Biology subjects

Ungricht, R.

Publications and source records attributed to Ungricht, R..

3 recordsLinked to original sources

bioRxiv2021

Genome-wide screening in human kidney organoids identifies novel aspects of nephrogenesis

Human organoids allow studying proliferation, lineage specification, and three-dimensional tissue development. Due to the inherent multicellular complexity, interrogation by systematic genetic methodologies is challenging. Here, we present the first genome-wide CRISPR screen in iPSC-derived kidney organoids. The combination of genome editing, longitudinal sampling and sorting of specific cell populations enabled us to uncover novel biology from development to tubular morphogenesis. We validated the high quality of our screen by individual hit follow up and comparisons to kidney disease datasets. The discovery of a novel regulatory mechanism which controls epithelial proliferation via a trans-activating but cis-inhibitory effect of the Notch ligand Jagged1 proves how mosaic knockouts generated by pooled CRISPR screening in organoids can identify novel ways of communication between heterogeneous cell populations in complex tissues. Collectively, these data demonstrate the feasibility of using complex iPSC- derived organoids for genome-scale screening and serves as a benchmark for future organoid CRISPR screens.

cell biology↗

bioRxiv2021

WILMS TUMORIGENESIS IN HUMAN KIDNEY ORGANOIDS

The loss or failure of cell differentiation is a hallmark of cancer, yet whether perturbation of differentiation is causal or consequential to malignant transformation is largely unclear. Wilms tumor is the most widespread kidney cancer in children. Here, we establish a model for Wilms tumorigenesis in human kidney organoids. We show that loss of the tumor suppressor WT1 during organoid formation induces overgrowth of kidney progenitor cells at the expense of differentiating tubules. Functional and gene expression analyses demonstrate that absence of WT1 halts progenitor cell progression at a pre-epithelialized cell state and recapitulates the transcriptional changes detected in a subgroup of Wilms tumor patients with ectopic myogenesis. By "transplanting" WT1 mutant cells into wild-type kidney organoids, we find that their propagation requires an untransformed microenvironment. Genetic engineering of cancer lesions in human organoids therefore permits phenotypic modeling of tumor initiation and progression, and complements the current toolbox of pre-clinical Wilms tumor models.

cancer biology↗

bioRxiv2020

Torsin ATPases influence chromatin interaction of the Torsin regulator LAP1

The inner nuclear membrane is functionalized by diverse transmembrane proteins that associate with nuclear lamins and/or chromatin. When cells enter mitosis, membrane-chromatin contacts must be broken to allow for proper chromosome segregation; yet how this occurs remains ill-understood. Unexpectedly, we observed that an imbalance in the levels of the lamina-associated polypeptide 1 (LAP1), an activator of ER-resident Torsin AAA+-ATPases, causes a failure in membrane removal from mitotic chromatin, accompanied by chromosome segregation errors and changes in post-mitotic nuclear morphology. These defects are dependent on a hitherto unknown chromatin-binding region of LAP1 that we have delineated. LAP1-induced NE abnormalities are efficiently suppressed by expression of wild-type but not ATPase-deficient Torsins. Furthermore, a dominant-negative Torsin induces chromosome segregation defects in a LAP1-dependent manner. These results indicate that association of LAP1 with chromatin in the nucleus can be modulated by Torsins in the perinuclear space, shedding new light on the LAP1-Torsin interplay.

cell biology↗