Recent studies have shown that certain types of transformed cells are extruded from an epithelial monolayer. However, it is not known whether and how neighbouring normal cells play an active role in this process. In this study, we demonstrate that filamin A and vimentin accumulate in normal cells specifically at the interface with Src-or RasV12-transformed cells. Knockdown of filamin A or vimentin in normal cells profoundly suppresses apical extrusion of the neighbouring transformed cells. In addition, we show in zebrafish embryos that filamin plays a positive role in the elimination of the transformed cells. Furthermore, the Rho/Rho kinase pathway regulates filamin accumulation and filamin acts upstream of vimentin in the apical extrusion. This is the first report demonstrating that normal epithelial cells recognize and actively eliminate neighbouring transformed cells and that filamin is a key mediator in the interaction between normal and transformed epithelial cells.

SummaryIn Drosophila, normal and transformed cells compete with each other for survival in a process called cell competition. However, it is not known whether comparable phenomena also occur in mammals. Scribble is a tumor suppressor protein in Drosophila and mammals. In this study we examine the interface between normal and Scribble-knockdown epithelial cells using Madin-Darby Canine Kidney (MDCK) cells expressing Scribble short hairpin RNA (shRNA) in a tetracycline-inducible manner. We observe that Scribbleknockdown cells undergo apoptosis and are apically extruded from the epithelium when surrounded by normal cells. Apoptosis does not occur when Scribble-knockdown cells are cultured alone, suggesting that the presence of surrounding normal cells induces the cell death. We also show that death of Scribble-knockdown cells occurs independently of apical extrusion. Finally, we demonstrate that apoptosis of Scribble-knockdown cells depends on activation of p38 mitogen-activated protein kinase (MAPK). This is the first demonstration that an oncogenic transformation within an epithelium induces cell competition in a mammalian cell culture system.

Selenoprotein P (SeP) functions as a selenium (Se)-supply protein. SeP is identified as a hepatokine, promoting insulin resistance in type 2 diabetes. Thus, the suppression of Se-supply activity of SeP might improve glucose metabolism. Here, we develop an anti-human SeP monoclonal antibody AE2 as with neutralizing activity against SeP. Administration of AE2 to mice significantly improves glucose intolerance and insulin resistance that are induced by human SeP administration. Furthermore, excess SeP administration significantly decreases pancreas insulin levels and high glucose-induced insulin secretion, which are improved by AE2 administration. Epitope mapping reveals that AE2 recognizes a region of human SeP adjacent to the first histidine-rich region (FHR). A polyclonal antibody against the mouse SeP FHR improves glucose intolerance and insulin secretion in a mouse model of diabetes. This report describes a novel molecular strategy for the development of type 2 diabetes therapeutics targeting SeP.

Amyloid β (Aβ) deposition in the brain is an early and invariable feature of Alzheimer’s disease (AD). The Aβ peptides are composed of about 40 amino acids and are generated from amyloid precursor proteins (APP), by β- and γ-secretases. The distribution of individual Aβ peptides in the brains of aged people, and those suffering from AD and cerebral amyloid angiopathy (CAA), is not fully characterized. We employed the matrix-assisted laser desorption/ionization-imaging mass spectrometry (MALDI-IMS) to illustrate the spatial distribution of a broad range of Aβ species in human autopsied brains. With technical advancements such as formic acid pretreatment of frozen autopsied brain samples, we have: i) demonstrated that Aβ1–42 and Aβ1–43 were selectively deposited in senile plaques while full-length Aβ peptides such as Aβ1–36, 1–37, 1–38, 1–39, 1–40, and Aβ1–41 were deposited in leptomeningeal blood vessels. ii) Visualized distinct depositions of N-terminal truncated Aβ40 and Aβ42, including pyroglutamate modified at Glu-3 (N3pE), only with IMS for the first time. iii) Demonstrated that one single amino acid alteration at the C-terminus between Aβ1–42 and Aβ1–41 results in profound changes in their distribution pattern. In vitro, this can be attributed to the difference in the self-aggregation ability amongst Aβ1–40, Aβ1–41, and Aβ1–42. These observations were further confirmed with immunohistochemistry (IHC), using the newly developed anti-Aβ1–41 antibody. Here, distinct depositions of truncated and/or modified C- and N-terminal fragments of Aβs in AD and CAA brains with MALDI-IMS were visualized in a spacio-temporal specific manner. Specifically, Aβ1–41 was detected both with MALDI-IMS and IHC suggesting that a single amino acid alteration at the C-terminus of Aβ results in drastic distribution changes. These results suggest that MALDI-IMS could be used as a standard approach in combination with clinical, genetic, and pathological observations in understanding the pathology of AD and CAA.Electronic supplementary materialThe online version of this article (10.1186/s40478-017-0477-x) contains supplementary material, which is available to authorized users.

At the initial stage of carcinogenesis, a mutation occurs in a single cell within a normal epithelial layer. We have previously shown that RasV12-transformed cells are apically extruded from the epithelium when surrounded by normal cells. However, the molecular mechanisms underlying this phenomenon remain elusive. Here, we demonstrate that Cav-1-containing microdomains and EPLIN (also known as LIMA1) are accumulated in RasV12-transformed cells that are surrounded by normal cells. We also show that knockdown of Cav-1 or EPLIN suppresses apical extrusion of RasV12-transformed cells, suggesting their positive role in the elimination of transformed cells from epithelia. EPLIN functions upstream of Cav-1 and affects its enrichment in RasV12-transformed cells that are surrounded by normal cells. Furthermore, EPLIN regulates non-cell-autonomous activation of myosin-II and protein kinase A (PKA) in RasV12-transformed cells. In addition, EPLIN substantially affects the accumulation of filamin A, a vital player in epithelial defense against cancer (EDAC), in the neighboring normal cells, and vice versa. These results indicate that EPLIN is a crucial regulator of the interaction between normal and transformed epithelial cells.