S-EPMC9010765 - The pattern of apolipoprotein A-I lysine carbamylation reflects its lipidation state and the chemical environment within human atherosclerotic aorta. - OmicsDI

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The pattern of apolipoprotein A-I lysine carbamylation reflects its lipidation state and the chemical environment within human atherosclerotic aorta.

ABSTRACT: Protein lysine carbamylation is an irreversible post-translational modification resulting in generation of homocitrulline (N-ε-carbamyllysine), which no longer possesses a charged ε-amino moiety. Two distinct pathways can promote protein carbamylation. One results from urea decomposition, forming an equilibrium mixture of cyanate (CNO^-) and the reactive electrophile isocyanate. The second pathway involves myeloperoxidase (MPO)-catalyzed oxidation of thiocyanate (SCN^-), yielding CNO^- and isocyanate. Apolipoprotein A-I (apoA-I), the major protein constituent of high-density lipoprotein (HDL), is a known target for MPO-catalyzed modification in vivo, converting the cardioprotective lipoprotein into a proatherogenic and proapoptotic one. We hypothesized that monitoring site-specific carbamylation patterns of apoA-I recovered from human atherosclerotic aorta could provide insights into the chemical environment within the artery wall. To test this, we first mapped carbamyllysine obtained from in vitro carbamylation of apoA-I by both the urea-driven (nonenzymatic) and inflammatory-driven (enzymatic) pathways in lipid-poor and lipidated apoA-I (reconstituted HDL). Our results suggest that lysine residues within proximity of the known MPO-binding sites on HDL are preferentially targeted by the enzymatic (MPO) carbamylation pathway, whereas the nonenzymatic pathway leads to nearly uniform distribution of carbamylated lysine residues along the apoA-I polypeptide chain. Quantitative proteomic analyses of apoA-I from human aortic atheroma identified 16 of the 21 lysine residues as carbamylated and suggested that the majority of apoA-I carbamylation in vivo occurs on "lipid-poor" apoA-I forms via the nonenzymatic CNO^- pathway. Monitoring patterns of apoA-I carbamylation recovered from arterial tissues can provide insights into both apoA-I structure and the chemical environment within human atheroma.

SUBMITTER: Battle S

PROVIDER: S-EPMC9010765 | biostudies-literature | 2022 Apr

REPOSITORIES: biostudies-literature

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The pattern of apolipoprotein A-I lysine carbamylation reflects its lipidation state and the chemical environment within human atherosclerotic aorta.

Battle Shawna S Gogonea Valentin V Willard Belinda B Wang Zeneng Z Fu Xiaoming X Huang Ying Y Graham Linda M LM Cameron Scott J SJ DiDonato Joseph A JA Crabb John W JW Hazen Stanley L SL

The Journal of biological chemistry 20220315 4

Protein lysine carbamylation is an irreversible post-translational modification resulting in generation of homocitrulline (N-ε-carbamyllysine), which no longer possesses a charged ε-amino moiety. Two distinct pathways can promote protein carbamylation. One results from urea decomposition, forming an equilibrium mixture of cyanate (CNO<sup>-</sup>) and the reactive electrophile isocyanate. The second pathway involves myeloperoxidase (MPO)-catalyzed oxidation of thiocyanate (SCN<sup>-</sup>), yiel ...[more]

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Project description:Protein lysine residue carbamylation is an irreversible post-translational modification, resulting in the generation of protein-bound homocitrulline (N--carbamyllysine). Carbamylation alters protein structure and can thus also alter protein function because of the loss of the charged -amino lysine moiety. Two distinct pathways can promote protein carbamylation. The first pathway occurs as a result of urea decomposition forming an equilibrium mixture of cyanate (CNO-) and the reactive electrophile isocyanate; the second (enzymatic) pathway occurs from myeloperoxidase (MPO)–catalyzed oxidation of thiocyanate (SCN-), yielding CNO- and isocyanate. We and others have previously shown that apolipoprotein A-I (apoA-I), the major protein constituent of high density lipoprotein (HDL), is a target for MPO-catalyzed modification in vivo altering its function, converting the traditionally cardio-protective lipoprotein into a pro-atherogenic and pro-apoptotic one. We hypothesized that insights into the chemical environment within the human artery wall could be gained by monitoring site-specific carbamylation patterns of apoA-I recovered from human atherosclerotic aorta. Toward testing this hypothesis, we first mapped and quantified carbamyllysine obtained from in vitro carbamylation of apoA-I by: (i) the urea driven (cyanate) vs. the inflammatory driven (MPO) pathways; as well as (ii) in lipid-poor vs. lipidated apoA-I (reconstituted nascent HDL). Our in vitro studies, interpreted in the context of existing structural models, suggest lysine residues within regional proximity of the known MPO binding sites on HDL are preferentially targeted by the enzymatic (MPO) carbamylation pathway, whereas the non-enzymatic (cyanate) pathway leads to nearly uniform distribution of carbamylated lysine residues along the apoA-I polypeptide chain. Quantitative proteomic analyses of apoA-I recovered from human aortic atheroma identified 16 of the 21 total lysine residues as carbamylated and suggests that the majority of apoA-I carbamylation in vivo occurs via the non-enzymatic cyanate pathway, and on ‘lipid-poor’ apoA-I forms. Monitoring the patterns of post translational modification of apoA-I lysine residues in vivo can provide insights into the chemical environment within human atheroma.

Project description:Background Penetrating ulcers of aorta, aortic dissections and intramural hematomas all come under acute aortic syndromes and have important similarities and differences. Case report We report a 67?year old man with rupture of a large penetrating ulcer of the distal ascending aorta with hemopericardium and left hemothorax. He underwent interposition graft replacement of ascending aorta and hemi-arch with a 30?mm Gelweave Vascutek graft but represented 6?months later with development of a penetrating ulcer which ruptured into a huge 14?cm pseudoaneurysm. This was repaired with a 28?mm Vascutek Gelseal graft replacement of arch and interposition graft reconstruction of innominate and left common carotid arteries. 6?weeks later, however, he ruptured his proximal descending aorta and underwent TEVAR satisfactorily. Unfortunately, 2?days later, he developed a pathological fracture of left proximal tibia with metastasis from a primary renal cell carcinoma. He died 3?weeks later from respiratory failure. We shall briefly outline the similarities and differences in presentation and management of penetrating aortic ulcers, aortic dissections and intramural haematomas. We shall discuss, in greater detail, penetrating ulcers of thoracic aorta, their natural history, location, complications and management. Conclusion This case report is unique on account of initial successful surgical redressal following rupture of penetrating ulcer of distal ascending aorta into left pleural and pericardial cavities, normally associated with instant death. The haemodynamic effects of the rupture were staggered due to initial contained rupture into a smaller pseudoaneurysm, followed by a further rupture into a false aneurysmal sac followed eventually by generalised rupture into the pleural and pericardial cavities - a unique way of aortic rupture. Further development of another penetrating ulcer and a small pseudoaneurysm in the distal arch 6?months later which further ruptured into a larger 14?cm false aneurysmal sac, which again did not result in exsanguination, is again extraordinarily rare. Thereafter he underwent emergency thoracic endovascular aortic repair (TEVAR) for a further rupture of descending thoracic aorta. All three ruptures were managed successfully and would usually be associated with near-certain death, only for the patient to succumb eventually to the complications of metastatic renal cell carcinoma.

Project description:Sporadic Alzheimer disease (AD) is caused in part by decreased clearance of the ?-amyloid (A?) peptide breakdown products. Lipid-depleted (LD) apolipoproteins are less effective at binding and clearing A?, and LD A? peptides are more toxic to neurons. However, not much is known about the lipid states of these proteins in human cerebrospinal fluid.To characterize the lipidation states of A? peptides and apolipoprotein E in the cerebrospinal fluid in adults with respect to cognitive diagnosis and APOE ?4 allele carrier status and after a dietary intervention.Randomized clinical trial.Veterans Affairs Medical Center clinical research unit.Twenty older adults with normal cognition (mean [SD] age, 69 [7] years) and 27 with amnestic mild cognitive impairment (67 [6] years).Randomization to a diet high in saturated fat content and with a high glycemic index (High diet; 45% of energy from fat [>25% saturated fat], 35%-40% from carbohydrates with a mean glycemic index >70, and 15%-20% from protein) or a diet low in saturated fat content and with a low glycemic index (Low diet; 25% of energy from fat [<7% saturated fat], 55%-60% from carbohydrates with a mean glycemic index <55, and 15%-20% from protein).Lipid-depleted A?42 and A?40 and apolipoprotein E in cerebrospinal fluid.Baseline levels of LD A? were greater for adults with mild cognitive impairment compared with adults with normal cognition (LD A?42, P = .05; LD A?40, P = .01). These findings were magnified in adults with mild cognitive impairment and the ?4 allele, who had higher LD apolipoprotein E levels irrespective of cognitive diagnosis (P < .001). The Low diet tended to decrease LD A? levels, whereas the High diet increased these fractions (LD A?42, P = .01; LD A?40, P = .15). Changes in LD A? levels with the Low diet negatively correlated with changes in cerebrospinal fluid levels of insulin (LD A?42 and insulin, r = -0.68 [P = .01]; LD A?40 and insulin, r = -0.78 [P = .002]).The lipidation states of apolipoproteins and A? peptides in the brain differ depending on APOE genotype and cognitive diagnosis. Concentrations can be modulated by diet. These findings may provide insight into the mechanisms through which apolipoprotein E4 and unhealthy diets impart risk for developing AD.