Long-Term Experimental Hyperglycemia Does Not Impair Macrovascular Endothelial Barrier Integrity and Function in vitro

Hyperglycemia is a hallmark of type 2 diabetes implicated in vascular endothelial dysfunction and cardiovascular complications. Many in vitro studies identified endothelial apoptosis as an early outcome of experimentally modeled hyperglycemia emphasizing cell demise as a significant factor of vascular injury. However, endothelial apoptosis has not been observed in vivo until the late stages of type 2 diabetes. Here, we studied the long-term (up to 4 weeks) effects of high glucose (HG, 30 mM) on human umbilical vein endothelial cells (HUVEC) in vitro. HG did not alter HUVEC monolayer morphology, ROS levels, NO production, and exerted minor effects on the HUVEC apoptosis markers. The barrier responses to various clues were indistinguishable from those by cells cultured in physiological glucose (5 mM). Tackling the key regulators of cytoskeletal contractility and endothelial barrier revealed no differences in the histamine-induced intracellular Ca2+ responses, nor in phosphorylation of myosin regulatory light chain or myosin light chain phosphatase. Altogether, these findings suggest that vascular endothelial cells may well tolerate HG for relatively long exposures and warrant further studies to explore mechanisms involved in vascular damage in advanced type 2 diabetes.

Amniogenesis in Human Amniotic Sac Embryoids after Exposures to Organophosphate Flame Retardants

BACKGROUND

Amniogenesis is a key event in biochemical pregnancy, and its failure may result in human embryonic death. However, whether and how environmental chemicals affect amniogenesis remain largely unknown.

OBJECTIVES

The objective of the present study was to screen chemicals that may disrupt amniogenesis in an amniotic sac embryoid model and to investigate the potential mechanism of amniogenesis failure, with a focus on organophosphate flame retardants (OPFRs).

METHODS

This study developed a high-throughput toxicity screening assay based on transcriptional activity of octamer-binding transcription factor 4 (Oct4). For the two positive OPFR hits with the strongest inhibitory activity, we used time-lapse and phase-contrast imaging to assess their effects on amniogenesis. Associated pathways were explored by RNA-sequencing and western blotting, and potential binding target protein was identified through a competitive binding experiment.

RESULTS

Eight positive hits exhibiting Oct4 expression were identified, with 2-ethylhexyl-diphenyl phosphate (EHDPP) and isodecyl diphenyl phosphate (IDDPP) showing the strongest inhibitory activity. EHDPP and IDDPP were found to disrupt the rosette-like structure of the amniotic sac or inhibit its development. Functional markers of squamous amniotic ectoderm and inner cell mass were also found disrupted in the EHDPP- and IDDPP-exposed embryoids. Mechanistically, embryoids exposed to each chemical exhibited abnormal accumulation of phosphorylated nonmuscle myosin (p-MLC-II) and were able to bind to integrin β1 (ITGβ1).

CONCLUSION

The amniotic sac embryoid models suggested that OPFRs disrupted amniogenesis likely by inhibiting the ITGβ1 pathway, thus providing direct in vitro evidence associating OPFRs with biochemical miscarriage. https://doi.org/10.1289/EHP11958.

A simple and accurate method to quantify real-time contraction of vascular smooth muscle cell in vitro

Vascular smooth muscle cells (VSMCs) constitute the medial layer of the blood vessel wall. Their contractile state regulates blood flow in physiological and pathological conditions. Current methods for assessing the contractility of VSMCs are not amenable to the high-throughput screening of pharmaceutical compounds. This study aimed to develop a method to address this shortcoming in the field. Real-time contraction was visualized in living VSMCs using the exogenous expression of green fluorescent protein (GFP). Image-Pro Plus software (IPPS) was used to measure various morphological cell indices. In phenylephrine-treated VSMCs, GFP fluorescence imaging was more accurate than brightfield imaging or phalloidin staining in representing VSMC morphology, as measured using IPPS. Among the multiple indices of VSMC shape, area and mean-diameter were more sensitive than length in reflecting the morphological changes in VSMC. We developed a new index, compound length, by combining the mean-diameter and length to differentiate contracted and uncontracted VSMCs. Based on the compound length, we further generated a contraction index to define a single-VSMC contractile status as single-VSMC contraction-index (SVCI). Finally, compound length and SVCI were validated to effectively assess cell contraction in VSMCs challenged with U46619 and KCl. In conclusion, GFP-based indices of compound length and SVCI can accurately quantify the real-time contraction of VSMCs. In future, the new method will be applied to high-throughput drug screening or basic cardiovascular research.

Phosphorylation-dependent subcellular redistribution of small myosin light chain kinase

BACKGROUND

Myosin light chain kinase (MLCK) is a Ca²⁺-calmodulin-dependent enzyme dedicated to phosphorylate and activate myosin II to provide force for various motile processes. In smooth muscle cells and many other cells, small MLCK (S-MLCK) is a major isoform. S-MLCK is an actomyosin-binding protein firmly attached to contractile machinery in smooth muscle cells. Still, it can leave this location and contribute to other cellular processes. However, molecular mechanisms for switching the S-MLCK subcellular localization have not been described.

METHODS

Site-directed mutagenesis and in vitro protein phosphorylation were used to study functional roles of discrete in-vivo phosphorylated residues within the S-MLCK actin-binding domain. In vitro co-sedimentation analysis was applied to study the interaction of recombinant S-MLCK actin-binding fragment with filamentous actin. Subcellular distribution of phosphomimicking S-MLCK mutants was studied by fluorescent microscopy and differential cell extraction.

RESULTS

Phosphorylation of S-MLCK actin-binding domain at Ser25 and/or Thr56 by proline-directed protein kinases or phosphomimicking these posttranslational modifications alters S-MLCK binding to actin filaments both in vitro and in cells, and induces S-MLCK subcellular translocation with no effect on the enzyme catalytic properties.

CONCLUSIONS

Phosphorylation of the amino terminal actin-binding domain of S-MLCK renders differential subcellular targeting of the enzyme and may, thereby, contribute to a variety of context-dependent responses of S-MLCK to cellular and tissue stimuli.

GENERAL SIGNIFICANCE

S-MLCK physiological function can potentially be modulated via phosphorylation of its actin recognition domain, a regulation distinct from the catalytic and calmodulin regulatory domains.

Bursa-Derived Cells Show a Distinct Mechano-Response to Physiological and Pathological Loading in vitro

The mechano-response of highly loaded tissues such as bones or tendons is well investigated, but knowledge regarding the mechano-responsiveness of adjacent tissues such as the subacromial bursa is missing. For a better understanding of the physiological role of the bursa as a friction-reducing structure in the joint, the study aimed to analyze whether and how bursa-derived cells respond to physiological and pathological mechanical loading. This might help to overcome some of the controversies in the field regarding the role of the bursa in the development and healing of shoulder pathologies. Cells of six donors seeded on collagen-coated silicon dishes were stimulated over 3 days for 1 or 4 h with 1, 5, or 10% strain. Orientation of the actin cytoskeleton, YAP nuclear translocation, and activation of non-muscle myosin II (NMM-II) were evaluated for 4 h stimulations to get a deeper insight into mechano-transduction processes. To investigate the potential of bursa-derived cells to adapt their matrix formation and remodeling according to mechanical loading, outcome measures included cell viability, gene expression of extracellular matrix and remodeling markers, and protein secretions. The orientation angle of the actin cytoskeleton increased toward a more perpendicular direction with increased loading and lowest variations for the 5% loading group. With 10% tension load, cells were visibly stressed, indicated by loss in actin density and slightly reduced cell viability. A significantly increased YAP nuclear translocation occurred for the 1% loading group with a similar trend for the 5% group. NMM-II activation was weak for all stimulation conditions. On the gene expression level, only the expression of TIMP2 was down-regulated in the 1 h group compared to control. On the protein level, collagen type I and MMP2 increased with higher/longer straining, respectively, whereas TIMP1 secretion was reduced, resulting in an MMP/TIMP imbalance. In conclusion, this study documents for the first time a clear mechano-responsiveness in bursa-derived cells with activation of mechano-transduction pathways and thus hint to a physiological function of mechanical loading in bursa-derived cells. This study represents the basis for further investigations, which might lead to improved treatment options of subacromial bursa-related pathologies in the future.

LncRNA HCG11 Suppresses Cell Proliferation and Promotes Apoptosis via Sponging miR-224-3p in Non-Small-Cell Lung Cancer Cells

INTRODUCTION

Studies have found that Lnc-HCG11 is an important regulator of cancer. However, the function of Lnc-HCG11 in NSCLC is not known. Therefore, this experimental design was based on Lnc-HCG11 to explore the pathogenesis of NSCLC.

METHODS

RT-qPCR was used to detect the expression of Lnc-HCG11 and miR-224-3p in NSCLC. The effects of Lnc-HCG11 and miR-224-3p on proliferation and apoptosis of NSCLC cells were detected by CCK-8 assay, Edu assay and Annexin V-FITC/PI assay. Target gene prediction and screening, luciferase reporter assays were used to verify downstream target genes for lnc-HCG11 and miR-224-3p. Western blotting was used to detect the protein expression of caspase-3. The tumor changes in mice were detected by in vivo.

RESULTS

Lnc-HCG11 was significantly reduced in NSCLC. Lnc-HCG11 significantly inhibited cell proliferation of NSCLC cells and induced apoptosis. miR-224-3p was significantly elevated in the NSCLC cell line. Moreover, miR-224-3p significantly increased cell proliferation and inhibited apoptosis of NSCLC cells. Furthermore, Lnc-HCG11 was negatively correlated with miR-224-3p expression. Lnc-HCG11 over-expression was up-regulated the expression levels of c-caspase-3 and caspase-3. Finally, the results of in vivo animal models confirmed that Lnc-HCG11 inhibited tumor growth by modulating the miR-224-3p/c-caspase-3 axis.

CONCLUSION

Lnc-HCG11 could inhibit the progression of NSCLC by modulating the miR-224-3p/caspase-3 axis, and Lnc-HCG11 may be a potential therapeutic target for NSCLC.

The Lnc LINC00461/miR-30a-5p facilitates progression and malignancy in non-small cell lung cancer via regulating ZEB2

Studies have found that Lnc LINC00461 is an important regulator of cancer. However, the function of Lnc LINC00461 in NSCLC is not known. Therefore, this experimental design was based on Lnc LINC00461 to explore the pathogenesis of Non-small cell lung cancer (NSCLC). RT-qPCR was used to detect the expression of lnc LINC00461 and miR-30a-5p in NSCLC. The CCK-8 method and Transwell assay were used to detect the effects of lnc LINC00461 and miR-30a-5p on proliferation, migration in NSCLC. Target gene prediction and screening, luciferase reporter assays were used to validate downstream target genes of lnc LINC00461 and miR-30a-5p. The protein expression of ZEB2 was detected by Western blot. The tumor changes in mice were detected by in vivo experiments. Lnc LINC00461 was significantly elevated in NSCLC. Lnc LINC00461 knockdown significantly inhibited proliferation and migration in NSCLC. miR-30a-5p was a direct target of lnc LINC00461 and miR-30a-5p was significantly reduced in NSCLC. shLINC00461 and miR-30a-5p inhibitor partially eliminated the effect of shLINC00461 on cell proliferation. And lnc LINC00461 was negatively correlated with miR-30a-5p expression. ZEB2 was a direct target of miR-30a-5p, and miR-30a-5p mimic and sh lnc LINC00461 significantly reduced ZEB2 expression levels. Finally, In vivo, lnc LINC00461 promoted tumor growth by modulating the miR-30a-5p / ZEB2 axis. In conclusion, LncLINC00461 promoted the progression of NSCLC by the miR-30a-5p / ZEB2 axis, and lnc LINC00461 may be a potential therapeutic target for NSCLC.