Lipid droplets (LDs)
are closely connected to many physiological processes and abnormal
LDs are related to many diseases. Herein, a family of two-photon fluorescence
compounds based on the aurone skeleton were developed as efficient
LDs imaging probes. They exhibit the obvious solvatochromism effect
from blue to orange emission (∼140 nm shift) in various solvents.
The robust probes possess low toxicity to living cells, high photobleaching
resistance, and superior photostability and can light up LDs with
high specificity. Furthermore, the probe DMMB (aurone skeleton with
dimethylamino) was carefully applied in real-time monitoring of the
morphological changes of LDs and the interactions between LDs and
mitochondria under specific physiological conditions (e.g., starvation).
We have observed for the first time the dynamic change between mitochondria
and LDs when mitochondrial damage is caused by a large excess of H2O2 in a short period of time.
Hypertonicity in renal medulla is critical for the kidney to produce concentrated urine. Renal medullary cells have to survive high medullary osmolarity during antidiuresis. Previous study reported that farnesoid X receptor (FXR), a nuclear receptor transcription factor activated by endogenous bile acids, increases urine concentrating ability by up-regulating aquaporin 2 expression in medullary collecting duct cells (MCDs). However, whether FXR is also involved in the maintenance of cell survival of MCDs under dehydration condition and hypertonic stress remains largely unknown. In the present study, we demonstrate that 24-hours water restriction selectively up-regulated renal medullary expression of FXR with little MCD apoptosis in wild-type mice. In contrast, water deprivation caused a massive apoptosis of MCDs in both global FXR gene-deficient mice and collecting duct-specific FXR knockout mice. In vitro studies showed that hypertonicity significantly increased FXR and tonicity response enhancer binding protein (TonEBP) expression in mIMCD3 cell line and primary cultured MCDs. Activation and overexpression of FXR markedly increased cell viability and decreased cell apoptosis under hyperosmotic conditions. In addition, FXR can increase gene expression and nuclear translocation of TonEBP. We conclude that FXR protects MCDs from hypertonicity-induced cell injury very likely via increasing TonEBP expression and nuclear translocation. This study provides insights into the molecular mechanism by which FXR enhances urine concentration via maintaining cell viability of MCDs under hyperosmotic condition.
A coumarin chalcone derivative with a levulinic acid terminal group acts as a ratiometric fluorescent probe for hydrazine based on deprotection, addition and a subsequent cyclization reaction mechanism.
Hydrazine is widely used in industrial and agricultural production, but excessive hydrazine possesses a serious threat to human health and environment. Here two new ratiometric fluorescence probes, DDP and DDC, with the hydroxyl coumarin chalcone unit as the sensing site are developed, which can achieve colorimetric and ratiometric recognition for hydrazine with good sensitivity, excellent selectivity, and anti-interference. The calculated fluorescence limits of detections are 0.26 μM (DDC) and 0.14 μM (DDP). The ratiometric fluorescence response to hydrazine is realized through the adjustment of donor and receptor units in coumarin conjugate structure terminals, accompanied by fluorescence peak shift about 200 nm (DDC, 188 nm; DDP, 229 nm). Stronger electropositivity in the carbon−carbon double bond is helpful to the first phase addition reaction between the probe and hydrazine. Higher phenol activity in the hydroxyl coumarin moiety will facilitate the following dihydro-pyrazole cyclization reaction. In addition, both of these probes realized the convenient detection of hydrazine vapor. The probes were also successfully applied to detect hydrazine in actual water samples, different soils, and living cells.
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