O'Connor, M. S. | Search bioRxiv

bioRxiv2024

Human Replication Protein A complex is a Telomerase Processivity Factor Essential for Telomere Maintenance

Telomerase is crucial for maintaining telomere length and safeguarding genome stability. In this study, we identified Replication Protein A (RPA) as a novel telomerase processivity factor, functioning alongside the telomerase recruitment factor TPP1-POT1. AlphaFold2 predictions revealed that RPA and TPP1 interact with telomerase at distinct binding sites. Using separation- of-function mutants, we discovered that RPA-mediated telomerase stimulation is indispensable for telomere elongation, while TPP1-POT1 primarily functions in recruiting telomerase to telomeres. Furthermore, we demonstrated that short telomere disease-associated telomerase mutations compromise RPAs ability to stimulate telomerase, establishing a link between impaired RPA-dependent processivity and telomeropathies. Our findings redefine human telomerase regulation by establishing RPA as a critical regulator and provide new insights into the molecular basis of telomere-related diseases.

molecular biology↗

bioRxiv2023

Selective Removal of 7KC by a Novel Atherosclerosis Therapeutic Candidate Reverts Foam Cells to a Macrophage-like Phenotype

The removal of the toxic oxidized cholesterol, 7-ketocholesterol (7KC), from cells through the administration of therapeutics has the potential to treat atherosclerosis and various other pathologies. While cholesterol is a necessary building block for homeostasis, oxidation of cholesterol can lead to the formation of toxic oxysterols involved in various pathologies, the most prominent of which is 7KC, which is formed through the non-enzymatic oxidation of cholesterol. Oxidized LDL (oxLDL) particles, highly implicated in heart disease, contain high levels of 7KC, and molecular 7KC is implicated in the pathogenesis of numerous diseases, including multiple sclerosis, hypercholesterolemia, sickle cell anemia, and multiple age related diseases. Of particular interest is the role of 7KC in the progression of atherosclerosis, with several studies associating elevated levels of 7KC with the etiology of the disease or in the transition of macrophages to foam cells. This research aims to elucidate the molecular mechanisms of UDP-003, a novel therapeutic, in mitigating the harmful effects of 7KC in mouse and human monocyte and macrophage cell lines. Experimental evidence demonstrates that administration of UDP-003 can reverse the foam cell phenotype, rejuvenating these cells by returning phagocytic function and decreasing both reactive oxygen species (ROS) and intracellular lipid droplet accumulation. Furthermore, our data suggests that the targeted removal of 7KC from foam cells with UDP-003 can potentially prevent and reverse atherosclerotic plaque formation. UDP-003 has the potential to be the first disease-modifying therapeutic approach to treating atherosclerotic disease.

cell biology↗