Autophagy and Its Association with Genetic Mutations in Parkinson Disease.

Parkinson disease is the second most common neurodegenerative disorder, affecting 0.1-0.2% of the general population. It is a progressive debilitating disorder caused by degeneration of dopaminergic neurons in the substantia nigra pars compacta. It is characterized by motor and non-motor symptoms. Parkinson disease can be caused by mutations in genes that encode proteins involved in the autophagic process, resulting in impaired autophagy. Indeed, autophagy has been implicated in the pathogenesis of Parkinson disease, particularly because its impairment causes the buildup of proteins. Thus, this review aims to provide an overview of Parkinson disease-related genetic mutations and their association with autophagy impairment in Parkinson disease, which can be helpful in improving the understanding of the pathogenesis of Parkinson disease, illustrating the potential therapeutic implications of agents that can enhance autophagy in Parkinson disease. Additionally, we will highlight the essential need for the development of highly sensitive and specific assays for gene-based diagnostic biomarkers. Finally, we will provide an overview on the potential gene-based therapeutic approaches for Parkinson disease, which have been most advanced and are associated with the most common targets being alpha-synuclein (SNCA), leucine-rich repeat kinase-2 (LRRK2), and glucocerebrosidase (GBA).

Programmed Cell Death in Diabetic Nephropathy: A Review of Apoptosis, Autophagy, and Necroptosis.

Diabetic nephropathy is a common complication of type I and type II diabetes, in which renal glomeruli are destroyed, resulting in renal damage, proteinuria, and hypertension. Apoptosis, autophagy, and necroptosis are 3 forms of programmed cell death that have been implicated in the pathogenesis of diabetic nephropathy. Apoptosis of podocytes leads to glomerular injury and podocyte depletion, which are associated with proteinuria and glomerular structural damage in diabetic nephropathy. Additionally, epithelial cells in the proximal convoluted tubules also undergo apoptosis in diabetic nephropathy, leading to tubular atrophy, which causes tubular cell depletion and the subsequent formation of atubular glomeruli in association with the loss of renal function. On the other hand, insufficiency of autophagy has been correlated with the pathogenesis of diabetic nephropathy. For instance, decreased autophagic activity has been shown in podocytes of the diabetic kidney, causing variations in podocyte function and subsequent disruption to the glomerular filtration barrier. Furthermore, attenuated autophagic activity has also been demonstrated in proximal tubular cells of the diabetic kidney, resulting in the buildup of impaired molecules and organelles, which are normally broken down by autophagy, leading to proteinuria. Moreover, necroptosis might have a key role in podocyte damage and subsequent decline in diabetic nephropathy. Thus, this article aims to review the mechanisms and effects of programmed cell death in diabetic nephropathy, including the roles of apoptosis, autophagy, and necroptosis.

Endurance exercise training suppresses myostatin upregulation and nuclear factor-kappa B activation in a mouse model of Parkinson's disease.

Background and Aim: Muscle atrophy is common in Parkinson's disease (PD). Although myostatin has been implicated in muscle atrophy, its expression in PD skeletal muscle has not been investigated. Therefore, this study aimed to elucidate the influence of PD induction and exercise training on myostatin expression in the gastrocnemius skeletal muscle. Materials and Methods: Thirty albino mice were randomly selected and separated into three groups of 10 mice each: Sedentary control, sedentary PD (SPD), and exercised PD (EPD). 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine and probenecid were used to induce chronic parkinsonism in the PD groups. Immunohistochemistry was used to investigate the expression of myostatin and nuclear factor kappa B (NF-kB) in gastrocnemius muscles of all three groups. Results: Myostatin expression and NF-kB nuclear localization, indicative of its activation, were significantly (p<0.01) higher in gastrocnemius skeletal muscle in the SPD group than in the control and EPD groups. Concomitantly, the average cross-sectional area of gastrocnemius muscle fibers in the SPD albino mice was significantly smaller (p<0.01) than in the control and EPD groups, indicating muscle atrophy. Conclusion: The present data are the first to indicate a correlation between PD induction and myostatin overexpression and NF-kB activation in the gastrocnemius muscle, potentially promoting the muscle atrophy commonly seen in PD. Additionally, the current data are the first to indicate the beneficial effects of exercise training on PD-associated myostatin overexpression, NF-κB activation, and muscle atrophy. Thus, our data are the first to suggest that myostatin and NF-κB might be regarded as potential therapeutic targets in an attempt to ameliorate skeletal muscle abnormalities commonly observed in PD.

Programmed cell death in cerebellar Purkinje neurons.

Apoptosis, autophagy and necrosis are the three main types of programmed cell death. One or more of these types of programmed cell death may take place in neurons leading to their death in various neurodegenerative disorders in humans. Purkinje neurons (PNs) are among the most highly vulnerable population of neurons to cell death in response to intrinsic hereditary diseases or extrinsic toxic, hypoxic, ischemic, and traumatic injury. In this review, we will describe the three main types of programmed cell death, including the molecular mechanisms and the sequence of events in each of them, and thus illustrating the intracellular proteins that mediate and regulate each of these types. Then, we will discuss the role of Ca2+ in PN function and increased vulnerability to cell death. Additionally, PN death will be described in animal models, namely lurcher mutant mouse and shaker mutant rat, in order to illustrate the potential therapeutic implications of programmed cell death in PNs by reviewing the previous studies that were carried out to interfere with the programmed cell death in an attempt to rescue PNs from death.

Apoptosis and its therapeutic implications in neurodegenerative diseases.

Neurodegenerative disorders are characterized by progressive loss of particular populations of neurons. Apoptosis has been implicated in the pathogenesis of neurodegenerative diseases, including Parkinson disease, Alzheimer disease, Huntington disease, and amyotrophic lateral sclerosis. In this review, we focus on the existing notions relevant to comprehending the apoptotic death process, including the morphological features, mediators and regulators of cellular apoptosis. We also highlight the evidence of neuronal apoptotic death in Parkinson disease, Alzheimer disease, Huntington disease, and amyotrophic lateral sclerosis. Additionally, we present evidence of potential therapeutic agents that could modify the apoptotic pathway in the aforementioned neurodegenerative diseases and delay disease progression. Finally, we review the clinical trials that were conducted to evaluate the use of anti-apoptotic drugs in the treatment of the aforementioned neurodegenerative diseases, in order to highlight the essential need for early detection and intervention of neurodegenerative diseases in humans.

Endurance exercise training suppresses Parkinson disease-induced overexpression of apoptotic mediators in the heart.

BACKGROUNDWe have shown elevated levels of p53 and active caspase-3 in the heart with Parkinson disease (PD). The main aim of this study is to examine the effect of treadmill training on the cardiac expression of p53 and active caspase-3 in the mouse with induced Parkinsonism. METHODS: Thirty randomly selected normal albino mice were equally divided into the following 3 groups: sedentary control (SC), sedentary Parkinson diseased (SPD), and exercised Parkinson diseased (EPD). 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine and probenecid (MPTP/p) were used to induce chronic Parkinson disease in the SPD and EPD animals. The expression of p53 and active caspase-3 was investigated, using immunohistochemistry, in the heart in each animal group. RESULTS: Both p53 and active caspase-3 expression was significantly (p value < 0.05) reduced in the PD heart following endurance exercise training. CONCLUSION: Our present data suggest that chronic exercise training reduced PD-induced upregulation of p53 and active caspase-3 in the heart. Thus, our study suggests that inhibiting p53 and/or active caspase-3 may be considered as a therapeutic approach to ameliorate PD cardiomyopathy.

Active caspase-3 upregulation is augmented in at-risk cerebellar Purkinje cells following inferior olive chemoablation in the shaker mutant rat: an immunofluorescence study.

OBJECTIVES: Mechanisms underlying Purkinje cell (PC) death, which leads to many diseases in humans, are still poorly elucidated. Progressive PC degeneration occurs in shaker mutant rat due to an X-linked recessive mutation leading to gait ataxia and total-body tremors. Chemoablation of the inferior olive (IO) and olivocerebellar deafferentation temporally accelerated PC death from the natural 6-8 week time-course to 1-2 weeks in the shaker mutant rat. The present study posits that IO chemoablation leads to the accelerated and augmented upregulation of the executioner active caspase-3 that triggers apoptosis of at-risk PCs throughout the ordinary phenotypic manifestation of the shaker mutation. METHODS: Immunofluorescence and double labeling for calbindin and active caspase-3 were used in vermal cerebellar sections from IO-chemoablated rats to demonstrate the effect of IO chemoablation on active caspase-3 expression in at-risk PCs. RESULTS: Active caspase-3 expression was enhanced in the anterior degeneration (ADC) and posterior degeneration (PDC) compartments to reach a peak in both degeneration compartments at 24 h following the injections for IO chemoablation. DISCUSSION: Consequently, it can be deduced that active caspase-3 expression in shaker mutant rats is modifiable suggesting the possibility of targeting it therapeutically in an attempt to rescue PCs from death. Abbreviation PC: Purkinje cell; IO: inferior olive; ADC: Anterior degeneration compartment; PDC: Posterior degeneration compartment; ISC: Intermediate survival compartment; FNSC: Flocculonodular survival compartment.

Treadmill exercise training could attenuate the upregulation of Interleukin-1 beta and tumor necrosis factor alpha in the skeletal muscle of mouse model of chronic/progressive Parkinson disease.

BACKGROUND: Induction of Parkinson disease (PD) causes interleukin-1 beta (IL-1ß) and tumor necrosis factor-alpha (TNF-α) upregulation in gastrocnemius skeletal muscles. Endurance exercise suppresses iNOS and HSP90 overexpression in PD skeletal muscle. The purpose of this study is to test the impact of treadmill exercise training on PD-associated IL-1ß and TNF-α upregulation in the gastrocnemius muscle. METHODS: Thirty normal albino mice were randomly selected and divided into three equal groups: sedentary control (SC), sedentary PD (SPD), and Exercised PD (EPD). Chronic Parkinsonism was induced by treating mice in the SPD and EPD groups with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine and probenecid (MPTP/p). Gastrocnemius muscles were examined for the expression of IL-1ß and TNF-α using immunohistochemistry in the three different groups. RESULTS: Endurance exercise training significantly decreased both IL-1ß and TNF-α expression in skeletal muscle in EPD (P value < 0.01) compared with that in the SPD. CONCLUSION: Our present data suggest that PD-induced upregulation of IL-1ß and TNF-α in the gastrocnemius muscle could be reversed following endurance exercise training. Accordingly, IL-1ß and TNF-α might be considered therapeutically to ameliorate skeletal muscle abnormalities characterizing PD.

Cerebellar Upregulation of Cell Surface Death Receptor-Mediated Apoptotic Factors in Harmaline-Induced Tremor: An Immunohistochemistry Study.

Active caspase-3-mediated apoptosis has been implicated in the pathogenesis of harmaline-induced tremor. The aim of this study is to illustrate the impact of tremor induction on the expression of factors mediating the cell surface death receptor-dependent apoptosis. A total of 20 normal Wistar rats were randomly selected and equally divided into control and experimental groups. Tremor was induced in the experimental group by injecting the rats with a single dose of harmaline (50 mg/kg). After that, cerebellar tissues were evaluated by immunohistochemistry to examine the expression of tumor necrosis factor α (TNF-α) and active caspase-8 in the 2 groups of animals. TNF-α and active caspase-8 expression was significantly higher in cerebella from experimental rats compared with that in those from the control rats (P value < .01). Thus, our present data suggest the association of tremor induction with the cerebellar overexpression of TNF-α and active caspase-8, correlative with Purkinje cell (PC) loss indicated by loss of calbindin immunoreactivity, indicating the induction of the cell surface death receptor-mediated apoptosis.

Association of Parkinson Disease Induction with Cardiac Upregulation of Apoptotic Mediators P53 and Active Caspase-3: An Immunohistochemistry Study.

BACKGROUND Apoptosis plays a key role in the pathogenesis of Parkinson disease (PD). Active caspase-3, which is a proapoptotic factor, has been shown to reduce cardiac contractility, causing cardiac dysfunction in many pathological diseases. Reduced cardiac contractility and cardiac autonomic dysfunction have been reported in PD patients and PD mice treated with MPTP. The aim of this study was to show the impact of PD induction on the expression of the apoptotic mediators p53 and active caspase-3 in the heart. MATERIAL AND METHODS Equal control and PD groups were formed by 20 randomly selected normal albino mice. We used 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (25 mg/kg) and probenecid (250 mg/kg) (MPTP/p) to induce chronic Parkinsonism in the PD group. Immunohistochemistry was performed to investigate the expression of p53, active caspase-3, and ß-adrenergic receptor in hearts from the 2 animal groups. RESULTS P53 and active caspase-3 expression was significantly higher in PD hearts than in the control hearts (p value <0.01). ß-adrenergic receptor expression was significantly lower in PD hearts than in control hearts (p value <0.01). CONCLUSIONS Our results show an association of PD with p53 and active caspase-3 overexpression and ß-adrenergic receptor underexpression in the heart, potentially promoting the cardiac autonomic dysfunction frequently observed in PD.

Autophagy precedes apoptosis among at risk cerebellar Purkinje cells in the shaker mutant rat: an ultrastructural study.

Cerebellar Purkinje cell (PC) death has been shown to occur in essential tremor, ataxia, and many other neurodegenerative diseases in humans. Shaker mutant rats have an X-linked recessive mutation that causes hereditary degeneration of "at risk" cerebellar PCs. This defect can occur in the restricted anterior (ADC) and posterior (PDC) vermal degeneration compartments postnatally within 7 to 14 weeks of age as a natural phenotype in the shaker mutant rat. "Secure" PCs persist in a flocculonodular survival compartment (FNSC). Because we have previously shown that "at risk" PCs die due to apoptosis in the shaker mutant rat, we hypothesized that the PC death observed in the hereditary shaker mutant rat may be due to the activation of more than one type of death pathway. This ultrastructural investigation suggests that "at risk" PCs die due to apoptosis as a result of autophagic activation. Moreover, our data suggest that both apoptosis and autophagy must be simultaneously inhibited to rescue "at risk" PCs from death.

Parkinson disease-induced upregulation of apoptotic mediators could be attenuated in the skeletal muscle following chronic exercise training.

BACKGROUND: We have shown elevated levels of p53 and active caspase-3 in gastrocnemius skeletal muscle with Parkinson's disease (PD). The main aim of this study is to examine the impact of endurance exercise training on the expression of p53 and active caspase-3 in the skeletal muscle of mouse with induced Parkinsonism. METHODS: Sedentary control (SC), sedentary Parkinson diseased (SPD), and exercised Parkinson diseased (EPD) groups were formed; each consisting of 10 randomly selected normal albino mice. Chronic Parkinson disease was induced in the SPD and EPD animals using 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine and probenecid (MPTP/p). The expression of p53 and active caspase-3 was investigated, using immunohistochemistry, in the gastrocnemius muscle in each animal group. RESULTS: Both p53 and active caspase-3 expression was significantly (p value < 0.05) reduced in the PD gastrocnemius skeletal muscle following endurance exercise training. CONCLUSION: Our present data suggest that chronic exercise training reduced Parkinson disease-induced upregulation of p53 and active caspase-3 in gastrocnemius skeletal muscle. Thus, our study suggests that inhibiting p53 and/or active caspase-3 may be considered as a therapeutic approach to ameliorate PD skeletal muscle abnormalities.

Cerebellar Purkinje cells die by apoptosis in the shaker mutant rat.

Cerebellar Purkinje cells (PCs) die in humans leading to a variety of diseases including ataxia and essential tremor. The etiology underlying PC death is poorly understood. Shaker mutant rat is a unique animal model of progressive PC degeneration that is compartmentalized and of adult-onset. In shaker mutant rats, hereditary degeneration of at risk PCs occurs between 7 and 14 postnatal weeks of age as a natural phenotypic expression of the shaker mutation and at earlier or later ages depending upon experimental conditions in restricted anterior (ADC) and posterior (PDC) vermal degeneration compartments. Secure PCs in a flocculonodular survival compartment (FNSC) always survive. In this study, we investigated DNA fragmentation and active caspase-3 expression characteristic of apoptosis using immunofluorescence and fluorescence microscopy. We also sought to confirm the occurrence of apoptosis in at risk PCs using transmission electron microscope. Purkinje neurons were the only cerebellar cells labeled for TUNEL and immunoreactive to active caspase-3 in the shaker mutant. Active caspase-3 expression observed was spatially and temporally congruous with the pattern of calbindin immunolabeling of degenerating PCs that is characterized by dendritic atrophy, shrinkage of PC cell bodies and the appearance of PC axonal torpedoes. DNA fragmentation, detected by TUNEL, as well as ultrastructural morphological changes characteristic for apoptosis, provided additional evidence for the occurrence of apoptosis in at risk PCs.

Apoptotic Mediators are Upregulated in the Skeletal Muscle of Chronic/Progressive Mouse Model of Parkinson's Disease.

Apoptosis has been implicated in the pathogenesis of Parkinson disease (PD). Parkinson disease is characterized by skeletal muscle abnormalities. The aim of this study is to illustrate the impact of PD induction on the expression of apoptotic mediators. Twenty normal albino mice were randomly selected and equally divided in control and PD groups. Chronic Parkinsonism was induced in the PD group using 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine and probenecid (MPTP/p). After that, samples from gastrocnemius muscles were evaluated by immunohistochemistry to examine the expression of p53 and active caspase-3 in the two groups of animals. P53 and active caspase-3 expression was significantly higher in gastrocnemius skeletal muscle in PD mice compared with that in the control mice (P value <0.01). Furthermore, we show PD gastrocnemius muscle atrophy measured by significant reduction (P < 0.01) in the muscle fiber cross-sectional area. Thus, our present data suggest that PD induction increased the expression of the apoptotic mediators p53 and active caspase-3 in gastrocnemius muscle, indicating the induction of apoptosis, which was correlative with gastrocnemius muscle atrophy subsequent to the induction of PD.

Treadmill Exercise Training Improves Vascular Endothelial Growth Factor Expression in the Cardiac Muscle of Type I Diabetic Rats.

BACKGROUND: Vascular endothelial growth factor (VEGF) expression is a potent mitogen for endothelial cells that is involved in angiogenesis. Cardiac VEGF is decreased in many pathologic conditions, including diabetes mellitus and aging. Exercise training has improved VEGF expression in the aging heart. Thus, the aim of our study is to illustrate the impact of treadmill exercise training on the cardiac VEGF expression in type I diabetic rats. METHODS: Twenty normal Sprague-Dawley rats and Sprague-Dawley rats with streptozotocin-induced diabetes were divided into the following equal groups: sedentary control (SC), exercised control (EC), sedentary diabetic rats (SD) and exercised diabetic rats (ED). Immunohistochemistry was used to investigate VEGF expression in the cardiac tissue in each of the four different groups. RESULTS: Cardiac VEGF expression was significantly (P < 0.05) lower in SD compared with that in SC. However, exercise training significantly (P < 0.01) enhanced VEGF expression in the cardiac tissue in ED compared with that in SD. CONCLUSION: Our present data suggest that treadmill exercise training improved diabetes-induced downregulation in the cardiac VEGF expression.