Alzheimer's disease (AD) is a progressive and deleterious neurodegenerative disease, strongly affecting the cognitive functions and memory of seniors worldwide. Around 58% of the affected patients live in low and middle-income countries, with estimates of increasing deaths caused by AD in the coming decade. AD is a multifactor pathology. Mitochondrial function declines in AD brain and is currently emerging as a hallmark of this disease. It has been considered as one of the intracellular processes severely compromised in AD. Many mitochondrial parameters decline already during aging; mitochondrial efficiency for energy production, reactive oxygen species (ROS) metabolism and the de novo synthesis of pyrimidines, to reach an extensive functional failure, concomitant with the onset of neurodegenerative conditions. Besides its impact on cognitive functions, AD is characterized by loss of synapses, extracellular amyloid plaques composed of the amyloid-β peptide (Aβ), and intracellular aggregates of hyperphosphorylated Tau protein, accompanied by drastic sleep disorders, sensory function alterations and pain sensitization. Unfortunately, till date, effective management of AD-related disorders and early, non-invasive AD diagnostic markers are yet to be found. MicroRNAs (miRNAs) are small non-coding nucleic acids that regulate key signaling pathway(s) in various disease conditions. About 70% of experimentally detectable miRNAs are expressed in the brain where they regulate neurite outgrowth, dendritic spine morphology, and synaptic plasticity. Increasing studies suggest that miRNAs are intimately involved in synaptic function and specific signals during memory formation. This has been the pivotal key for considering miRNAs crucial molecules to be studied in AD. MicroRNAs dysfunctions are increasingly acknowledged as a pivotal contributor in AD via deregulating genes involved in AD pathogenesis. Moreover, miRNAs have been proved to control pain sensitization processes and regulate circadian clock system that affects the sleep process. Interestingly, the differential expression of miRNA panels implies their emerging potential as diagnostic AD biomarkers. In this review, we will present an updated analysis of miRNAs role in regulating signaling processes that are involved in AD-related pathologies. We will discuss the current challenges against wider use of miRNAs and the future promising capabilities of miRNAs as diagnostic and therapeutic means for better management of AD.
Purpose
Polycystic ovary syndrome (PCOS) is a prevalent female endocrine disorder. 50–70% of PCOS patients suffer from glucose intolerance, insulin and β cell impairments. Updated studies reveal the crucial regulatory role of inflammation modulators in various diseases, by manipulating autophagy and oxidative stress. However, the data available about autophagy in PCOS pancreas, especially in relation to inflammation key players are little. This study investigated pancreatic autophagy status in PCOS rat model, with miR-223-3p and NF-κB levels as pivotal regulators of oxidative stress-autophagy axis, insulin, and β cell integrity. We then analyzed nanocurcumin effects as a putative anti-inflammatory nutraceutical on the disrupted parameters.
Methods
Nanocurcumin was characterized using transmission electron microscopy (TEM) and Fourier-transform IR (FT-IR) spectroscopy. Adult virgin Wistar rats were selected, and PCOS was induced using letrozole (1mg/kg). Nanocurcumin was ingested following letrozole. Sex hormones and insulin resistance were determined. miR-223-3p expression was determined using real-time PCR. Immunohistochemistry and Western blotting determined β cells, NF-κB, and autophagy markers p62 and LC3II.
Results
PCOS group showed significant disruptions in sex hormones and a double fold increase in glucose and insulin levels, exhibiting insulin resistance. Immunostaining confirmed around 46% deterioration of ß cell mass. Real-time PCR showed significant downregulation of miR-223-3p. Immunohistochemistry and Western blotting revealed a drastic upsurge of NF-κB, and autophagy markers p62 and LC3II, confirming bioinformatics target analysis. Interestingly, compared to PCOS group, nanocurcumin (200mg/kg) significantly upregulated miR-223-3p expression by 30%. It subsided NF-κB and autophagy eruption to restore ß cell mass and attenuate insulin resistance.
Conclusion
To the best of our knowledge, this study is the first to highlight the vital contribution of miR-223-3p and NF-κB levels in aggravating PCOS pancreatic autophagy and consequent impairments. It spots nanocurcumin potential as an inflammation and autophagy modulator, for possible better management of PCOS complications.
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