Actin-binding protein coronin 1A controls osteoclastic bone resorption by regulating lysosomal secretion of cathepsin K

The role and application of Coronin family in human tumorigenesis and immunomodulation

The Coronin family, a class of actin-binding proteins involved in the formation and maintenance of cytoskeleton structural stability, is aberrantly expressed in various tumors, including lung, gastric and head and neck cancers. They can regulate tumor cell metabolism and proliferation through RAC-1 and Wnt/β-Catenin signaling pathways and regulate invasion by influencing the PI3K, PAK4, and MT1-MMP signaling pathways and impacting the actin-network dynamics. In recent years, an increasing number of studies have highlighted the crucial roles of the cytoskeleton and immune modulation in the occurrence and development of tumors. The article delves into the Coronin family's pivotal role in tumor immune evasion, highlighting its modulation of neutrophil, T cell, and vesicular transport functions, as well as its interactions with tumorigenesis related organelles such as the endoplasmic reticulum, Golgi apparatus, mitochondria, and lysosomes. It also summarizes the potential therapeutic applications of the Coronin family in oncology. This review provides valuable insights into the mechanisms through which the Coronin family is implicated in the onset and progression of tumors. It also provides more theoretical foundation for tumor immunotherapy and combination drug therapy.

Cationic Hydroxyethyl Cellulose Nanocomplexes and RANK siRNA/Zoledronate Co-Delivery Systems for Osteoclast Inhibition

BACKGROUND/OBJECTIVES

In this study, HECP2k polymer, polyethylenimine2k (PEI2k)-modified hydroxyethyl cellulose (HEC) was utilized to form the nanocomplexes with receptor activator of nuclear factor k-B (RANK) siRNA and zoledronate (Zol) for osteoclast inhibition. HECP2k/(RANK siRNA + Zol) nanocomplexes prepared by simple mixing were anticipated to overcome the low transfection efficiency of siRNA and the low bioavailability of Zol.

METHODS

The characterization of both HECP2k/(pDNA + Zol) nanocomplexes and HECP2k/(RANK siRNA + Zol) nanocomplexes was performed.

RESULTS

The nanocomplexes were successfully formed even in the presence of Zol, showing about 200 nm sizes and about 20 mV of positive zeta potential values suitable for efficient cellular uptake. They also possessed high endosome buffering ability by PEI and Zol, suggesting the potential for efficient endosomal escape. It was found that the low cytotoxic nanocomplexes (>90% cell viability) displayed greater transfection efficiency than PEI25k and even HECP2k polyplexes. Finally, it was found by tartrate-resistant acid phosphatase (TRAP) assay and qPCR analysis that HECP2k/(RANK siRNA + Zol) nanocomplexes could inhibit the TRAP to about 50% value and another characteristic osteoclastic gene expression, increasing FAS gene expression to about 16 times higher than control and more efficiently (about 3 times and 5 times higher, respectively) than HECP2k/siRNA polyplexes and Zol only.

CONCLUSIONS

HECP2k/(RANK siRNA + Zol) nanocomplexes formed by simple mixing showed great potential for inhibiting osteoclast differentiation and osteoclast activity, inducing the apoptosis via combinatorial effects of RANK siRNA and Zol.

CREBH promotes autophagy to ameliorate NASH by regulating Coro1a

Dysfunctional autophagy aggravates oxidative stress and inflammation in hepatocytes and accelerates the progression of nonalcoholic steatohepatitis (NASH). Here, we demonstrated that cAMP-responsive element-binding protein H (CREBH) is a transcriptional regulator of hepatic autophagy in response to diet-induced NASH. The results showed that the upregulation of CREBH in lipid-overloaded hepatocytes improves cell damage, dysfunction of autophagic flux and associated abnormal accumulation of the autophagosome marker LC3-II and autophagic substrate p62. CREBH deficiency aggravated the dysfunctional autophagy and liver injury and even caused NASH-associated liver fibrosis. In addition, the changing trend of autolysosomes and lysosome membrane-associated protein (LAMP1) was consistent with the expression level of CREBH. This result indicated that CREBH might promote autophagic degradation by restoring the formation of autolysosomes, thereby improving the blocked autophagic flux. Moreover, we observed that CREBH inhibited the expression of Coronin 1a (Coro1a), an autophagosome-lysosome fusion-related gene, through transcriptional regulation. The overexpression of Coro1a in LO2 liver cells inhibited autophagic flux and elevated inflammatory cytokine levels upon palmitic acid (PA) stimulation. Overall, our findings provide new insights into the regulatory role of CREBH in the progression of NASH and reveal that Coro1a is a novel target gene of CREBH based on the autophagy pathway.

Gene expression in notochord and nuclei pulposi: a study of gene families across the chordate phylum

The transition from notochord to vertebral column is a crucial milestone in chordate evolution and in prenatal development of all vertebrates. As ossification of the vertebral bodies proceeds, involutions of residual notochord cells into the intervertebral discs form the nuclei pulposi, shock-absorbing structures that confer flexibility to the spine. Numerous studies have outlined the developmental and evolutionary relationship between notochord and nuclei pulposi. However, the knowledge of the similarities and differences in the genetic repertoires of these two structures remains limited, also because comparative studies of notochord and nuclei pulposi across chordates are complicated by the gene/genome duplication events that led to extant vertebrates. Here we show the results of a pilot study aimed at bridging the information on these two structures. We have followed in different vertebrates the evolutionary trajectory of notochord genes identified in the invertebrate chordate Ciona, and we have evaluated the extent of conservation of their expression in notochord cells. Our results have uncovered evolutionarily conserved markers of both notochord development and aging/degeneration of the nuclei pulposi.

Overview of multifunctional cysteinyl cathepsins in atherosclerosis-based cardiovascular disease: from insights into molecular functions to clinical implications

Cysteinyl cathepsins (CTSs) are widely known to have a proteolysis function that mediates recycling of unwanted proteins in endosomes and lysosomes, and investigation of CTSs has greatly improved with advances in live-imaging techniques both in vivo and in vitro, leading to three key findings. (1) CTSs are relocated from the lysosomes to other cellular spaces (i.e., cytosol, nucleus, nuclear membrane, plasma membrane, and extracellular milieu). (2) In addition to acidic cellular compartments, CTSs also exert biological activity in neutral environments. (3) CTSs also exert multiple nontraditional functions in, for example, extracellular matrix metabolism, cell signaling transduction, protein processing/trafficking, and cellular events. Various stimuli regulate the expression and activities of CTSs in vivo and vitro-e.g., inflammatory cytokines, oxidative stress, neurohormones, and growth factors. Accumulating evidence has confirmed the participation of CTSs in vascular diseases characterized by atherosclerosis, plaque rupture, thrombosis, calcification, aneurysm, restenosis/in-stent-restenosis, and neovasel formation. Circulating and tissue CTSs are promising as biomarkers and as a diagnostic imaging tool in patients with atherosclerosis-based cardiovascular disease (ACVD), and pharmacological interventions with their specific and non-specific inhibitors, and cardiovascular drugs might have potential for the therapeutic targeting of CTSs in animals. This review focuses on the update findings on CTS biology and the involvement of CTSs in the initiation and progression of ACVD and discusses the potential use of CTSs as biomarkers and small-molecule targets to prevent deleterious nontraditional functions in ACVD.

Coronin1C Is a GDP-Specific Rab44 Effector That Controls Osteoclast Formation by Regulating Cell Motility in Macrophages

Osteoclasts are multinucleated bone-resorbing cells that are formed by the fusion of macrophages. Recently, we identified Rab44, a large Rab GTPase, as an upregulated gene during osteoclast differentiation that negatively regulates osteoclast differentiation. However, the molecular mechanisms by which Rab44 negatively regulates osteoclast differentiation remain unknown. Here, we found that the GDP form of Rab44 interacted with the actin-binding protein, Coronin1C, in murine macrophages. Immunoprecipitation experiments revealed that the interaction of Rab44 and Coronin1C occurred in wild-type and a dominant-negative (DN) mutant of Rab44, but not in a constitutively active (CA) mutant of Rab44. Consistent with these findings, the expression of the CA mutant inhibited osteoclast differentiation, whereas that of the DN mutant enhanced this differentiation. Using a phase-contrast microscope, Coronin1C-knockdown osteoclasts apparently impaired multinuclear formation. Moreover, Coronin1C knockdown impaired the migration and chemotaxis of RAW-D macrophages. An in vivo experimental system demonstrated that Coronin1C knockdown suppresses osteoclastogenesis. Therefore, the decreased cell formation and fusion of Coronin1C-depleted osteoclasts might be due to the decreased migration of Coronin1C-knockdown macrophages. These results indicate that Coronin1C is a GDP-specific Rab44 effector that controls osteoclast formation by regulating cell motility in macrophages.

PMEPA1 and NEDD4 control the proton production of osteoclasts by regulating vesicular trafficking

Osteoclast bone resorption activity is critically regulated to maintain bone homeostasis. Osteoclasts resorb bone by producing protons and acid hydrolase via lysosomal secretion, however, a detailed mechanism remains elusive. PMEPA1 is a vesicular membrane protein, which binds to the NEDD4 family member of ubiquitin ligases. We have previously reported that Pmepa1 is highly expressed in bone resorbing osteoclasts, and regulates bone resorption. Here, we investigated the mechanism of bone resorption regulated by PMEPA1. Mutant mice lacking NEDD4-binding domains of PMEPA1 displayed enhanced bone volume, and reduced bone resorption activity in comparison with those of WT mice. Analysis with pH-sensitive fluorescence probe revealed that proton secretion from osteoclasts significantly decreased in Pmepa1 mutant osteoclasts. Immunofluorescence analysis revealed that PMEPA1 was colocalized with NEDD4, V0A3, and V0D2 subunits of vacuolar ATPase, which regulate the proton production of osteoclasts. In addition, Nedd4 knockdown reduced bone resorption and proton secretion of osteoclasts. Furthermore, Pmepa1 mutation and Nedd4 knockdown altered the cytoplasmic distribution of components of V-ATPase and expression of autophagy-related proteins, suggesting that lysosomal secretion is affected. Collectively, these findings indicate that PMEPA1 controls proton secretion from osteoclasts via NEDD4 by regulating vesicular trafficking, and NEDD4 is an important regulator of bone resorption.

Differential proteomic analysis of tibial subchondral bone from male and female guinea pigs with spontaneous osteoarthritis

A proteomic study on the tibial subchondral bone in guinea pigs with spontaneous osteoarthritis was performed to investigate the molecular alterations that occur in early osteoarthritis. A total of 132 healthy Hartley guinea pigs (aged 1 month; 66 female and 66 male) were randomly divided into 11 groups of six. Changes in articular cartilage and tibial subchondral bone were assessed using macroscopic examinations and micro-computed tomography. iTRAQ-integrated liquid chromatography-tandem mass spectrometry was used to identify differentially altered proteins in the tibial subchondral bone between 1- and 3-month-old guinea pigs, which were then validated using western blotting. A gradual progression of cartilage degeneration was observed in the knee joints of the subject animals from 5-11 months. With aging, the tibial subchondral trabecular bone acquired more plate-like and less anisotropic properties, with increased bone mineral density, bone volume, trabecular thickness and numbers. The proteomic study identified 138 and 113 proteins significantly differentially expressed between 3- and 1-month old guinea pigs in both the male and female animals, respectively. Western blotting confirmed the increased expression of osteoblast-associated protein S100 calcium-binding protein A8 (S100A8) and the deregulated expression of osteoclast-associated proteins coronin 1A (CORO1A) and T-cell immune regulator 1 (TCIRG1) in the 3-month old guinea pigs in comparison to the 1-month old guinea pigs. Spontaneous cartilage degeneration in the knee joints of male Hartley guinea pigs tended to be more serious compared with the females during the development of osteoarthritis. Together, the results suggest that osteoblast-associated protein S100A8 and osteoclast-associated proteins CORO1A and TCIRG1 are potentially key regulators of early osteoarthritic development in tibial subchondral bone.

Characterization of New Proteomic Biomarker Candidates in Mucopolysaccharidosis Type IVA

Mucopolysaccharidosis type IVA (MPS IVA) is a lysosomal storage disease caused by mutations in the N-acetylgalactosamine-6-sulfatase (GALNS) gene. Skeletal dysplasia and the related clinical features of MPS IVA are caused by disruption of the cartilage and its extracellular matrix, leading to a growth imbalance. Enzyme replacement therapy (ERT) with recombinant human GALNS has yielded positive results in activity of daily living and endurance tests. However, no data have demonstrated improvements in bone lesions and bone grow thin MPS IVA after ERT, and there is no correlation between therapeutic efficacy and urine levels of keratan sulfate, which accumulates in MPS IVA patients. Using qualitative and quantitative proteomics approaches, we analyzed leukocyte samples from healthy controls (n = 6) and from untreated (n = 5) and ERT-treated (n = 8, sampled before and after treatment) MPS IVA patients to identify potential biomarkers of disease. Out of 690 proteins identified in leukocytes, we selected a group of proteins that were dysregulated in MPS IVA patients with ERT. From these, we identified four potential protein biomarkers, all of which may influence bone and cartilage metabolism: lactotransferrin, coronin 1A, neutral alpha-glucosidase AB, and vitronectin. Further studies of cartilage and bone alterations in MPS IVA will be required to verify the validity of these proteins as potential biomarkers of MPS IVA.

Macrophages Switch to an Osteo-Modulatory Profile Upon RANKL Induction in a Medaka (Oryzias latipes) Osteoporosis Model

In mammals, osteoclasts differentiate from macrophages in the monocyte lineage. Although many factors driving osteoclast formation are known, the detailed processes underlying precursor recruitment, differentiation, and interaction of macrophages with other cell types involved in bone remodeling are poorly understood. Using live imaging in a transgenic medaka osteoporosis model, where ectopic osteoclasts are induced by RANKL expression, we show that a subset of macrophages is recruited to bone matrix to physically interact with bone-forming osteoblast progenitors. These macrophages subsequently differentiate into cathepsin K- (ctsk-) positive osteoclasts. One day later, other macrophages are recruited to clear dying osteoclasts from resorbed bone by phagocytosis. To better understand the molecular changes underlying these dynamic processes, we performed transcriptome profiling of activated macrophages upon RANKL induction. This revealed an upregulation of several bone-related transcripts. Besides osteoclast markers, we unexpectedly also found expression of osteoblast-promoting signals in activated macrophages, suggesting a possible non-cell autonomous role in osteogenesis. Finally, we show that macrophage differentiation into osteoclasts is dependent on inflammatory signals. Medaka deficient for TNFα or treated with the TNFα-inhibitor pentoxifylline exhibited impaired macrophage recruitment and osteoclast differentiation. These results show the involvement of inflammatory signals and the dynamics of a distinct subset of macrophages during osteoclast formation. © 2020 The Authors. JBMR Plus published by Wiley Periodicals LLC on behalf of American Society for Bone and Mineral Research.

Antiosteoclastic bone resorption activity of osteoprotegerin via enhanced AKT/mTOR/ULK1-mediated autophagic pathway

Autophagy plays a critical role in the maintenance of bone homeostasis. Osteoprotegerin (OPG) is an inhibitor of osteoclast-mediated bone resorption. However, whether autophagy is involved in the antiosteoclastogenic effects of OPG remains unclear. The present study aimed to investigate the potential mechanism of autophagy during OPG-induced bone resorption via inhibition of osteoclasts differentiated from bone marrow-derived macrophages in BALB/c mice. The results showed that after treatment with receptor activator of nuclear factor-κΒ ligand and macrophage colony-stimulating factor for 3 days, TRAP⁺ osteoclasts formed, representing the resting state of autophagy. These osteoclasts were treated with OPG and underwent autophagy, as demonstrated by LC3-II accumulation, acidic vesicular organelle formation, and the presence of autophagosomes. The levels of autophagy-related proteins, LC3-II increased and P62 decreased at 3 hr in OPG-treated osteoclasts. The viability, differentiation, and bone resorption activity of osteoclasts declined after OPG treatment. Treatment with OPG and chloroquine, an autophagy inhibitor, attenuated OPG-induced inhibition of osteoclastic bone resorption, whereas rapamycin (RAP), an autophagy inducer, enhanced OPG-induced inhibition of differentiation, survival, and bone resorption activity of osteoclasts. Furthermore, OPG reduced the amount of phosphorylated(p) protein kinase B (AKT) and pmTOR and increased the level of pULK, in a dose-dependant manner. LY294002, a phosphatidylinositol-4,5-bisphosphate 3-kinase (PI3K)/AKT pathway inhibitor, attenuated the decline in pAKT, but enhanced the decline in pmTOR and the increase in pULK1 following OPG treatment. RAP enhanced the OPG-induced increase in pULK1. The PI3K inhibitor 3-methyladenine partly blocked OPG-induced autophagy. Thus, the results revealed that OPG inhibits osteoclast bone resorption by inducing autophagy via the AKT/mTOR/ULK1 signaling pathway.