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Bone Research Jun 2024DNAX-associated protein 12 kD size (DAP12) is a dominant immunoreceptor tyrosine-based activation motif (ITAM)-signaling adaptor that activates costimulatory signals...
DNAX-associated protein 12 kD size (DAP12) is a dominant immunoreceptor tyrosine-based activation motif (ITAM)-signaling adaptor that activates costimulatory signals essential for osteoclastogenesis. Although several DAP12-associated receptors (DARs) have been identified in osteoclasts, including triggering receptor expressed on myeloid cells 2 (TREM-2), C-type lectin member 5 A (CLEC5A), and sialic acid-binding Ig-like lectin (Siglec)-15, their precise role in the development of osteoclasts and bone remodeling remain poorly understood. In this study, mice deficient in Trem-2, Clec5a, Siglec-15 were generated. In addition, mice double deficient in these DAR genes and FcεRI gamma chain (FcR)γ, an alternative ITAM adaptor to DAP12, were generated. Bone mass analysis was conducted on all mice. Notably, Siglec-15 deficient mice and Siglec-15/FcRγ double deficient mice exhibited mild and severe osteopetrosis respectively. In contrast, other DAR deficient mice showed normal bone phenotype. Likewise, osteoclasts from Siglec-15 deficient mice failed to form an actin ring, suggesting that Siglec-15 promotes bone resorption principally by modulating the cytoskeletal organization of osteoclasts. Furthermore, biochemical analysis revealed that Sigelc-15 activates macrophage colony-stimulating factor (M-CSF)-induced Ras-associated protein-1 (RAP1)/Ras-related C3 botulinum toxin substrate 1 (Rac1) pathway through formation of a complex with p130CAS and CrkII, leading to cytoskeletal remodeling of osteoclasts. Our data provide genetic and biochemical evidence that Siglec-15 facilitates M-CSF-induced cytoskeletal remodeling of the osteoclasts.
Topics: Animals; Osteoclasts; Signal Transduction; Macrophage Colony-Stimulating Factor; rap1 GTP-Binding Proteins; Mice; Cytoskeleton; Mice, Knockout; Mice, Inbred C57BL; Membrane Proteins; rac GTP-Binding Proteins; Membrane Glycoproteins; Receptors, Immunologic; Immunoglobulins
PubMed: 38849345
DOI: 10.1038/s41413-024-00340-w -
Scientific Reports Jun 2024The proteasome-associated deubiquitinase USP14 is a potential drug target. Using an inducible USP14 knockout system in colon cancer cells, we found that USP14 depletion...
The proteasome-associated deubiquitinase USP14 is a potential drug target. Using an inducible USP14 knockout system in colon cancer cells, we found that USP14 depletion impedes cellular proliferation, induces cell cycle arrest, and leads to a senescence-like phenotype. Transcriptomic analysis revealed altered gene expression related to cell division and cellular differentiation. USP14 knockout cells also exhibited changes in morphology, actin distribution, and expression of actin cytoskeletal components. Increased ubiquitin turnover was observed, offset by upregulation of polyubiquitin genes UBB and UBC. Pharmacological inhibition of USP14 with IU1 increased ubiquitin turnover but did not affect cellular growth or morphology. BioGRID data identified USP14 interactors linked to actin cytoskeleton remodeling, DNA damage repair, mRNA splicing, and translation. In conclusion, USP14 loss in colon cancer cells induces a transient quiescent cancer phenotype not replicated by pharmacologic inhibition of its deubiquitinating activity.
Topics: Humans; Cellular Senescence; Colorectal Neoplasms; Cell Proliferation; Ubiquitin Thiolesterase; Cell Line, Tumor; Phenotype; Proteasome Endopeptidase Complex; Cell Cycle Checkpoints; Gene Expression Regulation, Neoplastic; Ubiquitin
PubMed: 38844605
DOI: 10.1038/s41598-024-63791-5 -
Biophysics Reviews Jun 2024Cell migration is a fundamental process for life and is highly dependent on the dynamical and mechanical properties of the cytoskeleton. Intensive physical and... (Review)
Review
Cell migration is a fundamental process for life and is highly dependent on the dynamical and mechanical properties of the cytoskeleton. Intensive physical and biochemical crosstalk among actin, microtubules, and intermediate filaments ensures their coordination to facilitate and enable migration. In this review, we discuss the different mechanical aspects that govern cell migration and provide, for each mechanical aspect, a novel perspective by juxtaposing two complementary approaches to the biophysical study of cytoskeletal crosstalk: live-cell studies (often referred to as top-down studies) and cell-free studies (often referred to as bottom-up studies). We summarize the main findings from both experimental approaches, and we provide our perspective on bridging the two perspectives to address the open questions of how cytoskeletal crosstalk governs cell migration and makes cells move.
PubMed: 38840976
DOI: 10.1063/5.0198119 -
Proceedings of the National Academy of... Jun 2024O-GlcNAcase (OGA) is the only human enzyme that catalyzes the hydrolysis (deglycosylation) of O-linked beta--acetylglucosaminylation (O-GlcNAcylation) from numerous...
O-GlcNAcase (OGA) is the only human enzyme that catalyzes the hydrolysis (deglycosylation) of O-linked beta--acetylglucosaminylation (O-GlcNAcylation) from numerous protein substrates. OGA has broad implications in many challenging diseases including cancer. However, its role in cell malignancy remains mostly unclear. Here, we report that a cancer-derived point mutation on the OGA's noncatalytic stalk domain aberrantly modulates OGA interactome and substrate deglycosylation toward a specific set of proteins. Interestingly, our quantitative proteomic studies uncovered that the OGA stalk domain mutant preferentially deglycosylated protein substrates with +2 proline in the sequence relative to the O-GlcNAcylation site. One of the most dysregulated substrates is PDZ and LIM domain protein 7 (PDLIM7), which is associated with the tumor suppressor p53. We found that the aberrantly deglycosylated PDLIM7 suppressed p53 gene expression and accelerated p53 protein degradation by promoting the complex formation with E3 ubiquitin ligase MDM2. Moreover, deglycosylated PDLIM7 significantly up-regulated the actin-rich membrane protrusions on the cell surface, augmenting the cancer cell motility and aggressiveness. These findings revealed an important but previously unappreciated role of OGA's stalk domain in protein substrate recognition and functional modulation during malignant cell progression.
Topics: Humans; Tumor Suppressor Protein p53; LIM Domain Proteins; Cytoskeleton; Acetylglucosamine; Neoplasms; Cell Line, Tumor; Glycosylation; Hydrolysis; Mutation; Cell Movement; Antigens, Neoplasm; Hyaluronoglucosaminidase; Histone Acetyltransferases
PubMed: 38838015
DOI: 10.1073/pnas.2320867121 -
Langmuir : the ACS Journal of Surfaces... Jun 2024Actin, found in all eukaryotic cells as globular (G) or filamentous (F) actin, undergoes polymerization, with G-actin units changing shape to become F-actin. Thermal...
Actin, found in all eukaryotic cells as globular (G) or filamentous (F) actin, undergoes polymerization, with G-actin units changing shape to become F-actin. Thermal proteins, or proteinoids, are created by heating amino acids (160-200 °C), forming polymeric chains. These proteinoids can swell in an aqueous solution at around 50 °C, producing hollow microspheres filled with a solution, exhibiting voltage spikes. Our research explores the signaling properties of proteinoids, actin filaments, and hybrid networks combining actin and proteinoids. Proteinoids replicate brain excitation dynamics despite lacking specific membranes or ion channels. We investigate enhancing conductivity and spiking by using pure actin, yielding improved coordination in networks compared with individual filaments or proteinoids. Temperature changes (20 short-peptide supramolecular C to 80 °C) regulate conduction states, demonstrating external control over emergent excitability in protobrain systems. Adding actin to proteinoids reduces spike timing variability, providing a more uniform feature distribution. These findings support theoretical models proposing cytoskeletal matrices for functional specification in synthetic protocell brains, promoting stable interaction complexity. The study concludes that life-like signal encoding can emerge spontaneously within biological polymer scaffolds, incorporating abiotic chemistry.
Topics: Actin Cytoskeleton; Microspheres; Actins; Temperature; Animals
PubMed: 38837748
DOI: 10.1021/acs.langmuir.4c01107 -
Cellular and Molecular Life Sciences :... Jun 2024Contractile actomyosin bundles play crucial roles in various physiological processes, including cell migration, morphogenesis, and muscle contraction. The intricate...
Contractile actomyosin bundles play crucial roles in various physiological processes, including cell migration, morphogenesis, and muscle contraction. The intricate assembly of actomyosin bundles involves the precise alignment and fusion of myosin II filaments, yet the underlying mechanisms and factors involved in these processes remain elusive. Our study reveals that LUZP1 plays a central role in orchestrating the maturation of thick actomyosin bundles. Loss of LUZP1 caused abnormal cell morphogenesis, migration, and the ability to exert forces on the environment. Importantly, knockout of LUZP1 results in significant defects in the concatenation and persistent association of myosin II filaments, severely impairing the assembly of myosin II stacks. The disruption of these processes in LUZP1 knockout cells provides mechanistic insights into the defective assembly of thick ventral stress fibers and the associated cellular contractility abnormalities. Overall, these results significantly contribute to our understanding of the molecular mechanism involved in actomyosin bundle formation and highlight the essential role of LUZP1 in this process.
Topics: Actomyosin; Cell Movement; Humans; Muscle Contraction; Myosin Type II; Animals; Actin Cytoskeleton; Mice
PubMed: 38832964
DOI: 10.1007/s00018-024-05294-0 -
Archives of Toxicology Jun 2024Okadaic acid (OA), a prevalent marine biotoxin found in shellfish, is known for causing acute gastrointestinal symptoms. Despite its potential to reach the bloodstream...
Okadaic acid (OA), a prevalent marine biotoxin found in shellfish, is known for causing acute gastrointestinal symptoms. Despite its potential to reach the bloodstream and the liver, the hepatic effects of OA are not well understood, highlighting a significant research gap. This study aims to comprehensively elucidate the impact of OA on the liver by examining the transcriptome, proteome, and phosphoproteome alterations in human HepaRG liver cells exposed to non-cytotoxic OA concentrations. We employed an integrative multi-omics approach, encompassing RNA sequencing, shotgun proteomics, phosphoproteomics, and targeted DigiWest analysis. This enabled a detailed exploration of gene and protein expression changes, alongside phosphorylation patterns under OA treatment. The study reveals concentration- and time-dependent deregulation in gene and protein expression, with a significant down-regulation of xenobiotic and lipid metabolism pathways. Up-regulated pathways include actin crosslink formation and a deregulation of apoptotic pathways. Notably, our results revealed that OA, as a potent phosphatase inhibitor, induces alterations in actin filament organization. Phosphoproteomics data highlighted the importance of phosphorylation in enzyme activity regulation, particularly affecting proteins involved in the regulation of the cytoskeleton. OA's inhibition of PP2A further leads to various downstream effects, including alterations in protein translation and energy metabolism. This research expands the understanding of OA's systemic impact, emphasizing its role in modulating the phosphorylation landscape, which influences crucial cellular processes. The results underscore OA's multifaceted effects on the liver, particularly through PP2A inhibition, impacting xenobiotic metabolism, cytoskeletal dynamics, and energy homeostasis. These insights enhance our comprehension of OA's biological significance and potential health risks.
PubMed: 38832940
DOI: 10.1007/s00204-024-03796-1 -
Cardiovascular Research Jun 2024βII spectrin is a cytoskeletal protein known to be tightly linked to heart development and cardiovascular electrophysiology. However, the roles of βII spectrin in...
AIMS
βII spectrin is a cytoskeletal protein known to be tightly linked to heart development and cardiovascular electrophysiology. However, the roles of βII spectrin in cardiac contractile function and pathological post-myocardial infarction remodeling remain unclear. Here, we investigated whether and how βII spectrin, the most common isoform of non-erythrocytic spectrin in cardiomyocytes, is involved in cardiac contractile function and ischemia/reperfusion (I/R) injury.
METHODS AND RESULTS
We observed that the levels of serum βII spectrin breakdown products (βII SBDPs) were significantly increased in patients with acute myocardial infarction (AMI). Concordantly, βII spectrin was degraded into βII SBDPs by calpain in mouse hearts after I/R injury. Using tamoxifen-inducible cardiac-specific βII spectrin knockout mice, we found that deletion of βII spectrin in the adult heart resulted in spontaneous development of cardiac contractile dysfunction, cardiac hypertrophy and fibrosis at 5 weeks after tamoxifen treatment. Moreover, at 1 week after tamoxifen treatment, although spontaneous cardiac dysfunction in cardiac-specific βII spectrin knockout mice had not developed, deletion of βII spectrin in the heart exacerbated I/R-induced cardiomyocyte death and heart failure. Furthermore, restoration of βII spectrin expression via adenoviral small activating RNA (saRNA) delivery into the heart reduced I/R injury. Immunoprecipitation coupled with mass spectrometry (IP-LC-MS/MS) analyses and functional studies revealed that βII spectrin is indispensable for mitochondrial complex I activity and respiratory function. Mechanistically, βII spectrin promotes translocation of NADH:ubiquinone oxidoreductase 75 kDa Fe-S protein 1 (NDUFS1) from the cytosol to mitochondria by crosslinking with actin filaments (F-actin) to maintain F-actin stability.
CONCLUSION
βII spectrin is an essential cytoskeletal element for preserving mitochondrial homeostasis and cardiac function. Defects in βII spectrin exacerbate cardiac I/R injury.
PubMed: 38832923
DOI: 10.1093/cvr/cvae116 -
Biology of Reproduction Jun 2024Forkhead box L2 (FOXL2) is an indispensable key regulator of female follicular development, and it plays important roles in the morphogenesis, proliferation, and...
Forkhead box L2 (FOXL2) is an indispensable key regulator of female follicular development, and it plays important roles in the morphogenesis, proliferation, and differentiation of follicle granulosa cells (GCs), such as establishing normal estradiol signaling and regulating steroid hormone synthesis. Nevertheless, the effects of FOXL2 on GC morphology and the underlying mechanism remain unknown. Using FOXL2 ChIP-seq analysis, we found that FOXL2 target genes significantly enriched in the actin cytoskeleton-related pathways. We confirmed that FOXL2 inhibited the expression of RhoA, a key gene for actin cytoskeleton rearrangement, by binding to TCATCCATCTCT in RhoA promoter region. In addition, the overexpression of FOXL2 in GCs induced the depolymerization of F-actin and the disordered of the actin filaments, resulting in a slowdown in the expansion of GCs, while silencing FOXL2 inhibited F-actin depolymerization and stabilized the actin filaments, thereby accelerating GC expansion. RhoA/ROCK pathway inhibitor Y-27632 exhibited similar effects to FOXL2 overexpression, even reversed the actin polymerization in FOXL2 silencing GCs. This study revealed for the first time that FOXL2 regulated GC actin cytoskeleton by RhoA/ROCK pathway, thus affecting GC expansion. Our findings provide new insights for constructing the regulatory network of FOXL2 and propose a potential mechanism for facilitating rapid follicle expansion, thereby laying a foundation for further understanding follicular development.
PubMed: 38832713
DOI: 10.1093/biolre/ioae082 -
Journal of Cell Science Jun 2024Division plane positioning is crucial for proper growth and development in many organisms. In plants, the division plane is established before mitosis, by accumulation...
Division plane positioning is crucial for proper growth and development in many organisms. In plants, the division plane is established before mitosis, by accumulation of a cytoskeletal structure called the preprophase band (PPB). The PPB is thought to be essential for recruitment of division site-localized proteins, which remain at the division site after the PPB disassembles. Here, we show that the division site-localized protein TANGLED1 (TAN1) is recruited independently of the PPB to the cell cortex by the plant cytokinetic machinery, the phragmoplast, from experiments using both the PPB-defective mutant discordia1 (dcd1) and chemical treatments that disrupt the phragmoplast in maize. TAN1 recruitment to de novo sites on the cortex is partially dependent on intact actin filaments and the myosin XI motor protein OPAQUE1 (O1). These data imply a yet unknown role for TAN1 and possibly other division site-localized proteins during the last stages of cell division when the phragmoplast touches the cell cortex to complete cytokinesis.
Topics: Zea mays; Plant Proteins; Cytokinesis; Actin Cytoskeleton
PubMed: 38832513
DOI: 10.1242/jcs.262097