Small-Molecule Cdc25A Inhibitors Protect Neuronal Cells from Death Evoked by NGF Deprivation and 6-Hydroxydopamine

Cdc25A phosphatase is activated and mediates neuronal cell death by PUMA via pRb/E2F1 pathway in a model of Parkinson's disease

Parkinson's disease (PD) is a predominant movement disorder caused mainly due to selective loss of the dopaminergic neurons in the substantia nigra pars compacta of the mid brain. There is currently no cure for PD barring treatments to manage symptoms. The reasons might be due to lack of precise understanding of molecular mechanisms leading to neurodegeneration. Aberrant cell cycle activation has been implicated in neuronal death pathways of various neurodegenerative diseases including PD. This study investigates the role of cell cycle regulator Cell division cycle 25A (Cdc25A) in a PD-relevant neuron death model induced by 6-OHDA treatment. We find Cdc25A is rapidly elevated, activated and is playing a key role in neuron death by regulating Rb phosphorylation and E2F1 activity. Knockdown of Cdc25A via shRNA downregulates the levels of pro-apoptotic PUMA, an E2F1 target and cleaved Caspase-3 levels, suggesting Cdc25A may regulate neuronal apoptosis through these effectors. Our work sheds light on the intricate signaling networks involved in neurodegeneration and highlights Cdc25A as a potential therapeutic target for mitigating aberrant cell cycle re-entry underlying PD pathogenesis. These novel insights into molecular mechanisms provide a foundation for future development of neuroprotective strategies to slow or prevent progression of this debilitating disease.

Pathological Correlates of Cognitive Decline in Parkinson's Disease: From Molecules to Neural Networks

Parkinson's disease (PD) is a progressive neurodegenerative disorder caused by the death of dopaminergic neurons in the substantia nigra and appearance of protein aggregates (Lewy bodies) consisting predominantly of α-synuclein in neurons. PD is currently recognized as a multisystem disorder characterized by severe motor impairments and various non-motor symptoms. Cognitive decline is one of the most common and worrisome non-motor symptoms. Moderate cognitive impairments (CI) are diagnosed already at the early stages of PD, usually transform into dementia. The main types of CI in PD include executive dysfunction, attention and memory decline, visuospatial impairments, and verbal deficits. According to the published data, the following mechanisms play an essential role demonstrates a crucial importance in the decline of the motor and cognitive functions in PD: (1) changes in the conformational structure of transsynaptic proteins and protein aggregation in presynapses; (2) synaptic transmission impairment; (3) neuroinflammation (pathological activation of the neuroglia); (4) mitochondrial dysfunction and oxidative stress; (5) metabolic disorders (hypometabolism of glucose, dysfunction of glycolipid metabolism; and (6) functional rearrangement of neuronal networks. These changes can lead to the death of dopaminergic cells in the substantia nigra and affect the functioning of other neurotransmitter systems, thus disturbing neuronal networks involved in the transmission of information related to the regulation of motor activity and cognitive functions. Identification of factors causing detrimental changes in PD and methods for their elimination will help in the development of new approaches to the therapy of PD. The goal of this review was to analyze pathological processes that take place in the brain and underlie the onset of cognitive disorders in PD, as well as to describe the impairments of cognitive functions in this disease.