Coronary endothelial dysfunction appears to be a manifestation of a systemic process: A report from the Women’s Ischemia Syndrome Evaluation – Coronary Vascular Dysfunction (WISE-CVD) study

Background Coronary microvascular dysfunction (CMD) is prevalent in symptomatic women with ischemia but no obstructive coronary artery disease (INOCA). Urine albumin-creatinine ratio (UACR) is a measure of renal microvascular endothelial dysfunction. Both are predictors of adverse cardiovascular events. It is unknown if CMD could be a manifestation of a systemic process. We evaluated the relationship between renal microvascular dysfunction and CMD as measured by invasive coronary function testing (CFT). Methods and results We measured urine albumin and creatinine to provide UACR in 152 women enrolled in the Women’s Ischemia Syndrome Evaluation–Coronary Vascular Dysfunction (WISE-CVD) study (2008–2015) with suspected INOCA who underwent CFT. Invasive CFT measures of endothelial and non-endothelial dependent coronary microvascular function were obtained. Subjects were divided into those with detectable (≥20 mg/g) and undetectable urine albumin (<20 mg/g). The group mean age was 54 ± 11 years, with a moderate cardiac risk factor burden including low diabetes prevalence, and a mean UACR of 12 ± 55 mg/g (range 9.5–322.7 mg/g). Overall, coronary endothelial-dependent variables (change in coronary blood flow and coronary diameter in response to cold pressor testing) had significant inverse correlations with log UACR (r = -0.17, p = 0.05; r = -0.18, p = 0.03, respectively). Conclusions Among women with INOCA and relatively low risk factor including diabetes burden, renal microvascular dysfunction, measured by UACR, is related to coronary endothelial-dependent CMD. These results suggest that coronary endothelial-dependent function may be a manifestation of a systemic process. Enhancing efferent arteriolar vasodilatation in both coronary endothelial-dependent function and renal microvascular dysfunction pose potential targets for investigation and treatment. Clinical trial registration https://clinicaltrials.gov/ct2/show/NCT00832702.

A Novel Chemical Attack on Notch-mediated transcription by targeting the NACK ATPase

Notch Activation Complex Kinase, NACK, is a component of the Notch transcriptional machinery critical to Notch-mediated tumorigenesis. However, the mechanism by which NACK regulates the Notch-mediated transcription is not well understood. Here we demonstrate that NACK binds and hydrolyses ATP and that only ATP-bound NACK is able to bind to the Notch Ternary Complex (NTC). Considering this we sought to identify inhibitors of this ATP-Dependent function and, using computational pipelines, discovered the first small molecule inhibitor of NACK, Z271-0326, that directly blocks the activity of Notch-mediated transcription and shows potent antitumor activity in PDX mouse models. In conclusion, we have discovered the first inhibitor that holds promise for efficacious treatment of Notch-driven cancers by blocking the Notch downstream NTC activity.

Collagen’s enigmatic, highly conserved N-glycan has an essential proteostatic function

Intracellular procollagen folding begins at the protein’s C-terminal propeptide (C-Pro) domain, which initiates triple-helix assembly and defines the composition and chain register of fibrillar collagen trimers. The C-Pro domain is later proteolytically cleaved and excreted from the body, while the mature triple helix is incorporated into the extracellular matrix. The procollagen C-Pro domain possesses a single N-glycosylation site that is widely conserved in all the fibrillar procollagens across humans and diverse other species. Given that the C-Pro domain is removed once procollagen folding is complete, the N-glycan might be presumed to be important for folding. Surprisingly, however, there is no difference in the folding and secretion of N-glycosylated versus non-N-glycosylated collagen type-I, leaving the function of the N-glycan unclear. We hypothesized that the collagen N-glycan might have a context-dependent function, specifically, that it could be required to promote procollagen folding only when proteostasis is challenged. We show that removal of the N-glycan from misfolding-prone C-Pro domain variants does indeed cause serious procollagen and ER proteostasis defects. The N-glycan promotes folding and secretion of destabilized C-Pro variants by providing access to the ER’s lectin-based chaperone machinery. Finally, we show that the C-Pro N-glycan is actually critical for the folding and secretion of even wild-type procollagen under ER stress conditions. Such stress is commonly incurred during development, wound healing, and other processes in which collagen production plays a key role. Collectively, these results establish an essential, context-dependent function for procollagen’s previously enigmatic N-glycan, wherein the carbohydrate moiety buffers procollagen folding against proteostatic challenge.

Comment on “Improved pivot-slide model of the motion of a curling rock”

We point out three errors in a recent paper that is based on one of our two papers. Together our two papers describe a first-principles “pivot-slide model” of the motion of a curling rock. The most serious error is that the “improved pivot-slide model” (Mancini and de Schoulepnikoff. Can. J. Phys. 97(12), 1301 (2019) doi: 10.1139/cjp-2018-0356 ) is based on only our first paper, whereas the most important work in our model was described in our second paper, which those authors have overlooked. Another error is that the authors claim we use constant friction, whereas we actually use a velocity-dependent formulation of the ice friction coefficient. Thirdly, the authors use a time-dependent function for the ratio of pivoting time to sliding time, whereas in our second paper, we showed from first principles that this ratio does not depend on time.

Influence of prostaglandins and endothelial-derived hyperpolarizing factors on brachial and popliteal endothelial-dependent function in young adults

We compared changes in upper- and lower-limb artery endothelial-dependent vasodilatory and vasoconstrictor responses between control, prostaglandin inhibition, and endothelial-derived hyperpolarizing factor inhibition conditions. Neither prostaglandins nor endothelial-derived hyperpolarizing factor influenced flow-mediated dilation responses in either the brachial or popliteal artery. In contrast, endothelial-derived hyperpolarizing factor, but not prostaglandins, reduced resting brachial artery blood flow and shear rate and resting popliteal artery diameter, as well as low-flow-mediated constriction responses in both the popliteal and brachial arteries.

Beyond the RNA-dependent function of LncRNA genes

While long non-coding RNA (lncRNA) genes have attracted a lot of attention in the last decade, the focus regarding their mechanisms of action has been primarily on the RNA product of these genes. Recent work on several lncRNAs genes demonstrates that not only is the produced RNA species important, but also that transcription of the lncRNA locus alone can have regulatory functions. Like the functions of lncRNA transcripts, the mechanisms that underlie these genome-based functions are varied. Here we highlight some of these examples and provide an outlook on how the functional mechanisms of a lncRNA gene can be determined.