The Role of Peroxisome Proliferator-Activated Receptor in Addiction: A Novel Drug Target

Author(s):  
Carla Quiroga ◽  
Juan José Barberena ◽  
Jocelyne Alcaraz-Silva ◽  
Sérgio Machado ◽  
Claudio Imperatori ◽  
...  

: The peroxisome proliferator activated receptors (PPARs) are a superfamily of well-recognized ligand-binding nuclear receptors comprising three isoforms: PPARα, PPARγ, and PPARβ/δ. In response to endogenous lipid messengers, PPARs trigger the transcription of genes related to a wider spectrum of physiological phenomena, including fatty acid oxidation, inflammation, and adipogenesis among many others. Thus, the importance of PPARs as putative protective therapy in health issues has increased the interest in studying these nuclear receptors, including the management of neurodegenerative disorders, multiple sclerosis, and likely addiction. In recent years, several pieces of evidence from animal models have demonstrated the promising role of PPARs as a critical element for interventions in addictive behaviors by reducing the reinforcing properties of addictive substances such as alcohol. However, there is a lack of data in scope and has so far been unexplored the function of PPARs in additional drugs such as cannabis, opioids, methamphetamine, or cocaine. Similar scenario has been found for the management of binge-type eating disorders. Thus, here we review recent advances in understanding the relevance of the PPAR controlling addiction.

2013 ◽  
Vol 304 (11) ◽  
pp. C1064-C1072 ◽  
Author(s):  
Angela Ramjiawan ◽  
Rushita A. Bagchi ◽  
Alexandra Blant ◽  
Laura Albak ◽  
Maria A. Cavasin ◽  
...  

The transcriptional coactivator peroxisome proliferator-activated receptor-γ coactivator-1α (PGC-1α) is a key determinant of cardiac metabolic function by regulating genes governing fatty acid oxidation and mitochondrial biogenesis. PGC-1α expression is reduced in many cardiac diseases, and gene deletion of PGC-1α results in impaired cardiomyocyte metabolism and function. Reduced fuel supply generally induces PGC-1α expression, but the specific role of oxygen deprivation is unclear, and the mechanisms governing PGC-1α gene expression in these situations are poorly understood. During hypoxia of primary rat cardiomyocytes up to 12 h, we found that PGC-1α expression was downregulated via a histone deacetylation-dependent mechanism. Conversely, extended hypoxia to 24 h concomitant with glucose depletion upregulated PGC-1α expression via an AMP-activated protein kinase (AMPK)-mediated mechanism. Our previous work demonstrated that estrogen-related receptor-α (ERRα) regulates PGC-1α expression, and we show here that overexpression of ERRα was sufficient to attenuate PGC-1α downregulation in hypoxia. We confirmed that chronic hypoxia downregulated cardiac PGC-1α expression in a hypoxic but nonischemic hypobaric rat model of pulmonary hypertension. Our data demonstrate that depletion of oxygen or fuel results in repression or induction, respectively, of PGC-1α expression via discrete mechanisms, which may contribute to cardiac energetic derangement during hypoxia, ischemia, and failure.


2000 ◽  
Vol 14 (5) ◽  
pp. 733-740 ◽  
Author(s):  
Ichiro Takada ◽  
Ruth T. Yu ◽  
H. Eric Xu ◽  
Millard H. Lambert ◽  
Valerie G. Montana ◽  
...  

Abstract Three pharmacologically important nuclear receptors, the peroxisome proliferator-activated receptors (PPARs α,γ , and δ), mediate key transcriptional responses involved in lipid homeostasis. The PPARα and γ subtypes are well conserved from Xenopus to man, but the β/δ subtypes display substantial species variations in both structure and ligand activation profiles. Characterization of the avian cognates revealed a close relationship between chick (c) α and γ subtypes to their mammalian counterparts, whereas the third chicken subtype was intermediate to Xenopus (x) β and mammalian δ, establishing that β and δ are orthologs. Like xPPARβ, cPPARβ responded efficiently to hypolipidemic compounds that fail to activate the human counterpart. This provided the opportunity to address the pharmacological problem as to how drug selectivity is achieved and the more global evolutionary question as to the minimal changes needed to generate a new class of receptor. X-ray crystallography and chimeric analyses combined with site-directed mutagenesis of avian and mammalian cognates revealed that a Met to Val change at residue 417 was sufficient to switch the human and chick phenotype. These results establish that the genetic drive to evolve a novel and functionally selectable receptor can be modulated by a single amino acid change and suggest how nuclear receptors can accommodate natural variation in species physiology.


2013 ◽  
Vol 88 (6) ◽  
pp. 1029-1035 ◽  
Author(s):  
Emerson de Andrade Lima ◽  
Mariana Modesto Dantas de Andrade Lima ◽  
Cláudia Diniz Lopes Marques ◽  
Angela Luzia Branco Pinto Duarte ◽  
Ivan da Rocha Pita ◽  
...  

Psoriasis is a polygenic, inflammatory and progressive disease, characterized by an abnormal differentiation and hyperproliferation of keratinocytes, associated with impaired immunologic activation and systemic disorders, while psoriatic arthritis is a chronic inflammatory articular disease. Pathophysiology of psoriasis comprises a dysfunction of the immune system cells with an interactive network between cells and cytokines supporting the initiation and perpetuation of disease and leading to inflammation of skin, enthesis and joints. Recent studies have shown an important role of systemic inflammation in the development of atherosclerosis. Corroborating these findings, patients with severe Psoriasis have marked incidence of psoriatic arthritis, cardiovascular diseases, hypertension, dyslipidemia, obesity and diabetes mellitus, showing an increased risk for acute myocardial infarction, which suggests that the condition is not restricted to the skin. Nuclear receptors are ligand-dependent transcription factors, whose activation affects genes that control vital processes. Among them the peroxisome proliferator-activated receptor is responsible for establishing the relationship between lipids, metabolic diseases and innate immunity. In the skin, peroxisome proliferator-activated receptors have an important effect in keratinocyte homeostasis, suggesting a role in diseases such as psoriasis. The peroxisome proliferator-activated receptors agonists represent a relevant source of research in the treatment of skin conditions, however more clinical studies are needed to define the potential response of these drugs in patients with psoriasis and psoriatic arthritis.


PPAR Research ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-15
Author(s):  
Olga I. Rudko ◽  
Artemii V. Tretiakov ◽  
Elena A. Naumova ◽  
Eugene A. Klimov

Peroxisome proliferator-activated receptor (PPAR) group includes three isoforms encoded by PPARG, PPARA, and PPARD genes. High concentrations of PPARs are found in parts of the brain linked to anxiety development, including hippocampus and amygdala. Among three PPAR isoforms, PPARG demonstrates the highest expression in CNS, where it can be found in neurons, astrocytes, and glial cells. Herein, the highest PPARG expression occurs in amygdala. However, little is known considering possible connections between PPARs and anxiety behavior. We reviewed possible connections between PPARs and anxiety. We used the Pathway Studio software (Elsevier). Signal pathways were created according to previously developed algorithms. SNEA was performed in Pathway Studio. Current study revealed 14 PPAR-regulated proteins linked to anxiety. Possible mechanism of PPAR involvement in neuroinflammation protection is proposed. Signal pathway reconstruction and reviewing aimed to reveal possible connection between PPARG and CCK-ergic system was conducted. Said analysis revealed that PPARG-dependent regulation of MME and ACE peptidase expression may affect levels of nonhydrolysed, i.e., active CCK-4. Impairments in PPARG regulation and following MME and ACE peptidase expression impairments in amygdala may be the possible mechanism leading to pathological anxiety development, with brain CCK-4 accumulation being a key link. Literature data analysis and signal pathway reconstruction and reviewing revealed two possible mechanisms of peroxisome proliferator-activated receptors involvement in pathological anxiety: (1) cytokine expression and neuroinflammation mechanism and (2) regulation of peptidases targeted to anxiety-associated neuropeptides, primarily CCK-4, mechanism.


2010 ◽  
Vol 299 (3) ◽  
pp. E335-E340 ◽  
Author(s):  
Asmaà Fritah ◽  
Mark Christian ◽  
Malcolm G. Parker

RIP140 is a transcriptional coregulator highly expressed in metabolic tissues where it has important and diverse actions. RIP140-null mice show that it plays a crucial role in the control of lipid metabolism in adipose tissue, skeletal muscle, and the liver and is essential for female fertility. RIP140 has been shown to act as a ligand-dependent transcriptional corepressor for metabolic nuclear receptors such as estrogen-related receptors and peroxisome proliferator-activated receptors. The role of RIP140 as a corepressor has been strengthened by the characterization of RIP140-overexpressing mice, although it emerges through several studies that RIP140 can also behave as a coactivator. Nuclear localization of RIP140 is important for controlling transcription of target genes and is subject to regulation by posttranslational modifications. However, cytoplasmic RIP140 has been shown to play a role in the control of metabolism through direct regulation of glucose transport in adipocytes. In this review, we focus on recent advances highlighting the growing importance of RIP140 as a regulator of energy homeostasis.


PPAR Research ◽  
2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Lihong Chen ◽  
Guangrui Yang

Peroxisome proliferator-activated receptors (PPARs) are a group of nuclear receptors that function as transcription factors regulating the expression of numerous target genes. PPARs play an essential role in various physiological and pathological processes, especially in energy metabolism. It has long been known that metabolism and circadian clocks are tightly intertwined. However, the mechanism of how they influence each other is not fully understood. Recently, all three PPAR isoforms were found to be rhythmically expressed in given mouse tissues. Among them, PPARαand PPARγare direct regulators of core clock components, Bmal1 and Rev-erbα, and, conversely, PPARαis also a direct Bmal1 target gene. More importantly, recent studies using knockout mice revealed that all PPARs exert given functions in a circadian manner. These findings demonstrated a novel role of PPARs as regulators in correlating circadian rhythm and metabolism. In this review, we summarize advances in our understanding of PPARs in circadian regulation.


2002 ◽  
Vol 2 ◽  
pp. 1491-1500 ◽  
Author(s):  
Jihan Youssef ◽  
Mostafa Badr

Exposure to agonists of peroxisome proliferator-activated receptor alpha (PPARα) causes liver cancer in rodents, with aged animals being more susceptible than their younger counterparts to this effect. Treatment with these chemicals produced a five- to sevenfold higher yield of grossly visible hepatic tumors in old rats compared to young animals. The enhanced susceptibility of the aged livers to the carcinogenic effect of PPAR agonists could not be explained by differences in levels of peroxisomal and/or cell proliferation between young and old animals, as neither of these responses was exaggerated with aging. Reported studies have shown that activating PPARa results in the suppression of hepatic apoptosis. This effect is expected to diminish the ability of the liver to purge itself of pre-existing neoplastic cells, allowing them to progress to tumors. New findings from our laboratories show that the aged liver is exceedingly sensitive to the antiapoptotic effect of PPAR agonists. In addition, aged livers showed remarkably higher levels of the antiapoptotic protein Bcl-2 than livers of young, adult, and middle-aged animals. Interestingly, the PPARa agonist Wy-14,643 significantly diminished elements of the proapoptotic machinery (e.g., Bax, caspases, and fas) in the aged liver, while remarkably increasing elements of this machinery in younger animals. Taken together, while activation of PPARs appears to inhibit apoptosis in livers of senescent animals, activating these receptors seems to stimulate the apoptotic machinery in young animals. This paradoxical effect may be responsible for the exaggerated sensitivity of the aged liver to the carcinogenic effect of agents that activate PPARs.


Genes ◽  
2021 ◽  
Vol 12 (5) ◽  
pp. 645
Author(s):  
Emmanuel D. Dixon ◽  
Alexander D. Nardo ◽  
Thierry Claudel ◽  
Michael Trauner

Obesity and type 2 diabetes mellitus (T2DM) are metabolic disorders characterized by metabolic inflexibility with multiple pathological organ manifestations, including non-alcoholic fatty liver disease (NAFLD). Nuclear receptors are ligand-dependent transcription factors with a multifaceted role in controlling many metabolic activities, such as regulation of genes involved in lipid and glucose metabolism and modulation of inflammatory genes. The activity of nuclear receptors is key in maintaining metabolic flexibility. Their activity depends on the availability of endogenous ligands, like fatty acids or oxysterols, and their derivatives produced by the catabolic action of metabolic lipases, most of which are under the control of nuclear receptors. For example, adipose triglyceride lipase (ATGL) is activated by peroxisome proliferator-activated receptor γ (PPARγ) and conversely releases fatty acids as ligands for PPARα, therefore, demonstrating the interdependency of nuclear receptors and lipases. The diverse biological functions and importance of nuclear receptors in metabolic syndrome and NAFLD has led to substantial effort to target them therapeutically. This review summarizes recent findings on the roles of lipases and selected nuclear receptors, PPARs, and liver X receptor (LXR) in obesity, diabetes, and NAFLD.


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