The NTPase activity of the double FYVE domain-containing protein 1 regulates lipid droplet metabolism.

Lipid droplets (LDs) are transient lipid storage organelles that can be readily tapped to resupply cells with energy or lipid building blocks and therefore play a central role in cellular metabolism. However, the molecular factors and underlying mechanisms that regulate the growth and degradation of LDs are poorly understood. It has emerged that proteins that establish contacts between LDs and the endoplasmic reticulum play a critical role in regulating LD metabolism. Recently, the autophagy-related protein, double FYVE domain-containing protein 1 (DFCP1/ZFYVE1) was shown to reside at the interface of the endoplasmic reticulum and LDs, however, little is known about the involvement of DFCP1 in autophagy and LD metabolism. Here, we show that DFCP1 is a novel NTPase that regulates free fatty acid metabolism. Specifically, we show that DFPC1-knockdown, particularly during starvation, increases cellular free fatty acids and decreases the levels of cellular TAGs, resulting in accumulated small LDs. Using selective truncations, we demonstrate that DFCP1 accumulation on LDs in cells and in vitro is regulated by a previously unknown NTPase domain. Using spectroscopic approaches, we show that this NTPase domain can dimerize and can hydrolyze both ATP and GTP. Furthermore, mutations in DFCP1 that either impact nucleotide hydrolysis or dimerization result in changes in the accumulation of DFCP1 on LDs, changes in LD density and size, and colocalization of LDs to autophagosomes. Collectively, our findings suggest that DFCP1 is an NTPase that modulates the metabolism of LDs in cells.

Visualization of atherosclerosis as detected by coronary artery calcium and carotid intima-media thickness reveals significant atherosclerosis in a cross-sectional study of psoriasis patients in a tertiary care center.

BACKGROUND: Psoriasis is a chronic inflammatory disease of the skin and joints that may also have systemic inflammatory effects, including the development of cardiovascular disease (CVD). Multiple epidemiologic studies have demonstrated increased rates of CVD in psoriasis patients, although a causal link has not been established. A growing body of evidence suggests that sub-clinical systemic inflammation may develop in psoriasis patients, even from a young age. We aimed to evaluate the prevalence of atherosclerosis and identify specific clinical risk factors associated with early vascular inflammation. METHODS: We conducted a cross-sectional study of a tertiary care cohort of psoriasis patients using coronary artery calcium (CAC) score and carotid intima-media thickness (CIMT) to detect atherosclerosis, along with high sensitivity C-reactive protein (hsCRP) to measure inflammation. Psoriasis patients and controls were recruited from our tertiary care dermatology clinic. Presence of atherosclerosis was defined using validated numeric values within CAC and CIMT imaging. Descriptive data comparing groups was analyzed using Welch's t test and Pearson Chi square tests. Logistic regression was used to analyze clinical factors associated with atherosclerosis, and linear regression to evaluate the relationship between psoriasis and hsCRP. RESULTS: 296 patients were enrolled, with 283 (207 psoriatic and 76 controls) having all data for the hsCRP and atherosclerosis analysis. Atherosclerosis was found in 67.6 % of psoriasis subjects versus 52.6 % of controls; Psoriasis patients were found to have a 2.67-fold higher odds of having atherosclerosis compared to controls [95 % CI (1.2, 5.92); p = 0.016], after adjusting for age, gender, race, BMI, smoking, HDL and hsCRP. In addition, a non-significant trend was found between HsCRP and psoriasis severity, as measured by PASI, PGA, or BSA, again after adjusting for confounders. CONCLUSIONS: A tertiary care cohort of psoriasis patients have a high prevalence of early atherosclerosis, increased hsCRP, and psoriasis remains a risk factor for the presence of atherosclerosis even after adjustment of key confounding clinical factors. Psoriasis may contribute to an accelerated systemic inflammatory cascade resulting in increased risk of CVD and CV events.