Papers by Michalina Hanzel
SUMMARYThe SEL1L-HRD1 protein complex represents the most conserved branch of endoplasmic reticul... more SUMMARYThe SEL1L-HRD1 protein complex represents the most conserved branch of endoplasmic reticulum (ER)-associated degradation (ERAD); however, definitive evidence for the importance of SEL1L in HRD1 ERAD is lacking. Here we report that attenuation of the interaction between SEL1L and HRD1 impairs HRD1 ERAD function and has pathological consequences in mice. Our data show thatSEL1Lvariantp.Ser658Pro(SEL1LS658P) previously identified in Finnish Hound suffering cerebellar ataxia is a recessive hypomorphic mutation, causing partial embryonic lethality, developmental delay, and early-onset cerebellar ataxia in homozygous mice carrying the bi-allelic variant. Mechanistically,SEL1LS658Pvariant attenuates the SEL1L-HRD1 interaction and causes HRD1 dysfunction by generating electrostatic repulsion between SEL1L F668 and HRD1 Y30 residues. Proteomic screens of SEL1L and HRD1 interactomes revealed that the SEL1L-HRD1 interaction is prerequisite for the formation of a functional HRD1 ERAD com...
Scientific Reports, 2019
The developing cerebellum of amniotes is characterised by a unique, transient, secondary prolifer... more The developing cerebellum of amniotes is characterised by a unique, transient, secondary proliferation zone: the external germinal layer (EGL). The EGL is comprised solely of granule cell precursors, whose progeny migrate inwardly to form the internal granule cell layer. While a range of cell morphologies in the EGL has long been known, how they reflect the cells’ differentiation status has previously only been inferred. Observations have suggested a deterministic maturation from outer to inner EGL that we wished to test experimentally. To do this, we electroporated granule cell precursors in chick with plasmids encoding fluorescent proteins and probed labelled cells with markers of both proliferation (phosphohistone H3) and differentiation (Axonin1/TAG1 and NeuroD1). We show that granule cell precursors can display a range of complex forms throughout the EGL while mitotically active. Overexpression of full length NeuroD1 within granule cell precursors does not abolish proliferation...
Cerebellar granule cell precursors (GCPs) form a secondary germinative epithelium, the external g... more Cerebellar granule cell precursors (GCPs) form a secondary germinative epithelium, the external germinal layer (EGL) where they proliferate extensively to produce the most numerous cell type in the brain. The morphological sequence of events that characterizes the differentiation of GCPs in the EGL is well established. However, morphologies of individual GCP and their differentiation status have never been correlated. Here, we examine the morphological features and transitions of GCPs in the chicken cerebellum by labelling a subset of GCPs with a stable genomic expression of a GFP transgene and following their development within the EGL in fixed tissue and using time-lapse imaging. We use immunohistochemistry to observe cellular morphologies of mitotic and differentiating GCPs to better understand their differentiation dynamics. Results reveal that mitotic activities of GCPs are more complex and dynamic than currently appreciated. While most GCPs divide in the outer and middle EGL, ...
Journal of Visualized Experiments, 2015
The cerebellar external granule layer is the site of the largest transit amplification in the dev... more The cerebellar external granule layer is the site of the largest transit amplification in the developing brain. Here, we present a protocol to target genetic modification to this layer at the peak of proliferation using ex vivo electroporation and culture of cerebellar slices from embryonic day 14 chick embryos.
Development (Cambridge, England), 2014
The cerebellum has evolved elaborate foliation in the amniote lineage as a consequence of extensi... more The cerebellum has evolved elaborate foliation in the amniote lineage as a consequence of extensive Atoh1-mediated transit amplification in an external germinal layer (EGL) comprising granule cell precursors. To explore the evolutionary origin of this layer, we have examined the molecular geography of cerebellar development throughout the life cycle of Xenopus laevis. At metamorphic stages Xenopus displays a superficial granule cell layer that is not proliferative and expresses both Atoh1 and NeuroD1, a marker of postmitotic cerebellar granule cells. Premature misexpression of NeuroD1 in chick partially recapitulates the amphibian condition by suppressing transit amplification. However, unlike in the amphibian, granule cells fail to enter the EGL. Furthermore, misexpression of NeuroD1 once the EGL is established both triggers radial migration and downregulates Atoh1. These results show that the evolution of transit amplification in the EGL required adaptation of NeuroD1, both in the...
The cerebellum has evolved elaborate foliation in the amniote lineage as a consequence of extensi... more The cerebellum has evolved elaborate foliation in the amniote lineage as a consequence of extensive Atoh1-mediated transit amplification in an external germinal layer (EGL) comprising granule cell precursors. To explore the evolutionary origin of this layer, we have examined the molecular geography of cerebellar development throughout the life cycle of Xenopus laevis. At metamorphic stages Xenopus displays a superficial granule cell layer that is not proliferative and expresses both Atoh1 and NeuroD1, a marker of postmitotic cerebellar granule cells. Premature misexpression of NeuroD1 in chick partially recapitulates the amphibian condition by suppressing transit amplification. However, unlike in the amphibian, granule cells fail to enter the EGL. Furthermore, misexpression of NeuroD1 once the EGL is established both triggers radial migration and downregulates Atoh1. These results show that the evolution of transit amplification in the EGL required adaptation of NeuroD1, both in the timing of its expression and in its regulatory function, with respect to Atoh1.
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Papers by Michalina Hanzel