In JoVE (1)

Other Publications (3)

Articles by Maria E. Bernis in JoVE

Other articles by Maria E. Bernis on PubMed

Wingless-type Family Member 3A Triggers Neuronal Polarization Via Cross-activation of the Insulin-like Growth Factor-1 Receptor Pathway

Frontiers in Cellular Neuroscience. 2013  |  Pubmed ID: 24298236

Initial axonal elongation is essential for neuronal polarization and requires polarized activation of IGF-1 receptors (IGF-1r) and the phosphatidylinositol 3 kinase (PI3k) pathway. Wingless-type family growth factors (Wnts) have also been implied in the regulation of axonal development. It is not known, however, if Wnts have any participation in the regulation of initial axonal outgrowth and the establishment of neuronal polarity. We used cultured hippocampal neurons and growth cone particles (GCPs) isolated from fetal rat brain to show that stimulation with the wingless family factor 3A (Wnt3a) was sufficient to promote neuronal polarization in the absence of IGF-1 or high insulin. We also show that Wnt3a triggered a strong activation of IGF-1r, PI3k, and Akt in developmental Stage 2 neurons and that the presence of activatable IGF-1r and PI3k activation were necessary for Wnt3a polarizing effects. Surface plasmon resonance (SPR) experiments show that Wnt3a did not bind specifically to the IGF-1r. Using crosslinking and immuno-precipitation experiments, we show that stimulation with Wnt3a triggered the formation of a complex including IGF-1r-Wnt3a-Frizzled-7. We conclude that Wnt3a triggers polarization of neurons via cross-activation of the IGF-1r/PI3k pathway upon binding to Fz7.

Prion-like Propagation of Human Brain-derived Alpha-synuclein in Transgenic Mice Expressing Human Wild-type Alpha-synuclein

Acta Neuropathologica Communications. Nov, 2015  |  Pubmed ID: 26612754

Parkinson's disease (PD) and multiple system atrophy (MSA) are neurodegenerative diseases that are characterized by the intracellular accumulation of alpha-synuclein containing aggregates. Recent increasing evidence suggests that Parkinson's disease and MSA pathology spread throughout the nervous system in a spatiotemporal fashion, possibly by prion-like propagation of alpha-synuclein positive aggregates between synaptically connected areas. Concurrently, intracerebral injection of pathological alpha-synuclein into transgenic mice overexpressing human wild-type alpha-synuclein, or human alpha-synuclein with the familial A53T mutation, or into wild-type mice causes spreading of alpha-synuclein pathology in the CNS. Considering that wild-type mice naturally also express a threonine at codon 53 of alpha-synuclein, it has remained unclear whether human wild-type alpha-synuclein alone, in the absence of endogenously expressed mouse alpha-synuclein, would support a similar propagation of alpha-synuclein pathology in vivo.

Neuroinvasion of α-Synuclein Prionoids After Intraperitoneal and Intraglossal Inoculation

Journal of Virology. Oct, 2016  |  Pubmed ID: 27489279

α-Synuclein is a soluble, cellular protein that in a number of neurodegenerative diseases, including Parkinson's disease and multiple system atrophy, forms pathological deposits of protein aggregates. Because misfolded α-synuclein has some characteristics that resemble those of prions, we investigated its potential to induce disease after intraperitoneal or intraglossal challenge injection into bigenic Tg(M83(+/-):Gfap-luc(+/-)) mice, which express the A53T mutant of human α-synuclein and firefly luciferase. After a single intraperitoneal injection with α-synuclein fibrils, four of five mice developed paralysis and α-synuclein pathology in the central nervous system, with a median incubation time of 229 ± 17 days. Diseased mice accumulated aggregates of Sarkosyl-insoluble and phosphorylated α-synuclein in the brain and spinal cord, which colocalized with ubiquitin and p62 and were accompanied by gliosis. In contrast, only one of five mice developed α-synuclein pathology in the central nervous system after intraglossal injection with α-synuclein fibrils, after 285 days. These findings are novel and important because they show that, similar to prions, α-synuclein prionoids can neuroinvade the central nervous system after intraperitoneal or intraglossal injection and can cause neuropathology and disease.

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