Sarcolemmal ATP-sensitive potassium channel protects cardiac myocytes against lipopolysaccharide-induced apoptosis.

The sarcolemmal ATP-sensitive K+ (sarcKATP) channel plays a cardioprotective role during stress. However, the role of the sarcKATP channel in the apoptosis of cardiomyocytes and association with mitochondrial calcium remains unclear. For this purpose, we developed a model of LPS-induced sepsis in neonatal rat cardiomyocytes (NRCs). The TUNEL assay was performed in order to detect the apoptosis of cardiac myocytes and the MTT assay was performed to determine cellular viability. Exposure to LPS significantly decreased the viability of the NRCs as well as the expression of Bcl-2, whereas it enhanced the activity and expression of the apoptosis-related proteins caspase-3 and Bax, respectively. The sarcKATP channel blocker, HMR-1098, increased the apoptosis of NRCs, whereas the specific sarcKATP channel opener, P-1075, reduced the apoptosis of NRCs. The mitochondrial calcium uniporter inhibitor ruthenium red (RR) partially inhibited the pro-apoptotic effect of HMR-1098. In order to confirm the role of the sarcKATP channel, we constructed a recombinant adenovirus vector carrying the sarcKATP channel mutant subunit Kir6.2AAA to inhibit the channel activity. Kir6.2AAA adenovirus infection in NRCs significantly aggravated the apoptosis of myocytes induced by LPS. Elucidating the regulatory mechanisms of the sarcKATP channel in apoptosis may facilitate the development of novel therapeutic targets and strategies for the management of sepsis and cardiac dysfunction.

Dually enriched Cu:CdS@ZnS QDs with both polyvinylpyrrolidone twisting and SiO2 loading for improved cell imaging.

Through harvesting of the increased Stokes shift of CdS QDs via Cu-doping, the concentration-quenching or aggregation-quenching of CdS QDs was largely alleviated. A dually-enriched strategy with both polyvinylpyrrolidone (PVP) twisting and SiO2 loading was developed for generating a highly luminescent doped-dots (d-dots) assembly for improved cell imaging.

[The expression of KATP; channel mutant subunit Kir6.2AAA in rat cardiomyocytes].

OBJECTIVE: To construct a recombinant adenovirus vector carrying KATP; channel mutant subunit Kir6.2AAA and express it in rat cardiomyocytes. METHODS: Based on the primers for Kir6.2 subunits, Kir6.2 GFG amino acids were site-directed mutated into AAA by means of overlap PCR. PCR products were cloned into pShuttle vector for sequence analysis. After Pme I linearization, it was transformed into adenovirus expression vector pAdEasy-1. Then the pAdEasy-1 was packaged into liposome and transfected into primary cultured rat cardiomyocytes. The expression of Kir6.2AAA was confirmed by reverse transcription PCR(RT-PCR) and Western blotting. RESULTS: The recombinant adenovirus carrying the gene fragment Kir6.2AAA and EGFP was constructed successfully, and the virus titer was 2.64×10(11); VP/mL. After infected by the recombinant adenovirus expressing Kir6.2AAA, rat cardiomyocytes expressed EGFP and emitted green fluorescence under a fluorescence microscope. RT-PCR demonstrated that the expression of Kir6.2AAA was significantly up-regulated in the infected cardiomyocytes, and Western blotting also proved the over-expression of Kir6.2AAA in the cardiomyocytes. CONCLUSION: The recombinant adenovirus carrying the gene fragment Kir6.2AAA and EGFP was constructed successfully and expressed correctly in rat cardiomyocytes.

Fast imaging of eccrine latent fingerprints with nontoxic Mn-doped ZnS QDs.

Fingerprints are unique characteristics of an individual, and their imaging and recognition is a top-priority task in forensic science. Fast LFP (latent fingerprint) acquirement can greatly help policemen in screening the potential criminal scenes and capturing fingerprint clues. Of the two major latent fingerprints (LFP), eccrine is expected to be more representative than sebaceous in LFP identification. Here we explored the heavy metal-free Mn-doped ZnS quantum dots (QDs) as a new imaging moiety for eccrine LFPs. To study the effects of different ligands on the LFP image quality, we prepared Mn-doped ZnS QDs with various surface-capping ligands using QDs synthesized in high-temperature organic media as starting material. The orange fluorescence emission from Mn-doped ZnS QDs clearly revealed the optical images of eccrine LFPs. Interestingly, N-acetyl-cysteine-capped Mn-doped ZnS QDs could stain the eccrine LFPs in as fast as 5 s. Meanwhile, the levels 2 and 3 substructures of the fingerprints could also be simultaneously and clearly identified. While in the absence of QDs or without rubbing and stamping the finger onto foil, no fluorescent fingerprint images could be visualized. Besides fresh fingerprint, aged (5, 10, and 50 days), incomplete eccrine LFPs could also be successfully stained with N-acetyl-cysteine-capped Mn-doped ZnS QDs, demonstrating the analytical potential of this method in real world applications. The method was also robust for imaging of eccrine LFPs on a series of nonporous surfaces, such as aluminum foil, compact discs, glass, and black plastic bags.

Hypoxia promotes ligand-independent EGF receptor signaling via hypoxia-inducible factor-mediated upregulation of caveolin-1.

Caveolin-1 (CAV1) is an essential structural constituent of caveolae, specialized lipid raft microdomains on the cell membrane involved in endocytosis and signal transduction, which are inexplicably deregulated and are associated with aggressiveness in numerous cancers. Here we identify CAV1 as a direct transcriptional target of oxygen-labile hypoxia-inducible factor 1 and 2 that accentuates the formation of caveolae, leading to increased dimerization of EGF receptor within the confined surface area of caveolae and its subsequent phosphorylation in the absence of ligand. Hypoxia-inducible factor-dependent up-regulation of CAV1 enhanced the oncogenic potential of tumor cells by increasing the cell proliferative, migratory, and invasive capacities. These results support a concept in which a crisis in oxygen availability or a tumor exhibiting hypoxic signature triggers caveolae formation that bypasses the requirement for ligand engagement to initiate receptor activation and the critical downstream adaptive signaling during a period when ligands required to activate these receptors are limited or are not yet available.