Biology subjects

Schwarz, T. L.

Publications and source records attributed to Schwarz, T. L..

6 recordsLinked to original sources

bioRxiv2026

The kinetochore proteins Ndc80 and Dsn1 are required for survival of postmitotic neurons

Dsn1 and Ndc80 are essential proteins of the kinetochore complex and required for chromosome segregation in dividing cells and for regulating development and microtubule dynamics in postmitotic neurons. With conditional deletion of floxed alleles, we here show that Dsn1 and Ndc80 are also required for the viability of postmitotic neurons, both in cultures of hippocampal and cortical neurons and in vivo in the retina. Loss of these proteins triggers apoptosis, as indicated by caspase cleavage and an increase in nuclear DNA breakage. The pro-survival function of the kinetochore components is distinct from that which was previously demonstrated for regulation of neuronal synaptogenesis. The microtubule-binding domain of Ndc80 is required for the synaptogenic functions but Ndc80 lacking this domain can nonetheless rescue the viability of neurons from which Ndc80 has been deleted. Similarly, whereas the synaptogenic function involves regulation of microtubules in axons and dendrites, a nucleus-localized Dsn1 is sufficient to rescue the viability of neurons from which Dsn1 has been deleted. Thus, postmitotic neurons retain a nuclear requirement for components of the kinetochore in order to prevent apoptosis.

neuroscience↗

bioRxiv2024

Loss of SARM1 protects against retinal ganglion cell degeneration in Autosomal Dominant Optic Atrophy

Autosomal Dominant Optic Atrophy (ADOA), the most prevalent inherited optic neuropathy, leads to retinal ganglion cell (RGC) degeneration and vision loss. ADOA is primarily caused by mutations in the OPA1 gene, which encodes a conserved GTPase important for mitochondrial inner membrane dynamics. To date, the disease mechanism remains unclear, and no therapies are available. Here, we present a novel mouse model carrying the pathogenic Opa1R290Q/+ allele that recapitulates key features of human ADOA, including mitochondrial defects, age-related RGC loss, optic nerve degeneration, and reduced RGC functions. We identify SARM1, a neurodegeneration switch, as a key driver of RGC degeneration in these mice. Sarm1 knockout nearly completely suppresses all the degeneration phenotypes. Additionally, we show that SARM1 is located within the mitochondrial intermembrane space (IMS). These findings indicate that SARM1 is activated downstream of mitochondrial dysfunction in ADOA, highlighting it as a promising therapeutic target.

neuroscience↗

bioRxiv2022

Miro GTPase domains regulate assembly of the mitochondrial motor-adaptor complex

Mitochondrial transport relies on a motor-adaptor complex containing Miro1, a mitochondrial outer membrane protein with two GTPase domains, as well as TRAK1/2, kinesin-1, and dynein. Using a peroxisome-directed Miro1, we quantified the ability of GTPase mutations to influence peroxisomal recruitment of complex components. Miro1 whose N-GTPase is locked in the GDP-state doesnt recruit TRAK1/2, kinesin or P135 to peroxisomes whereas the GTP-state does. Miro1 C-GTPase mutations have little influence on complex recruitment. Though Miro2 is thought to support mitochondrial motility, peroxisome-directed Miro2 did not recruit the other complex components regardless of the state of its GTPase domains. Neurons expressing peroxisomal Miro1 with the GTP-state form of the N-GTPase had markedly increased peroxisomal transport to growth cones while the GDP-state caused their retention in the soma. Thus, the N-GTPase of Miro1 is critical for regulating Miro1s interaction with the other components of the motor-adaptor complex and thereby for regulating mitochondrial motility. SummaryA Miro-containing complex mediates mitochondrial motility. Relocalizing Miro1 and 2 to peroxisomes and systematically manipulating each GTPase domain of Miro revealed the importance of the N-terminal GTPase domain of Miro1 for governing interaction with TRAK proteins, motors, and transport.

cell biology↗

bioRxiv2021

Discovery of small molecule pathway regulators by image profile matching

Identifying chemical regulators of biological pathways is a time-consuming bottleneck in developing therapeutics and research compounds. Typically, thousands to millions of candidate small molecules are tested in target-based biochemical screens or phenotypic cell-based screens, both expensive experiments customized to each disease. Here, our uncustomized, virtual profile-based screening approach instead identifies compounds that match to pathways based on phenotypic information in public cell image data, created using the Cell Painting assay. Our straightforward correlation-based computational strategy retrospectively uncovered the expected, known small molecule regulators for 32% of positive-control gene queries. In prospective, discovery mode, we efficiently identified new compounds related to three query genes, and validated them in subsequent gene-relevant assays, including compounds that phenocopy or pheno-oppose YAP1 overexpression and kill a Yap1-dependent sarcoma cell line. This image profile-based approach could replace many customized labor- and resource-intensive screens and accelerate the discovery of biologically and therapeutically useful compounds. One sentence summaryIf a genetic perturbation impacts cell morphology, a computational query can reveal compounds whose morphology "matches".

bioinformatics↗

bioRxiv2021

Neuronal mitochondria transport Pink1 mRNA via Synaptojanin 2 to support local mitophagy

PTEN-induced kinase 1 (PINK1) is a very short-lived protein that is required for the removal of damaged mitochondria through Parkin translocation and mitophagy. Because the short half-life of PINK1 limits its ability to be trafficked into neurites, local translation is required for this mitophagy pathway to be active far from the soma. The Pink1 transcript is associated with and cotransported with neuronal mitochondria. In concert with translation, the mitochondrial outer membrane protein Synaptojanin 2 binding protein (SYNJ2BP) and Synaptojanin 2 (SYNJ2) are required for tethering Pink1 mRNA to mitochondria via an RNA-binding domain in SYNJ2. This neuron-specific adaptation for local translation of PINK1 provides distal mitochondria with a continuous supply of PINK1 for activation of mitophagy.

neuroscience↗

bioRxiv2020

Local neuronal secretory trafficking dynamics revealed with zapERtrap: a light-inducible ER release system

For normal synapse and circuit function, neurons must regulate the abundance and localization of transmembrane receptor, channel and adhesion proteins over vast cellular expanses, including remote sites in dendrites and axons. Whether the secretory network can support long-range trafficking of synaptic proteins synthesized in the cell body or precise trafficking of locally generated proteins at remote sites remains poorly characterized. We developed an approach for locally triggering secretory trafficking from specific subcellular domains to explore the rate, activity dependence and cargo-specificity of central and remote trafficking networks. Surprisingly, different postsynaptic proteins processed in the cell body were transported deep into dendrites, but with strikingly different kinetics, spatial distributions and activity dependencies. Proteins locally processed in dendrites were broadly dispersed prior to surface insertion, but could be directed locally to synapses. These results provide a novel interrogation of compartmentalized trafficking and reveal basic principles for protein targeting in complex cellular environments.

cell biology↗