Glycolytic enzyme Enolase-1 regulates insulin gene expression in pancreatic β-cell

Enolase-1 (Eno1) plays a critical role in regulating glucose metabolism; however, its specific impact on pancreatic islet β-cells remains elusive. This study aimed to provide a preliminary exploration of Eno1 function in pancreatic islet β-cells. The findings revealed that the expression of ENO1 mRNA in type 2 diabetes donors was significantly increased and positively correlated with HbA1C and negatively correlated with insulin gene expression. A high level of Eno1 in human insulin-secreting rat INS-1832/13 cells with co-localization with intracellular insulin proteins was accordingly observed. Silencing of Eno1 using siRNA or inhibiting Eno1 protein activity with an Eno1 antagonist significantly reduced insulin secretion and insulin content in β-cells, while the proinsulin/insulin content ratio remained unchanged. This reduction in β-cells function was accompanied by a notable decrease in intracellular ATP and mitochondrial cytochrome C levels. Overall, our findings confirm that Eno1 regulates the insulin secretion process, particularly glucose metabolism and ATP production in the β-cells. The mechanism primarily involves its influence on insulin production, suggesting that Eno1 represents a potential target for β-cell protection and diabetes treatment.

Monoclonal enolase-1 blocking antibody ameliorates pulmonary inflammation and fibrosis

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is a chronic fatal disease with limited therapeutic options. The infiltration of monocytes and fibroblasts into the injured lungs is implicated in IPF. Enolase-1 (ENO1) is a cytosolic glycolytic enzyme which could translocate onto the cell surface and act as a plasminogen receptor to facilitate cell migration via plasmin activation. Our proprietary ENO1 antibody, HL217, was screened for its specific binding to ENO1 and significant inhibition of cell migration and plasmin activation (patent: US9382331B2).

METHODS

In this study, effects of HL217 were evaluated in vivo and in vitro for treating lung fibrosis.

RESULTS

Elevated ENO1 expression was found in fibrotic lungs in human and in bleomycin-treated mice. In the mouse model, HL217 reduced bleomycin-induced lung fibrosis, inflammation, body weight loss, lung weight gain, TGF-β upregulation in bronchial alveolar lavage fluid (BALF), and collagen deposition in lung. Moreover, HL217 reduced the migration of peripheral blood mononuclear cells (PBMC) and the recruitment of myeloid cells into the lungs. In vitro, HL217 significantly reduced cell-associated plasmin activation and cytokines secretion from primary human PBMC and endothelial cells. In primary human lung fibroblasts, HL217 also reduced cell migration and collagen secretion.

CONCLUSIONS

These findings suggest multi-faceted roles of cell surface ENO1 and a potential therapeutic approach for pulmonary fibrosis.

Nuclear Enolase-1/ MBP-1 expression and its association with the Wnt signaling in epithelial ovarian cancer

BACKGROUND

Enolase-1, primarily known for its role in glucose metabolism, is overexpressed in various cancer entities. In contrast its alternative spliced nuclear isoform MBP-1 acts as a tumor suppressor. The aim of this study is to analyze the prognostic impact of Enolase-1/ MBP-1 and its functional significance in epithelial ovarian cancer (EOC).

METHODS

By immunohistochemistry, Enolase-1 staining was examined in 156 EOC samples. Evaluation of Enolase-1 staining was conducted in the nucleus and the cytoplasm using the semi-quantitative immunoreactive score. Expression levels were correlated with clinical and pathological parameters as well as with overall survival to assess for prognostic impact.

RESULTS

Cytoplasmic and nuclear Enolase-1 expression did not show a significant difference between the histological subtypes (p = 0.1). High nuclear Enolase-1/ MBP-1 staining negativly correlated with the tumor grading (p<0.001; Cc= -0.318). Cytoplasmic Enolase-1 did not correlate with clinicopathological data. Higher nuclear Enolase-1/ MBP-1 staining was detected in low-grade serous cancer cases compared to high-grade ones (median IRS 3 (range 0-8) vs. median IRS 2 (range 0-4), p<0.001). Nuclear Enolase-1/ MBP-1 expression correlated with the Wnt signaling markers membranous beta-catenin (p = 0.007; Cc=0.235), serine residue 9-phosphorylated glycogen synthase kinase 3 beta (p<0.001; Cc=0.341) and snail/slug (p = 0.004; Cc= -0.257). High nuclear Enolase-1/ MBP-1 expression was associated with improved overall survival (88.6 vs. 33.1 months, median; p = 0.013).

CONCLUSION

Additional knowledge of Enolase-1/ MBP-1 as a biomarker and its interactions within the Wnt signaling pathway and epithelial-mesenchymal transition potentially improve the prognosis of therapeutic approaches in EOC.

Nano-LC based proteomic approach identifies that E6AP interacts with ENO1 and targets it for degradation in breast cancer cells

E6AP (E6 associated protein) is a HECT domain containing protein having dual E3 ligase and ERα coactivation activity in breast cancer cells. Although E6AP is known to possess antitumorigenic activity, the underlying molecular mechanism is poorly understood. In the present study, we applied nano-LC based proteomics approach to identify E6AP-interacting proteins where we performed GST-pull down using GST-E6AP from whole cell extracts of MCF7 cells, resolved the differentially interacting proteins on 1D-SDS-PAGE, excised the gel bands that were trypsin digested followed by fractionation and spotting on MALDI-TOF/TOF plate through Nano-LC MALDI spotter. Subsequently, fractionated and spotted peptides were identified using MALDI-TOF/TOF. We identified several E6AP interacting proteins including previously reported such as HSP70 and new ones such as Enolase-1. We further confirmed that E6AP and Enolase1 interacted and colocalized more in the cytoplasmic periphery in breast cancer cells and further demonstrated that E6AP also targeted ENO1 for ubiquitin-mediated degradation in these cells.