Fibroblast interaction with cell-membrane

MFBs synthesize far more actin fibers than standard fibroblasts, and also have myosin fibers that, when interacting with actin, constitute the contractile motor activity of MFBs. MFBs are found in healing tissue, of which they form 40% of the total number of fibroblasts present. A large number of MFBs are also foimd in the periprosthetic capsule of encapsulated breast implants, while there is no evidence of MFBs if no capsule has formed around the prosthesis. In pathology, abnormal quantities of MFBs are found in diseases such as pulmonary fibrosis and Crohn s disease. Many SMCs respond to a kind of paracrine stimulation, where the mediator is released into the environment of the target cells and diffuses towards the cell, where it interacts with a membrane receptor. 

During the healing process, hybrid cells, known as myofibroblasts, appear in the dermis. They have the morphological characteristics of both fibroblasts and smooth muscle cells. They are responsible for tissue contraction-retraction during healing. Their cytoplasm contains networks of myofilaments that are in contact with specialized zones of the plasma membrane and can interact with the adjacent cells or connective tissue. These myofibroblasts appear to be differentiated fibroblasts that have acquired the properties of smooth muscle cells. Controlled stimulation with DMAE, for example, is a good way to achieve a tightening effect on the skin. 

When ODAR attaches to the osteoblast surface-bound ODF, the receptor/ligand complex activates a membrane-associated tyrosine-protein kinase to induce synthesis of the ruffled membrane. A tyrosine residue on C1IC-5 (Sect. 10.1.4) is phosphorylated by an activated protein kinase, called c-src, the normal cytosolic homologue of a viral tyrosine kinase which causes a sarcoma (transforms fibroblasts into cancer cells). The phosphorylated C1IC-5 interacts with phospholipids, a chloride channel protein (C1C-7) and two transporter proteins, the ATPase proton transporter, and the proton-dependent phosphate transporter. Mutations that suppress c-src or prevent expression or functioning of C1C-7 or C1IC-5 in mice or humans prevent osteoclast development and cause overly dense, brittle bones (osteopetrosis). 

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