Inhibition of the PERK-Dependent Unfolded Protein Response Signaling Pathway Involved in the Pathogenesis of Alzheimer's Disease

OBJECTIVES

There is a body of evidence that neurodegenerative disease entities are directly correlated with the perturbations on the molecular level. Hence, the ER stress-mediated Unfolded Protein Response (UPR) is activated resulting in PERK-dependent phosphorylation of the Eukaryotic initiation factor 2 (eIF2α). Thus, the levels of ATF4 and CHOP proteins are significantly increased, which subsequently switches the pro-adaptive branch of the UPR into the pro-apoptotic directly leading to neuronal loss and initiation of the neurodegenerative process. The aim of the presented study was the evaluation of the biological activity of highly specific, small-molecule inhibitors of the PERKdependent UPR signaling pathway.

METHODS

The study was conducted on rat astrocytic DI TNC1 cell line. The level of p-eIF2α was measured by Western blot technique, the cytotoxicity of the investigated compound was assessed by the MTT assay and using the FITC-conjugated Annexin V (Annexin V-FITC) to indicate apoptosis and propidium iodide (PI) to indicate necrosis. The effect of tested compound on cell cycle progression was measured by flow cytometry, where the PI-labelled nuclei were analysed for DNA content.

RESULTS

As a result one of the investigated compound LDN-0060609 triggers a significant inhibition of the eIF2α phosphorylation in DI TNC1 cell line. Moreover, we showed that compound LDN-0060609 is non-cytotoxic and has no effect on cell cycle progression.

CONCLUSION

In conclusion, LDN-0060609 may constitute a novel, targeted treatment approach against neurodegenerative diseases, including Alzheimer's disease (AD), where pathogenesis and progression are closely associated with the overactivation of the PERK-dependent UPR signaling pathway.

[Treatment problems of idiopathic arterial pulmonary hypertension--case report]

Pulmonary arterial hypertension (PAH) is characterized by elevations in the pulmonary arterial pressure and the vascular resistance in pulmonary placenta. One of the kinds of the pulmonary hypertension is the idiopathic arterial pulmonary hypertension, which etiology is not known. Below we present the case of 51 year old woman with idiopathic arterial pulmonary hypertension. Due to worsening shortness of breath occurring at night and heart palpitations, the noninvasive and invasive diagnostics were conducted. The diagnostics have shown a dilatation of the right atrium and ventricle, widening of the pulmonary vessels with the pressure in the pulmonary artery 108 mmHg, and moderate regurgitation of tricuspid valve and pulmonary artery. In spite of the treatment, increasing right sided heart failure was the cause of patient's further hospitalization. After the introduction of Ambrisentan therapy, her condition has improved. She waited for a lung transplant. The last exacerbation of ascites was probably a result of the cessation of the use of the above mentioned drug. Then there was a sudden cardiac arrest and, despite of the treatment the patient has died.