No abstract

Glandular tissues form ducts (tubes) and acini (spheres) in multicellular organisms. This process is best demonstrated in the organization of the ductal tree of the mammary gland and in 3D models of morphogenesis in culture. Here, we asked a fundamental question: How do single adult epithelial cells generate polarized acini when placed in a surrogate basement membrane 3D gel? Using human breast epithelial cells from either reduction mammoplasty or nonmalignant breast cell lines, we observed a unique cellular movement where single cells undergo multiple rotations and then maintain it cohesively as they divide to assemble into acini. This coherent angular motion (CAMo) was observed in both primary cells and breast cell lines. If CAMo was disrupted, the final geometry was not a sphere. The malignant counterparts of the human breast cell lines in 3D were randomly motile, did not display CAMo, and did not form spheres. Upon "phenotypic reversion" of malignant cells, both CAMo and spherical architecture were restored. We show that cell-cell adhesion and tissue polarity are essential for the formation of acini and link the functional relevance of CAMo to the establishment of spherical architecture rather than to multicellular aggregation or growth. We propose that CAMo is an integral step in the formation of the tissue architecture and that its disruption is involved in malignant transformation.actin dynamics | cancer | cell migration | multicellular assembly | cellular rotation E pithelial organs form elaborate architectures consisting of ducts and acini in kidney, lung, salivary-and mammary-glands in vertebrates and invertebrates alike (1, 2). In tissues, loss of polarity markers is one of the earliest changes detected during malignant transformation (3, 4). The terminal unit of the arboreal tree, the acinus, was robustly recapitulated in 3D cultures of the mammary epithelial in laminin-rich gels (lrECM), where cells divide and organize into growth-arrested polarized spheres with basolateral and apical membrane domains surrounding a central lumen (5, 6). These models have shown the differential response of preinvasive and malignant epithelial cells to lrECM, where cells no longer form acini but aggregate into nonpolarized geometries similar to neoplastic lesions and tumors in vivo (6-11). To understand how tissue polarity and architecture are lost during transformation, one needs to first understand how the normal cells are able to form acini. However, the processes by which a single epithelial cell is able to recapitulate polarized structures that resemble structural units of function in 3D gels and in vivo are not known. We hypothesized that adult cells undergo a specific morphogenetic program to form and maintain quiescent acini, and that this program is corrupted in malignant transformation.Using real-time imaging and lrECM gels, we uncovered a unique cellular movement where single breast epithelial cells completed multiple rotations that were maintained as they divided to assemble into acini. This movement is re...

Thyroid hormone action is an important determinant of energy and glucose metabolism. T4 metabolism is regulated by the deiodinases of which type 2 is expressed in humans in skeletal muscle and brown adipose tissue, where its transcription is stimulated by the ␤-3 adrenergic pathway. We performed molecular scanning of the human type 2 deiodinase (DIO2) gene and evaluated a novel variant for associations with obesity and insulin resistance, assessing both the main effect and interaction with the Trp64Arg ␤-3-adrenergic receptor (

Summary For decades, the work of cell and developmental biologists has demonstrated the striking ability of the mesenchyme and the stroma to instruct epithelial form and function in the mammary gland [1–3], but the role of extracellular matrix (ECM) molecules in mammary pattern specification has not been elucidated. Here, we show that stromal collagen I (Col-I) fibers in the mammary fat pad are axially oriented prior to branching morphogenesis. Upon puberty, the branching epithelium orients along these fibers, thereby adopting a similar axial bias. To establish a causal relationship from Col-I fiber to epithelial orientation, we embedded mammary organoids within axially oriented Col-I fiber gels and observed dramatic epithelial co-orientation. Whereas a constitutively active form of Rac1, a molecule implicated in cell motility, prevented a directional epithelial response to Col-I fiber orientation, inhibition of the RhoA/Rho-associated kinase (ROCK) pathway did not. However, time-lapse studies revealed that, within randomly oriented Col-I matrices, the epithelium axially aligns fibers at branch sites via RhoA/ROCK-mediated contractions. Our data provide an explanation for how the stromal ECM encodes architectural cues for branch orientation as well as how the branching epithelium interprets and reinforces these cues through distinct signaling processes.