Aging-induced dysregulation of dicer1-dependent microRNA expression impairs angiogenic capacity of rat cerebromicrovascular endothelial cells

Age-related impairment of angiogenesis is likely to play a central role in cerebromicrovascular rarefaction and development of vascular cognitive impairment, but the underlying mechanisms remain elusive. To test the hypothesis that dysregulation of Dicer1 (ribonuclease III, a key enzyme of the microRNA [miRNA] machinery) impairs endothelial angiogenic capacity in aging, primary cerebromicrovascular endothelial cells (CMVECs) were isolated from young (3 months old) and aged (24 months old) Fischer 344 × Brown Norway rats. We found an age-related downregulation of Dicer1 expression both in CMVECs and in small cerebral vessels isolated from aged rats. In aged CMVECs, Dicer1 expression was increased by treatment with polyethylene glycol-catalase. Compared with young cells, aged CMVECs exhibited altered miRNA expression profile, which was associated with impaired proliferation, adhesion to vitronectin, collagen and fibronectin, cellular migration (measured by a wound-healing assay using electric cell-substrate impedance sensing technology), and impaired ability to form capillary-like structures. Overexpression of Dicer1 in aged CMVECs partially restored miRNA expression profile and significantly improved angiogenic processes. In young CMVECs, downregulation of Dicer1 (siRNA) resulted in altered miRNA expression profile associated with impaired proliferation, adhesion, migration, and tube formation, mimicking the aging phenotype. Collectively, we found that Dicer1 is essential for normal endothelial angiogenic processes, suggesting that age-related dysregulation of Dicer1-dependent miRNA expression may be a potential mechanism underlying impaired angiogenesis and cerebromicrovascular rarefaction in aging.

Targets in epigenetics: inhibiting the methyl writers of the histone code

Growing evidence suggests that protein lysine methyltransferases (PKMTs) and protein arginine methyltransferases (PRMTs) are associated with the development of various human diseases, including cancer, inflammation, and psychiatric disorders. Given the significant role of these proteins in human disease, efforts to discover selective small-molecule inhibitors of these enzymes are quickly gaining momentum. In this review, we focus on the recent progress in the discovery of selective PKMT and PRMT inhibitors. A future perspective on developing methyltransferase inhibitors is also offered.

Stem cells as vehicles for youthful regeneration of aged tissues

Stem cells hold great promise for regenerative therapies for a wide spectrum of diseases and disorders of aging by virtue of their ability to regenerate tissues and contribute to their homeostasis. Aging is associated with a marked decline in these functionalities of adult stem cells. As such, regeneration of aged tissues is both less efficient and less effective than that of young tissues. Recent studies have revealed the remarkably dynamic responses of stem cells to systemic signals, including the ability of "youthful" factors in the blood of young animals to enhance the functionality of aged stem cells. Thus, there is much hope that even aged stem cells retain a remarkable regenerative potential if provided with the correct cues and environment to engage in tissue repair. The overall focus of the presentations of this session is to address the determinants of changes in stem cell functionality with age, the key characteristics of stem cells in aged tissues, the extent to which those characteristics are capable of being rejuvenated and by what signals, and the potential for stem cell therapeutics for chronic diseases and acute injuries in aged individuals.

The Influence of DNA Methylation on Bone Cells

DNA methylation in eukaryotes invokes heritable alterations of the of the cytosine base in DNA without changing the underlying genomic DNA sequence. DNA methylation may be modified by environmental exposures as well as gene polymorphisms and may be a mechanistic link between environmental risk factors and the development of disease. In this review, we consider the role of DNA methylation in bone cells (osteoclasts/osteoblasts/osteocytes) and their progenitors with special focus on in vitro and ex vivo analyses. The number of studies on DNA methylation in bone cells is still somewhat limited, nevertheless it is getting increasingly clear that this type of the epigenetic changes is a critical regulator of gene expression. DNA methylation is necessary for proper development and function of bone cells and is accompanied by disease characteristic functional alterations as presently reviewed including postmenopausal osteoporosis and mechanical strain.

Vitamin B12 as an epidrug for regulating peripheral blood biomarkers in long COVID-associated visuoconstructive deficit

Approximately four months after recovering from a mild COVID-19 infection, around 25% of individuals developed visuoconstructive deficit (VCD), which was found to be correlated with an increase in peripheral immune markers and alterations in structural and metabolic brain imaging. Recently, it has been demonstrated that supplemental vitamin B12 regulates hyperinflammation during moderate and severe COVID-19 through methyl-dependent epigenetic mechanisms. Herein, whole peripheral blood cultures were produced using samples obtained from patients with confirmed persistent VCD, and controls without impairment, between 10 and 16 months after mild COVID-19. This experimental model was used to assess the leukocyte expression patterns of 11 biomarkers previously associated with VCD in long COVID and explore the potential of pharmacological B12 in regulating these genes. The results showed that patients with persistent VCD displayed continued upregulation of CCL11 and LIF compared to controls. It is worth noting that elevated serum levels of CCL11 have been previously linked to age-related neurodegenerative diseases. Notably, the addition of 1 nM of vitamin B12 to blood cultures from individuals with VCD normalized the mRNA levels of CCL11, upregulated the neuroprotective HGF, and, to a lesser extent, downregulated CSF2 and CXCL10. There was an inverse correlation observed between CCL11 mRNA levels and methylation levels of specific cytosines in its promoter region. These findings underscore the significance of systemic inflammation in persistent VCD associated with long COVID. Moreover, the study provides evidence suggesting that B12, acting as an epidrug, shows promise as a therapeutic approach for addressing this cognitive impairment.