cord. While our previously engineered imidazole-poly(organophosphazene) (I-5) hydrogel effectively prevented cavity formation by promoting extracellular matrix remodeling, NSCs transplanted with 10% hydrogel exhibited poor survival. Remarkably, increasing the hydrogel concentration to 16%, which created a 5-fold stiffer matrix, significantly enhanced NSC graft survival and synaptic integration. Using in vitro models with controlled substrate stiffness, we found that NSCs on stiffer substrates displayed enhanced adhesion, complex morphology, and increased viability. Importantly, we identified the mechanosensitive ion channel Piezo1 as the key molecular mediator of these stiffness-dependent behaviors. CRISPR/Cas9-mediated Piezo1 gene editing in NSCs significantly reduced graft survival in vivo when transplanted with 16% hydrogel, confirming that Piezo1-mediated mechanotransduction is essential for NSC survival in the injured spinal cord. Our findings reveal a previously unrecognized mechanism governing graft survival in the injured spinal cord and suggest that optimizing the mechanical properties of biomaterial scaffolds or targeting Piezo1-dependent mechanotransduction could substantially improve outcomes of cell-based therapies for neurological disorders.

neuroscience↗

bioRxiv2024

Intracortical injection of immune checkpoint inhibitor promotes monocyte/macrophage infiltration and restores microglial function and neuronal activity in an AD mouse model

Alzheimer's disease (AD) involves complex neuroimmune interactions. However, the role of immune checkpoint pathways in regulating the glial and neuronal functions of the AD brain remains unclear. This study aims to investigate how the brain-specific modulation of the PD-1/PD-L1 axis affects glial and neuronal function in an AD mouse model, which is characterized by the significant upregulation of microglial PD-1 and astrocytic PD-L1. A single intracortical administration of anti-PD-L1 antibody reshaped the glial microenvironment, which was accompanied by the restoration of impaired microglial process convergence. Astrocyte-specific Pd-l1 knockdown using the pSico system validated the essential role of astrocytic PD-L1 in enhancing microglial responses. Notably, the blockade of the PD-1/PD-L1 signaling pathway increased the microglial P2RY12 expression, a key marker of microglial homeostasis, which likely contributed to the restoration of neuronal hyperactivity. Collectively, these findings confirmed the potential of targeting the astrocyte-microglia PD-1/PD-L1 axis to mitigate AD pathology.

neuroscience↗

bioRxiv2024

Gut microbiota dysbiosis induced by brain tumor modulates the efficacy of immunotherapy

BackgroundAlthough the influence of gut microbiota on various tumors has gained recognition, the intricate mechanisms underlying their effects on brain tumors remain largely unexplored. In this study, our objective was to unveil pivotal gut microbiota that contribute significantly to the anti-tumor immune response against brain tumors. ResultsDuring the progression of brain tumors, our research uncovered a notable shift in the gut microbiome, as revealed through comprehensive 16S rRNA sequencing analysis. This shift coincided with a substantial decrease in the concentration of tryptophan in fecal samples, indicating a potential link between tryptophan levels and microbiome composition. Intriguingly, dietary supplementation with tryptophan significantly mitigated these microbial alterations, suggesting a restorative effect on the gut microbiota composition. This intervention not only reversed the changes observed in the gut microbiome but also markedly improved survival rates, a phenomenon that was determined to be dependent on the gut microbiota. The mechanism underlying this improvement appears to involve an enhancement in T cell circulation, which in turn boosts the efficacy of immunotherapeutic approaches. Upon further investigation into the specific microbial species that were positively influenced by tryptophan supplementation, some candidates were screened. Among several gut microbiota strains restored by tryptophan supplementation, the most significant is Duncaniella dubosii. Through sole colonization into germ-free mice, we found that the presence of Duncaniella dubosii alone was able to replicate the beneficial effects observed with tryptophan supplementation. ConclusionsThis study highlights Duncaniella dubosiis crucial role in linking tryptophan supplementation to positive shifts in the gut microbiome, immune modulation, and enhanced survival during brain tumor progression. It underscores the complex interaction between diet, microbiota, and immune responses, offering novel insights for boosting cancer immunotherapys success.

microbiology↗

bioRxiv2024

Untargeted Plasma Metabolomics Unveils Distinct Metabolite Profiles in Parkinson Disease Subtypes: A Focus on idiopathic REM Sleep Behavior Disorders

BackgroundParkinsons disease (PD) is characterized by diverse clinical presentations and etiological complexities, with rapid eye movement (REM) sleep behavior disorder (RBD) serving as a prodromal marker. While extensive unbiased metabolic profiling of plasma samples from PD subjects has been conducted to identify novel PD metabolic biomarkers, comprehensive metabolic profiling of PD subtypes based on RBD status remains limited. MethodsWe conducted a comprehensive metabolic profiling of PD subtypes at disease onset, considering the presence or absence of RBD, utilizing an untargeted metabolomics approach. Plasma samples were collected from subjects with PD with and without RBD at the initial stages of disease, idiopathic RBD, and healthy controls to elucidate similarities and differences among PD subtypes. Based on ordination analysis and metabolome-wide association study (Wilcoxon rank-sum tests and generalized fold changes), we identified specific groups of metabolites enriched in the PD_Only group and RBD groups (iRBD & PD_RBD+), with few metabolites shared between groups. Furthermore, pathway enrichment analysis (hypergeometric tests) identified specific groups enriched with metabolites from specific origins and associated biospecimens, as well as disease-associated metabolites. Finally, we evaluated the biomarker potential of the identified disease metabolites by ROC curves and proposed logistic regression models of key biomarkers and clinical parameters for predicting disease status. ResultsMetabolomic analysis revealed distinct metabolic profiles between PD subtypes with and without RBD. Our analysis confirmed previously reported PD metabolic markers, such as a reduction in caffeine and urate, as well as an increase in cortisol, secondary bile acids, and p-cresol sulfate. However, our stratified analyses based on the presence of RBD discriminated RBD-associated metabolites from those associated with PD_Only (without RBD). PD patients with RBD exhibited enrichment of gut microbial-origin metabolites, including secondary bile acids and p-cresol sulfate, compared to PD patients without RBD. Conversely, metabolites associated with neuro-psychiatric diseases were enriched in PD patients without RBD. ConclusionsOur study elucidates the heterogeneous nature of PD subtypes, particularly differentiated with the presence of RBD. The metabolic features of PD with RBD subtype supports the "body-first" concept of PD pathogenesis originating from the gut.

systems biology↗

bioRxiv2024

Targeting phosphatase DUSP22 ameliorates skeletal muscle wasting via Akt independent JNK-FOXO3a repression

Skeletal muscle wasting results from numerous conditions, such as sarcopenia, glucocorticoid therapy or intensive care. It prevents independent living in the elderly, predisposes to secondary diseases, and ultimately reduces lifespan. There is no approved drug therapy and the major causative mechanisms are not fully understood. Dual specificity phosphatase 22 (DUSP22) is a pleiotropic signaling molecule that plays important roles in immunity and cancer. However, the role of DUSP22 in skeletal muscle wasting is unknown. In this study, DUSP22 was found to be upregulated in sarcopenia patients and models of skeletal muscle wasting. DUSP22 knockdown or pharmacological inhibition prevented multiple forms of muscle wasting. Mechanistically, targeting DUSP22 suppressed FOXO3a, a master regulator of skeletal muscle wasting, via downregulation of the stress-activated kinase JNK, which occurred independently of aberrant Akt activation. DUSP22 targeting was also effective in human skeletal muscle cells undergoing atrophy. In conclusion, phosphatase DUSP22 is a novel target for preventing skeletal muscle wasting. The DUSP22-JNK-FOXO3a axis could be exploited to treat sarcopenia or related aging disorders.

cell biology↗

bioRxiv2024

Phospholipase C β4 promotes RANKL-dependent osteoclastogenesis by interacting with MKK3 and p38 MAPK

Phospholipase C beta (PLC{beta}) exerts diverse biological processes, including inflammatory responses and neurogenesis; however, its role in bone cell function is largely unknown. Among the PLC{beta} isoforms ({beta}1-{beta}4), we found that PLC{beta}4 was most highly upregulated during osteoclastogenesis. In this study, we used global knockout and osteoclast lineage-specific PLC{beta}4 conditional knockout (LysM-PLC{beta}4-/-) mice and demonstrated that PLC{beta}4 is a crucial regulator of receptor activator of nuclear factor {kappa}B ligand (RANKL)-induced osteoclast differentiation. Deletion of PLC{beta}4, both globally and in the osteoclast lineage, resulted in a significant reduction in osteoclast formation and the downregulation of osteoclast marker genes. Importantly, LysM-PLC{beta}4-/- male mice exhibited greater bone mass and a lower number of osteoclasts in vivo than their wild-type littermates, without altering osteoblast function. Mechanistically, we found that PLC{beta}4 forms a complex with p38 mitogen-activated protein kinase (MAPK) and MAPK kinase 3 (MKK3) in response to RANKL, thereby modulating p38 activation. An immunofluorescence assay further confirmed the colocalization of PLC{beta}4 with p38 after RANKL exposure. Moreover, p38 activation rescued the impaired osteoclast formation and restored the reduced p38 phosphorylation due to PLC{beta}4 deficiency. Thus, our findings reveal that PLC{beta}4 controls osteoclastogenesis via the RANKL-dependent MKK3-p38 MAPK pathway, and PLC{beta}4 may be a potential therapeutic candidate for bone diseases such as osteoporosis.

cell biology↗

bioRxiv2024

Dimeric R25CPTH(1-34) Activates the Parathyroid Hormone-1 Receptor in vitro and Stimulates Bone Formation in Osteoporotic Female Mice

Osteoporosis, characterized by reduced bone density and strength, increases fracture risk, pain, and limits mobility. Established therapies of Parathyroid hormone (PTH) analogs effectively promote bone formation and reduce fractures in severe osteoporosis, but their use is limited by potential adverse effects. In the pursuit of safer osteoporosis treatments, we investigated R25CPTH, a PTH variant wherein the native arginine at position 25 is substituted by cysteine. These studies were prompted by our finding of high bone mineral density in a hypoparathyroidism patient with the R25C homozygous mutation, and we explored its effects on PTH type-1 receptor (PTH1R) signaling in cells and bone metabolism in mice. Our findings indicate that R25CPTH(1-84) forms dimers both intracellularly and extracellularly, and the synthetic dimeric peptide, R25CPTH(1-34), exhibits altered activity in PTH1R-mediated cAMP response. Upon a single injection in mice, dimeric R25CPTH(1-34) induced acute calcemic and phosphaturic responses comparable to PTH(1-34). Furthermore, repeated daily injections increased calvarial bone thickness in intact mice and improved trabecular and cortical bone parameters in ovariectomized (OVX) mice, akin to PTH(1-34). The overall results reveal a capacity of a dimeric PTH peptide ligand to activate the PTH1R in vitro and in vivo as PTH, suggesting a potential path of therapeutic PTH analog development.

genomics↗