| 1. |
- Kristensen, Kristian K., et al.
(författare)
-
A disordered acidic domain in GPIHBP1 harboring a sulfated tyrosine regulates lipoprotein lipase
- 2018
-
Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 115:26, s. E6020-E6029
-
Tidskriftsartikel (refereegranskat)abstract
- The intravascular processing of triglyceride-rich lipoproteins depends on lipoprotein lipase (LPL) and GPIHBP1, a membrane protein of endothelial cells that binds LPL within the subendothelial spaces and shuttles it to the capillary lumen. In the absence of GPIHBP1, LPL remains mislocalized within the subendothelial spaces, causing severe hypertriglyceridemia (chylomicronemia). The N-terminal domain of GPIHBP1, an intrinsically disordered region (IDR) rich in acidic residues, is important for stabilizing LPL's catalytic domain against spontaneous and ANGPTL4-catalyzed unfolding. Here, we define several important properties of GPIHBP1's IDR. First, a conserved tyrosine in the middle of the IDR is posttranslationally modified by O-sulfation; this modification increases both the affinity of GPIHBP1-LPL interactions and the ability of GPIHBP1 to protect LPL against. ANGPTL4-catalyzed unfolding. Second, the acidic IDR of GPIHBP1 increases the probability of a GPIHBP1-LPL encounter via electrostatic steering, increasing the association rate constant (k(on)) for LPL binding by >250-fold. Third, we show that LPL accumulates near capillary endothelial cells even in the absence of GPIHBP1. In wild-type mice, we expect that the accumulation of LPL in close proximity to capillaries would increase interactions with GPIHBP1. Fourth, we found that GPIHBP1's IDR is not a key factor in the pathogenicity of chylomicronemia in patients with the GPIHBP1 autoimmune syndrome. Finally, based on biophysical studies, we propose that the negatively charged IDR of GPIHBP1 traverses a vast space, facilitating capture of LPL by capillary endothelial cells and simultaneously contributing to GPIHBP1's ability to preserve LPL structure and activity.
|
|
| 2. |
- Mohammad, M. A., et al.
(författare)
-
Trends in Clinical Practice and Outcomes After Percutaneous Coronary Intervention of Unprotected Left Main Coronary Artery
- 2022
-
Ingår i: Journal of the American Heart Association. - : Ovid Technologies (Wolters Kluwer Health). - 2047-9980. ; 11:7
-
Tidskriftsartikel (refereegranskat)abstract
- Background The use of percutaneous coronary intervention (PCI) to treat unprotected left main coronary artery disease has expanded rapidly in the past decade. We aimed to describe nationwide trends in clinical practice and outcomes after PCI for left main coronary artery disease. Methods and Results Patients (n=4085) enrolled in the SCAAR (Swedish Coronary Angiography and Angioplasty Registry) as undergoing PCI for left main coronary artery disease from 2005 to 2017 were included. A count regression model was used to analyze time-related differences in procedural characteristics. The 3-year major adverse cardiovascular and cerebrovascular event rate defined as death, myocardial infarction, stroke, and repeat revascularization was calculated with the Kaplan-Meier estimator and Cox proportional hazard model. The number of annual PCI procedures grew from 121 in 2005 to 589 in 2017 (389%). The increase was greater for men (479%) and individuals with diabetes (500%). Periprocedural complications occurred in 7.9%, decreasing from 10% to 6% during the study period. A major adverse cardiovascular and cerebrovascular event occurred in 35.7% of patients, falling from 45.6% to 23.9% (hazard ratio, 0.56; 95% CI, 0.41-0.78; P=0.001). Radial artery access rose from 21.5% to 74.2% and intracoronary diagnostic procedures from 14.0% to 53.3%. Use of bare-metal stents and first-generation drug-eluting stents fell from 19.0% and 71.9%, respectively, to 0, with use of new-generation drug-eluting stents increasing to 95.2%. Conclusions Recent changes in clinical practice relating to PCI for left main coronary artery disease are characterized by a 4-fold rise in procedures conducted, increased use of evidence-based adjunctive treatment strategies, intracoronary diagnostics, newer stents, and more favorable outcomes.
|
|
| 3. |
- Savonen, R, et al.
(författare)
-
Chylomicron metabolism in an animal model for hyperlipoproteinemia type I.
- 1999
-
Ingår i: Journal of Lipid Research. - 0022-2275 .- 1539-7262. ; 40:7, s. 1336-46
-
Tidskriftsartikel (refereegranskat)abstract
- Mink homozygous for the mutation Pro214Leu in lipoprotein lipase (LPL) had only traces of LPL activity but amounts of LPL protein in their tissues similar to those of normal mink. In normal mink, lymph chylomicrons from rats given [3H]retinol (incorporated into retinyl esters, providing a core label) and [14C]oleic acid (incorporated mainly in triglycerides (TG)) were rapidly cleared from the circulation. In the homozygous mink, clearance was much retarded. The ratio of TG to core label in plasma did not decrease and much less [14C]oleic acid appeared in plasma. Still, half of the labeled material disappeared from the circulating blood within 30;-40 min and the calculated total turnover of TG in the hypertriglyceridemic mink was almost as large as in normal mink. The core label was distributed to the same tissues in hypertriglyceridemic mink as in normal mink. Half to two-thirds of the cleared core label was in the liver. The large difference was that in the hypertriglyceridemic mink, TG label (about 40% of the total amount removed) followed the core label to the liver and there was no preferential uptake of TG over core label in adipose or muscle tissue. In normal mink, only small amounts of TG label (<10%) appeared in the liver, while most was in adipose and muscle tissues. Apolipoprotein B-48 dominated in the accumulated TG-rich lipoproteins in blood of hypertriglyceridemic mink, even in fasted animals.
|
|
| 4. |
- Dorfmeister, B, et al.
(författare)
-
Effects of six APOA5 variants, identified in patients with severe hypertriglyceridemia, on in vitro lipoprotein lipase activity and receptor binding
- 2008
-
Ingår i: Arteriosclerosis, Thrombosis and Vascular Biology. - 1079-5642 .- 1524-4636. ; 28:10, s. 1866-1871
-
Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE: The purpose of this study was to identify rare APOA5 variants in 130 severe hypertriglyceridemic patients by sequencing, and to test their functionality, since no patient recall was possible. METHODS AND RESULTS: We studied the impact in vitro on LPL activity and receptor binding of 3 novel heterozygous variants, apoAV-E255G, -G271C, and -H321L, together with the previously reported -G185C, -Q139X, -Q148X, and a novel construct -Delta139 to 147. Using VLDL as a TG-source, compared to wild type, apoAV-G255, -L321 and -C185 showed reduced LPL activation (-25% [P=0.005], -36% [P<0.0001], and -23% [P=0.02]), respectively). ApoAV-C271, -X139, -X148, and Delta139 to 147 had little affect on LPL activity, but apoAV-X139, -X148, and -C271 showed no binding to LDL-family receptors, LR8 or LRP1. Although the G271C proband carried no LPL and APOC2 mutations, the H321L carrier was heterozygous for LPL P207L. The E255G carrier was homozygous for LPL W86G, yet only experienced severe hypertriglyceridemia when pregnant. CONCLUSIONS: The in vitro determined function of these apoAV variants only partly explains the high TG levels seen in carriers. Their occurrence in the homozygous state, coinheritance of LPL variants or common APOA5 TG-raising variant in trans, appears to be essential for their phenotypic expression.
|
|
| 5. |
- Kristensen, Kristian K., et al.
(författare)
-
Unfolding of monomeric lipoprotein lipase by ANGPTL4 : Insight into the regulation of plasma triglyceride metabolism
- 2020
-
Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 117:8, s. 4337-4346
-
Tidskriftsartikel (refereegranskat)abstract
- The binding of lipoprotein lipase (LPL) to GPIHBP1 focuses the intravascular hydrolysis of triglyceride-rich lipoproteins on the surface of capillary endothelial cells. This process provides essential lipid nutrients for vital tissues (e.g., heart, skeletal muscle, and adipose tissue). Deficiencies in either LPL or GPIHBP1 impair triglyceride hydrolysis, resulting in severe hypertriglyceridemia. The activity of LPL in tissues is regulated by angiopoietin-like proteins 3, 4, and 8 (ANGPTL). Dogma has held that these ANGPTLs inactivate LPL by converting LPL homodimers into monomers, rendering them highly susceptible to spontaneous unfolding and loss of enzymatic activity. Here, we show that binding of an LPL-specific monoclonal antibody (5D2) to the tryptophan-rich lipid-binding loop in the carboxyl terminus of LPL prevents homodimer formation and forces LPL into a monomeric state. Of note, 5D2-bound LPL monomers are as stable as LPL homodimers (i.e., they are not more prone to unfolding), but they remain highly susceptible to ANGPTL4-catalyzed unfolding and inactivation. Binding of GPIHBP1 to LPL alone or to 5D2-bound LPL counteracts ANGPTL4-mediated unfolding of LPL. In conclusion, ANGPTL4-mediated inactivation of LPL, accomplished by catalyzing the unfolding of LPL, does not require the conversion of LPL homodimers into monomers. Thus, our findings necessitate changes to long-standing dogma on mechanisms for LPL inactivation by ANGPTL proteins. At the same time, our findings align well with insights into LPL function from the recent crystal structure of the LPL•GPIHBP1 complex.
|
|
| 6. |
|
|
| 7. |
|
|
| 8. |
|
|
