Deep CRISPR mutagenesis characterizes the functional diversity of TP53 mutations.

The mutational landscape of TP53, a tumor suppressor mutated in about half of all cancers, includes over 2,000 known missense mutations. To fully leverage TP53 mutation status for personalized medicine, a thorough understanding of the functional diversity of these mutations is essential. We conducted a deep mutational scan using saturation genome editing with CRISPR-mediated homology-directed repair to engineer 9,225 TP53 variants in cancer cells.

Mutant p53-ENTPD5 control of the calnexin/calreticulin cycle: a druggable target for inhibiting integrin-α5-driven metastasis.

Background: TP53, encoding the tumor suppressor p53, is frequently mutated in various cancers, producing mutant p53 proteins (mutp53) which can exhibit neomorphic, gain-of-function properties. The latter transform p53 into an oncoprotein that promotes metastatic tumor progression via downstream effectors such as ENTPD5, an endoplasmic reticulum UDPase involved in the calnexin/calreticulin cycle of N-glycoprotein biosynthesis. Elucidating the mechanisms underlying the pro-metastatic functions of the mutp53-ENTPD5 axis is crucial for developing targeted therapies for aggressive metastatic cancer.

Extracellular Vesicles: Messengers of p53 in Tumor-Stroma Communication and Cancer Metastasis.

Tumor progression to a metastatic and ultimately lethal stage relies on a tumor-supporting microenvironment that is generated by reciprocal communication between tumor and stromal host cells. The tumor-stroma crosstalk is instructed by the genetic alterations of the tumor cells-the most frequent being mutations in the gene () that are clinically correlated with metastasis, drug resistance and poor patient survival. The crucial mediators of tumor-stroma communication are tumor-derived extracellular vesicles (EVs), in particular exosomes, which operate both locally within the primary tumor and in distant organs, at pre-metastatic niches as the future sites of metastasis.

Upregulation of mesothelial genes in ovarian carcinoma cells is associated with an unfavorable clinical outcome and the promotion of cancer cell adhesion.

A hallmark of ovarian high-grade serous carcinoma (HGSC) is its early and massive peritoneal dissemination via the peritoneal fluid. It is generally believed that tumor cells must breach the mesothelium of peritoneal organs to adhere to the underlying extracellular matrix (ECM) and initiate metastatic growth. However, the molecular mechanisms underlying these processes are only partially understood.

Behavioural effects of extracellular matrix protein Fras1 depletion in the mouse.

Fras1 is an extracellular protein of the basement membranes that surround embryonic epithelia, choroid plexuses and meninges in foetal mouse brain. Depletion of Fras1 in knockout mice results in sub-epidermal blistering and fusion of eyelids and digits as well as malformation of lungs and kidneys. Mutations in the human counterpart FRAS1 are responsible for the Fraser Syndrome with clinical manifestations similar to the murine phenotype.

p53's Extended Reach: The Mutant p53 Secretome.

p53 suppresses tumorigenesis by activating a plethora of effector pathways. While most of these operate primarily inside of cells to limit proliferation and survival of incipient cancer cells, many extend to the extracellular space. In particular, p53 controls expression and secretion of numerous extracellular factors that are either soluble or contained within extracellular vesicles such as exosomes.

Residual apoptotic activity of a tumorigenic p53 mutant improves cancer therapy responses.

Engineered p53 mutant mice are valuable tools for delineating p53 functions in tumor suppression and cancer therapy. Here, we have introduced the R178E mutation into the Trp53 gene of mice to specifically ablate the cooperative nature of p53 DNA binding. Trp53 mice show no detectable target gene regulation and, at first sight, are largely indistinguishable from Trp53 mice.

Mutant p53 promotes tumor progression and metastasis by the endoplasmic reticulum UDPase ENTPD5.

Mutations in the p53 tumor suppressor gene are the most frequent genetic alteration in cancer and are often associated with progression from benign to invasive stages with metastatic potential. Mutations inactivate tumor suppression by p53, and some endow the protein with novel gain of function (GOF) properties that actively promote tumor progression and metastasis. By comparative gene expression profiling of p53-mutated and p53-depleted cancer cells, we identified ectonucleoside triphosphate diphosphohydrolase 5 (ENTPD5) as a mutant p53 target gene, which functions as a uridine 5'-diphosphatase (UDPase) in the endoplasmic reticulum (ER) to promote the folding of N-glycosylated membrane proteins.

Control of cerebral size and thickness.

The mammalian neocortex is a sheet of cells covering the cerebrum that provides the structural basis for the perception of sensory inputs, motor output responses, cognitive function, and mental capacity of primates. Recent discoveries promote the concept that increased cortical surface size and thickness in phylogenetically advanced species is a result of an increased generation of neurons, a process that underlies higher cognitive and intellectual performance in higher primates and humans. Here, we review some of the advances in the field, focusing on the diversity of neocortical progenitors in different species and the cellular mechanisms of neurogenesis.

Segmental and restricted localization pattern of Fras1 in the developing meningeal basement membrane in mouse.

The Fras1/Frem family of extracellular matrix proteins consists of Fras1 and its structurally related proteins, Frem1 (Fras1-related extracellular matrix protein 1), Frem2 and Frem3. These are co-localized in embryonic epithelial basement membranes (BMs), where they contribute to epithelial-mesenchymal adhesion. Although Fras1 localization pattern in epithelial BMs has been well defined, it has not yet been comprehensively studied in the central nervous system.

Scratch2 modulates neurogenesis and cell migration through antagonism of bHLH proteins in the developing neocortex.

Scratch genes (Scrt) are neural-specific zinc-finger transcription factors (TFs) with an unknown function in the developing brain. Here, we show that, in addition to the reported expression of mammalian Scrt2 in postmitotic differentiating and mature neurons in the developing and early postnatal brain, Scrt2 is also localized in subsets of mitotic and neurogenic radial glial (RGP) and intermediate (IP) progenitors, as well as in their descendants-postmitotic IPs and differentiating neurons at the border subventricular/intermediate zone. Conditional activation of transgenic Scrt2 in cortical progenitors in mice promotes neuronal differentiation by favoring the direct mode of neurogenesis of RGPs at the onset of neurogenesis, at the expense of IP generation.

The role of Fras1/Frem proteins in the structure and function of basement membrane.

Basement membranes constitute architecturally complex extracellular matrix (ECM) protein networks of great structural and regulatory importance. Recently, a novel group of basement membrane proteins, Fras1 (Fraser syndrome protein (1) and the Fras1-related extracellular matrix proteins Frem1, Frem2 and Frem3, has emerged. They comprise components of the sublamina densa region and contribute to embryonic epithelial-mesenchymal integrity.

pH-dependent antigen unmasking in paraformaldehyde-fixed tissue cryosections.

Fras1/Frem family of basement membrane proteins has been associated with the "bleb" phenotype in mouse and the Fraser syndrome in man. Fras1 and Frem2 proteins are known to be colocalized in all epithelial basement membranes during embryonic development. The functional significance of their colocalization has been demonstrated in the corresponding mouse mutants, where the absence of Fras1 results in complete depletion of Frem2 from epithelial basement membranes and vice versa.

In vitro controlled drug release from loaded microspheres--dose regulation through formulation.

Purpose: Drug release profiles were established for ibuprofen encapsulated within several types of microspheres and a range of dissolution buffer media to study the effect these variables have in controlling the rate and extent of drug release.

Methods: Fatty acid microspheres containing ibuprofen were prepared by a process previously developed and refined to produce microspheres of a known size and composition, namely 80-125 mum diameter and an excipient to ibuprofen ratio of 3:1. Drug release profiles from these encapsulated formulations were compared with those obtained for the dissolution of ibuprofen alone under the same conditions.

Basement membrane localization of Frem3 is independent of the Fras1/Frem1/Frem2 protein complex within the sublamina densa.

The Fraser syndrome protein Fras1 and the structurally related proteins Frem1, Frem2 and Frem3 comprise a novel family of extracellular matrix proteins implicated in the structural adhesion of the embryonic epidermis to the underlying mesenchyme. Fras1, Frem1 and Frem2 have been shown to be simultaneously and interdependently stabilized in the basement membrane by forming a ternary complex located underneath the lamina densa. However, the functional relationships between Frem3 and the other Fras1/Frem proteins remain unknown.

Spatiotemporal distribution of Fras1/Frem proteins during mouse embryonic development.

The Fras1/Frem gene family encodes for structurally similar, developmentally regulated extracellular matrix proteins. Mutations in Fras1, Frem1 and Frem2 have been identified in different classes of mouse bleb mutants, while defects in the human orthologs FRAS1 and FREM2 are causative for Fraser syndrome. The hallmark phenotypic feature of bleb mice is embryonic skin blistering due to dermal-epidermal detachment.

Basement membrane distortions impair lung lobation and capillary organization in the mouse model for fraser syndrome.

Fras1 is a putative extracellular matrix protein that has been implicated in the structural adhesion of embryonic epidermis to dermis. Moreover, mutations in Fras1/FRAS1 have been associated with the mouse blebbed phenotype and the human rare genetic disorder Fraser syndrome, respectively. Here we report the mapping of Fras1 within the extracellular space and evaluate the effects of Fras1 deficiency on lung development in the mouse.