Culture at low glucose up-regulates mitochondrial function in pancreatic β cells with accompanying effects on viability

Modelling human placental villous development: designing cultures that reflect anatomy

The use of in vitro tools to study trophoblast differentiation and function is essential to improve understanding of normal and abnormal placental development. The relative accessibility of human placentae enables the use of primary trophoblasts and placental explants in a range of in vitro systems. Recent advances in stem cell models, three-dimensional organoid cultures, and organ-on-a-chip systems have further shed light on the complex microenvironment and cell-cell crosstalk involved in placental development. However, understanding each model's strengths and limitations, and which in vivo aspects of human placentation in vitro data acquired does, or does not, accurately reflect, is key to interpret findings appropriately. To help researchers use and design anatomically accurate culture models, this review both outlines our current understanding of placental development, and critically considers the range of established and emerging culture models used to study this, with a focus on those derived from primary tissue.

Altered Transcriptional Profile of Mitochondrial DNA-Encoded OXPHOS Subunits, Mitochondria Quality Control Genes, and Intracellular ATP Levels in Blood Samples of Patients with Parkinson's Disease

Mitochondrial dysfunctions are significant contributors to neurodegeneration. One result or a cause of mitochondrial dysfunction might be the disruption of mtDNA transcription. Limited data indicated an altered expression of mtDNA encoded transcripts in Alzheimer's disease (AD) or Parkinson's disease (PD). The number of mitochondria is high in cells with a high energy demand, such as muscle or nerve cells. AD or PD involves increased risk of cardiomyopathy, suggesting that mitochondrial dysfunction might be systemic. If it is systemic, we should observe it in different cell types. Given that, we wanted to investigate any disruption in the regulation of mtDNA encoded gene expression in addition to PINK1, PARKIN, and ATP levels in peripheral blood samples of PD cases who are affected by a neurodegenerative disorder that is very well known by its mitochondrial aspects. Our results showed for the first time that: 1) age of onset > 50 PD sporadic (PDS) cases: mtDNA transcription and quality control genes were affected; 2) age of onset <50 PDS cases: only mtDNA transcription was affected; and 3) PD cases with familial background: only quality control genes were affected. mtDNA copy number was not a confounder. Intracellular ATP levels of PD case subgroups were significantly higher than those of healthy subjects. We suggest that a systemic dysregulation of transcription of mtDNA or mitochondrial quality control genes might result in the development of a sporadic form of the disease. Additionally, ATP elevation might be an independent compensatory and response mechanism. Hyperactive cells in AD and PD require further investigation.

Liraglutide regulates the viability of pancreatic α-cells and pancreatic β-cells through cAMP-PKA signal pathway

AIMS

As a glucagon-like peptide-1 receptor agonist, liraglutide could effectively increase insulin secretion from pancreatic β-cells and suppress glucagon secretion from pancreatic α-cells in the treatment of hyperglycemia in type 2 diabetes patients. However, the mechanisms for the different regulation of pancreatic α-cells and β-cells are still unclear. In this study, we mainly explored the different effects of liraglutide on mouse pancreatic α-cell line and β-cell line in vitro.

MAIN METHODS

Herein, mouse pancreatic α-cell line, α-TC1-6, and mouse pancreatic β-cell line, β-TC-tet, were used to analyze the biological effects of liraglutide in different concentrations. Cell proliferation, cell apoptosis and cell secretion ability were detected in different groups. Besides, the level of miR-375 and cAMP-PKA signal pathway were further evaluated using qPCR and western blot.

KEY FINDINGS

The results indicated that liraglutide could increase the level of miR-375 and cell apoptosis in pancreatic α-cells through inhibiting the cAMP-PKA signal pathway, but activate cAMP-PKA signal pathway in pancreatic β-cells, and further lead to the down-regulation of miR-375 and improve cell viability. Therefore, the treatment with liraglutide could down-regulate the glucagon secretion ability of α-TC1-6 cells, and the insulin secretion ability of β-TC-tet cells was enhanced with the liraglutide treatment in a dose-dependent manner.

SIGNIFICANCE

In conclusion, we mainly found that liraglutide could regulate the viability of pancreatic α-cells and pancreatic β-cells through inhibiting and activating cAMP-PKA signal pathway respectively. The better understanding of the mechanism could help us to develop more novel therapy methods for diabetes in the future.