Nm23-H1 regulates glucose-stimulated insulin secretion in pancreatic β-cells via Arf6-Rac1 signaling axis

Integrated analysis of mRNAs and lncRNAs reveals candidate marker genes and potential hub lncRNAs associated with growth regulation of the Pacific Oyster, Crassostrea gigas

BACKGROUND

The Pacific oyster, Crassostrea gigas, is an economically important shellfish around the world. Great efforts have been made to improve its growth rate through genetic breeding. However, the candidate marker genes, pathways, and potential lncRNAs involved in oyster growth regulation remain largely unknown. To identify genes, lncRNAs, and pathways involved in growth regulation, C. gigas spat was cultured at a low temperature (15 ℃) to yield a growth-inhibited model, which was used to conduct comparative transcriptome analysis with spat cultured at normal temperature (25 ℃).

RESULTS

In total, 8627 differentially expressed genes (DEGs) and 1072 differentially expressed lncRNAs (DELs) were identified between the normal-growth oysters (cultured at 25 ℃, hereinafter referred to as NG) and slow-growth oysters (cultured at 15 ℃, hereinafter referred to as SG). Functional enrichment analysis showed that these DEGs were mostly enriched in the AMPK signaling pathway, MAPK signaling pathway, insulin signaling pathway, autophagy, apoptosis, calcium signaling pathway, and endocytosis process. LncRNAs analysis identified 265 cis-acting pairs and 618 trans-acting pairs that might participate in oyster growth regulation. The expression levels of LNC_001270, LNC_003322, LNC_011563, LNC_006260, and LNC_012905 were inducible to the culture temperature and food abundance. These lncRNAs were located at the antisense, upstream, or downstream of the SREBP1/p62, CDC42, CaM, FAS, and PIK3CA genes, respectively. Furthermore, the expression of the trans-acting lncRNAs, including XR_9000022.2, LNC_008019, LNC_015817, LNC_000838, LNC_00839, LNC_011859, LNC_007294, LNC_006429, XR_002198885.1, and XR_902224.2 was also significantly associated with the expression of genes enriched in AMPK signaling pathway, insulin signaling pathway, autophagy, apoptosis, calcium signaling pathway, and endocytosis process.

CONCLUSIONS

In this study, we identified the critical growth-related genes and lncRNAs that could be utilized as candidate markers to illustrate the molecular mechanisms underlying the growth regulation of Pacific oysters.

A Novel 5-Chloro-N-phenyl-1H-indole-2-carboxamide Derivative as Brain-Type Glycogen Phosphorylase Inhibitor: Validation of Target PYGB

Brain-type glycogen phosphorylase (PYGB) inhibitors are recognized as prospective drugs for treating ischemic brain injury. We previously reported compound 1 as a novel glycogen phosphorylase inhibitor with brain-protective properties. In this study, we validated whether PYGB could be used as the therapeutic target for hypoxic-ischemic diseases and investigated whether compound 1 exerts a protective effect against astrocyte hypoxia/reoxygenation (H/R) injury by targeting PYGB. A gene-silencing strategy was initially applied to downregulate PYGB proteins in mouse astrocytes, which was followed by a series of cellular experiments with compound 1. Next, we compared relevant indicators that could prove the protective effect of compound 1 on brain injury, finding that after PYGB knockdown, compound 1 could not obviously alleviate astrocytes H/R injury, as evidenced by cell viability, which was not significantly improved, and lactate dehydrogenase (LDH) leakage rate, intracellular glucose content, and post-ischemic reactive oxygen species (ROS) level, which were not remarkably reduced. At the same time, cellular energy metabolism did not improve, and the degree of extracellular acidification was not downregulated after administration of compound 1 after PYGB knockdown. In addition, it could neither significantly increase the level of mitochondrial aerobic energy metabolism nor inhibit the expression of apoptosis-associated proteins. The above results indicate that compound 1 could target PYGB to exert its protective effect against cellular H/R injury in mouse astrocytes. Simultaneously, we further demonstrated that PYGB could be an efficient therapeutic target for ischemic-hypoxic diseases. This study provides a new reference for further in-depth study of the action mechanism of the efficacy of compound 1.

A Novel 5-Chloro-N-phenyl-1H-indole-2-carboxamide Derivative as Brain-Type Glycogen Phosphorylase Inhibitor: Potential Therapeutic Effect on Cerebral Ischemia

Brain-type glycogen phosphorylase inhibitors are potential new drugs for treating ischemic brain injury. In our previous study, we reported compound 1 as a novel brain-type glycogen phosphorylase inhibitor with cardioprotective properties. We also found that compound 1 has high blood–brain barrier permeability through the ADMET prediction website. In this study, we deeply analyzed the protective effect of compound 1 on hypoxic-ischemic brain injury, finding that compound 1 could alleviate the hypoxia/reoxygenation (H/R) injury of astrocytes by improving cell viability and reducing LDH leakage rate, intracellular glucose content, and post-ischemic ROS level. At the same time, compound 1 could reduce the level of ATP in brain cells after ischemia, improve cellular energy metabolism, downregulate the degree of extracellular acidification, and improve metabolic acidosis. It could also increase the level of mitochondrial aerobic energy metabolism during brain cell reperfusion, reduce anaerobic glycolysis, and inhibit apoptosis and the expression of apoptosis-related proteins. The above results indicated that compound 1 is involved in the regulation of glucose metabolism, can control cell apoptosis, and has protective and potential therapeutic effects on cerebral ischemia-reperfusion injury, which provides a new reference and possibility for the development of novel drugs for the treatment of ischemic brain injury.

Heterozygous Nme7 Mutation Affects Glucose Tolerance in Male Rats

Complex metabolic conditions such as type 2 diabetes and obesity result from the interaction of numerous genetic and environmental factors. While the family of Nme proteins has been connected so far mostly to development, proliferation, or ciliary functions, several lines of evidence from human and experimental studies point to the potential involvement of one of its members, NME7 (non-metastatic cells 7, nucleoside diphosphate kinase 7) in carbohydrate and lipid metabolism. As a complete lack of Nme7 is semilethal in rats, we compared morphometric, metabolic, and transcriptomic profiles of standard diet-fed heterozygous Nme7+/− on male rats vs. their wild-type Nme7+/+ controls. Nme7+/− animals showed increased body weight, adiposity, higher insulin levels together with decreased glucose tolerance. Moreover, they displayed pancreatic islet fibrosis and kidney tubular damage. Despite no signs of overt liver steatosis or dyslipidemia, we found significant changes in the hepatic transcriptome of Nme7+/− male rats with a concerted increase of expression of lipogenic enzymes including Scd1, Fads1, Dhcr7 and a decrease of Cyp7b1 and Nme7. Network analyses suggested possible links between Nme7 and the activation of Srebf1 and Srebf2 upstream regulators. These results further support the implication of NME7 in the pathogenesis of glucose intolerance and adiposity.

Identification of Urinary Biomarkers for Exercise-Induced Immunosuppression by iTRAQ Proteomics

Purpose

To identify noninvasive immune biomarkers of exercise-induced immunosuppression using the iTRAQ proteomics technique.

Methods

Fifteen healthy males were recruited and subjected to a four-week incremental treadmill running training program. After each week of training, WBC counts and CD4⁺ and CD8⁺ lymphocytes were measured to monitor the immune function status. iTRAQ proteomics technology was used to identify differential proteins and their characteristics in urine.

Results

Our data showed that the WBC counts, CD4⁺ lymphocytes, and CD4⁺/CD8⁺ ratio decreased by more than 10% after four weeks of training, suggesting exercise-induced immunosuppression. A total of 1854 proteins were identified in urine during the incremental running using the iTRAQ technology. Compared with the urine before training, there were 89, 52, 77, and 148 proteins significantly upregulated and 66, 27, 68, and 114 proteins significantly downregulated after each week, respectively. Among them, four upregulated proteins, SEMG-1, PIP, PDGFRL, and NDPK, increased their abundance with the increased exercise intensity. Bioinformatics analysis indicates that these proteins are involved in stress response and immune function.

Conclusion

Four weeks of incremental treadmill running induced immunosuppression in healthy males. By using iTRAQ proteomics, four proteins in the urine, SEMG-1, PIP, PDGFRL, and NDPK, were found to increase incrementally with the increased exercise intensity, which have the potential to be used as noninvasive immune biomarkers of exercise-induced immunosuppression.

Cdc42: A Novel Regulator of Insulin Secretion and Diabetes-Associated Diseases

Cdc42, a member of the Rho GTPases family, is involved in the regulation of several cellular functions including cell cycle progression, survival, transcription, actin cytoskeleton organization and membrane trafficking. Diabetes is a chronic and metabolic disease, characterized as glycometabolism disorder induced by insulin deficiency related to β cell dysfunction and peripheral insulin resistance (IR). Diabetes could cause many complications including diabetic nephropathy (DN), diabetic retinopathy and diabetic foot. Furthermore, hyperglycemia can promote tumor progression and increase the risk of malignant cancers. In this review, we summarized the regulation of Cdc42 in insulin secretion and diabetes-associated diseases. Organized researches indicate that Cdc42 is a crucial member during the progression of diabetes, and Cdc42 not only participates in the process of insulin synthesis but also regulates the insulin granule mobilization and cell membrane exocytosis via activating a series of downstream factors. Besides, several studies have demonstrated Cdc42 as participating in the pathogenesis of IR and DN and even contributing to promote cancer cell proliferation, survival, invasion, migration, and metastasis under hyperglycemia. Through the current review, we hope to cast light on the mechanism of Cdc42 in diabetes and associated diseases and provide new ideas for clinical diagnosis, treatment, and prevention.

Small molecule activator of Nm23/NDPK as an inhibitor of metastasis

Nm23-H1/NDPK-A is a tumor metastasis suppressor having NDP kinase (NDPK) activity. Nm23-H1 is positively associated with prolonged disease-free survival and good prognosis of cancer patients. Approaches to increasing the cellular levels of Nm23-H1 therefore have significance in the therapy of metastatic cancers. We found a small molecule, (±)-trans-3-(3,4-dimethoxyphenyl)-4-[(E)-3,4-dimethoxystyryl]cyclohex-1-ene, that activates Nm23, hereafter called NMac1. NMac1 directly binds to Nm23-H1 and increases its NDPK activity. Employing various NMac1 derivatives and hydrogen/deuterium mass spectrometry (HDX-MS), we identified the pharmacophore and mode of action of NMac1. We found that NMac1 binds to the C-terminal of Nm23-H1 and induces the NDPK activation through its allosteric conformational changes. NMac1-treated MDA-MB-231 breast cancer cells showed dramatic changes in morphology and actin-cytoskeletal organization following inhibition of Rac1 activation. NMac1 also suppressed invasion and migration in vitro, and metastasis in vivo, in a breast cancer mouse model. NMac1 as an activator of NDPK has potential as an anti-metastatic agent.

Modulation of small GTPase activity by NME proteins

NME proteins are reported to influence signal transduction activity of small GTPases from the Ras superfamily by diverse mechanisms in addition to their generic NDP kinase activity, which replenishes the cytoplasmic pool of GTP. Comprehensive evidence shows that NME proteins modulate the activity of Ras GTPases, in particular members of the Rho family, via binding to their major activators GEFs. Direct interaction between several NMEs and Ras GTPases were also indicated in vitro and in vivo. These modes of regulation are mainly independent of the NME's kinase activity. NMEs also modulate the Ras-mediated signal transduction by interfering with the formation of a Ras signaling complex at the plasma membrane. In several examples, NMEs were proposed to perform the role of GAP proteins by promoting hydrolysis of the bound GTP, but this activity still requires additional verification. Early suggestions that NMEs can activate small GTPases by direct phosphorylation of the bound GDP, or by high-rate loading of GTP onto a closely apposed GTPase, were largely dismissed. In this review article, we survey and put into perspective published examples of identified and hypothetical mechanisms of Ras signaling modulation by NME proteins. We also point out involvement of NMEs in the transcriptional regulation of components of Ras GTPases-mediated signal transduction pathways, and reciprocal regulation of NME function by small GTPases, particularly related to NME's binding to membranes.

Cysteinyl leukotriene receptor 1 regulates glucose-stimulated insulin secretion (GSIS)

Insulin resistance is an important pathological hallmark of type 2 diabetes mellitus. Glucose-stimulated insulin secretion (GSIS) plays a key role in maintaining blood glucose levels within normal range. Impaired GSIS has been associated with type 2 diabetes, however, the underlying molecular mechanisms remain largely unknown. Cysteinyl leukotriene receptor 1 (cysLT1R) is an important G protein-coupled receptor mediating the biological functions of cysteinyl leukotrienes (cys-LTs). Little is known about the effects of cysLT1R in insulin secretion and pathogenesis of T2DM. In the present study, we aimed to define the physiological functions of cysLT1R in GSIS in MIN6 β-cells. Using reverse transcription polymerase chain reaction (RT-PCR) and western blot analysis, we found that cysLT1R was expressed in pancreatic MIN6 β-cells. We also reported that glucose increased the expression of cysLT1R in MIN6 cells. Additionally, the cysLT1R antagonist montelukast promoted GSIS in a dose dependent manner, however, the cysLT1R agonist LD4 inhibited GSIS, suggesting an antagonistic effect of cysLT1R on GSIS. Silencing of cysLT1R by transfection with cysLT1R siRNA enhanced GSIS while overexpression of cysLT1R reduced GSIS in pancreatic MIN6 β-cells. Mechanistically, we found that the Arf6/Cdc42/Rac1 pathway was involved in this process. Collectively, our findings highlight the essential role of cysLT1R in suppressing pancreatic insulin secretion, and potentially provided a new insight into understanding the mechanical regulation of glucose homeostasis.

Impact of laparoscopy on the biological behavior and gene expression of endometrial adenocarcinoma cells

The current study investigated the effect of laparoscopy on the biological behavior and gene expression of endometrial adenocarcinoma cells. Totally, 40 patients with stage I endometrial adenocarcinoma and 20 patients with benign uterine diseases were enrolled in this study. For patients with endometrial adenocarcinoma, laparoscopy was performed in 20 cases and laparotomy was carried out in the other 20 cases. Total laparoscopic hysterectomy was performed in patients with benign diseases. Cell apoptotic rate and the gene expression of N-myc, Fas, metastasis-associated protein 1 (MTA1), and nm23-H1 were determined in the normal and cancerous endometrial tissues both preoperatively and postoperatively. For endometrial adenocarcinoma cells, laparoscopy, instead of laparotomy, promoted the apoptosis of endometrial adenocarcinoma cells, down-regulated the expression of apoptosis suppressor gene N-myc and metastasis-promoting gene MTA1, up-regulated the expression of apoptosis-promoting gene Fas and metastasis suppressor gene nm23-H1. However, laparoscopy did not affect the apoptotic rate and gene expression in normal endometrial cells. Laparoscopy may be used as a safe and effective intervention for endometrial cancer.

Dual functions of NME1 in suppression of cell motility and enhancement of genomic stability in melanoma

The NME1 gene represents the prototypical metastasis suppressor, whose expression inhibits cell motility and metastasis without impact on primary tumor growth in a number of different human cancers. This report outlines our recent efforts to define the molecular mechanisms through which NME1 both suppresses cell motility and promotes genomic integrity in the setting of human melanoma. Forced NME1 expression in a variety of melanoma-derived cell lines was shown to induce dynamic changes in cell morphology and reorganization of the actin cytoskeleton, with formation of a network of thick stress fibers and assembly of fibronectin fibrils at large focal adhesions. Moreover, NME1 expression results in adhesion reprogramming through an impact on integrin repertoire and focal adhesion dynamics. Having previously demonstrated that NME1 expression promotes repair of DNA damage induced by ultraviolet radiation (UVR) in both yeast and mammalian cells, probably via the nucleotide excision repair pathway, we have more recently demonstrated that NME1 is rapidly recruited to double-strand breaks. This preliminary result represents the first evidence of direct interactions between NME1 and DNA in the context of DNA repair and has set the stage for current efforts to probe its functional interactions with double-strand break repair pathways. Discussed herein are molecular models to explain the interactions of NME1 with such diverse cellular functions as cell motility and DNA repair, potentially through its nucleoside diphosphate kinase and 3'-5' exonuclease activities.