E-Cadherin Endocytosis In Morphogenesis: Recycling And Growth Factor Induced Uptake.
Funder
National Health and Medical Research Council
Funding Amount
$498,088.00
Summary
E-cadherin is a cell-cell adhesion protein expressed in all epithelia with essential roles in establishing cell polarity and in tissue patterning during development. In the adult, E-cadherin functions to maintain epithelial integrity. E-cadherin is also a vital tumour suppressor, protecting cells against metastatic transformation. Our earlier studies showed that E-cadherin is constantly moved, or trafficked, to and from the surface of epithelial cells. The endocytosis or internalisation of cell ....E-cadherin is a cell-cell adhesion protein expressed in all epithelia with essential roles in establishing cell polarity and in tissue patterning during development. In the adult, E-cadherin functions to maintain epithelial integrity. E-cadherin is also a vital tumour suppressor, protecting cells against metastatic transformation. Our earlier studies showed that E-cadherin is constantly moved, or trafficked, to and from the surface of epithelial cells. The endocytosis or internalisation of cell surface E-cadherin serves to regulate its role in adhesion. More recently, we and others have shown that E-cadherin is endocytosed in response to growth factors, in conjunction with the activated growth factor receptors themselves. E-cadherin can influence the trafficking and signaling of these receptor tyrosine kinases. This joint endocytosis is an elegant mechanism for the simultaneous downregulation of cell adhesion and activation of signaling for cell growth and motility. The growth and differentiation of epithelial cells during tissue patterning or morphogenesis relies critically on these endocytic pathways. Our research is aimed at defining the endosomes and cellular machinery involved in E-cadherin-receptor endocytosis, moreover we will pursue initial findings suggesting that there are different pathways and fates for E-cadherin endocytosed at the behest of different growth factors. We will study endocytosis during the processes of epithelial cyst formation and tubulation of cysts as an in vitro model for mammalian morphogenesis. These studies will provide important and novel information for understanding the roles of E-cadherin in adhesion and in growth factor signaling during epithelial morphogenesis. Ultimately these findings will be of relevance to epithelial development and the prevention of cancer.Read moreRead less
The Functional Roles Of ADAMs In The Regulation Of Embryo Implantation.
Funder
National Health and Medical Research Council
Funding Amount
$211,527.00
Summary
The initiation of pregnancy in humans and rodents hinges upon the ability of the embryo to attach to the wall of the uterus and invade into the uterine tissue. This process of embryo implantation is tightly regulated and depends on the secretion of enzymes and regulators of these enzymes. A newly identified family of enzymes which might be important in this process is the ADAMs family. These enzymes have the potential to facilitate both cell attachment and cell invasion and also to activate othe ....The initiation of pregnancy in humans and rodents hinges upon the ability of the embryo to attach to the wall of the uterus and invade into the uterine tissue. This process of embryo implantation is tightly regulated and depends on the secretion of enzymes and regulators of these enzymes. A newly identified family of enzymes which might be important in this process is the ADAMs family. These enzymes have the potential to facilitate both cell attachment and cell invasion and also to activate other enzymes and growth factors. Recent studies in our laboratory have shown the ADAMs to be expressed both at the most invasive time of implantation and when invasion is being down-regulated. This project will examine the role of the ADAMs in embryo implantation facilitating attachment and invasion into the uterus by acting enzymatically on the uterine tissue and by activating other enzymes. It will also determine the role of ADAMs in down-regulating invasion potentially by activating a growth factor, TNF-alpha. Knowledge of this process and particularly its regulation is important for the treatment of pregnancy associated diseases that arise from improper implantation. These include infertility, placenta accreta, choriocarcinoma, miscarriage and pre-eclampsia. Furthermore, an understanding of the regulation of implantation will contribute to the treatment of other conditions associated with cell invasion such as cancer metastasis.Read moreRead less
Insulin resistance (the inability of ordinarily insulin-sensitive tissues such as muscle and adipose tissue to respond to insulin) contributes to a number of diseases including diabetes and obesity. A key metabolic step in these tissues is the uptake of glucose from the blood stream. This step is accelerated by insulin thus allowing efficient clearance of glucose from the bloodstream after a meal. Our laboratory has played a major role in showing that insulin regulates glucose uptake into muscle ....Insulin resistance (the inability of ordinarily insulin-sensitive tissues such as muscle and adipose tissue to respond to insulin) contributes to a number of diseases including diabetes and obesity. A key metabolic step in these tissues is the uptake of glucose from the blood stream. This step is accelerated by insulin thus allowing efficient clearance of glucose from the bloodstream after a meal. Our laboratory has played a major role in showing that insulin regulates glucose uptake into muscle and adipose tissue by stimulating the movement of a glucose transport protein from inside the cell to the cell surface (see http:--www.imb.uq.edu.au-groups-james-glut4 for an animated description of this process). The purpose of this proposal is to dissect the molecular mechanisms by which this glucose transporter can be held inside the cell in the absence of insulin and then allowed to be released from this site moving to the surface in the presence of insulin. Our studies over the past 5 years have brought us much closer to understanding this process in detail. The identification of the molecules responsible for this regulatory step will not only aid our understanding of this process but it will also provide a valuable target for development of therapeutic agents that can be used to combat insulin resistance.Read moreRead less
Polarized Trafficking Of E-cadherin In Epithelial Cells.
Funder
National Health and Medical Research Council
Funding Amount
$515,564.00
Summary
The cell adhesion protein E-cadherin is expressed in all epithelial tissues of the body where it has essential functions during development and in the adult in establishing and maintaining polarized cell monolayers. E-cadherin is also a vital tumour suppressor, its normal function guarantees that cells or even early tumours cannot metastasise; in contrast E-cadherin is always lost or malfunctions in malignant tumours. Earlier studies showed that E-cadherin is constantly moved, or trafficked, to ....The cell adhesion protein E-cadherin is expressed in all epithelial tissues of the body where it has essential functions during development and in the adult in establishing and maintaining polarized cell monolayers. E-cadherin is also a vital tumour suppressor, its normal function guarantees that cells or even early tumours cannot metastasise; in contrast E-cadherin is always lost or malfunctions in malignant tumours. Earlier studies showed that E-cadherin is constantly moved, or trafficked, to and from the surface of epithelial cells. This trafficking has dual roles, firstly in delivering newly-made E-cadherin to the surface where it functions and secondly, in regulating its adhesive function. Our research in this project is focussed on the molecules and intracellular compartments that control the delivery of E-cadherin to the cell surface. E-cadherin must be sorted in order to be delivered to the correct side of the cell. Having previously discovered the sorting signal in E-cadherin, we will now identify the cognate adaptor protein(s) that accomplish this sorting. New imaging techniques allow us to study protein trafficking inside live cells. Such studies have recently revealed that E-cadherin passes through a recycling endosome compartment on its way to the cell surface. This unexpected route, and the structure and role of the recycling endosome will now be studied in detail in live cells. Finally we will compare the sorting and trafficking of E-cadherin with the closely-related N-cadherin protein, to determine whether there are inherent differences in their trafficking that could explain their opposite roles in tumour cells, where N-cadherin is substituted for E-cadherin and allows metastatic behaviour. These studies will provide important information for understanding the adhesive and tumour suppressive roles of E-cadherin. In addition our findings will generate information fundamental to our understanding of cell polarity and protein sorting.Read moreRead less