Bone-resorbing osteoclasts (OCLs) are formed by differentiation and fusion of monocyte precursor cells, generating large multi-nucleated cells. Tightly-regulated cell fusion during osteoclastogenesis leads to formation of resorption-competent OCLs, whose sizes fall within a predictable physiological range. The molecular mechanisms that regulate the onset of OCL fusion and its subsequent arrest are, however, largely unknown. We have previously shown that OCLs cultured from mice homozygous for the R51Q mutation in the vesicle trafficking-associated protein sorting nexin 10, a mutation that induces autosomal recessive osteopetrosis in humans and in mice, display deregulated and continuous fusion that generates gigantic, inactive OCLs. Fusion of mature OCLs is therefore arrested by an active, genetically-encoded, cell-autonomous, and SNX10-dependent mechanism. In order to directly examine whether SNX10 performs a similar role in vivo, we generated SNX10-deficient (SKO) mice and demonstrated that they display massive osteopetrosis and that their OCLs fuse uncontrollably in culture, as do homozygous R51Q SNX10 (RQ/RQ) mice. OCLs that lack SNX10 exhibit persistent presence of DC-STAMP protein at their periphery, which may contribute to their uncontrolled fusion. In order to visualize endogenous SNX10-mutant OCLs in their native bone environment we genetically labelled the OCLs of wild-type, SKO and RQ/RQ mice with EGFP, and then visualized the three-dimensional organization of resident OCLs and the pericellular bone matrix by two-photon, confocal, and second harmonics generation microscopy. We show that the volumes, surface areas and, in particular, the numbers of nuclei in the OCLs of both mutant strains were on average 2-6 fold larger than those of OCLs from wild-type mice, indicating that deregulated, excessive fusion occurs in the mutant mice. We conclude that the fusion of OCLs, and consequently their size, are regulated in vivo by SNX10-dependent arrest of fusion of mature OCLs.
Osteoclasts (OCLs) are cells that degrade bone. These cells are generated by fusion of monocyte precursor cells, but the mechanisms that regulate this process and eventually arrest it are unknown. We had previously shown that OCLs cultured from mice carrying the R51Q mutation in the protein sorting nexin 10 (SNX10) lose their resorptive capacity and become gigantic due to uncontrolled fusion. To examine whether SNX10 is required for OCL fusion arrest also in vivo, we inactivated the Snx10 gene in mice and fluorescently labelled their OCLs and OCLs of R51Q SNX10 mice, isolated their femurs, and used advanced 3D microscopy methods to visualize OCLs within the bone matrix. As expected, mice lacking SNX10 exhibited excessive bone mass, indicating that their OCLs are inactive. OCLs within bones of both mutant mouse strains were on average 2-6-fold larger than in control mice, and contained proportionally more nuclei. We conclude that OCL fusion is arrested in control, but not SNX10 mutant, mice, indicating that the sizes of mature OCLs are limited in vivo by an active, SNX10-dependent mechanism that suppresses cell fusion.

BACKGROUND: Liver ischemia reperfusion (IR) injury is a common cause of liver dysfunction in patients post liver partial resection and liver transplantation. However, the cellular defense mechanisms underlying IR are not well understood. Macrophage mediated sterile inflammation plays critical roles in liver IR injury. Sorting nexin (SNX) 10, a member of the SNX family which functions in regulation of endosomal sorting. This study aimed to explore the role of sorting nexin 10 (SNX10) during liver IR injury with a focus on regulating macrophage function.
METHODS: Both the gene and protein expression levels of SNX10 were analyzed in human specimens from 10 patients undergoing liver partial resection with ischemic insult and in a mouse model of liver IR. The in vivo effects of SNX10 in liver IR injury and sterile inflammation in mice were investigated. Bone marrow derived macrophages (BMDMs) were used to determine the role of SNX10 in modulating macrophage function in vitro.
RESULTS: Increased expression of SNX10 was observed both in human specimens and mice livers post IR. SNX10 knockdown alleviated IR induced sterile inflammation and liver damage in mice. SNX10 promoted M1 polarization of macrophage treated with LPS and facilitated inflammatory response by activating NLRP3 inflammasome.
CONCLUSIONS: We report for the first time that SNX10 is upregulated in IR-stressed livers. SNX10 activation aggravates liver IR injury and sterile inflammation by facilitating macrophage M1 polarization and inflammatory response suggesting SNX10 as a potential therapeutic target for liver IR injury.

BACKGROUND: Sorting nexin 10 (SNX10) has recently been identified as a critical regulator of colorectal carcinogenesis, whose deletion promoted cell proliferation and survival in human CRC cells, and promoted colorectal tumor growth and upregulated amino-acid metabolism in mice. However, what happens when silencing SNX10 in normal human intestinal epithelial cells (IECs) remains unknown, and no drugs targeting SNX10 have been reported. Here, we first investigated the biological function and underlying mechanisms of SNX10 in normal human IECs, and found that α-hederin, a pentacyclic triterpenoid saponin, has a regulatory effect on SNX10 expression.
OBJECTIVE: This study aimed to explore the function of SNX10 in IECs to provide a new target for the prevention and treatment of malignant transformation and the intervention mechanism of α-hederin for further development of potential novel agents targeting SNX10.
METHODS: The transfection approach was used to construct SNX10 stable knockdown cells. Cell proliferation was detected by CCK8, clone formation, EdU, flow cytometry, and wound healing assays. Enzyme activity assays for glucose metabolism, qRT-PCR, western blotting, and immunofluorescence staining were performed to investigate the protein expression of signaling pathways.
RESULTS: Silencing SNX10 promoted cell proliferation and cycle transition in IECs and increased the activity of key enzymes involved in glucose metabolism. Moreover, DEPDC5 expression was significantly decreased following SNX10 knockdown, followed by activation of the mTORC1 pathway. α-hederin reversed the accelerated cell proliferation, cycle progression, and glucose metabolic activity, as well as the activated mTORC1 pathway caused by SNX10 knockdown, by notably increasing SNX10 expression in a dose-dependent manner.
CONCLUSIONS: We first reported that knockdown of SNX10 in normal human IECs promoted cell proliferation and activated glucose metabolism by activating the mTORC1 pathway. Meanwhile, we first found that α-hederin down-regulated glucose metabolism activity and slowed cell proliferation by increasing SNX10 expression in IECs.

Erosive destruction of joint structures is an important event in the rheumatoid arthritis (RA) development where fibroblast-like synoviocytes (FLS) represent the main effectors. The implication of long noncoding RNAs (lncRNAs) in RA has not been clearly established. Here, we sought to assess the function of lncRNA H19 in RA by assessing its contribution to the phenotype of FLS. H19 was overexpressed in RA-FLS, and H19 promoted RA-FLS proliferation, invasion as well as angiogenesis and reduced RA-FLS apoptosis. Moreover, H19 loss significantly alleviated joint redness and swelling and reduced inflammatory response, synovial hyperplasia and cartilage damage in arthritic mice induced by collagen. Mechanistically, H19 significantly increased the transcription of sorting nexin (SNX) 10 in RA-FLS by promoting STAT1 translocation into the nucleus. Overexpression of SNX10 or STAT1 mitigated the repressing effects of H19 loss on RA in mice. Our findings highlight that H19 upregulation may result in the development of FLS-mediated RA via the STAT1/SNX10 axis. H19 might serve as a possible therapeutic target for RA treatment.

The clinical and radiological variability seen in different forms of osteopetrosis, all due to impaired osteoclastic bone resorption, reflect many causal genes. Both defective differentiation of osteoclasts from hematopoietic stem cells as well as disturbed functioning of osteoclasts can be the underlying pathogenic mechanism. Pathogenic variants in PLEKHM1 and SNX10 can be classified among the latter as they impair vesicular transport within the osteoclast and therefore result in the absence of a ruffled border. Some of the typical radiological hallmarks of osteopetrosis can be seen, and most cases present as a relatively mild form segregating in an autosomal recessive mode of inheritance.

Prior studies have noted the importance of microRNAs (miRNAs) in development and progression of osteosarcoma (OS), but the influence of miR-301b is less investigated. This investigation aimed to explore the biological role of miR-301b/SNX10 in OS. GSE28423 and GSE28424 arrays delivered the corresponding miR-301b and sorting nexin 10 (SNX10) expression levels in OS samples. miR-301b and SNX10 expressions were also measured by quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and western blotting in cells. Cell counting kit (CCK)-8 and transwell analysis were applied to measure cell characteristics. Luciferase reporter assay and Pearson correlation analysis were used to detect the relevance between miR-301b and SNX10. miR-301b was extremely increased in OS tissues compared with normal tissues, while SNX10 was decreased. The proliferation, invasion, and migration capabilities were limited following a low expression level of miR-301b whereas miR-301b overexpression promoted cellular malignant behaviors. miR-301b negatively targeted SNX10. The elevated SNX10 expression highlighted the inhibitory function on cell proliferation, migration, and invasion in OS cells treated by miR-301b inhibitor. Reduction of miR-301b induced the decrease of epithelial-mesenchymal transition (EMT)-related markers including N-cadherin, Vimentin, and matrix metallo-proteinase 9 (MMP)9. These results are added to the complete expanding field of the potential effects of miR-301b in OS cell malignant behaviors and demonstrate its promising role for further use to treat human OS.

Altered intestinal microbial composition promotes intestinal barrier dysfunction and triggers the initiation and recurrence of inflammatory bowel disease (IBD). Current treatments for IBD are focused on control of inflammation rather than on maintaining intestinal epithelial barrier function. Here, we show that the internalization of Gram-negative bacterial outer membrane vesicles (OMVs) in human intestinal epithelial cells promotes recruitment of caspase-5 and PIKfyve to early endosomal membranes via sorting nexin 10 (SNX10), resulting in LPS release from OMVs into the cytosol. Caspase-5 activated by cytosolic LPS leads to Lyn phosphorylation, which in turn promotes nuclear translocalization of Snail/Slug, downregulation of E-cadherin expression, and intestinal barrier dysfunction. SNX10 deletion or treatment with DC-SX029, a novel SNX10 inhibitor, rescues OMV-induced intestinal barrier dysfunction and ameliorates colitis in mice by blocking cytosolic LPS release, caspase-5 activation, and downstream signaling. Our results show that targeting SNX10 may be a new therapeutic approach for restoring intestinal epithelial barrier function and promising strategy for IBD treatment.

BACKGROUND: Cervical cancer (CC) is the primary cause of death in women. This study sought to investigate the potential mechanism and prognostic genes of CC.
METHODS: We downloaded four gene expression profiles from GEO. The RRA method was used to integrate and screen differentially expressed genes (DEGs) between CC and normal samples. Functional analysis was performed by clusterprofiler. We built PPI network by Search Tool for the Retrieval of Interacting Genes Database (STRING) and selected hub modules via Molecular COmplex Detection (MCODE). CMap database was used to find molecules with therapeutic potential for CC. The hub genes were validated in GEO datasets, Gene Expession Profiling Interactive Analysis (GEPIA), immunohistochemistry, Cox regression analysis, TCGA methylation analysis and ONCOMINE were carried out. ROC curve analysis and GSEA were also performed to describe the prognostic significance of hub genes.
RESULTS: Functional analysis revealed that 147 DEGs were significantly enriched in binding, cell proliferation, transcriptional activity and cell cycle regulation. PPI network screened 30 hub genes, with CDK1 having the strongest connectivity with CC. Cmap showed that apigenin, thioguanine and trichostatin A might be used to treat CC(P < 0.05). Eight genes (APOD, CXCL8, MMP1, MMP3, PLOD2, PTGDS, SNX10 and SPP1) were screened out through GEPIA. Of them, only PTGDS and SNX10 had not appeared in previous studies about CC. The validation in GEO showed that PTGDS showed low expression while SNX10 presented high expression in tumor tissues. Their expression profiles were consistent with the results in immunohistochemistry. ROC curve analysis indicated that the model had a good diagnostic efficiency (AUC = 0.738). GSEA analysis demonstrated that the two genes were correlated with the chemokine signaling pathway (P < 0.05). TCGA methylation analysis showed that patients with lowly-expressed and highly-methylated PTGDS had a worse prognosis than those with highly-expressed and lowly-methylated PTGDS (p = 0.037). Cox regression analysis showed that SNX10 and PTGDS were independent prognostic indicators for OS among CC patients (P = 0.007 and 0.003).
CONCLUSIONS: PTGDS and SNX10 showed abnormal expression and methylation in CC. Both genes might have high prognostic value of CC patients.

Bone homeostasis is a complex, multi-step process, which is based primarily on a tightly orchestrated interplay between bone formation and bone resorption that is executed by osteoblasts and osteoclasts (OCLs), respectively. The essential physiological balance between these cells is maintained and controlled at multiple levels, ranging from regulated gene expression to endocrine signals, yet the underlying cellular and molecular mechanisms are still poorly understood. One approach for deciphering the mechanisms that regulate bone homeostasis is the characterization of relevant pathological states in which this balance is disturbed. In this article we describe one such \"error of nature,\" namely the development of acute recessive osteopetrosis (ARO) in humans that is caused by mutations in sorting nexin 10 (SNX10) that affect OCL functioning. We hypothesize here that, by virtue of its specific roles in vesicular trafficking, SNX10 serves as a key selective regulator of the composition of diverse membrane compartments in OCLs, thereby affecting critical processes in the sequence of events that link the plasma membrane with formation of the ruffled border and with extracellular acidification. As a result, SNX10 determines multiple features of these cells either directly or, as in regulation of cell-cell fusion, indirectly. This hypothesis is further supported by the similarities between the cellular defects observed in OCLs form various models of ARO, induced by mutations in SNX10 and in other genes, which suggest that mutations in the known ARO-associated genes act by disrupting the same plasma membrane-to-ruffled border axis, albeit to different degrees. In this article, we describe the population genetics and spread of the original arginine-to-glutamine mutation at position 51 (R51Q) in SNX10 in the Palestinian community. We further review recent studies, conducted in animal and cellular model systems, that highlight the essential roles of SNX10 in critical membrane functions in OCLs, and discuss possible future research directions that are needed for challenging or substantiating our hypothesis.

Sorting nexin 10 (SNX10) has been reported as a critical regulator in macrophage function, and germline SNX10 knockout effectively alleviated mouse colitis. Here, we investigated the precise role of SNX10 in inflammatory responses in macrophages in mouse colitis, and explored the druggability of SNX10 as a therapeutic target for inflammatory bowel disease (IBD). Our results revealed that myeloid-specific SNX10 deletion alleviated inflammation and pathological damage induced by dextran sulfate sodium (DSS). In vitro experiments showed that SNX10 deletion contributed to inflammation elimination by inhibiting PIKfyve-mediated TANK-binding kinase 1 (TBK1) /c-Rel signaling activation. Further study provided rational mechanism that SNX10 was required for the recruitment of PIKfyve to the TRIF-positive endosomes, through which PIKfyve activated TBK1/c-Rel for LPS-induced inflammation response. Based on the structure of SNX10, we discovered a new small-molecule inhibitor DC-SX029, which targeted SNX10 to block the SNX10-PIKfyve interaction, thereby decreased the TBK1/c-Rel signaling activation. Additionally, therapeutic efficiency of DC-SX029 was evaluated in both DSS-induced and IL10-deficient mouse colitis models. Our data demonstrate a new mechanism by which SNX10-PIKfyve interaction regulates LPS-induced inflammation response in macrophages via the TBK1/c-Rel signaling pathway. In vivo and in vitro pharmacological studies of SNX10 protein-protein interaction (PPI) inhibitor DC-SX029 demonstrate the feasibility of targeting SNX10 in IBD treatment.