Jordi Camps

A consensus view of protein dynamics

The dynamics of proteins in aqueous solution has been investigated through a massive approach based on “state of the art” molecular dynamics simulations performed for all protein metafolds using the four most popular force fields (OPLS, CHARMM, AMBER, and GROMOS). A detailed analysis of the massive database of trajectories (>1.5 terabytes of data obtained using ≈50 years of CPU) allowed us to obtain a robust-consensus picture of protein dynamics in aqueous solution.

The paraoxonases: role in human diseases and methodological difficulties in measurement

Research into the paraoxonase (PON) gene family has flourished over the past few years. In the 1970s and 1980s, only PON1 was known, and the investigations were conducted, essentially, by toxicologists focusing on protection against organophosphate poisoning. Since then, two new members of the family, PON2 and PON3, have been identified, both being shown to play antioxidant and anti-inflammatory roles. Evidence exists indicating that the PON family is central to a wide variety of human illnesses such as cardiovascular disease, diabetes mellitus, metabolic syndrome, obesity, non-alcoholic steatohepatitis, and several mental disorders. However, research is hampered considerably by the methods currently available to measure the activity of these enzymes. In this review, we summarize the state of knowledge on PON biochemistry and function, the influence of genetic variations, and the involvement of PON in several diseases. The problems associated with PON measurement, such as sample acquisition, lack of reference methods, and variety of substrates, will be presented. Also, we cover some of the present lines of research and propose some others for future progress in this field.

Regulation of Serum Paraoxonase Activity by Genetic, Nutritional, and Lifestyle Factors in the General Population

BACKGROUND Paraoxonase may protect lipoproteins and cell membranes from peroxidation, and alterations in the activity of this enzyme have been associated with some chronic diseases. Serum paraoxonase appears to be mainly under genetic control, but some studies suggest that environmental factors may also modulate its activity. The aim of the present study was to investigate whether diet and lifestyle affect serum paraoxonase activity. METHODS We studied a population-based sample of 388 individuals (194 women and 194 men; age range, 18-75 years) and assessed their daily dietary intake using a 3-day estimated food record. The variables studied included serum paraoxonase activity, paraoxonase polymorphisms at positions 55 and 192, age, gender, smoking status, physical exercise, body mass index, energy consumption, nutrient intake (total lipids, saturated fatty acids, beta-carotenes, vitamins C and E), and serum lipid concentrations. RESULTS Multiple linear regression analysis showed that only genetic polymorphisms, serum cholesterol, HDL-cholesterol concentrations, and cigarette smoking were significant predictors of serum paraoxonase activity. HDL-cholesterol concentrations were also related to body mass index, daily energy consumption, and saturated fatty acid intake. CONCLUSIONS The between-individual variability of serum paraoxonase activity is regulated mainly by genetic determinants. Although HDL-cholesterol and tobacco smoking may contribute to the modulation of this enzyme, the other nutritional and lifestyle factors do not seem to play a significant role.

Immunohistochemical analysis of paraoxonases-1, 2, and 3 expression in normal mouse tissues.

The paraoxonase (PON) enzyme family, comprising PON1, PON2, and PON3, are antioxidant enzymes that degrade oxidised phospholipids. We describe the immunohistochemical localisation of the PON proteins in the normal mouse. Antibodies were obtained by inoculating rabbits with peptides derived from specific sequences of mature PONs. PON1 and PON3 were detected in the skin external epithelium, acini of the sebaceous glands, tongue epithelium, acini of the submandibular gland, surface epithelia of the stomach and the intestine, hepatocytes, exocrine pancreas acini, fibre tracts of the encephalon and the spinal cord, skeletal and cardiac muscle, eye lens epithelium and retinal layers, adipocytes, chondrocytes, epithelial cells of the trachea and bronchiole, ovary follicular fluid, seminiferous tubules, spermatozoa, and kidney proximal tubules. PON2 expression was weaker than that of PON1 and PON3, and was absent in some of the tissues studied, such as submandibular gland, nerve cells, and adipocytes. In muscle cells, PON2 expression was restricted to the endomysium. Apolipoprotein A-I did not colocalise with PONs, suggesting local synthesis. This study provides an experimental model to investigate the role played by these enzymes as antioxidants and their relationship with the development of a variety of diseases.

Effects of S-adenosylmethionine on lipid peroxidation and liver fibrogenesis in carbon tetrachloride-induced cirrhosis.

BACKGROUND/AIM The aim of this study was to investigate the effects of S-adenosylmethionine on liver peroxidation and liver fibrogenesis in carbon tetrachloride-induced cirrhosis. METHODS Cirrhosis was induced in three groups of six rats by repeated injections of carbon tetrachloride over 9 weeks. One group of animals was treated only with carbon tetrachloride, and the other two received carbon tetrachloride plus S-adenosylmethionine (10 mg/kg intramuscularly daily) from week 3 to week 9, and from week 6 to week 9 of the study, respectively. Two additional groups of six rats, a control group and a group treated only with S-adenosylmethionine, were also studied. Glutathione concentration, thiobarbituric acid-reactive substances, collagen content, prolyl hydroxylase activity, and procollagen type I mRNA expression were determined in liver samples. RESULTS All carbon tetrachloride-treated rats had cirrhosis at the end of the study. Cirrhosis was also present in five of the six carbon tetrachloride-treated rats receiving S-adenosylmethionine for 3 weeks, but in only one of the six rats that received S-adenosylmethionine for 6 weeks. Hepatic glutathione was significantly diminished in carbon tetrachloride-treated rats (2.7 +/- 0.3 mumol/g tissue) and returned to normal in rats receiving S-adenosylmethionine for 3 or 6 weeks (3.7 +/- 0.13 and 3.9 +/- 0.11 mumol/g tissue, respectively). The hepatic thiobarbituric acid-reactive substances were significantly lower in rats treated with carbon tetrachloride and S-adenosylmethionine for 6 weeks (98 +/- 5 nmol/g) than in rats treated with carbon tetrachloride (134 +/- 12 nmol/g) and in those treated with carbon tetrachloride and S-adenosylmethionine for 3 weeks (127 +/- 13 nmol/g). There were no differences in either hepatic collagen and prolyl hydroxylase activity between rats that received only carbon tetrachloride and those treated with S-adenosylmethionine for 3 weeks. In contrast, carbon tetrachloride-treated rats receiving S-adenosylmethionine for 6 weeks had significantly lower collagen and prolyl hydroxylase activity than the other two groups. A much greater increase in procollagen type I mRNA was found in carbon tetrachloride-treated rats than in rats treated with carbon tetrachloride and S-adenosylmethionine for 6 weeks. Furthermore, there was a significant correlation between the hepatic thiobarbituric acid-reactive substances and prolyl hydroxylase activity and hepatic collagen. CONCLUSIONS We conclude that the early administration of S-adenosylmethionine in a model of carbon tetrachloride-induced liver injury restores glutathione levels and reduces lipid peroxidation, resulting in less advanced liver fibrosis.

Insulin resistance, inflammation, and obesity: role of monocyte chemoattractant protein-1 (or CCL2) in the regulation of metabolism.

To maintain homeostasis under diverse metabolic conditions, it is necessary to coordinate nutrient-sensing pathways with the immune response. This coordination requires a complex relationship between cells, hormones, and cytokines in which inflammatory and metabolic pathways are convergent at multiple levels. Recruitment of macrophages to metabolically compromised tissue is a primary event in which chemokines play a crucial role. However, chemokines may also transmit cell signals that generate multiple responses, most unrelated to chemotaxis, that are involved in different biological processes. We have reviewed the evidence showing that monocyte chemoattractant protein-1 (MCP-1 or CCL2) may have a systemic role in the regulation of metabolism that sometimes is not necessarily linked to the traffic of inflammatory cells to susceptible tissues. Main topics cover the relationship between MCP-1/CCL2, insulin resistance, inflammation, obesity, and related metabolic disturbances.

Urinary excretion of 6-keto-prostaglandin F1α, thromboxane B2 and prostaglandin E2 in cirrhosis with ascites: Relationship to functional renal failure (hepatorenal syndrome)

The aim of the study was to investigate the urinary excretion of 6-keto-PGF1 alpha (a stable metabolite of PGI2), thromboxane B2 (TxB2; a stable metabolite of TxA2), and PGE2 in 18 normal subjects, 49 cirrhotics with ascites without renal failure (GFR = 90 +/- 4 ml/min, means +/- S.E.M.) and 20 cirrhotics with functional renal failure (FRF) (GFR = 36 +/- 3). The study was made after 5 days on a 50 mEq sodium diet and without diuretics. Plasma renin activity (PRA), plasma norepinephrine concentration (NE) and plasma antidiuretic hormone concentration (ADH) were also measured. Cirrhotics without FRF showed a significantly higher urinary excretion of 6-keto-PGF1 alpha, TxB2 and PGE, (15.9 +/- 1.7 ng/h, 3.0 +/- 0.3 ng/h, and 6.2 +/- 1.0 ng/h) than did normal subjects (9.2 +/- 0.9, 1.3 +/- 0.1 and 2.3 +/- 0.4). On the contrary, the urinary excretion of these prostaglandins was normal or reduced in patients with FRF (5.3 +/- 0.8, 1.3 +/- 0.2 and 1.9 +/- 0.4). PRA, NE and ADH were significantly increased in cirrhotics with FRF (15.2 +/- 3.9 ng/ml/h, 1026 +/- 149 pg/ml and 4.1 +/- 0.3 pg/ml) and in patients without FRF (8.0 +/- 1.4, 667 +/- 67 and 3.9 +/- 0.3) as compared to normal controls (1.3 +/- 0.2, 275 +/- 46 and 2.4 +/- 0.2). These results suggest that renal hemodynamics in cirrhosis depends upon a critical equilibrium between the activity of endogenous vasoconstrictor systems and the renal production of the vasodilator prostaglandins PGI2 and PGE2. In addition, they do not support FRF in cirrhosis being related to an increased renal production of the vasoconstrictor prostaglandin TxA2.

Xenohormetic and anti-aging activity of secoiridoid polyphenols present in extra virgin olive oil: a new family of gerosuppressant agents.

Aging can be viewed as a quasi-programmed phenomenon driven by the overactivation of the nutrient-sensing mTOR gerogene. mTOR-driven aging can be triggered or accelerated by a decline or loss of responsiveness to activation of the energy-sensing protein AMPK, a critical gerosuppressor of mTOR. The occurrence of age-related diseases, therefore, reflects the synergistic interaction between our evolutionary path to sedentarism, which chronically increases a number of mTOR activating gero-promoters (e.g., food, growth factors, cytokines and insulin) and the “defective design” of central metabolic integrators such as mTOR and AMPK. Our laboratories at the Bioactive Food Component Platform in Spain have initiated a systematic approach to molecularly elucidate and clinically explore whether the “xenohormesis hypothesis,” which states that stress-induced synthesis of plant polyphenols and many other phytochemicals provides an environmental chemical signature that upregulates stress-resistance pathways in plant consumers, can be explained in terms of the reactivity of the AMPK/mTOR-axis to so-called xenohormetins. Here, we explore the AMPK/mTOR-xenohormetic nature of complex polyphenols naturally present in extra virgin olive oil (EVOO), a pivotal component of the Mediterranean style diet that has been repeatedly associated with a reduction in age-related morbid conditions and longer life expectancy. Using crude EVOO phenolic extracts highly enriched in the secoiridoids oleuropein aglycon and decarboxymethyl oleuropein aglycon, we show for the first time that (1) the anticancer activity of EVOO secoiridoids is related to the activation of anti-aging/cellular stress-like gene signatures, including endoplasmic reticulum (ER) stress and the unfolded protein response, spermidine and polyamine metabolism, sirtuin-1 (SIRT1) and NRF2 signaling; (2) EVOO secoiridoids activate AMPK and suppress crucial genes involved in the Warburg effect and the self-renewal capacity of “immortal” cancer stem cells; (3) EVOO secoiridoids prevent age-related changes in the cell size, morphological heterogeneity, arrayed cell arrangement and senescence-associated β-galactosidase staining of normal diploid human fibroblasts at the end of their proliferative lifespans. EVOO secoiridoids, which provide an effective defense against plant attack by herbivores and pathogens, are bona fide xenohormetins that are able to activate the gerosuppressor AMPK and trigger numerous resveratrol-like anti-aging transcriptomic signatures. As such, EVOO secoiridoids constitute a new family of plant-produced gerosuppressant agents that molecularly “repair” the aimless (and harmful) AMPK/mTOR-driven quasi-program that leads to aging and aging-related diseases, including cancer.

MoDEL (Molecular Dynamics Extended Library): A Database of Atomistic Molecular Dynamics Trajectories

More than 1700 trajectories of proteins representative of monomeric soluble structures in the protein data bank (PDB) have been obtained by means of state-of-the-art atomistic molecular dynamics simulations in near-physiological conditions. The trajectories and analyses are stored in a large data warehouse, which can be queried for dynamic information on proteins, including interactions. Here, we describe the project and the structure and contents of our database, and provide examples of how it can be used to describe the global flexibility properties of proteins. Basic analyses and trajectories stripped of solvent molecules at a reduced resolution level are available from our web server.

Nonconcordance between subclinical atherosclerosis and the calculated Framingham risk score in HIV-infected patients: relationships with serum markers of oxidation and inflammation.

HIV‐infected patients show an increased cardiovascular disease (CVD) risk resulting, essentially, from metabolic disturbances related to chronic infection and antiretroviral treatments. The aims of this study were: (1) to evaluate the agreement between the CVD risk estimated using the Framingham risk score (FRS) and the observed presence of subclinical atherosclerosis in HIV‐infected patients; (2) to investigate the relationships between CVD and plasma biomarkers of oxidation and inflammation.