1
|
Identification of cis-acting determinants mediating the unconventional secretion of tau. Sci Rep 2021; 11:12946. [PMID: 34155306 PMCID: PMC8217235 DOI: 10.1038/s41598-021-92433-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Accepted: 05/31/2021] [Indexed: 12/23/2022] Open
Abstract
The deposition of tau aggregates throughout the brain is a pathological characteristic within a group of neurodegenerative diseases collectively termed tauopathies, which includes Alzheimer’s disease. While recent findings suggest the involvement of unconventional secretory pathways driving tau into the extracellular space and mediating the propagation of the disease-associated pathology, many of the mechanistic details governing this process remain elusive. In the current study, we provide an in-depth characterization of the unconventional secretory pathway of tau and identify novel molecular determinants that are required for this process. Here, using Drosophila models of tauopathy, we correlate the hyperphosphorylation and aggregation state of tau with the disease-related neurotoxicity. These newly established systems recapitulate all the previously identified hallmarks of tau secretion, including the contribution of tau hyperphosphorylation as well as the requirement for PI(4,5)P2 triggering the direct translocation of tau. Using a series of cellular assays, we demonstrate that both the sulfated proteoglycans on the cell surface and the correct orientation of the protein at the inner plasma membrane leaflet are critical determinants of this process. Finally, we identify two cysteine residues within the microtubule binding repeat domain as novel cis-elements that are important for both unconventional secretion and trans-cellular propagation of tau.
Collapse
|
2
|
Abstract
Steroid hormones induce cascades of gene activation and repression with transformative effects on cell fate . Steroid transduction plays a major role in the development and physiology of nearly all metazoan species, and in the progression of the most common forms of cancer. Despite the paramount importance of steroids in developmental and translational biology, a complete map of transcriptional response has not been developed for any hormone . In the case of 20-hydroxyecdysone (ecdysone) in Drosophila melanogaster, these trajectories range from apoptosis to immortalization. We mapped the ecdysone transduction network in a cohort of 41 cell lines, the largest such atlas yet assembled. We found that the early transcriptional response mirrors the distinctiveness of physiological origins: genes respond in restricted patterns, conditional on the expression levels of dozens of transcription factors. Only a small cohort of genes is constitutively modulated independent of initial cell state. Ecdysone-responsive genes tend to organize into directional same-stranded units, with consecutive genes induced from the same strand. Here, we identify half of the ecdysone receptor heterodimer as the primary rate-limiting step in the response, and find that initial receptor isoform levels modulate the activated cohort of target transcription factors. This atlas of steroid response reveals organizing principles of gene regulation by a model type II nuclear receptor and lays the foundation for comprehensive and predictive understanding of the ecdysone transduction network in the fruit fly.
Collapse
|
3
|
Wen J, Mohammed J, Bortolamiol-Becet D, Tsai H, Robine N, Westholm JO, Ladewig E, Dai Q, Okamura K, Flynt AS, Zhang D, Andrews J, Cherbas L, Kaufman TC, Cherbas P, Siepel A, Lai EC. Diversity of miRNAs, siRNAs, and piRNAs across 25 Drosophila cell lines. Genome Res 2015; 24:1236-50. [PMID: 24985917 PMCID: PMC4079977 DOI: 10.1101/gr.161554.113] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
We expanded the knowledge base for Drosophila cell line transcriptomes by deeply sequencing their small RNAs. In total, we analyzed more than 1 billion raw reads from 53 libraries across 25 cell lines. We verify reproducibility of biological replicate data sets, determine common and distinct aspects of miRNA expression across cell lines, and infer the global impact of miRNAs on cell line transcriptomes. We next characterize their commonalities and differences in endo-siRNA populations. Interestingly, most cell lines exhibit enhanced TE-siRNA production relative to tissues, suggesting this as a common aspect of cell immortalization. We also broadly extend annotations of cis-NAT-siRNA loci, identifying ones with common expression across diverse cells and tissues, as well as cell-restricted loci. Finally, we characterize small RNAs in a set of ovary-derived cell lines, including somatic cells (OSS and OSC) and a mixed germline/somatic cell population (fGS/OSS) that exhibits ping-pong piRNA signatures. Collectively, the ovary data reveal new genic piRNA loci, including unusual configurations of piRNA-generating regions. Together with the companion analysis of mRNAs described in a previous study, these small RNA data provide comprehensive information on the transcriptional landscape of diverse Drosophila cell lines. These data should encourage broader usage of fly cell lines, beyond the few that are presently in common usage.
Collapse
Affiliation(s)
- Jiayu Wen
- Department of Developmental Biology, Sloan-Kettering Institute, New York, New York 10065, USA
| | - Jaaved Mohammed
- Department of Developmental Biology, Sloan-Kettering Institute, New York, New York 10065, USA; Department of Biological Statistics and Computational Biology, Cornell University, Ithaca, New York 14853, USA; Tri-Institutional Training Program in Computational Biology and Medicine, New York, New York 10065, USA
| | - Diane Bortolamiol-Becet
- Department of Developmental Biology, Sloan-Kettering Institute, New York, New York 10065, USA
| | - Harrison Tsai
- Department of Developmental Biology, Sloan-Kettering Institute, New York, New York 10065, USA
| | - Nicolas Robine
- Department of Developmental Biology, Sloan-Kettering Institute, New York, New York 10065, USA; New York Genome Center, New York, New York 10022, USA
| | - Jakub O Westholm
- Department of Developmental Biology, Sloan-Kettering Institute, New York, New York 10065, USA
| | - Erik Ladewig
- Department of Developmental Biology, Sloan-Kettering Institute, New York, New York 10065, USA
| | - Qi Dai
- Department of Developmental Biology, Sloan-Kettering Institute, New York, New York 10065, USA
| | - Katsutomo Okamura
- Department of Developmental Biology, Sloan-Kettering Institute, New York, New York 10065, USA; Temasek Life Sciences, Temasek Lifesciences Laboratory, National University of Singapore, 117604 Singapore
| | - Alex S Flynt
- Department of Developmental Biology, Sloan-Kettering Institute, New York, New York 10065, USA
| | - Dayu Zhang
- Department of Biology, Indiana University, Bloomington, Indiana 47405, USA
| | - Justen Andrews
- Department of Biology, Indiana University, Bloomington, Indiana 47405, USA
| | - Lucy Cherbas
- Department of Biology, Indiana University, Bloomington, Indiana 47405, USA
| | - Thomas C Kaufman
- Department of Biology, Indiana University, Bloomington, Indiana 47405, USA
| | - Peter Cherbas
- Department of Biology, Indiana University, Bloomington, Indiana 47405, USA
| | - Adam Siepel
- Department of Biological Statistics and Computational Biology, Cornell University, Ithaca, New York 14853, USA
| | - Eric C Lai
- Department of Developmental Biology, Sloan-Kettering Institute, New York, New York 10065, USA
| |
Collapse
|