A cis-regulatory change underlying the motor neuron-specific loss of Ebf expression in immotile tunicate larvae

The Role of N6-Methyladenosine (m6A) RNA Modification in the Pathogenesis of Parkinson's Disease

Parkinson's disease (PD) is a neurodegenerative disease with a high prevalence among the middle-aged and elderly population. The pathogenesis of PD is closely linked to the misfolding and aggregation of α-synuclein, which contributes to the formation of Lewy bodies. These processes are associated with the degeneration of dopaminergic neurons, a key neuropathological change that underlies the motor symptoms of PD. In addition, genetic susceptibility, mitochondrial dysfunction, oxidative stress and neuroinflammation are involved in the progress of the disease. Previous studies indicated that the dysregulation of epigenetic modifications, including DNA methylation and histone acetylation, may be the key pathophysiological factors in PD. N6-methyladenosine (m6A) is a dynamically reversible modification in eukaryotes RNA, and could regulate mRNA degradation, stability, maturation, and translation. Recently, clinical research has shown that the global m6A level is significantly reduced in PD patients as well as the expression changes in m6A-associated proteins. Moreover, the dysregulation of m6A modification was shown to impact dopamine metabolism and damage dopaminergic neurons, indicating that m6A RNA modification may play a critical role in the pathogenesis of PD. In this review, we summarize recent clinical studies on m6A RNA modification in PD patients and discuss the regulatory role of m6A modification in dopamine metabolism and dopaminergic neurons death. Furthermore, based on the different m6A modification databases and prediction websites, we analyzed the potential m6A modification sites on the mRNA of key PD pathogenic genes (SNCA, PRKN, PINK1, and LRRK2) for the first time, aiming to offer new gene targets and perspectives understanding the pathogenesis of PD.

Early B Cell Factor 3 (EBF3) attenuates Parkinson's disease through directly regulating contactin-associated protein-like 4 (CNTNAP4) transcription: An experimental study

Parkinson's disease (PD) is a gradually debilitating neurodegenerative syndrome. Here, we analyzed GSE7621 chip data obtained from the Gene Expression Omnibus (GEO) database to explore the pathogenesis of PD. Early B Cell Factor 3 (EBF3), a member of the highly evolutionarily conserved EBF-transcription factor family, is involved in neuronal development. EBF3 expression is low in the substantia nigra of patients with PD. However, whether EBF3 is implicated in dopaminergic neuron death during PD has not yet been investigated. Therefore, we aimed to reveal the potential anti-apoptotic effect and molecular mechanism of EBF3 in PD. We established a 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP)-induced PD mouse model in vivo and a 1-methyl-4-phenylpyridine (MPP+)-induced SH-SY5Y cell model in vitro. EBF3 was downregulated in the substantia nigra of PD mice and SH-SY5Y cells treated with MPP+, and the m6A methylation modification level was low. Fat mass and obesity-associated protein (FTO) siRNA upregulated m6A methylation modification of EBF3 and extended the EBF3 mRNA half-life. Functionally, as demonstrated by the results of the open-field test, pole test and gait analysis, EBF3 overexpression ameliorated MPTP-induced behavioral disorder. Further, EBF3 overexpression suppressed neuronal apoptosis in vivo, as evidenced by decreased TUNEL+ cells, and the increased activation of caspase-3 and caspase-9. Similar results were obtained in vitro, as reflected by increased cell viability, decreased LDH activity and restored mitochondrial function, collectively protecting SH-SY5Y cells from MPP+-induced apoptosis. Mechanistically, the results of luciferase reporter, ch-IP and DNA pull-down assays confirmed that, as a transcription factor, EBF3 bound to the promoter of CNTNAP4 (a protein associated with neuronal differentiation) and directly regulated CNTNAP4 transcription. Strikingly, CNTNAP4 knockdown markedly abolished the effect of EBF3 on cell apoptosis, thus aggravating PD. In conclusion, the low level of m6A methylation modification may contribute to the low expression of EBF3 during PD. Additionally, EBF3 attenuates PD by activating CNTNAP4 transcription, suggesting that EBF3 may be a novel therapeutic target in PD.

Development and circuitry of the tunicate larval Motor Ganglion, a putative hindbrain/spinal cord homolog

The Motor Ganglion (MG) is a small collection of neurons that control the swimming movements of the tunicate tadpole larva. Situated at the base of the tail, molecular and functional comparisons suggest that may be a homolog of the spinal cord and/or hindbrain ("rhombospinal" region) of vertebrates. Here we review the most current knowledge of the development, connectivity, functions, and unique identities of the neurons that comprise the MG, drawn mostly from studies in Ciona spp. The simple cell lineages, minimal cellular composition, and comprehensively mapped "connectome" of the Ciona MG all make this an excellent model for studying the development and physiology of motor control in aquatic larvae.

Loss of collagen gene expression in the notochord of the tailless tunicate Molgula occulta

In tunicates, several species in the Molgulidae family have convergently lost the tailed, swimming larval body plan, including the morphogenesis of the notochord, a major chordate-defining trait. Through the comparison of tailless M. occulta and a close relative, the tailed species M. oculata, we show that notochord-specific expression of the Collagen Type I/II Alpha (Col1/2a) gene appears to have been lost specifically in the tailless species. Using CRISPR/Cas9-mediated mutagenesis in the tailed laboratory model tunicate Ciona robusta, we demonstrate that Col1/2a plays a crucial role in the convergent extension of notochord cells during tail elongation. Our results suggest that the expression of Col1/2a in the notochord, although necessary for its morphogenesis in tailed species, is dispensable for tailless species. This loss is likely a result of the accumulation of cis-regulatory mutations in the absence of purifying selective pressure. More importantly, the gene itself is not lost, likely due to its roles in other developmental processes, including during the adult stage. Our study further confirms the Molgulidae as an interesting family in which to study the evolutionary loss of tissue-specific expression of indispensable genes.