Chiasma

Newspaper reporting on events at the Boston University School of Medicine in the 1960s

Tuberous sclerosis complex exhibits a new renal cystogenic mechanism

Tuberous sclerosis complex (TSC) is a tumor predisposition syndrome with significant renal cystic and solid tumor disease. While the most common renal tumor in TSC, the angiomyolipoma, exhibits a loss of heterozygosity associated with disease, we have discovered that the renal cystic epithelium is composed of type A intercalated cells that have an intact Tsc gene that have been induced to exhibit Tsc‐mutant disease phenotype. This mechanism appears to be different than that for ADPKD. The murine models described here closely resemble the human disease and both appear to be mTORC1 inhibitor responsive. The induction signaling driving cystogenesis may be mediated by extracellular vesicle trafficking.TSC renal cystic disease develops in about half of the patients. The disease appears to caused by an induction mechanism such that a small population of mutant cells can cause significant renal cystic disease comprised of mostly genetically normal cells.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/147796/1/phy213983.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/147796/2/phy213983_am.pd

Glomerulocystic kidney disease

Glomerulocystic disease is a rare renal cystic disease with a long descriptive history. Findings from recent studies have significantly advanced the pathophysiological understanding of the disease processes leading to this peculiar phenotype. Many genetic syndromes associated with glomerulocystic disease have had their respective proteins localized to primary cilia or centrosomes. Transcriptional control of renal developmental pathways is dysregulated in obstructive diseases that also lead to glomerulocystic disease, emphasizing the importance of transcriptional choreography between renal development and renal cystic disease

Cell cycle control and DNA damage response of conditionally immortalized urothelial cells.

Children with complex urogenital anomalies often require bladder reconstruction. Gastrointestinal tissues used in bladder augmentations exhibit a greatly increased risk of malignancy, and the bladder microenvironment may play a role in this carcinogenesis. Investigating the influences of the bladder microenvironment on gastrointestinal and urothelial cell cycle checkpoint activation and DNA damage response has been limited by the lack of an appropriate well-differentiated urothelial cell line system.To meet this need, we have developed a well-differentiated conditionally immortalized urothelial cell line by isolating it from the H-2K(b)-tsA58 transgenic mouse. These cells express a thermosensitive SV40 large T antigen that can be deactivated by adjustment of cell culture conditions, allowing the cell line to regain normal control of the cell cycle. The isolated urothelial cell line demonstrates a polygonal, dome-shaped morphology, expresses cytokeratin 18, and exhibits well-developed tight junctions. Adaptation of the urothelial cell line to hyperosmolal culture conditions induces expression of both cytokeratin 20 and uroplakin II, markers of a superficial urothelial cell or "umbrella cell." This cell line can be maintained indefinitely in culture under permissive conditions but when cultured under non-permissive conditions, large T antigen expression is reduced substantially, leading to increased p53 activity and reduced cellular proliferation.This new model of urothelial cells, along with gastrointestinal cell lines previously derived from the H-2K(b)-tsA58 transgenic mouse, will be useful for studying the potential mechanisms of carcinogenesis of the augmented bladder

The ULTI mouse urothelial cell line is conditionally immortalized under permissive conditions, but restores cell cycle control under non-permissive conditions.

<p>A) Crystal violet proliferation assay, in which absorbances were normalized to that of 10% FBS to reduce interexperimental variability. Open circles represent cells grown under permissive conditions (33°C +IFN-γ), whereas closed circles represent cells grown under non-permissive conditions (37°C -IFN-γ). Error bars represent standard error of the mean. B) Cell cycle analysis of ULTI cells under both permissive and non-permissive conditions, and with 10% and 0.5% FBS concentration, by propidium iodide DNA labeling flow cytometry. C) Quantitation of cell cycle phase of ULTI cells under both permissive and non-permissive conditions, and with 10% and 0.5% FBS concentration. Dark grey bars indicate percent of cells in G0/G1, white bars indicate percent of cells in S phase, and light grey bars indicate percent of cells in G2/M phase. Error bars represent standard error of the mean.</p

The ULTI cell line expresses epithelial markers of differentiation.

<p>A) Cytokeratin 18 immunofluorescence of ULTI cells, obtained with 40X objective. Filamentous staining is noted characteristic of the cytokeratins. B) Cytokeratin 18 immunofluorescence of RT4 transitional cell carcinoma cells, obtained with 40X objective. Similar staining to ULTI cells is noted. Withholding primary antibody to assess nonspecific binding of the secondary antibody found no such staining. C) Confocal immunofluorescence of ULTI cells. Circumferential linear staining is noted with occludin (green, left panel) and ZO-1 (red, middle panel), which colocalizes upon merge of the images (yellow, right panel). D) Orthogonal reconstruction of axial images demonstrating colocalization of occludin and ZO-1.</p