Congestive heart failure in COX2 deficient rats

Non-steroidal anti-inflammatory drugs(NSAIDs)inhibit prostaglandin(PG)formation by targeting cyclooxygenase(COX)1 and 2.Long-term use of NSAIDs that selectively inhibit COX2 increases the risk for thrombotic events,cardiac failure,and hypertension.However,the underlying mechanisms remain unclear.In this study,COX1-and COX2-deficient rats were created via Cas9/RNA-mediated gene targeting.DNA genotyping and Western blot analysis confirmed successful generation of COX1^(-/-) and COX2^(-/-) rats.Adult COX1^(-/-) rats grew normally,while more than 70%of COX2^(-/-) rats after wean died within 2 months.Echocardiography showed markedly reduced left ventricular ejection fraction and fractional shortening in adult COX2^(-/-) rats compared to those in wildtype(WT)controls.Histological analysis revealed accumulation of inflammatory cells and severe interstitial and perivascular fibrosis in COX2^(-/-)cardiac tissues.Moreover,cardiac ATP and acetyl-Co A production was dramatically decreased in COX2^(-/-) rats.Consistently,the expression of genes related to mitochondrial oxidation,such as those that encode for subunits of pyruvate dehydrogenase complex and acyl Co A dehydrogenases,were downregulated,while glycolytic hexokinase 1(HK1)was upregulated in COX2^(-/-) heart tissues.These observations indicate that COX2-deficient rats developed spontaneously heart failure,likely as a result of dysregulated cardiac energy metabolism.

dsRNA binding protein PACT/RAX in gene silencing, development and diseases

PACT （Protein kinase, interferon-inducible double stranded RNA dependent activator） and its murine ortholog RAX （PKR-associated protein X） were originally identified as a protein activator for the dsRNA-dependent, interferon-inducible protein kinase （PKR）. Endogenous PACT/RAX activates PKR in response to diverse stress signals such as serum starvation, and peroxide or arsenite treatment. PACT/RAX heterodimerized with PKR and activated it with its third motif in the absence of dsRNA. The activation of PKR leads to enhanced eIF2a phosphorylation followed by apoptosis or inhibition of growth. Besides the role of activating PKR, PACT is associated with a ~500 kDa complex that contains Dicer, hAgo2, and TRBP （TAR RNA binding protein） and it associates with Dicer to facilitate the production of small interfering RNA. PACT/RAX plays an important role in diverse physiological and pathological processes. Pact^-/- mice exhibit notable developmental abnormalities including microtia, with craniofacial ear, and hearing defects. Pact^-/- mice had smaller body sizes and fertility defects, both of which were caused by defective pituitary functions. It was found that dRAX disrupted fly embryos homozygous, displayed highly abnormal commissural axon structure of the central nervous system, and 70% of the flies homozygous for the mutant allele died prior to adulthood. Using high density SNP genotyping arrays, it was found that a mutation in PRKRA （the PACT/RAX gene） is the causative genetic mutation in DYT16, a novel autosomal recessive dystonia-parkinsonism syndrome in Brazilian patients.

A peptide-based near-infrared fluorescence probe for dynamic monitoring senile plaques in Alzheimer＇s disease mouse model

In vivo monitoring neuropathological changes in Alzheimer＇s disease （AD） animal model is critical for drug development. Here, by integrating blood-brain barrier penetrable peptide, we have developed a peptide probe which based on angiopep-2. Angiopep-based probe exhibited high binding affinity to Aβ aggregates and labeled senile plaques in vivo. Remarkably, the in vivo near-infrared imaging data revealed that fluorescence signals of this probe were nearly 3-fold higher in the brains of 16-monthold APP/PSI transgenic mice compared to C57 mice and exhibited linear correlation with the senile plaques load process in 4-, 8-, 16-month-old APP/PSI transgenic mice. Moreover, senile plaques load was detected in vivo as early as 4 months of age that even at the very beginning of plaques developed in APP/PS1 transgenic mice. Taken together, this novel peptide-based probe achieved dynamic monitoring senile plaques in APP/PS1 transgenic mice and have been ready to use in drug development in AD mouse model.