Identification of Ethylene Responsive miRNAs and Their Targets from Newly Harvested Banana Fruits Using High-Throughput Sequencing.

The roles of microRNAs (miRNAs) related to ethylene response in banana fruits remain unknown because many miRNAs are differentially expressed as the fruit ripens, making the identification of ethylene-responsive miRNAs difficult. Using newly harvested banana fruits (within 5 h after harvest) as material, we found that these fruit did not ripen when treated with 5 µL/L of ethylene for 12 h at 22 °C. Two miRNA libraries were generated from newly harvested banana fruits with and without ethylene treatment and sequenced. In total, 128 known miRNAs belonging to 42 miRNA families were obtained, and 12 novel miRNAs were identified. Among them, 22 were differentially expressed in response to ethylene treatment, among which 6 known miRNAs and their putative targets were validated using qRT-PCR. These putative targets encoded proteins including GATA, ARF, DLC, and AGO, etc. KEGG and GO analyses showed that miRNAs differentially expressed in response to ethylene mainly function in the molecular and biological processes.

Synaptic activity reduces intraneuronal Abeta, promotes APP transport to synapses, and protects against Abeta-related synaptic alterations.

A central question in Alzheimer's disease research is what role synaptic activity plays in the disease process. Synaptic activity has been shown to induce beta-amyloid peptide release into the extracellular space, and extracellular beta-amyloid has been shown to be toxic to synapses. We now provide evidence that the well established synaptotoxicity of extracellular beta-amyloid requires gamma-secretase processing of amyloid precursor protein. Recent evidence supports an important role for intraneuronal beta-amyloid in the pathogenesis of Alzheimer's disease. We show that synaptic activity reduces intraneuronal beta-amyloid and protects against beta-amyloid-related synaptic alterations. We demonstrate that synaptic activity promotes the transport of the amyloid precursor protein to synapses using live cell imaging, and that the protease neprilysin is involved in reduction of intraneuronal beta-amyloid with synaptic activity.

Truncation and mutagenesis analysis of the human X-arrestin gene promoter.

X-arrestin (arrestin-3) is an arrestin present specifically in the outer segments of red-, green-, and blue-cone photoreceptors. The X-arrestin gene is on Xcen-q22, and consists of 17 exons with a promoter containing a TATA box and elements important for photoreceptor expression, including three CRX and one PCE-1-like element. In order to delineate the promoter structure necessary for the pan-cone-specific expression of X-arrestin, the expression of the gene in retinoblastoma cell lines was investigated, and a structure-function analysis of the promoter was conducted in the appropriate cellular substrate. Expression of X-arrestin was detected at a low level in the Y79 retinoblastoma cell line but not in the WERI retinoblastoma cell line. Truncation and expression analysis of the X-arrestin promoter in Y79 showed maximal activity in the proximal 378-bp region containing the CRX and PCE-1-like elements upstream of the TATA and CAAT boxes and a negative regulator in the distal 1-2-kbp region. Mutagenesis of the three CRX and PCE-1-like elements and expression analysis demonstrated complete elimination of the promoter activity. Mutagenesis of the TATA box and PCE-1-like element individually resulted in similar decrease in promoter activity, but the decrease in the promoter activity was greater when the CRX elements were mutagenized with a 5' to 3' spatial gradient in the negative effect, suggesting a cooperative effect of the three CRX elements. The regulation of expression from this promoter may involve the binding of a multi-protein enhanceosome complex at the CRX triplet and the PCE-1-like element, resulting in the recruitment and activation of the RNA polymerase II complex at the downstream TATA box.