Human apolipoproptein A-I: 
Structure, function and patogenicity


Team of work

Garda, Horacio Alberto
Principal Investigator
hgarda@med.unlp.edu.ar
González, Marina Cecilia
Investigator
marinacego@hotmail.com
Toledo, Juan Domingo
Investigator
jtoledo51@hotmail.com
Jimenez Dalmaroni, Maximiliano
Guest Investigator
mjimenez@med.unlp.edu.ar
Díaz, Lodovico Ivo 
Research Fellow

diazludovico@gmail.com
Tarraga, Wilson
Research Fellow
wilson14_17@hotmail.com
Lynn, Soledad
Research Fellow
soledadlynn@gmail.com
Hernández, Laura Edith
Support Staff
lauraeh1900@hotmail.com
Bernasconi, Ana
Support Staff
ambernas@hotmail.com
   


Collaborators from other institutions

International


Gratton, Enrico
Laboratorio de Dinámica de fluorescencia. Universidad de California en Irvine. USA

Lamy, María T. 
Departamento de Física. Universidad de Sao Paulo. Sao Paulo. Brasil

Grasa, María del Mar
Universidad Autónoma de Barcelona (UB). España

Esteve, Montserrat
Universidad Autónoma de Barcelona (UB). España

Mendoza, Aminta 
Departamento de Física. Universidad Nacional de Colombia. Bogotá. Colombia

Soulages, José Luis 
Departamento de Bioquímica y Biología Molecular. Oklahoma. Universidad Estatal. USA


National

Gennaro, Ana María 
Departamento de Física. Universidad Nacional del Litoral. Santa Fé. Argentina


Line overview

Biochemistry and Biophysics of High-density lipoproteins (HDLs) apolipoprotein A-I

The apolipoprotein A-I (apoAI) is the major protein of high density lipoproteins (HDL) which serum levels are inversely related to atherogenic risk. Antiatherogenicity of apoAI and HDL may be attributed to their participation in the transport of excess cholesterol from peripheral tissues to liver for its catabolism and excretion, as well as their capacity to neutralize endotoxins and to inhibit the inflammatory response. 
In order to know the molecular mechanisms involved in this process, the structure-function-pathogenicity relationship of apoAI should be studied in the context of the following sublines.

Important conformational changes are necessary for the apoAI to alternate its functional cycle, either free or bound to lipid surfaces such as membranes or different HDL complexes. In its free state it presents a loose and flexible bunch of amphipatic helices which opens for the interaction of lipid surfaces. The goal of this work is to get insight into the structural basis of the apoAI interaction with lipids and conformational flexibility. In particular, we are interested in investigating a central protein region that would be involved in a structural, functional domain which would be responsible for the interaction of apoAI and discoidal HDL with membranes as well as for some cellular responses as the mobilization of endogenous stores of cholesterol. Different biophysical procedures have been used, either wild protein or with mutants at certain positions (trytophan or cysteine which are covalently bound to fluorescent or paramagnetic groups). These modified proteins are essential to know the reporting group, and estimate inter- or intra molecular distances that can reveal the spatial conformation. Also, a strategy to utilize computer methods for modeling and molecular dynamics has been designed.

Depending on the cell type, apoAI is able to trigger multiple responses, though mechanisms and involved signaling pathways are still poorly known. For the last years we have paid special attention to one of those responses that is the endogenous store mobilization of esterified cholesterol. Not only the identification of signaling pathways but also the functional domains involved in these cell responses are crucial to understand those processes at a molecular level. Different types of culture cells are utilized for investigating cell responses to apoAI, different types of HDL complexes, and artificial or natural mutants of apoAI. Thus, we try to gather information on the apoAI conformation and the involved protein domains. Currently, a natural mutant with a deletion at the central region (DK107) which carriers have an increased atherogenic risk is being investigated.

Inflammatory response mediated by Low Density Lipoproteins (LDLs)
and glucocorticoids
(PI: Gonzalez Marina).

Atherosclerosis is a pathology that involves an underlying inflammatory state which influences the progression of the disease. The pathology implies the synthesis of a great number of pro- and anti-inflammatory cytokines. Also the development of an atherosclerotic plaque starts with the recruitment and infiltration of circulating monocytes in areas of lipid deposition with physical damage in which “foams cells” macrophages or “foamy cells” are differentiated when endocyting altered lipoproteins such as oxidized low density lipoproteins (LDL-Ox) internalized in the arterial wall. Cortisol is a glucocorticoid with anti-inflammatory action that acts in the inflammatory resolution through, among other actions, the activation of the population of type M2c anti-inflammatory macrophages, inhibition of pro-inflammatory cytokines and inhibition of LDL-Ox-specific receptors (Toll like receptor type 4). The present line of work includes the study of molecular mechanisms involved in the endogenous anti-inflammatory response through glucocorticoids

Effects of inhibitors with antiatherogenic implication on the activity
of the lipid transfer protein (CETP).
(PI: Gonzalez Marina and Garda Horacio).

The cholesteryl ester transfer protein (CETP) has an integral role in the metabolism of plasmatic lipoproteins. CETP facilitates the remodeling of high density proteins (HDL) in plasma because it promotes apoA-I interconversion contained in the spherical HDLs in “lipid- poor particles” and preβ-HDLs, as well as it exchanges cholesteryl esters among the different subparticles of HDLs, activity named homotypic. Also CETP is involved in ester cholesterol (EC) transference from HDLs to low density and very low density lipoproteins (LDL and VLDL) and in the transference of triglycerides (TG) from VLDL/LDL to HDLs, activity named heterotypic. In this way, CETP favors the increase of cholesterol content in LDL with the subsequent propensity to the development of the atherogenic plaque. CETP heterotypic inhibition could be effective to reduce atherosclerosis by a mechanism dependent on the cholesterol reduction of VLDL-LDL and its increase in HDLs. The use of “in-silico” tools of molecular docking and virtual sieving are usually effective for the search of inhibitors.
The present line of research also includes biochemical testing methodology of inhibitors in macrophage cellular lines. CETP pharmacological inhibition could lead to a cardiovascular risk reduction what constitutes a current strategy of interest in the field of cardiovascular medicine.

 

Publications

 

  • Role of cortisol in inflammationtriggered by macrophages exposition to modified LDL.
    Toledo, J. D; Montserrat, E; Grasa, M. Del M; Ledda, A; Garda, H. A; Gulfo, J; Díaz, L. I; Ramella, N; Gonzalez, M. C.
    2016.
    Data in brief-journal: Elsevier, vol. 8, p. 251-257
  • Data related to inflammation and cholesterol deposition triggered by macrophages exposition to modified LDL.
    Toledo, J. D; Rafols, M; Grasa, M; Ledda, A; Garda, H. A; Gulfo, J; Diaz, L. I; Ramella, N; Gonzalez, M. C.
    2016. Data in brief: Elsevier, vol. 8, p. 251-257
  • Decreased OxLDL uptake and cholesterol efflux in THP1 cells elicited by cortisol and by cortisone through 11b-hydroxysteroid dehydrogenase type 1.
    Ledda, A; Gonzalez. M; Gulfo, J; Díaz, L. I; Ramella, N; Toledo, J; Garda, H; Grasa, M; Montserrat, E.
    2016. Atherosclerosis. Amsterdam: ELSEVIER IRELAND LTD, vol. 250, p. 84-94. ISSN 0021-9150

  • Aminolevulinic acid dendrimers in photodynamic treatment of cancer and atheromatous disease.
    Rodriguez, L; Vallecorsa, P; Battah, S; Di Venosa, G; Calvo, G; Mamone, L; Saenz, D; Gonzalez, M. C; Batlle, A; Macrobert, A. J; Casas, A.
    2015. Photochemical and Photobiological Sciences. , CAMBRIDGE: ROYAL SOC CHEMISTRY. vol. 14, n° 9, p. 1617-1627. ISSN 1474-905X

  • Apolipoprotein A-I configuration and cell cholesterol efflux activity of discoidal lipoproteins depend on the reconstitution process.
    Cuellar, L. A; Prieto, E; Cabaleiro, L; Garda, H. A. 
    2014. Biochimica et Biophysica acta-molecular and cell biology of lipids. , Amsterdam: ELSEVIER SCIENCE BV,. vol. 1841, p. 180-189. ISSN 1388-1981

  • Apolipoprotein A-I Helsinki promotes intracellular acyl-CoA cholesterol acyltransferase (ACAT) protein accumulation.
    Toledo, J. D; Garda, H. A; Cabaleiro, L. V; Cuellar, A; Pellón Maison, M; González Baró, M; Gonzalez M. C. 
    2013. Molecular and cellular biochemistry. , New York: SPRINGER. vol. 377, n° 1-2, p. 197-205. ISSN 0300-8177
  • Apolipoproteína A-I y lipoproteínas de alta densidad: Estructura y rol en la homeostasis del colesterol celular.
    Garda, H. A; Toledo, J. D; Gonzalez, M. C; Prieto, E; Cuellar, L. A; Cabaleiro, L. V; Chirillano, L. A; Almeyra, C. M. 
    2013. Acta Bioquímica Clínica Latinoamericana. La Plata: Federacion Bioquímica Provincia Buenos Aires, vol. 47, n° 2, p. 327-341. ISSN 0325-2957
  • El Dr. Rodolfo R. Brennner y una de sus principales obras: El Instituto de Investigaciones Bioquímicas de La Plata (INIBIOLP). 
    Garda, H. A. 
    2013. La Plata. Acta Bioquímica Clínica Latinoamericana. Federacion Bioquimica Provincia Buenos Aires. vol. 47, n° 2, p. 249-266. ISSN 0325-2957
  • Characterization of a human apolipoprotein A-I construct expressed in a bacterial system.
    Prieto, E. D; Ramella, N; Cuellar, L. A; Tricerri, M. A; Garda,  H. A. 
    2012. Protein journal. , Berlin: Springer, vol. 31, n° 8, p. 681-688


  • Effect of reconstituted discoidal high density lipoproteins on lipid mobilization in RAW 264.7 and CHOK1 cells. 
    Toledo, J. D; Cabaleiro,  L. V; Garda, H. A; González,  M. C. 
    2012. Journal of cellular biochemistry. , New York: Wiley-Liss, Div John Wiley & Sons Inc. vol. 113, n° 4, p. 1208-1216

  • Membrane insertion topology of the central apolipoprotein A-I region.Fluorescence studies using single tryptophan mutants. 
    Prieto, E. D; Garda, H. A. 
    2011. Biochemistry  50, 466 - 79
    Editorial: American Chemical Society.
  • Human Apolipoprotein A-I-Derived Amyloid: it’s Association with Atherosclerosis. 
    Ramella, N. A; Rimoldi, O. J; Prieto, E. D; Schinella, G. R; Sanchez, S. A; Jaureguiberry, M.S; Vela, M.E; Ferreira, S. T; Tricerri, M. A.
    2011. PLoS One. 2011 ;6 (7):e22532. Epub 2011 Jul 19 
  • Structure and stability of crustacean lipovitellin: Influence of lipid content and composition
    García, C. F; Cunningham, M; Soulages, J. L; Heras, H; Garda, H. A. 
    2010. Comparative biochemistry and physiology. part b, biochemistry & molecular biology. Elsevier Science Inc. vol. 155, n° 2, p. 126 - 131
  • Membrane Organization and Regulation of Cellular Cholesterol. 
    Jaureguiberry, M. S; Tricerri, M. A; Sanchez, S. A; Garda, H. A; Finarelli, G. S; Gonzalez, M. C; Rimoldi. O. J. 
    2010. Journal of membrane biology. New York: Springer. vol. 234, p. 183 - 194
  • The central type Y amphipathic ahelices of apolipoprotein AI are involved in the mobilization of intracellular cholesterol depots. 
    González, M. C; Toledo, J. D; Tricerri, M. A; Garda, H. A.  
    2008. Archives of biochemistry and biophysics. Amsterdam: Elsevier, vol. 473, n° 1, p. 34 - 41
  • Embryo lipoproteins and yolk lipovitellin consumption during embryogenesis in Macrobrachium borellii (Crustacea: Palaemonidae). 
    García, C. F; Cunningham, M; Garda, H. A; Heras, H. 
    2008. Comparative biochemistry and physiology. part b, biochemistry & molecular biology, vol. 151, p. 317 - 322

Awards

  • “Premio SAB al mejor trabajo” 
    III Congreso Iberoamericano de Biofísica y XXVI Reunión Anual de la Sociedad Argentina de Biofísica
    . Buenos Aires. Septiembre de 1997. 
    Conformation of apolipoprotein A-I in reconstituted lipoprotein particles and particle-membrane interaction. Effect of size and cholesterol. 
    Tricerri, M. A; Córsico, B; Toledo, J. D; Garda, H. A; Brenner, R. R.
  • “Premio SAB al mejor trabajo” 
    XXXI Reunión Anual de SAB. Buenos Aires. Diciembre de 2002.
    Interacción del dominio central de apolipoproteína A-I con membranas
    Prieto, E. D; Toledo, J. D; Garda, H. A.
  • “Mención de honor” 
    IV Congresso de Biofísica do Cone-Sul XXIX Reunión Anual de SAB. Campinas, SP, Brazil. Agosto de 2000. 
    Trabajo: Interacción de complejos lipoproteicos discoidales de apolipoproteína A-I con vesículas lipídicas estudiada con reactivos fotoactivables
    Córsico, B; Toledo, J. D; Garda, H. A.
  • “Mejor poster de ciencias básicas” 
    Otorgado en Jornadas de la Facultad de Ciencias Médicas. La Plata. Octubre de 2010. Correspondiente al trabajo: 
    Configuración de la apolipoproteína A-I ( LL5/2 en dHDL) fisiológicamente activa en la remoción de colesterol de células RAW

    Cuellar, L. A; Prieto, E. D; Cabaleiro, L. V; González, M. C; Garda, H. A.




INIBIOLP - Instituto de Investigaciones Bioquímicas de La Plata "Profesor Doctor Rodolfo R. Brenner"
Consejo Nacional de Investigaciones Científicas y Técnicas - Facultad de Ciencias Médicas - U.N.L.P.
Avenida 60 y 120 - C.P. 1900 La Plata - Prov. de Buenos Aires - Argentina. Tel. 54-221-4824894 - Fax. 54-221-4258988 - E-mail :