gdnf affects early diencephalic dopaminergic neuron development through regulation of differentiation‐associated transcription factors in zebrafish

Abstract

Glial cell line-derived neurotrophic factor (GDNF) has been reported to enhance dopaminergic neuron survival and differentiation in vitro and in vivo, although those results are still being debated. Glial cell line-derived neurotrophic factor (gdnf) is highly conserved in zebrafish and plays a role in enteric nervous system function. However, little is known about gdnf function in the teleost brain. Here, we employed clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9 to impede gdnf function in the maintenance of dopaminergic neuron development. Genotyping of gdnf crispants revealed successful deletions of the coding region with various mutant band sizes and down-regulation of gdnf transcripts at 1, 3 and 7 day(s) post fertilization. Notably, ~20% reduction in ventral diencephalic dopaminergic neuron numbers in clusters 8 and 13 was observed in the gdnf-deficient crispants. In addition, gdnf depletion caused a modest reduction in dopaminergic neurogenesis as determined by 5-ethynyl-2'-deoxyuridine pulse chase assay. These deleterious effects could be partly attributed to deregulation of dopaminergic neuron fate specification-related transcription factors (otp, lmx1b, shha, and ngn1) in both crispants and established homozygous mutants with whole mount in-situ hybridization (WISH) on gdnf mutants showing reduced otpb and lmx1b.1 expression in the ventral diencephalon. Interestingly, locomotor function of crispants was only impacted at 7 dpf, but not earlier. Lastly, as expected, gdnf deficiency heightened crispants vulnerability to 1-methyl-4-phenylpyridinium toxic insult. Our results suggest conservation of teleost gdnf brain function with mammals and revealed the interactions between gdnf and transcription factors in dopaminergic neuron differentiation.

Atypical Teratoid Rhabdoid Tumours Are Susceptible to Panobinostat-Mediated Differentiation Therapy

“…Detailed inspection of these functional groups further revealed enrichment of genes that are essential in nervous system development (Figure 4a,b). Several key promoters and regulators in central nervous system development (Nitric Oxide Synthase 1 (NOS1) [33][34][35][36]), neuron differentiation (T-box Transcription Factor 3 (TBX3) [37], Desmoplakin 3 (DPF3) [38,39], Bone Morphogenetic Protein 4 (BMP4) [37,40]) and neuronal development (Neurexin 2 (NRXN2) [41,42], Ataxin 1 (ATXN1) [43,44]) were upregulated, supporting neuronal differentiation [45] (Figure 4a,b). Additionally, there was also a prevalence of functional groups associated with cell division regulation including the mitotic cell cycle, nuclear division, regulation of metaphase/anaphase transition of the cell cycle, regulation of chromosome separation and spindle organization (Figure 3c,d).…”

Understanding the Potential of Genome Editing in Parkinson’s Disease

“…Within this gene family, GDNF and NRTN have received the most attention. The therapeutic potential of GDNF for PD has been known for quite some time [297], as it has been associated with reduced neuronal development [298]. Attempts to develop therapeutic applications based on GDNF include the direct injection of the GNDF protein into the putamen, where results have shown a continued survival of lesioned nigral neurons for four months in rats [297] and monkeys [299].…”

“…The therapeutic potential of GDNF for PD has been known for quite some time [297], as it has been associated with reduced neuronal development [298]. Attempts to develop therapeutic applications based on GDNF include the direct injection of the GNDF protein into the putamen, where results have shown a continued survival of lesioned nigral neurons for four months in rats [297] and monkeys [299]. These findings on animal models paved the way for Phase I clinical trials to evaluate the safety and efficacy of this type of therapy [300,301].…”

Chemical and Genetic Zebrafish Models to Define Mechanisms of and Treatments for Dopaminergic Neurodegeneration

“…The loss of function of glial cell line-derived neurotrophic factor (gdnf ) led to alterations in expression of multiple transcription factors that are involved in DA neuron development in zebrafish, including lmx1b, otp, and nr4a2 (Table 1) [31]. Knockout of gdnf decreased expression of otpb in the preoptic region and posterior tuberculum at 72 hpf.…”