Search

Optogenetics has been harnessed to shed new mechanistic light on current and future therapeutic strategies. This has been to date achieved by the regulation of ion flow and electrical signals in neuronal cells and neural circuits that are known to be affected by disease. In contrast, the optogenetic delivery of trophic biochemical signals, which support cell survival and are implicated in degenerative disorders, has never been demonstrated in an animal model of disease. Here, we reengineered the human and Drosophila melanogaster REarranged during Transfection (hRET and dRET) receptors to be activated by light, creating one-component optogenetic tools termed Opto-hRET and Opto-dRET. Upon blue light stimulation, these receptors robustly induced the MAPK/ERK proliferative signaling pathway in cultured cells. In PINK1B9 flies that exhibit loss of PTEN-induced putative kinase 1 (PINK1), a kinase associated with familial Parkinson’s disease (PD), light activation of Opto-dRET suppressed mitochondrial defects, tissue degeneration and behavioral deficits. In human cells with PINK1 loss-of-function, mitochondrial fragmentation was rescued using Opto-dRET via the PI3K/NF-кB pathway. Our results demonstrate that a light-activated receptor can ameliorate disease hallmarks in a genetic model of PD. The optogenetic delivery of trophic signals is cell type-specific and reversible and thus has the potential to inspire novel strategies towards a spatio-temporal regulation of tissue repair., Author summary The death of physiologically important cells and tissues underlies of a wide range of diseases, including the neurodegenerative disorder Parkinson’s disease. Currently, the two major strategies to counter cell degeneration are the injection of soluble growth factor peptides and growth factor gene therapy. Importantly, both strategies can lead to the undesired activation of healthy bystander cells or the non-natural permanent modification of cells and their internal signals. Here, we developed a light-based method to overcome these limitations. The use of optogenetics allowed delivering cell type-specific pro-survival signals in a genetic model of Parkinson’s disease. In Drosophila and human cells that exhibit loss of the PINK1 gene, akin to autosomal recessive Parkinson’s disease, we efficiently suppressed disease phenotypes using a light-activated tyrosine kinase receptor. This work demonstrates a ‘remote controlled’ and thus spatio-temporally precise strategy to interfere with degeneration and may open new avenues towards tissue repair in a variety of disease models, including but not limited to diseases of the brain.

Migrating cells penetrate tissue barriers during development, inflammatory responses, and tumor metastasis. We study if migration in vivo in such three-dimensionally confined environments requires changes in the mechanical properties of the surrounding cells using embryonic Drosophila melanogaster hemocytes, also called macrophages, as a model. We find that macrophage invasion into the germband through transient separation of the apposing ectoderm and mesoderm requires cell deformations and reductions in apical tension in the ectoderm. Interestingly, the genetic pathway governing these mechanical shifts acts downstream of the only known tumor necrosis factor superfamily member in Drosophila, Eiger, and its receptor, Grindelwald. Eiger-Grindelwald signaling reduces levels of active Myosin in the germband ectodermal cortex through the localization of a Crumbs complex component, Patj (Pals-1-associated tight junction protein). We therefore elucidate a distinct molecular pathway that controls tissue tension and demonstrate the importance of such regulation for invasive migration in vivo.

Aberrant display of the truncated core1 O-glycan T-antigen is a common feature of human cancer cells that correlates with metastasis. Here we show that T-antigen in Drosophila melanogaster macrophages is involved in their developmentally programmed tissue invasion. Higher macrophage T-antigen levels require an atypical major facilitator superfamily (MFS) member that we named Minerva which enables macrophage dissemination and invasion. We characterize for the first time the T and Tn glycoform O-glycoproteome of the Drosophila melanogaster embryo, and determine that Minerva increases the presence of T-antigen on proteins in pathways previously linked to cancer, most strongly on the sulfhydryl oxidase Qsox1 which we show is required for macrophage tissue entry. Minerva’s vertebrate ortholog, MFSD1, rescues the minerva mutant’s migration and T-antigen glycosylation defects. We thus identify a key conserved regulator that orchestrates O-glycosylation on a protein subset to activate a program governing migration steps important for both development and cancer metastasis., eLife digest Proteins, the workhorses of the body, participate in virtually every single process in a cell. Different types of molecules, such as sugars, can be added onto a protein to change its role or location, but this process may also play a role in cancer. Indeed, tumor cells that contain certain sugar modifications are more likely to be able to spread through the body. For example, a specific combination of sugars called T antigen is rarely present in healthy adult cells; yet, it is commonly found in cancer cells that leave the tumor where they were born and invade another tissue to form a new tumor. However, it is not clear whether T antigen actively helps this process inside the body, or is simply present during it. To answer this question, Valosková, Biebl et al. used genetic and biochemistry tools to study developing fruit fly embryos, where certain immune cells carry T antigen on their proteins. Like invading cancer cells, these immune cells can get inside tissues during development. The experiments revealed that a protein called Minerva helps attach T antigen onto proteins. When embryos were engineered to contain less Minerva, the amount of T antigen in the immune cells dropped, and the cells could not easily make their way into tissues anymore. When the mouse version of Minerva was then added to the embryos, the immune cells of the fruit flies had higher T antigen levels on their proteins and could invade tissues again. Some of the proteins targeted by Minerva were known to be involved in cancer, but not all of them. Future experiments will investigate which role the human version of Minerva plays in cancer cells that get inside new tissues, and if it could help us predict whether a cancer is likely to spread.