Biology subjects

Wodarz, A.

Publications and source records attributed to Wodarz, A..

4 recordsLinked to original sources

bioRxiv2024

Lysosomal uptake of mtDNA mitigates heteroplasmy

Mitochondrial DNA is exposed to multiple insults produced by normal cellular function. Upon mtDNA replication stress the mitochondrial genome transfers to endosomes where it is degraded. Here, using proximity proteomics we found that mtDNA replication stress leads to the rewiring of the mitochondrial proximity proteome, increasing mitochondria association with lysosomal and vesicle-associated proteins, such as the GTPase RAB10 and the retromer. We found that upon mtDNA replication stress, RAB10 enhances mitochondrial fragmentation and relocates from the ER to lysosomes containing mtDNA. The retromer enhances and coordinates the expulsion of mitochondrial matrix components through mitochondrial-derived vesicles, and mtDNA with direct transfer to lysosomes. Using a Drosophila model carrying a long deletion on the mtDNA ({Delta}mtDNA), we evaluated in vivo the role of the retromer in mtDNA extraction and turnover in the larval epidermis. The presence of {Delta}mtDNA elicits the activation of a specific transcriptome profile related to counteract mitochondrial damage. Expression of the retromer component Vps35 is sufficient to restore mtDNA homoplasmy and mitochondrial defects associated with {Delta}mtDNA. Our data reveal novel regulators involved in the specific elimination of mtDNA. We demonstrate that modulation of the retromer in vivo is a successful mechanism to restore mitochondrial function associated with mtDNA damage.

cell biology↗

bioRxiv2023

Re-assessment of the subcellular localization of Bazooka/Par-3 in Drosophila: No evidence for localization to the nucleus and the neuromuscular junction

Bazooka/Par-3 (Baz) is an evolutionarily conserved scaffold protein that together with its binding partners atypical protein kinase C (aPKC) and Par-6 forms the Par complex. This protein complex functions as a master regulator for the establishment and maintenance of cell polarity in many different cell types. In the vast majority of published research papers Par complex members have been reported to localize at the cell cortex and at intercellular junctions. However, there have also been several reports claiming localization and function of Par complex members at additional subcellular sites, in particular the nucleus, the nuclear envelope and the neuromuscular junction. In this study we have re-assessed this issue for Baz in a systematic manner. We used a variety of antibodies raised in different host animals against different epitopes of Baz for confocal imaging of Drosophila tissues. We tested the specificity of these antisera by using mosaic analysis with null mutant baz alleles and tissue-specific RNAi against baz. In addition, we used a GFP-tagged gene trap line for Baz and a bacterial artificial chromosome (BAC) expressing GFP-tagged Baz under control of its endogenous promoter in a baz null mutant background to compare the subcellular localization of the respective GFP-Baz fusion proteins to the staining results with anti-Baz antisera. Together, these experiments did not provide any evidence for specific localization of Baz to the nucleus or the neuromuscular junction.

cell biology↗

bioRxiv2020

Par3A and Par3B orchestrate podocyte architecture by regulating RhoA levels

Glomerular diseases are a major cause for chronic kidney disorders. In the majority of cases podocyte injury is causative for disease development. Cytoskeletal rearrangements and morphological changes are hallmark features of podocyte injury and result in dedifferentiation and subsequent loss of podocytes. Here, we establish a link between components of the Par3 polarity complex and actin regulators, which are necessary to establish and maintain the podocytes architecture utilizing both, mouse and Drosophila models. We demonstrate that the two mammalian Par3 proteins, Par3A and Par3B, share redundant functions despite differing in their ability to interact with other components of the Par complex. Only simultaneous inactivation of both Par3 proteins causes a severe disease phenotype in mouse podocytes by regulating Rho-GTP levels involving the actin regulators Synaptopodin and CD2AP in an aPKC independent manner.

cell biology↗

bioRxiv2018

Ykt6 membrane-to-cytosol cycling regulates exosomal Wnt secretion

Protein trafficking in the secretory pathway, for example the secretion of Wnt proteins, requires tight regulation. These ligands activate Wnt signaling pathways and are crucially involved in development and disease. Wnt is transported to the plasma membrane by its cargo receptor Evi, where Wnt/Evi complexes are endocytosed and sorted onto exosomes for long-range secretion. However, the trafficking steps within the endosomal compartment are not fully understood. The promiscuous SNARE Ykt6 folds into an auto-inhibiting conformation in the cytosol, but a portion associates with membranes by its farnesylated and palmitoylated C-terminus. Here, we demonstrate that membrane detachment of Ykt6 is essential for exosomal Wnt secretion. We identified conserved phosphorylation sites within the SNARE domain of Ykt6, which block Ykt6 cycling from the membrane to the cytosol. In Drosophila, Ykt6 RNAi-mediated block of Wg secretion is rescued by wildtype but not phosphomimicking Ykt6. We show that phosphomimicking Ykt6 accumulates at membranes, while wildtype Ykt6 regulates Wnt trafficking between the plasma membrane and multivesicular bodies in a dose-dependent manner. Taken together, we show that exosomal sorting of Wnts is fine-tuned by a regulatory switch in Ykt6 shifting it from a membrane-bound to cytosolic state at the level of endosomal maturation.

cell biology↗