The factors for the early and late development of midbrain dopaminergic neurons segregate into two distinct evolutionary clusters

A review article on the development of dopaminergic neurons and establishment of dopaminergic neuron-based in vitro models by using immortal cell lines or stem cells to study and treat Parkinson's disease

The primary pathological hallmark of Parkinson's disease (PD) is the degeneration of dopaminergic (DA) neurons in the substantia nigra pars compacta, a critical midbrain region. In vitro models based on DA neurons provide a powerful platform for investigating the cellular and molecular mechanisms of PD and testing novel therapeutic strategies. A deep understanding of DA neuron development, including the signalling pathways and transcription factors involved, is essential for advancing PD research. This article first explores the differentiation and maturation processes of DA neurons in the midbrain, detailing the relevant signalling pathways. It then compares various in vitro models, including primary cells, immortalized cell lines, and stem cell-based models, focusing on the advantages and limitations of each. Special attention is given to the role of immortalized and stem cell models in PD research. This review aims to guide researchers in selecting the most appropriate model for their specific research goals. Ethical considerations and clinical implications of using stem cells in PD research are also discussed.

Transcription Factors as Important Regulators of Changes in Behavior through Domestication of Gray Rats: Quantitative Data from RNA Sequencing

Studies on hereditary fixation of the tame-behavior phenotype during animal domestication remain relevant and important because they are of both basic research and applied significance. In model animals, gray rats Rattus norvegicus bred for either an enhancement or reduction in defensive response to humans, for the first time, we used high-throughput RNA sequencing to investigate differential expression of genes in tissue samples from the tegmental region of the midbrain in 2-month-old rats showing either tame or aggressive behavior. A total of 42 differentially expressed genes (DEGs; adjusted p-value  <  0.01 and fold-change  >  2) were identified, with 20 upregulated and 22 downregulated genes in the tissue samples from tame rats compared with aggressive rats. Among them, three genes encoding transcription factors (TFs) were detected: Ascl3 was upregulated, whereas Fos and Fosb were downregulated in tissue samples from the brains of tame rats brain. Other DEGs were annotated as associated with extracellular matrix components, transporter proteins, the neurotransmitter system, signaling molecules, and immune system proteins. We believe that these DEGs encode proteins that constitute a multifactorial system determining the behavior for which the rats have been artificially selected. We demonstrated that several structural subtypes of E-box motifs—known as binding sites for many developmental TFs of the bHLH class, including the ASCL subfamily of TFs—are enriched in the set of promoters of the DEGs downregulated in the tissue samples of tame rats’. Because ASCL3 may act as a repressor on target genes of other developmental TFs of the bHLH class, we hypothesize that the expression of TF gene Ascl3 in tame rats indicates longer neurogenesis (as compared to aggressive rats), which is a sign of neoteny and domestication. Thus, our domestication model shows a new function of TF ASCL3: it may play the most important role in behavioral changes in animals.

The Dopaminergic Control of Movement-Evolutionary Considerations

Dopamine is likely the most studied modulatory neurotransmitter, in great part due to characteristic motor deficits in Parkinson's disease that arise after the degeneration of the dopaminergic neurons in the substantia nigra pars compacta (SNc). The SNc, together with the ventral tegmental area (VTA), play a key role modulating motor responses through the basal ganglia. In contrast to the large amount of existing literature addressing the mammalian dopaminergic system, comparatively little is known in other vertebrate groups. However, in the last several years, numerous studies have been carried out in basal vertebrates, allowing a better understanding of the evolution of the dopaminergic system, especially the SNc/VTA. We provide an overview of existing research in basal vertebrates, mainly focusing on lampreys, belonging to the oldest group of extant vertebrates. The lamprey dopaminergic system and its role in modulating motor responses have been characterized in significant detail, both anatomically and functionally, providing the basis for understanding the evolution of the SNc/VTA in vertebrates. When considered alongside results from other early vertebrates, data in lampreys show that the key role of the SNc/VTA dopaminergic neurons modulating motor responses through the basal ganglia was already well developed early in vertebrate evolution.

The Role of PAX2 in Neurodevelopment and Disease

In developmental biology, transcription factors are involved in regulating the process of neural development, controlling the differentiation of nerve cells, and affecting the normal functioning of neural circuits. Transcription factors regulate the expression of multiple genes at the same time and have become a key gene category that is recognized to be disrupted in neurodevelopmental disorders such as autism spectrum disorders. This paper briefly introduces the expression and role of PAX2 in neurodevelopment and discusses the neurodevelopmental disorders associated with Pax2 mutations and its possible mechanism. Firstly, mutations in the human Pax2 gene are associated with abnormalities in multiple systems which can result in neurodevelopmental disorders such as intellectual disability, epilepsy and autism spectrum disorders. Secondly, the structure of Pax2 gene and PAX2 protein, as well as the function of Pax2 gene in neural development, was discussed. Finally, a diagram of the PAX2 protein regulatory network was made and a possible molecular mechanism of Pax2 mutations leading to neurodevelopmental disorders from the perspectives of developmental process and protein function was proposed.