microtubule

Cytoskeletal connectors: Deciphering the fundamental mechanisms of cytoskeletal dynamics and transport

PROJECT SUMMARY The cytoskeleton is a dynamic network of filamentous structures, including microtubules and actin, that regulate essential cellular processes such as cell shape, growth, and signaling. Cytoskeleton also serves as tracks for molecular motors, which transport a variety of cellular cargoes, including organelles, macromolecules, and vesicles. These cargoes are linked to motors by specialized connector proteins. Disruptions in connector proteins are implicated in a range of neurodevelopmental and neurodegenerative diseases, as well as cancers. Despite their importance, these proteins continue to be understudied, primarily due to their perceived role as passive linkers and the technical challenges in working with them. However, recent discoveries suggest that connector proteins may play more active roles, in some cases even have enzymatic functions. This proposal aims to uncover mechanisms of connector protein functions through a detailed investigation of actin-microtubule and motor-cargo interactions. Actin and microtubules are linked by the spectraplakin family of large and evolutionarily conserved proteins, critical for neuronal development and differentiation. Recent discoveries of ATPase domains within these proteins suggest they may haves beyond simply linking cytoskeletal components. One goal of this proposal is to investigate the role of spectraplakin’s ATPase domains via structural, biochemical, and cell biology approaches. Another goal is to explore how dynamic changes in motor-cargo connectors facilitate the transport of diverse cargoes along microtubule tracks. The focus will be on the cytoplasmic dynein-1 (dynein) and the connectors (adaptors) that activate and link dynein to cargo. Dynein is a microtubule minus-end directed motor that plays essential roles in cell division, and transports hundreds of different cellular cargoes. While several motor-cargo connectors have been identified, the regulatory mechanisms enabling cargo transport are not fully understood. We are investigating whether connector proteins work together to activate dynein movement and/or facilitate cargo handoff between different dynein complexes. Using innovative approaches, including time- resolved cryo-EM, complex in-vitro reconstitutions, and live-cell imaging in induced neurons, we are uncovering critical mechanisms that govern cytoskeletal connector proteins, furthering our understanding of how the cytoskeleton regulates essential cellular processes.

Development of a synthetic human centromere

PROJECT SUMMARY/ABSTRACT Human artificial chromosomes (HACs) are mini-chromosomes that can be stably inherited across many cellular generation. HACs are potentially powerful gene therapy vectors and extremely useful tools in biological research. The stability of HACs depends on the presence of a functional centromere. Centromeres are unique genomic loci that mediate the segregation of chromosomes during mitosis by forming kinetochores leading to microtubule attachment. These sites are specified by the incorporation of distinct nucleosomes in which histone H3 is replaced by CENP- A. Most centromeric nucleosomes are embedded in highly repetitive alpha-satellite DNA. The current versions of the HACs contain alpha-satellite centromeric DNA, are relatively inefficient and frequently recombine into the genome. Despite the presence of alpha-satellite DNA at centromeres, it is not absolutely required for centromere function. This is evidenced by the existence of neocentromeres in some people, and work from our lab and others that centromeres can be induced to form at non-centromeric sites. Deposition of centromeric nucleosomes is mediated by the CENP-A specific chaperone HJURP and the Mis18 complex. Previous work has shown that artificially targeting HJURP and Mis18 proteins to LacO arrays can create de novo centromeres at non-centromeric sites. This approach leads to the formation of a full centromere, recapitulating most of the characteristics of an endogenous centromere. Here we propose to develop a more versatile approach which can be re-programmed to target many different sequences. This powerful approach will provide new and exciting insight into the rules of centromere formation. The proposal will explore the practical application of de novo centromere formation in supporting the stability of human artificial chromosomes (HACs). We will test if these synthetic centromeres (SynCen) can lead to stable inheritance of a human artificial chromosome. More efficient stable non-repetitive synthetic centromere will greatly expand the potential use of HACs as gene therapy vectors.

The tubulin code in neuron health and disease : focus on detyrosination

Untitled Seminar

Rachel Moore- Microtubules are not required to generate a nascent axon in embryonic spinal neurons in vivo Michael Notaras-TBA Rachel Wong- Circuit assembly in the vertebrate retina

Numbing intraneuronal Tau levels to prevent neurodegeneration in tauopathies

Intraneuronal accumulation of the microtubule associated protein Tau is largely recognized as an important toxic factor linked to neuronal cell death in Alzheimer’s disease and tauopathies. While there has been progress uncovering mechanisms leading to the formation of toxic Tau tangles, less is known about how intraneuronal Tau levels are regulated in health and disease. Here, I will discuss our recent work showing that the intracellular trafficking adaptor protein Numb is critical to control intraneuronal Tau levels. Inactivation of Numb in retinal ganglion cells increases monomeric and oligomeric Tau levels and leads to axonal blebbing in optic nerves, followed by significant neuronal cell loss in old mice. Interestingly, overexpression of the long isoform of Numb (Numb-72) decreases intracellular Tau levels by promoting exocytosis of monomeric Tau. In TauP301S and triple transgenic AD mouse models, expression of Numb-72 in RGCs reduces the number of axonal blebs and prevents neurodegeneration. Finally, inactivation of Numb in TauP301S mice accelerates neurodegeneration in both the retina and spinal cord and leads to precocious paralysis. Taken together, these results uncover Numb as a essential regulator of Tau homeostasis in neurons and as a potential therapeutic agent for AD and tauopathies.

CDKL5’s role in microtubule-based transport and cognitive function

The Effect of Radiofrequency Electromagnetic Fields on Neuronal Activity: Implication of Microtubules

Fidgetin-like 1, a novel regulator of the microtubule/actin crosstalk required for axon outgrowth and navigation

Janus Kinase and Microtubule-Interacting Protein 1 (JAKMIP1), a novel regulator of nuclear RNA export in neurons: coupling transcription to cytoplasmic translation through the microtubule cytoskeleton

Neuronal MAP6 coordinates actin and microtubule nucleation in vitro

A novel role for Janus Kinase and Microtubule-Interacting Protein 1 (JAKMIP1) in modulating Signal Transducer and Activator of Transcription-3 (STAT3)-mediated cytokine signalling in neuronal cells

Polyglutamylation of microtubules drives motor axon remodelling

Screening tyrosine kinases for their involvement in synaptotoxicity induced by tau microtubule-binding region fibrils

Sex-specific regulation of NMDAR-independent long-term depression by the microtubule-associated protein tau

Visualization of MAP6-positive microtubules throughout the neuronal MT network: input of expansion microscopy

In vitro microfluidic design to study mitochondria-microtubules interactions after an axonal traumatic injury

Microtubule depolymerization contributes to spontaneous neurotransmitter release

FENS Forum 2024

Novel lissencephaly-associated DCX variants affect microtubule binding, dynamics, and neuronal migration

FENS Forum 2024

A novel microtubule doublet regulator in neuronal primary cilia

FENS Forum 2024

Physiological measurements of activity and microtubule health in human iPSC-derived neurons using fluorescence and second harmonic microscopy

FENS Forum 2024

Synaptic control of microtubule organisation in parvalbumin interneurons

FENS Forum 2024

Towards a mathematical model of microtubules in neurites

FENS Forum 2024

Upregulation of Stathmin-2 induces microtubule-dependent synaptic modifications during the rewiring of neuronal connectivity

FENS Forum 2024