scholarly journals ApoE and apoC-III-defined HDL subtypes: A descriptive study of their lecithin cholesterol acyl transferase and cholesteryl ester transfer protein content and activity

2020 ◽  
Author(s):  
Mateo Amaya-Montoya ◽  
Jairo A Pinzón-Cortés ◽  
Lina S Silva-Bermúdez ◽  
Daniel Ruiz-Manco ◽  
Maria C Perez-Matos ◽  
...  
Keyword(s):  
Size Distribution ◽  
Plasma Cholesterol ◽  
Inverse Correlation ◽  
High Density Lipoproteins ◽  
Acyl Transferase ◽  
Lcat Activity ◽  
Cholesterol Acyl Transferase ◽  
Lecithin Cholesterol Acyl Transferase ◽  
Transfer Protein ◽  
Plasma Lcat

Abstract Background The functionality of high-density lipoproteins (HDL) is a better cardiovascular risk predictor than HDL concentrations. One of the key elements of HDL functionality is its apolipoprotein composition. Lecithin-cholesterol acyl transferase (LCAT) and cholesterol-ester transfer protein (CETP) are enzymes involved in HDL-mediated reverse cholesterol transport. This study assessed the concentration and activity of LCAT and CETP in HDL subspecies defined by their content of apolipoproteins E (apoE) and C-III (apoC-III) in humans. Methods Eighteen adults (ten women and eight men, mean age 55.6, BMI 26.9 Kg/m 2 , HbA1c 5.4%) were studied. HDL from each participant were isolated and divided into four subspecies containing respectively: No apoE and no apoC-III (E-C-), apoE but not apoC-III (E+C-), apoC-III but no apoE (E-C+) and both apoE and apoC-III (E+C+). The concentration and enzymatic activity of LCAT and CETP were measured within each HDL subspecies using immunoenzymatic and fluorometric methods. Additionally, the size distribution of HDL in each apolipoprotein-defined fraction was determined using non-denaturing electrophoresis and anti-apoA-I western blotting. Results HDL without apoE or apoC-III was the predominant HDL subtype. The size distribution of HDL was very similar in all the four apolipoprotein-defined subtypes. LCAT was most abundant in E-C- HDL (3.58 mg/mL, 59.6 % of plasma LCAT mass), while HDL with apoE or apoC-III had much less LCAT (19.8%, 12.2% and 8.37% of plasma LCAT respectively for E+C-, E-C+ and E+C+). LCAT mass was lower in E+C- HDL relative to E-C- HDL, but LCAT activity was similar in both fractions, signaling a greater activity-to-mass ratio associated with the presence of apoE. Both CETP mass and CETP activity showed only slight variations across HDL subspecies. There was an inverse correlation between plasma LCAT activity and concentrations of both E-C+ pre-beta HDL (r=-0.55, P =0.017) and E-C- alpha 1 HDL (r=-0.49, P =0.041). Conversely, there was a direct correlation between plasma CETP activity and concentrations of E-C+ alpha 1 HDL (r=0.52, P =0.025). Conclusions The presence of apoE in small HDL is correlated with increased LCAT activity and esterification of plasma cholesterol. These results favor an interpretation that LCAT and apoE interact to enhance anti-atherogenic pathways of HDL.

scholarly journals ApoE and apoC-III-defined HDL subtypes: A descriptive study of their LCAT and CETP content and activity

2020 ◽  
Author(s):  
Mateo Amaya-Montoya ◽  
Jairo A Pinzón-Cortés ◽  
Lina S Silva-Bermúdez ◽  
Daniel Ruiz-Manco ◽  
Maria C Perez-Matos ◽  
...  
Keyword(s):  
Size Distribution ◽  
Plasma Cholesterol ◽  
Inverse Correlation ◽  
High Density Lipoproteins ◽  
Lcat Activity ◽  
Cholesterol Acyl Transferase ◽  
Lecithin Cholesterol Acyl Transferase ◽  
Transfer Protein ◽  
Plasma Lcat ◽  
Apolipoproteins E

Abstract Background High-density lipoproteins (HDL) in plasma are strongly and negatively associated with cardiovascular risk, yet interventions to raise HDL have not improved cardiovascular outcomes. HDL functionality and heterogeneity may hold the clue to this paradox. The apolipoprotein composition of HDL may be an important determinant of their functionality. Lecithin-cholesterol acyl transferase (LCAT) and cholesterol-ester transfer protein (CETP) are key enzymes for HDL-mediated reverse cholesterol transport. We assessed the distribution and activity of LCAT and CETP in HDL subspecies defined by their content of apolipoproteins E (apoE) and C-III (apoC-III) in humans. Methods We isolated in adult humans of both sexes (mean age 55.6, BMI 26.9 Kg/m2, HbA1c 5.4%), four subspecies of HDL containing respectively: No apoE and no apoC-III (E-C-), apoE but not apoC-III (E+C-), apoC-III but no apoE (E-C+) and both apoE and apoC-III (E+C+). In each HDL subspecies, we measured LCAT and CETP concentration and activity using immunoenzymatic and fluorometric methods. Additionally, we determined the size distribution of HDL in each apolipoprotein-defined fraction using non-denaturing electrophoresis and anti-ApoA-I western blot. Results Similar to previous studies, HDL in the E-C- fraction was the predominant subtype. The size distribution of HDL was very similar across all four apolipoprotein-defined fractions. LCAT was most abundant in E-C- HDL (3.58 mg/mL, 59.6 % of plasma LCAT mass), while HDL with apoE or apoC-III had much less LCAT (19.8%, 12.2% and 8.37% of plasma LCAT respectively for E+C-, E-C+ and E+C+). Despite a much lower LCAT mass, LCAT activity in E+C- HDL was comparable to that in E-C- HDL. Both CETP mass and CETP activity showed only slight variations across HDL subspecies. There was an inverse correlation between plasma LCAT activity and both E-C+ pre-beta HDL (r=-0.55, p=0.017) and E-C- alpha 1 HDL (r=-0.49, p=0.041). Conversely, there was a direct correlation between E-C+ alpha 1 HDL and CETP activity in plasma (r=0.52, p=0.025). Conclusions Our results suggest that LCAT activity in humans is influenced by the presence of small interchangeable apolipoproteins. The presence of apoE in small HDL is correlated with increased LCAT activity and esterification of plasma cholesterol.

scholarly journals ApoE and apoC-III-defined HDL subtypes: A descriptive study of their LCAT and CETP content and activity

2020 ◽  
Author(s):  
Mateo Amaya-Montoya ◽  
Jairo A Pinzón-Cortés ◽  
Lina S Silva-Bermúdez ◽  
Daniel Ruiz-Manco ◽  
Maria C Perez-Matos ◽  
...  
Keyword(s):  
Size Distribution ◽  
Plasma Cholesterol ◽  
Inverse Correlation ◽  
High Density Lipoproteins ◽  
Lcat Activity ◽  
Cholesterol Acyl Transferase ◽  
Lecithin Cholesterol Acyl Transferase ◽  
Transfer Protein ◽  
Plasma Lcat ◽  
Apolipoproteins E

Abstract Background High-density lipoproteins (HDL) functionality predicts cardiovascular risk better than HDL concentrations. The apolipoprotein composition of HDL may be a determinant of their function. Lecithin-cholesterol acyl transferase (LCAT) and cholesterol-ester transfer protein (CETP) are key enzymes for HDL-mediated reverse cholesterol transport. We assessed the distribution and activity of LCAT and CETP in HDL subspecies defined by their content of apolipoproteins E (apoE) and C-III (apoC-III) in humans. Methods We isolated in 18 adult humans of both sexes (mean age 55.6, BMI 26.9 Kg/m2, HbA1c 5.4%), four subspecies of HDL containing respectively: No apoE and no apoC-III (E-C-), apoE but not apoC-III (E+C-), apoC-III but no apoE (E-C+) and both apoE and apoC-III (E+C+). In each HDL subspecies, we measured LCAT and CETP concentration and activity using immunoenzymatic and fluorometric methods. Additionally, we determined the size distribution of HDL in each apolipoprotein-defined fraction using non-denaturing electrophoresis and anti-ApoA-I western blot. Results Similar to previous studies, HDL in the E-C- fraction was the predominant subtype. The size distribution of HDL was very similar across all four apolipoprotein-defined fractions. LCAT was most abundant in E-C- HDL (3.58 mg/mL, 59.6 % of plasma LCAT mass), while HDL with apoE or apoC-III had much less LCAT (19.8%, 12.2% and 8.37% of plasma LCAT respectively for E+C-, E-C+ and E+C+). LCAT mass was lower in E+C- HDL relative to E-C- HDL, but LCAT activity was similar in both fractions, signaling a greater activity-to-mass ratio associated with the presence of apoE. Both CETP mass and CETP activity showed only slight variations across HDL subspecies. There was an inverse correlation between plasma LCAT activity and both E-C+ pre-beta HDL (r=-0.55, p=0.017) and E-C- alpha 1 HDL (r=-0.49, p=0.041). Conversely, there was a direct correlation between E-C+ alpha 1 HDL and CETP activity in plasma (r=0.52, p=0.025). Conclusions Our results suggest that LCAT activity in humans is influenced by the presence of small interchangeable apolipoproteins. The presence of apoE in small HDL is correlated with increased LCAT activity and esterification of plasma cholesterol.

Abstract 541: The Molecular Interaction of Apolipoprotein A-I Containing High Density Lipoproteins with Lecithin: Cholesterol Acyl Transferase

2016 ◽  
Vol 36 (suppl_1) ◽  
Author(s):  
Allison Cooke ◽  
John T Melchior ◽  
Jamie C Morris ◽  
Rong Huang ◽  
W. Gray Jerome ◽  
...  
Keyword(s):  
Protein Interactions ◽  
Density Lipoprotein ◽  
Negative Control ◽  
High Density ◽  
High Density Lipoproteins ◽  
Acyl Transferase ◽  
Lcat Activity ◽  
Wild Type ◽  
Cholesterol Acyl Transferase ◽  
Hdl Function

The structure of apolipoprotein (apo)A-I on a high density lipoprotein (HDL) particle can elucidate the protein interactions and cardioprotective functions of HDL. This includes critical interactions with HDL modifying proteins like lecithin:cholesterol acyl transferase (LCAT) which performs a key function in reverse cholesterol transport by using apoA-I as a cofactor to esterify cholesterol. Data from our lab and others demonstrate that apoA-I molecules dimerize into an antiparallel stacked ring structure that encapsulates lipid in reconstituted (r)HDL particles. Cross-linking analysis of rHDL particles imply two possible registries: one with the fifth helical repeat of an apoA-I molecule adjacent to the fifth helical repeat of its antiparallel partner (5/5), and the other with the fifth helical repeat adjacent to the second helical repeat of its antiparallel partner (5/2). We hypothesized that apoA-I registry on rHDL can modulate LCAT activity. Site-directed cysteine mutagenesis was used to lock two apoA-I molecules into each of the aforementioned helical registries, and an intermediate registry created as a negative control. rHDL particles were generated using these dimerized mutants, and their ability to activate LCAT was determined. The 5/5 mutant demonstrated higher LCAT activity than wild-type rHDL particles while the 5/2 and intermediate mutants showed dramatically lower LCAT activity (p<0.001). To determine where LCAT interacts with apoA-I, rHDL containing wild-type apoA-I was cross-linked to LCAT. The majority of the cross-links were concentrated between S240 of LCAT and a region encompassing helices 4-6 of apoA-I. We propose that LCAT binds to a discontinuous epitope comprised of two apoA-I molecules in rHDL and that changes in this registry can alter LCAT function. These studies provide a basis for understanding how apoA-I structure may modulate the association and activity of a multitude of different HDL protein partners. This implicates apoA-I conformation as a target for altering HDL function in order to enhance the cardioprotective properties of HDL.

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