Tubular structures found in tissues and cultures. Naturally occurring and stress induced tubular structures from mammalian cells, a survival mechanism Yonnie Wu, Richard C Laughlin, David C Henry, Darryl E Krueger, JoAn S Hudson, Cheng-Yi Kuan, Jian He, Jason Reppert, Jeffrey P Tomkins BMC Cell Biology 2007, 8:36 (16 August 2007) © 2007 Wu et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
The aim of the experiment in this research article was to demonstrate the fundamental role of the membrane-bound metalloproteinase MT1-MMP catalyst in preparing collagen fibrils for phagocytic degradation of collagen in adult tissues. Confocal laser microscopy has been utilized in this experiment to show that human fibroblasts do in fact initiate degradation of collagen through the collagenase activity of the membrane-bound metalloproteinase MT1-MMP. And examination of the collagen degradation under a confocal microscope revealed that cell surface MT1-MMP was in fact associated with degrading collagen fibrils therefore satisyfing the aim of the experiment.
This article puts forward a model that hypothesizes that extracellular regulation of cell division and differentiation acts through only two communication channels. They consist of a “series of redundant components: extracellular messenger hormones; these hormones' receptors; cytoplasmic proteins activated by the hormone-receptor complex; and trans-activating nuclear regulatory proteins.” The channels in this model are labeled as such: "D" ("differentiate"), includes transforming growth factor-beta as one of its hormones; the other, labeled "G'" ("growth") includes epidermal growth factor. The article uses a cell type in an adult mammal capable of either division or differentiation, which in this case is a stem cell from an epithelium. The principal prediction of this hypothesis is that when appropriate experimental conditions are implemented the addition of various ratios of D- and G-class growth factors will lead to different consequences.