Structure, Functions, and Implications of Selected Lipocalins in Human Disease.

The lipocalin proteins are a large family of small extracellular proteins that demonstrate significant heterogeneity in sequence similarity and have highly conserved crystal structures. They have a variety of functions, including acting as carrier proteins, transporting retinol, participating in olfaction, and synthesizing prostaglandins. Importantly, they also play a critical role in human diseases, including cancer. Additionally, they are involved in regulating cellular homeostasis and immune response and dispensing various compounds. This comprehensive review provides information on the lipocalin family, including their structure, functions, and implications in various diseases. It focuses on selective important human lipocalin proteins, such as lipocalin 2 (LCN2), retinol binding protein 4 (RBP4), prostaglandin D2 synthase (PTGDS), and α1-microglobulin (A1M).

Astrocyte lipocalin-2 modestly effects disease severity in a mouse model of multiple sclerosis while reducing mature oligodendrocyte protein and mRNA expression.

Roles for lipocalin-2 (LCN2, also referred to as neutrophil gelatinase associated lipocalin, NGAL) in the progression of disease in multiple sclerosis and its animal models have been reported; however, the importance of astrocyte-derived LCN2, a major source of LCN2, have not been defined. We found that clinical scores in experimental autoimmune encephalomyelitis (EAE) were modestly delayed in mice with conditional knockout of LCN2 from astrocytes, associated with a small decrease in astrocyte GFAP expression. Immunostaining and qPCR of spinal cord samples showed decreased oligodendrocyte proteolipid protein and transcription factor Olig2 expression, but no changes in PDGFRα expression. These results suggest astrocyte LCN2 contributes to early events in EAE and reduces damage to mature oligodendrocytes at later times.

A comparison of Illumina and PacBio methods to build tick salivary gland transcriptomes confirms large expression of lipocalins and other salivary protein families that are not represented in available tick genomes.

Tick saliva helps blood feeding by its antihemostatic and immunomodulatory activities. Tick salivary gland transcriptomes (sialotranscriptomes) revealed thousands of transcripts coding for putative secreted polypeptides. Hundreds of these transcripts code for groups of similar proteins, constituting protein families, such as the lipocalins and metalloproteases. However, while many of these transcriptome-derived protein sequences matches sequences predicted by tick genome assemblies, the majority are not represented in these proteomes. The diversity of these transcriptome-derived transcripts could derive from artifacts generated during assembly of short Illumina reads or derive from polymorphisms of the genes coding for these proteins. To investigate this discrepancy, we collected salivary glands from blood-feeding ticks and, from the same homogenate, made and sequenced libraries following Illumina and PacBio protocols, with the assumption that the longer PacBio reads would reveal the sequences generated by the assembly of Illumina reads. Using both Rhipicephalus zambeziensis and Ixodes scapularis ticks, we have obtained more lipocalin transcripts from the Illumina library than the PacBio library. To verify whether these unique Illumina transcripts were real, we selected 9 uniquely Illumina-derived lipocalin transcripts from I. scapularis and attempted to obtain PCR products. These were obtained and their sequences confirmed the presence of these transcripts in the I. scapularis salivary homogenate. We further compared the predicted salivary lipocalins and metalloproteases from I. scapularis sialotranscriptomes with those found in the predicted proteomes of 3 publicly available genomes of I. scapularis. Results indicate that the discrepancy between the genome and transcriptome sequences for these salivary protein families is due to a high degree of polymorphism within these genes.

Reduced secretion of LCN2 (lipocalin 2) from reactive astrocytes through autophagic and proteasomal regulation alleviates inflammatory stress and neuronal damage.

LCN2/neutrophil gelatinase-associated lipocalin/24p3 (lipocalin 2) is a secretory protein that acts as a mammalian bacteriostatic molecule. Under neuroinflammatory stress conditions, LCN2 is produced and secreted by activated microglia and reactive astrocytes, resulting in neuronal apoptosis. However, it remains largely unknown whether inflammatory stress and neuronal loss can be minimized by modulating LCN2 production and secretion. Here, we first demonstrated that LCN2 was secreted from reactive astrocytes, which were stimulated by treatment with lipopolysaccharide (LPS) as an inflammatory stressor. Notably, we found two effective conditions that led to the reduction of induced LCN2 levels in reactive astrocytes: proteasome inhibition and macroautophagic/autophagic flux activation. Mechanistically, proteasome inhibition suppresses NFKB/NF-κB activation through NFKBIA/IκBα stabilization in primary astrocytes, even under inflammatory stress conditions, resulting in the downregulation of Lcn2 expression. In contrast, autophagic flux activation via MTOR inhibition reduced the intracellular levels of LCN2 through its pre-secretory degradation. In addition, we demonstrated that the N-terminal signal peptide of LCN2 is critical for its secretion and degradation, suggesting that these two pathways may be mechanistically coupled. Finally, we observed that LPS-induced and secreted LCN2 levels were reduced in the astrocyte-cultured medium under the above-mentioned conditions, resulting in increased neuronal viability, even under inflammatory stress.Abbreviations: ACM, astrocyte-conditioned medium; ALP, autophagy-lysosome pathway; BAF, bafilomycin A1; BTZ, bortezomib; CHX, cycloheximide; CNS, central nervous system; ER, endoplasmic reticulum; GFAP, glial fibrillary acidic protein; GFP, green fluorescent protein; JAK, Janus kinase; KD, knockdown; LCN2, lipocalin 2; LPS, lipopolysaccharide; MACS, magnetic-activated cell sorting; MAP1LC3/LC3, microtubule-associated protein 1 light chain 3; MTOR, mechanistic target of rapamycin kinase; NFKB/NF-κB, nuclear factor of kappa light polypeptide gene enhancer in B cells 1, p105; NFKBIA/IκBα, nuclear factor of kappa light polypeptide gene enhancer in B cells inhibitor, alpha; OVEX, overexpression; SLC22A17, solute carrier family 22 member 17; SP, signal peptide; SQSTM1, sequestosome 1; STAT3, signal transducer and activator of transcription 3; TNF/TNF-α, tumor necrosis factor; TUBA, tubulin, alpha; TUBB3/ß3-TUB, tubulin, beta 3 class III; UB, ubiquitin; UPS, ubiquitin-proteasome system.

Tumor-derived OBP2A promotes prostate cancer castration resistance.

Androgen deprivation therapy (ADT) is a systemic therapy for advanced prostate cancer (PCa); although most patients initially respond to ADT, almost all cancers eventually develop castration-resistant PCa (CRPC). Currently, most research focuses on castration-resistant tumors, and the role of tumors in remission is almost completely ignored. Here, we report that odorant-binding protein (OBP2A) released from tumors in remission during ADT catches survival factors, such as CXCL15/IL8, to promote PCa cell androgen-independent growth and enhance the infiltration of myeloid-derived suppressor cells (MDSCs) into tumor microenvironment, leading to the emergence of castration resistance. OBP2A knockdown significantly inhibits CRPC and metastatic CRPC development and improves therapeutic efficacy of CTLA-4/PD-1 antibodies. Treatment with OBP2A-binding ligand α-pinene interrupts the function of OBP2A and suppresses CRPC development. Furthermore, α-pinene-conjugated doxorubicin/docetaxel can be specifically delivered to tumors, resulting in improved anticancer efficacy. Thus, our studies establish a novel concept for the emergence of PCa castration resistance and provide new therapeutic strategies for advanced PCa.

Anti-inflammatory effects of the prostaglandin D2/prostaglandin DP1 receptor and lipocalin-type prostaglandin D2 synthase/prostaglandin D2 pathways in bacteria-induced bovine endometrial tissue.

Dairy cows often develop different degrees of endometritis after calving and this is attributed to pathogenic bacterial infections such as by Escherichia coli and Staphylococcus aureus. Infection of the bovine endometrium causes tissue damage and increases the expression of prostaglandin D2 (PGD2), which exerts anti-inflammatory effects on lung inflammation. However, the roles of PGD2 and its DP1 receptor in endometritis in cows remain unclear. Here, we examined the anti-inflammatory roles of the lipocalin-type prostaglandin D2 synthase (L-PGDS)/PGD2 and DP1 receptor regulatory pathways in bovine endometritis. We evaluated the regulatory effects of PGD2 on inflammation and tissue damage in E. coli- and S. aureus-infected bovine endometrial cells cultured in vitro. We found that the secretion of pro-inflammatory cytokines interleukin (IL)-6, IL-1ß, and tumour necrosis factor (TNF)-α as well as expression of matrix metalloproteinase (MMP)-2, platelet-activating factor receptor (PAFR), and high mobility group box (HMGB)-1 were suppressed after DP1 receptor agonist treatment. In contrast, IL-6, IL-1ß, and TNF-α release and MMP-2, PAFR, and HMGB-1 expression levels were increased after treatment of bovine endometrial tissue with DP1 receptor antagonists. DP1-induced anti-inflammatory effects were dependent on cellular signal transduction. The L-PGDS/PGD2 pathway and DP1 receptor induced anti-inflammatory effects in bovine endometrium infected with S. aureus and E. coli by inhibiting the mitogen-activated protein kinase and nuclear factor-κB signalling pathways, thereby reducing tissue damage. Overall, our findings provide important insights into the pathophysiological roles of PGD2 in bovine endometritis and establish a theoretical basis for applying prostaglandins or non-steroidal anti-inflammatory drugs for treating endometrial inflammatory infertility in bovines.

Down-regulated TINAGL1 in fibroblasts impairs wound healing in diabetes.

Matricellular proteins, a group of extracellular matrix (ECM) proteins, are key regulators of skin repair and their dysregulation impairs wound healing in diabetes. Tubulointerstitial nephritis antigen like 1 (TINAGL1) is a new member of matricellular protein family, and the understanding of its functional role is still relatively limited. In the current study, we detected the expression of TINAGL1 in diabetic skin wound tissues through RT-PCR, ELISA and Western blot analysis, investigated the contribution of TINAGL1 to wound healing through cutaneous administration of recombinant TINAGL1 protein, and characterized its regulation by hyperglycemia through RNA-seq and signal pathway inhibition assay. We showed that TINAGL1 expression has dynamic change and reaching a peak on day-9 after wound during the wound healing process in wild-type (WT) mice. Interestingly, decreased TINAGL1 expression is detected in skin tissues of diabetic patients and mice after wound. Then, we found that high glucose (HG), an important factor that impairs wound healing, reduces the expression of TINAGL1 in fibroblasts through JNK pathway. Notably, the histology analysis, Masson trichrome assay and IHC assay showed that exogenous TINAGL1 promotes wound healing in diabetic mice by accelerating the formation of granulation tissues. Our study provides evidence that TINAGL1 has an essential role in diabetic wound healing, and meanwhile, indicates that manipulation of TINAGL1 might be a possible therapeutic approach.

Glycoprotein PTGDS promotes tumorigenesis of diffuse large B-cell lymphoma by MYH9-mediated regulation of Wnt-ß-catenin-STAT3 signaling.

Glycoprotein prostaglandin D2 synthase (PTGDS) is a member of the lipocalin superfamily and plays dual roles in prostaglandins metabolism and lipid transport. PTGDS has been involved in various cellular processes including the tumorigenesis of solid tumors, yet its role in carcinogenesis is contradictory and the significance of PTGDS in hematological malignancies is ill-defined. Here, we aimed to explore the expression and function of PTGDS in diffuse large B-cell lymphoma (DLBCL), especially the potential role of PTGDS inhibitor, AT56, in lymphoma therapy. Remarkable high expression of PTGDS was found in DLBCL, which was significantly correlated with poor prognosis. PTGDS overexpression and rhPTGDS were found to promote cell proliferation. Besides, in vitro and in vivo studies indicated that PTGDS knockdown and AT56 treatment exerted an anti-tumor effect by regulating cell viability, proliferation, apoptosis, cell cycle, and invasion, and enhanced the drug sensitivity to adriamycin and bendamustine through promoting DNA damage. Moreover, the co-immunoprecipitation-based mass spectrum identified the interaction between PTGDS and MYH9, which was found to promote DLBCL progression. PTGDS inhibition led to reduced expression of MYH9, and then declined activation of the Wnt-ß-catenin-STAT3 pathway through influencing the ubiquitination and degradation of GSK3-ß in DLBCL. The rescue experiment demonstrated that PTGDS exerted an oncogenic role through regulating MYH9 and then the Wnt-ß-catenin-STAT3 pathway. Based on point mutation of glycosylation sites, we confirmed the N-glycosylation of PTGDS in Asn51 and Asn78 and found that abnormal glycosylation of PTGDS resulted in its nuclear translocation, prolonged half-life, and enhanced cell proliferation. Collectively, our findings identified for the first time that glycoprotein PTGDS promoted tumorigenesis of DLBCL through MYH9-mediated regulation of Wnt-ß-catenin-STAT3 signaling, and highlighted the potential role of AT56 as a novel therapeutic strategy for DLBCL treatment.

Lipocalin-type Prostaglandin D2 Synthase appears to function as a Novel Adipokine Preventing Adipose Dysfunction in response to a High Fat Diet.

Adipose dysfunction is the primary defect in obesity that contributes to the development of dyslipidemia, insulin resistance, cardiovascular diseases, type 2 diabetes, non-alcoholic fatty liver disease (NAFLD) and some cancers. Previously, we demonstrated the development of NAFLD in lipocalin-type prostaglandin D2 synthase (L-PGDS) knockout mice regardless of diet. In the present study, we examined the role of L-PGDS in adipose in response to a high fat diet. We observed decreased expression of L-PGDS in adipose tissue and concomitant lower plasma levels in a dietary model of obesity as well as in insulin resistant 3T3-L1 adipocytes. We show reduced adiponectin expression and phosphorylation of AMPK in white adipose tissue of L-PGDS KO mice after 14 weeks on a high fat diet as compared to control C57BL/6 mice. We also observe an increased fat content in L-PGDS KO mice as demonstrated by adipocyte hypertrophy and increased expression of lipogenenic genes. We confirmed our in vivo findings in in vitro 3T3-L1 adipocytes, using an enzymatic inhibitor of L-PGDS (AT56). Rosiglitazone treatment drastically increased L-PGDS expression in insulin resistant 3T3-L1 adipocytes and increased adiponectin expression and AMPK phosphorylation in AT56 treated 3T3-L1 adipocytes. We conclude that the absence of L-PGDS has a deleterious effect on adipose tissue functioning, which further reduces insulin sensitivity in adipose tissue. Consequently, we propose L-PGDS appears to function as a potential member of the adipokine secretome involved in the regulation of the obesity-associated metabolic syndrome.

Tinagl1 Gene Therapy Suppresses Growth and Remodels the Microenvironment of Triple Negative Breast Cancer.

Triple negative breast cancer (TNBC) remains one of the most challenging subtypes of breast cancer to treat and is responsible for approximately 12% of breast cancer cases in the US per year. In 2019, the protein Tinagl1 was identified as a key factor for improved prognoses in certain TNBC patients. While the intracellular mechanism of action has been thoroughly studied, little is known about the role of Tinagl1 in the tumor microenvironment. In this study, we developed a lipid nanoparticle-based gene therapy to directly target the expression of Tinagl1 in tumor cells for localized expression. Additionally, we sought to characterize the changes to the tumor microenvironment induced by Tinagl1 treatment, with the goal of informing future choices for combination therapies including Tinagl1. We found that Tinagl1 gene therapy was able to slow tumor growth from the first dose and that the effects held steady for nearly a week following the final dose. No toxicity was found with this treatment. Additionally, the use of Tinagl1 increases the tumor vasculature by 3-fold but does not increase the tumor permeability or risk of metastasis. However, the increase in vasculature arising from Tinagl1 therapy reduced the expression of Hif1a significantly (p < 0.01), which may decrease the risk of drug resistance.

A cell-specific regulatory region of the human ABO blood group gene regulates the neighborhood gene encoding odorant binding protein 2B.

The human ABO blood group system is of great importance in blood transfusion and organ transplantation. ABO transcription is known to be regulated by a constitutive promoter in a CpG island and regions for regulation of cell-specific expression such as the downstream + 22.6-kb site for epithelial cells and a site in intron 1 for erythroid cells. Here we investigated whether the + 22.6-kb site might play a role in transcriptional regulation of the gene encoding odorant binding protein 2B (OBP2B), which is located on the centromere side 43.4 kb from the + 22.6-kb site. In the gastric cancer cell line KATOIII, quantitative PCR analysis demonstrated significantly reduced amounts of OBP2B and ABO transcripts in mutant cells with biallelic deletions of the site created using the CRISPR/Cas9 system, relative to those in the wild-type cells, and Western blotting demonstrated a corresponding reduction of OBP2B protein in the mutant cells. Moreover, single-molecule fluorescence in situ hybridization assays indicated that the amounts of both transcripts were correlated in individual cells. These findings suggest that OBP2B could be co-regulated by the + 22.6-kb site of ABO.

Changes of Taste, Smell and Eating Behavior in Patients Undergoing Bariatric Surgery: Associations with PROP Phenotypes and Polymorphisms in the Odorant-Binding Protein OBPIIa and CD36 Receptor Genes.

Bariatric surgery is the most effective long-term treatment for severe obesity and related comorbidities. Although patients who underwent bariatric surgery report changes of taste and smell perception, results from sensory studies are discrepant and limited. Here, we assessed taste and smell functions in 51 patients before, one month, and six months after undergoing bariatric surgery. We used taste strip tests to assess gustatory function (including sweetness, saltiness, sourness, umaminess, bitterness and oleic acid, a fatty stimulus), the "Sniffin' Sticks" test to assess olfactory identification and the 3-Factor Eating Questionnaire to assess eating behavior. We also explored associations between these phenotypes and flavor-related genes. Results showed an overall improvement in taste function (including increased sensitivity to oleic acid and the bitterness of 6-n-propylthiouracil (PROP)) and in olfactory function (which could be related to the increase in PROP and oleic acid sensitivity), an increase in cognitive restraint, and a decrease in disinhibition and hunger after bariatric surgery. These findings indicate that bariatric surgery can have a positive impact on olfactory and gustatory functions and eating behavior (with an important role of genetic factors, such PROP tasting), which in turn might contribute to the success of the intervention.

Upregulation of Tubulointerstitial nephritis antigen like 1 promotes gastric cancer growth and metastasis by regulating multiple matrix metallopeptidase expression.

BACKGROUND AND AIM: Tubulointerstitial nephritis antigen-like 1 (TINAGL1), as a novel matricellular protein, has been demonstrated to participate in cancer progression, whereas the potential function of TINAGL1 in gastric cancer (GC) remains unknown. METHODS: The expression pattern of TINAGL1 in GC was examined by immunohistochemistry, ELISA, real-time polymerase chain reaction, and Western blot. Correlation between TINAGL1 and matrix metalloproteinases (MMPs) was analyzed by the GEPIA website and Kaplan-Meier plots database. The lentivirus-based TINAGL1 knockdown, CCK-8, and transwell assays were used to test the function of TINAGL1 in vitro. The role of TINAGL1 was confirmed by subcutaneous xenograft, abdominal dissemination, and lung metastasis model. Microarray experiments, ELISA, real-time polymerase chain reaction, and Western blot were used to identify molecular mechanism. RESULTS: TINAGL1 was increased in GC tumor tissues and associated with poor patient survival. Moreover, TINAGL1 significantly promoted GC cell proliferation and migration in vitro as well as facilitated GC tumor growth and metastasis in vivo. TINAGL1 expression in GC cells was accompanied with increasing MMPs including MMP2, MMP9, MMP11, MMP14, and MMP16. GEPIA database revealed that these MMPs were correlated with TINAGL1 in GC tumors and that the most highly expressed MMP was MMP2. Mechanically, TINAGL1 regulated MMP2 through the JNK signaling pathway activation. CONCLUSIONS: Our data highlight that TINAGL1 promotes GC growth and metastasis and regulates MMP2 expression, indicating that TINAGL1 may serve as a therapeutic target for GC.

YAP promotes self-renewal of gastric cancer cells by inhibiting expression of L-PTGDS and PTGDR2.

INTRODUCTION: Cancer stem cells have been implicated angiogenesis of tumor and invasiveness, drug resistance in tumors. Yes-associated protein 1 (YAP) owns carcinogenic roles in various organs, but the role of YAP in cancer stem cells of gastric cancer (GC) remains unclear. In this study, we explored the function and mechanism of YAP in GC cancer stem cells. MATERIALS AND METHODS, AND RESULTS: First, we confirmed that the expression of YAP mRNA and protein in GC tissues was higher than in adjacent tissues by RT-PCR, western blot and immunohistochemistry. Immunofluorescence staining of the GC tissues revealed that the region of YAP expression coincided with the region of expression of the cancer stem cell marker SALL4 but did not overlap with that of the epithelial marker cytokeratin 14 (CK14). Additional research revealed that spherical cells expressed relatively high levels of YAP protein, and YAP overexpression reinforced self-renewal and expression of stem cell markers in the GC cells. Knockdown the expression of YAP reversed this phenomenon. Second, we examined the expression patterns of lipocalin-type prostaglandin D2 synthase (L-PTGDS) and prostaglandin D2 receptor 2 (PTGDR2) in GC tissues and proved that there was negatively correlation between the expression of L-PTGDS and PTGDR2 and YAP in GC tissues. Finally, we confirmed that YAP inhibited the expression of L-PTGDS and PTGDR2 by gain- and loss-of-function experiments. Moreover, the overexpression of L-PTGDS and PTGDR2 suppressed the proliferation and self-renewal induced by YAP in vitro and reversed the pro-tumor effect of YAP in vivo. CONCLUSION: Our results revealed a novel function of YAP and the mechanism underlying cancer stem cell regulation by YAP.

Role of Lipocalin-Type Prostaglandin D Synthase in Experimental Osteoarthritis.

OBJECTIVE: Lipocalin-type prostaglandin D synthase (L-PGDS) catalyzes the formation of prostaglandin D2 (PGD2 ), which has important roles in inflammation and cartilage metabolism. We undertook this study to investigate the role of L-PGDS in the pathogenesis of osteoarthritis (OA) using an experimental mouse model. METHODS: Experimental OA was induced in wild-type (WT) and L-PGDS-deficient (L-PGDS-/- ) mice (n = 10 per genotype) by destabilization of the medial meniscus (DMM). Cartilage degradation was evaluated by histology. The expression of matrix metalloproteinase 13 (MMP-13) and ADAMTS-5 was assessed by immunohistochemistry. Bone changes were determined by micro-computed tomography. Cartilage explants from L-PGDS-/- and WT mice (n = 6 per genotype) were treated with interleukin-1α (IL-1α) ex vivo in order to evaluate proteoglycan degradation. Moreover, the effect of intraarticular injection of a recombinant adeno-associated virus type 2/5 (rAAV2/5) encoding L-PGDS on OA progression was evaluated in WT mice (n = 9 per group). RESULTS: Compared to WT mice, L-PGDS-/- mice had exacerbated cartilage degradation and enhanced expression of MMP-13 and ADAMTS-5 (P < 0.05). Furthermore, L-PGDS-/- mice displayed increased synovitis and subchondral bone changes (P < 0.05). Cartilage explants from L-PGDS-/- mice showed enhanced proteoglycan degradation following treatment with IL-1α (P < 0.05). Intraarticular injection of rAAV2/5 encoding L-PGDS attenuated the severity of DMM-induced OA-like changes in WT mice (P < 0.05). The L-PGDS level was increased in OA tissues of WT mice (P < 0.05). CONCLUSION: Collectively, these findings suggest a protective role of L-PGDS in OA, and therefore enhancing levels of L-PGDS may constitute a promising therapeutic strategy.

Lipocalin-type prostaglandin D2 synthase deletion induces dyslipidemia and non-alcoholic fatty liver disease.

Non-alcoholic fatty liver disease (NAFLD) is an emerging risk factor for type 2 diabetes mellitus, cardiovascular disease, and all-cause mortality. Previously, we demonstrated that lipocalin-type prostaglandin D2 synthase (L-PGDS) knockout mice show increased glucose intolerance and accelerated atherosclerosis. In the present study, we investigated the role of L-PGDS in mediating NAFLD utilizing L-PGDS knockout (KO) and control C57BL/6 mice fed either low fat (LFD) or high fat diet (HFD) for 14 weeks. Our present study demonstrates that L-PGDS KO mice remain slightly lighter in weight compared to control mice, yet develop NAFLD faster and eventually progress to the more severe non-alcoholic steatohepatitis (NASH). We found increased lipid accumulation in the liver of KO mice over time on both diets, as compared to control mice. The L-PGDS KO mice showed elevated fasting glucose and insulin levels and developed insulin resistance on both LFD and HFD. Lipogenesis marker proteins such as SREBP-1c and LXRα were increased in L-PGDS KO mice after 14 weeks on both diets, when compared to control mice. We replicated our in vivo findings in vitro using HepG2 cells treated with a combination of free fatty acids (oleic and palmitic acid) and exposure to a L-PGDS inhibitor and prostaglandin D2 receptor (DP1) antagonists. We conclude that the absence or inhibition of L-PGDS results in dyslipidemia, altered expression of lipogenesis genes and the acceleration of NAFLD to NASH, independent of diet and obesity. We propose L-PGDS KO mice as a useful model to explore the pathogenesis of NAFLD and NASH, and L-PGDS as a potential therapeutic target for treatment.

Delay in hepatocyte proliferation and prostaglandin D2 synthase expression for cholestasis due to endotoxin during partial hepatectomy in rats.

Infection is a frequent complication of liver transplantation or partial hepatectomy (PH) and sometimes results in cholestasis. We examined factors involved in infection­induced cholestasis after PH, employing a rat PH model and lipopolysaccharide (LPS) as a bacterial toxin. Male Sprague­Dawley rats were subjected to 70% PH and/or LPS injection, and tissues were harvested at 0, 24, 72 and 168 h. Gene expression was analyzed by microarray analysis and reverse transcription­quantitative polymerase chain reaction, and protein levels and localization were analyzed by western blotting and immunohistochemistry, respectively. Plasma bile acid levels were significantly higher in the LPS + PH group than in the PH group. Ribonucleotide reductase regulatory subunit M2 and proliferating cell nuclear antigen peaked at 24 and 72 h in the PH group and LPS + PH group, respectively, indicating a delay in cell proliferation in the latter group. The sodium­dependent taurocholate cotransporting polypeptide and organic­anion­transporting polypeptide 1a1 and 1a2 were reduced in the PH group at 24 h, and were not further decreased in the LPS + PH group. Chemokine ligand 9 (Cxcl9), a chemokine involved in M2 macrophage polarization, increased after 24 h in the LPS and the LPS + PH groups. The number and shape of Cxcl9­positive cells were similar to CD163­positive cells, suggesting that such cells produced the chemokine. Hematopoietic prostaglandin D2 synthase (Ptgds2) was only detected in hepatocytes of the LPS + PH group exhibiting a delay in cell proliferation. Thus, Kupffer cells activated with LPS were suggested to be responsible for a delay in hepatocyte proliferation after PH.

LCN2-interacting proteins and their expression patterns in brain tumors.

Lipocalin 2 (LCN2) is a member of the lipocalin family. Elevated expression of LCN2 has been observed in many human tumors, suggesting it might be a potential biomarker and/or therapeutic target in malignancies. In this study, we aimed to explore LCN2 interacting proteins through bioinformatics, as well as their biological functions. Protein-protein interaction networks (PPIN) were constructed using LCN2 and its interacting proteins as the core node. These PPINs were scale free biological networks in which LCN2 and its interacting proteins could connect or cross-talk with at least one partner protein. Both functional and KEGG pathway enrichment analyses identified the known and potential biological functions of the PPIN, such as cell migration and cancer-related pathways. Expression levels of the PPIN proteins, as well as their expression correlations, in five types of brain tumor, were analyzed and integrated into the PPIN to illustrate a dynamic change. A significant correlation was found between the survival time of glioblastoma patients and the expression level of 10 genes (LCN2, MMP9, MMP2, PDE4DIP, L2HGDH, HNRNPA1, DDX31, LOXL2, FAM60A and RNF25). Taken together, our results suggest that LCN2 and its interacting proteins are mostly differentially expressed and have a distinguishing co-expression pattern. They might promote proliferation and migration via cell migration signaling and cancer-related pathways. LCN2 and its interacting proteins might be potential biomarkers in glioblastoma.

A Parkinson's disease gene, DJ-1, regulates anti-inflammatory roles of astrocytes through prostaglandin D2 synthase expression.

Dysfunctional regulation of inflammation may contribute to the progression of neurodegenerative diseases. The results of this study revealed that DJ-1, a Parkinson's disease (PD) gene, regulated expression of prostaglandin D2 synthase (PTGDS) and production of prostaglandin D2 (PGD2), by which DJ-1 enhanced anti-inflammatory function of astrocytes. In injured DJ-1 knockout (KO) brain, expression of tumor necrosis factor-alpha (TNF-α) was more increased, but that of anti-inflammatory heme oxygenase-1 (HO-1) was less increased compared with that in injured wild-type (WT) brain. Similarly, astrocyte-conditioned media (ACM) prepared from DJ-1-KO astrocytes less induced HO-1 expression and less inhibited expression of inflammatory mediators in microglia. With respect to the underlying mechanism, we found that PTGDS that induced expression of HO-1 was lower in DJ-1 KO astrocytes and brains compared with their WT counterparts. In addition, PTGDS levels increased in the injured brain of WT mice, but barely in that of KO mice. We also found that DJ-1 regulated PTGDS expression through Sox9. Thus, Sox9 siRNAs reduced PTGDS expression in WT astrocytes, and Sox9 overexpression rescued PTGDS expression in DJ-1 KO astrocytes. In agreement with these results, ACM from Sox9 siRNA-treated astrocytes and that from Sox9-overexpression astrocytes exerted opposite effects on HO-1 expression and anti-inflammation. These findings suggest that DJ-1 positively regulates anti-inflammatory functions of astrocytes, and that DJ-1 dysfunction contributes to the excessive inflammatory response in PD development.

Tinagl1 Suppresses Triple-Negative Breast Cancer Progression and Metastasis by Simultaneously Inhibiting Integrin/FAK and EGFR Signaling.

Triple-negative breast cancer (TNBC) patients have the worst prognosis and distant metastasis-free survival among all major subtypes of breast cancer. The poor clinical outlook is further exacerbated by a lack of effective targeted therapies for TNBC. Here we show that ectopic expression and therapeutic delivery of the secreted protein Tubulointerstitial nephritis antigen-like 1 (Tinagl1) suppresses TNBC progression and metastasis through direct binding to integrin α5ß1, αvß1, and epidermal growth factor receptor (EGFR), and subsequent simultaneous inhibition of focal adhesion kinase (FAK) and EGFR signaling pathways. Moreover, Tinagl1 protein level is associated with good prognosis and reversely correlates with FAK and EGFR activation status in TNBC. Our results suggest Tinagl1 as a candidate therapeutic agent for TNBC by dual inhibition of integrin/FAK and EGFR signaling pathways.