scholarly journals Repurposing Small Molecules to Target PPAR-γ as New Therapies for Peripheral Nerve Injuries

Biomolecules ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1301
Author(s):  
Melissa L. D. Rayner ◽  
Jess Healy ◽  
James B. Phillips
Keyword(s):  
Peripheral Nerve ◽  
Nerve Regeneration ◽  
In Vivo Studies ◽  
Peroxisome Proliferator ◽  
Neural Cells ◽  
Loss Of Function ◽  
Peroxisome Proliferator Activated Receptor ◽  
Ppar Γ

The slow rate of neuronal regeneration that follows peripheral nerve repair results in poor recovery, particularly where reinnervation of muscles is delayed, leading to atrophy and permanent loss of function. There is a clear clinical need to develop drug treatments that can accelerate nerve regeneration safely, restoring connections before the target tissues deteriorate irreversibly. The identification that the Rho/Rho-associated kinase (ROCK) pathway acts to limit neuronal growth rate is a promising advancement towards the development of drugs. Targeting Rho or ROCK directly can act to suppress the activity of this pathway; however, the pathway can also be modulated through the activation of upstream receptors; one of particular interest being peroxisome proliferator-activated receptor gamma (PPAR-γ). The connection between the PPAR-γ receptor and the Rho/ROCK pathway is the suppression of the conversion of inactive guanosine diphosphate (GDP)-Rho to active guanosine triphosphate GTP-Rho, resulting in the suppression of Rho/ROCK activity. PPAR-γ is known for its role in cellular metabolism that leads to cell growth and differentiation. However, more recently there has been a growing interest in targeting PPAR-γ in peripheral nerve injury (PNI). The localisation and expression of PPAR-γ in neural cells following a PNI has been reported and further in vitro and in vivo studies have shown that delivering PPAR-γ agonists following injury promotes nerve regeneration, leading to improvements in functional recovery. This review explores the potential of repurposing PPAR-γ agonists to treat PNI and their prospective translation to the clinic.

scholarly journals The Novel Role of PGC1α in Bone Metabolism

2021 ◽  
Vol 22 (9) ◽  
pp. 4670
Author(s):  
Cinzia Buccoliero ◽  
Manuela Dicarlo ◽  
Patrizia Pignataro ◽  
Francesco Gaccione ◽  
Silvia Colucci ◽  
...  
Keyword(s):  
Bone Metabolism ◽  
Osteoblastic Differentiation ◽  
In Vivo Studies ◽  
Peroxisome Proliferator ◽  
Sirtuin 3 ◽  
Peroxisome Proliferator Activated Receptor ◽  
Increased Risk

Peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1α) is a protein that promotes transcription of numerous genes, particularly those responsible for the regulation of mitochondrial biogenesis. Evidence for a key role of PGC1α in bone metabolism is very recent. In vivo studies showed that PGC1α deletion negatively affects cortical thickness, trabecular organization and resistance to flexion, resulting in increased risk of fracture. Furthermore, in a mouse model of bone disease, PGC1α activation stimulates osteoblastic gene expression and inhibits atrogene transcription. PGC1α overexpression positively affects the activity of Sirtuin 3, a mitochondrial nicotinammide adenina dinucleotide (NAD)-dependent deacetylase, on osteoblastic differentiation. In vitro, PGC1α overexpression prevents the reduction of mitochondrial density, membrane potential and alkaline phosphatase activity caused by Sirtuin 3 knockdown in osteoblasts. Moreover, PGC1α influences the commitment of skeletal stem cells towards an osteogenic lineage, while negatively affects marrow adipose tissue accumulation. In this review, we will focus on recent findings about PGC1α action on bone metabolism, in vivo and in vitro, and in pathologies that cause bone loss, such as osteoporosis and type 2 diabetes.

scholarly journals Role of Hyaluronan in Human Adipogenesis: Evidence from in-Vitro and in-Vivo Studies

2019 ◽  
Vol 20 (11) ◽  
pp. 2675 ◽  
Author(s):  
Nicholas Wilson ◽  
Robert Steadman ◽  
Ilaria Muller ◽  
Mohd Draman ◽  
D. Aled Rees ◽  
...  
Keyword(s):  
Stem Cell Differentiation ◽  
In Vivo Studies ◽  
Peroxisome Proliferator ◽  
Synthesis Inhibitor ◽  
Peroxisome Proliferator Activated Receptor ◽  
Inhibitory Role ◽  
The Impact

Hyaluronan (HA), an extra-cellular matrix glycosaminoglycan, may play a role in mesenchymal stem cell differentiation to fat but results using murine models and cell lines are conflicting. Our previous data, illustrating decreased HA production during human adipogenesis, suggested an inhibitory role. We have investigated the role of HA in adipogenesis and fat accumulation using human primary subcutaneous preadipocyte/fibroblasts (PFs, n = 12) and subjects of varying body mass index (BMI). The impact of HA on peroxisome proliferator-activated receptor gamma (PPARγ) expression was analysed following siRNA knockdown or HA synthase (HAS)1 and HAS2 overexpression. PFs were cultured in complete or adipogenic medium (ADM) with/without 4-methylumbelliferone (4-MU = HA synthesis inhibitor). Adipogenesis was evaluated using oil red O (ORO), counting adipogenic foci, and measurement of a terminal differentiation marker. Modulating HA production by HAS2 knockdown or overexpression increased (16%, p < 0.04) or decreased (30%, p = 0.01) PPARγ transcripts respectively. The inhibition of HA by 4-MU significantly enhanced ADM-induced adipogenesis with 1.52 ± 0.18- (ORO), 4.09 ± 0.63- (foci) and 2.6 ± 0.21-(marker)-fold increases compared with the controls, also increased PPARγ protein expression (40%, (p < 0.04)). In human subjects, circulating HA correlated negatively with BMI and triglycerides (r = −0.396 (p = 0.002), r = −0.269 (p = 0.038), respectively), confirming an inhibitory role of HA in human adipogenesis. Thus, enhancing HA action may provide a therapeutic target in obesity.

scholarly journals PPAR, PTEN, and the Fight against Cancer

PPAR Research ◽  
2008 ◽  
Vol 2008 ◽  
pp. 1-6 ◽  
Author(s):  
Rosemary E. Teresi ◽  
Kristin A. Waite
Keyword(s):  
Tumor Suppressor ◽  
Hormone Receptors ◽  
Susceptibility Gene ◽  
Genetic Alterations ◽  
Cellular Growth ◽  
In Vivo Studies ◽  
Peroxisome Proliferator ◽  
Peroxisome Proliferator Activated Receptor

Peroxisome proliferator-activated receptor gamma (PPAR) is a ligand-activated transcription factor, which belongs to the family of nuclear hormone receptors. Recent in vitro studies have shown that PPAR can regulate the transcription ofphosphatase and tensin homolog on chromosometen(PTEN), a known tumor suppressor.PTENis a susceptibility gene for a number of disorders, including breast and thyroid cancer. Activation of PPAR through agonists increases functional PTEN protein levels that subsequently induces apoptosis and inhibits cellular growth, which suggests that PPAR may be a tumor suppressor. Indeed, several in vivo studies have demonstrated that genetic alterations of PPAR can promote tumor progression. These results are supported by observations of the beneficial effects of PPAR agonists in the in vivo cancer setting. These studies signify the importance of PPAR andPTEN's interaction in cancer prevention.

scholarly journals Piperine Alleviates Doxorubicin-Induced Cardiotoxicity via Activating PPAR-γ in Mice

PPAR Research ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-11 ◽  
Author(s):  
Jie Yan ◽  
Si-Chi Xu ◽  
Chun-Yan Kong ◽  
Xiao-Yang Zhou ◽  
Zhou-Yan Bian ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Cardiac Injury ◽  
Inflammatory Factors ◽  
Peroxisome Proliferator ◽  
Protective Effects ◽  
Peroxisome Proliferator Activated Receptor ◽  
Ppar Γ ◽  
Myocardial Oxidative Stress

Background. Oxidative stress, inflammation and cardiac apoptosis were closely involved in doxorubicin (DOX)-induced cardiac injury. Piperine has been reported to suppress inflammatory response and pyroptosis in macrophages. However, whether piperine could protect the mice against DOX-related cardiac injury remain unclear. This study aimed to investigate whether piperine inhibited DOX-related cardiac injury in mice. Methods. To induce DOX-related acute cardiac injury, mice in DOX group were intraperitoneally injected with a single dose of DOX (15 mg/kg). To investigate the protective effects of piperine, mice were orally treated for 3 weeks with piperine (50 mg/kg, 18:00 every day) beginning two weeks before DOX injection. Results. Piperine treatment significantly alleviated DOX-induced cardiac injury, and improved cardiac function. Piperine also reduced myocardial oxidative stress, inflammation and apoptosis in mice with DOX injection. Piperine also improved cell viability, and reduced oxidative damage and inflammatory factors in cardiomyocytes. We also found that piperine activated peroxisome proliferator-activated receptor-γ (PPAR-γ), and the protective effects of piperine were abolished by the treatment of the PPAR-γ antagonist in vivo and in vitro. Conclusions. Piperine could suppress DOX-related cardiac injury via activation of PPAR-γ in mice.

The role of Toll-like receptor proteins (TLR) 2 and 4 in mediating inflammation in proximal tubules

2013 ◽  
Vol 305 (2) ◽  
pp. F143-F154 ◽  
Author(s):  
Harshini Mudaliar ◽  
Carol Pollock ◽  
Muralikrishna Gangadharan Komala ◽  
Steven Chadban ◽  
Huiling Wu ◽  
...  
Keyword(s):  
Diabetic Nephropathy ◽  
Inflammatory Responses ◽  
Proximal Tubules ◽  
Peroxisome Proliferator ◽  
Tlr2 Expression ◽  
Peroxisome Proliferator Activated Receptor ◽  
Ppar Γ ◽  
Diagnostic Threshold

Inflammatory responses are central to the pathogenesis of diabetic nephropathy. Toll-like receptors (TLRs) are ligand-activated membrane-bound receptors which induce inflammatory responses predominantly through the activation of NF-κB. TLR2 and 4 are present in proximal tubular cells and are activated by endogenous ligands upregulated in diabetic nephropathy, including high-mobility group box-1 (HMGB1) and fibronectin. Human proximal tubules were exposed to 5 mM (control), 11.2 mM (approximating the clinical diagnostic threshold for diabetes mellitus), and 30 mM (high) glucose for 72 h or 7 days. Cells were harvested for protein, mRNA, and nuclear extract to assess for TLR2, 4, and inflammatory markers. Glucose (11.2 mM) maximally increased TLR2 and 4 expression, HMGB1 release, and NF-κB activation with increased expression of cytokines. However, only TLR2 expression and subsequent NF-κB binding were sustained at 7 days. Recombinant HMGB1 induced NF-κB activation, which was prevented by both TLR2 silencing [small interfering (si)RNA] and TLR4 inhibition. Peroxisome proliferator-activated receptor-γ (PPAR-γ) transcription was reduced by exposure to 11.2 mM glucose with an increase observed at 30 mM glucose at 24 h. This may reflect a compensatory increase in PPAR-γ induced by exposure to 30 mM glucose, limiting the inflammatory response. Therefore, short-term moderate increases in glucose in vitro increase HMGB1, which mediates NF-κB activation through both TLR2 and 4. Furthermore, in vivo, streptozotocin-induced diabetic mice exhibited an increase in tubular TLR2 and HMGB1 expression. These results collectively suggest that TLR2 is likely to be the predominant long-term mediator of NF-κB activation in transducing inflammation in diabetic nephropathy.

Effect of Arecoline on Regeneration of Injured Peripheral Nerves

2013 ◽  
Vol 41 (04) ◽  
pp. 865-885 ◽  
Author(s):  
Sheng-Chi Lee ◽  
Chin-Chuan Tsai ◽  
Chun-Hsu Yao ◽  
Yuan-Man Hsu ◽  
Yueh-Sheng Chen ◽  
...  
Keyword(s):  
Sciatic Nerve ◽  
Peripheral Nerve ◽  
Nerve Regeneration ◽  
Peripheral Nerve Regeneration ◽  
In Vitro Study ◽  
Control Group ◽  
Neural Cells ◽  
In Vivo Evaluation

The present study provides in vitro and in vivo evaluation of arecoline on peripheral nerve regeneration. In the in vitro study, we found that arecoline at 50 μg/ml could significantly promote the survival and outgrowth of cultured Schwann cells as compared to the controls treated with culture medium only. In the in vivo study, we evaluated peripheral nerve regeneration across a 10-mm gap in the sciatic nerve of the rat, using a silicone rubber nerve chamber filled with the arecoline solution. In the control group, the chambers were filled with normal saline only. At the end of the fourth week, morphometric data revealed that the arecoline-treated group at 5 μg/ml significantly increased the number and the density of myelinated axons as compared to the controls. Immunohistochemical staining in the arecoline-treated animals at 5 μg/ml also showed their neural cells in the L4 and L5 dorsal root ganglia ipsilateral to the injury were strongly retrograde-labeled with fluorogold and lamina I–II regions in the dorsal horn ipsilateral to the injury were significantly calcitonin gene-related peptide-immunolabeled compared with the controls. In addition, we found that the number of macrophages recruited in the distal sciatic nerve was increased as the concentration of arecoline was increased. Electrophysiological measurements showed the arecoline-treated groups at 5 and 50 μg/ml had a relatively larger nerve conductive velocity of the evoked muscle action potentials compared to the controls. These results indicate that arecoline could stimulate local inflammatory conditions, improving the recovery of a severe peripheral nerve injury.

scholarly journals Sepsis-induced inhibition of neutrophil chemotaxis is mediated by activation of peroxisome proliferator-activated receptor-γ

Blood ◽  
2008 ◽  
Vol 112 (10) ◽  
pp. 4250-4258 ◽  
Author(s):  
Raju C. Reddy ◽  
Venkata R. Narala ◽  
Venkateshwar G. Keshamouni ◽  
Jami E. Milam ◽  
Michael W. Newstead ◽  
...  
Keyword(s):  
Actin Polymerization ◽  
Peroxisome Proliferator ◽  
Peroxisome Proliferator Activated Receptor ◽  
Ppar Γ ◽  
Extracellular Signal ◽  
Tnf Α ◽  
Human Pmns ◽  
Inflammatory Regulation

AbstractNeutrophils (polymorphonuclear leukocytes [PMNs]) are critical to the immune response, including clearance of infectious pathogens. Sepsis is associated with impaired PMN function, including chemotaxis. PMNs express peroxisome proliferator-activated receptor-γ (PPAR-γ), a ligand-activated nuclear transcription factor involved in immune and inflammatory regulation. The role of PPAR-γ in PMN responses, however, is not well characterized. We report that freshly isolated human PMNs constitutively express PPAR-γ, which is up-regulated by the sepsis-induced cytokines TNF-α and IL-4. PMN chemotactic responses to formylmethionyl-leucyl-phenylalanine (fMLP) and IL-8 were dose-dependently inhibited by treatment with the PPAR-γ ligands troglitazone and 15-deoxy-Δ12,14-prostaglandin J2 (15d-PGJ2) and by transfection of PMN-like HL-60 cells with a constitutively active PPAR-γ construct. Inhibition of chemotaxis by PPAR-γ ligands correlated with decreases in extracellular signal-regulated kinase-1 and -2 activation, actin polymerization, and adherence to a fibrinogen substrate. Furthermore, PMN expression of PPAR-γ was increased in sepsis patients and mice with either of 2 models of sepsis. Finally, treatment with the PPAR-γ antagonist GW9662 significantly reversed the inhibition of PMN chemotaxis and increased peritoneal PMN recruitment in murine sepsis. This study indicates that PPAR-γ activation is involved in PMN chemotactic responses in vitro and may play a role in the migration of these cells in vivo.

scholarly journals Study of the Radiosensitizing and Radioprotective Efficacy of Bromelain (a Pineapple Extract): In Vitro and In Vivo

2020 ◽  
Vol 19 ◽  
pp. 153473542095046 ◽  
Author(s):  
Mai H. Mekkawy ◽  
Hanan A. Fahmy ◽  
Ahmed S. Nada ◽  
Ola S. Ali
Keyword(s):  
Radiation Effects ◽  
Histopathological Examination ◽  
Ehrlich Ascites Carcinoma ◽  
In Vivo Studies ◽  
Pon1 Activity ◽  
Peroxisome Proliferator ◽  
Γ Irradiation ◽  
Peroxisome Proliferator Activated Receptor

This study hypothesizes that, bromelain (BL) acts as radiosensitizer of tumor cells and that it protects normal cells from radiation effects. In vitro and in vivo studies have been carried out to prove that assumption. In vitro MTT cell proliferation assay has shown that the irradiated Ehrlich ascites carcinoma (EAC) cell line could be sensitized by BL pretreatment. In vivo: animals were randomly divided into 5 groups, Group 1: control (PBS i.p for 10 days), Group 2: Ehrlich solid tumor (EST) bearing mice, Group 3: EST + γ-radiation (fractionated dose, 1 Gy × 5), Group 4: EST + BL (6 mg/kg, i.p), daily for 10 days, Group 5: EST + BL for 10 days followed by γ-irradiation (1 Gy × 5). The size and weight of tumors in gamma-irradiated EST bearing mice treated with BL decreased significantly with a significant amelioration in the histopathological examination. Besides, BL mitigated the effect of γ-irradiation on the liver relative gene expression of poly ADP ribose polymerase-1 (PARP1), nuclear factor kappa activated B cells (NF-κB), and peroxisome proliferator-activated receptor α (PPAR-α), and it restored liver function via amelioration of paraoxonase1 (PON1) activity, reactive oxygen species (ROS) content, lipid peroxidation (LPO) and serum aspartate transaminase (AST), alanine transaminase (ALT), and albumin (ALB). It is concluded that BL can be considered as a radio-sensitizer and radio-protector, suggesting a possible role in reducing radiation exposure dose during radiotherapy.

Controversy: PPARγ as a target for treatment of colorectal cancer

2002 ◽  
Vol 283 (2) ◽  
pp. G266-G269 ◽  
Author(s):  
Rajnish A. Gupta ◽  
Raymond N. Dubois
Keyword(s):  
Colorectal Cancer ◽  
Xenograft Model ◽  
Nuclear Hormone Receptor ◽  
Peroxisome Proliferator ◽  
Loss Of Function ◽  
Preneoplastic Lesions ◽  
Peroxisome Proliferator Activated Receptor ◽  
Mouse Xenograft Model

Colorectal cancer (CRC) represents a significant cause of morbidity and mortality worldwide. Recently, ligands for the nuclear hormone receptor peroxisome proliferator-activated receptor γ (PPARγ) have exhibited promise in the treatment of CRC. For example, activation of PPARγ reduces the proliferation of cultured CRC cells grown in vitro or in vivo using the nude mouse xenograft model of tumor growth. Furthermore, agonists of the receptor also reduce the development of preneoplastic lesions in a model of carcinogen-induced CRC in rats. However, ligands for the receptor paradoxically enhance intestinal adenoma formation in another murine model of intestinal polyposis, the APC Min mice. These disparate results may be due to the inherent limitations of the APC Min mouse as a model for humans with CRC. Finally, genetic studies identifying loss of function mutations of PPARγ in human CRC specimens strongly suggest a tumor suppressive role for the receptor during the development of CRC.

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