Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0012739 (disseminated intravascular coagulation)
 8,673 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Evidence for a structural precursor of the focal contact in cultured fibroblasts and continuing studies on the development of the precursor and contact are discussed. The structural precursor consists of an F-actin-rich, rib-like fiber within the motile lamellipodium. The focal contact forms beneath the fiber, part of which is retained at the contact as the initial adhesion plaque. Therefore, F-actin is present at the contact from the beginning. Vinculin accumulates at the plaque during a 90-second period after the contact forms. A novel feature of the distribution of talin has been found. The protein is present along the distal margin of the lamellipodium, where it is further concentrated as a series of nodes at the tips of each precursor and between precursors. This distribution of talin is independent of that which develops at the plaque after the contact forms. The structural development of the precursor has been followed with AVEC-DIC optics. The process begins with the development of fine oblique fibers from small structural nodes at the margin of the lamellipodium, and continues with the fusion of the nodes at the margin and inward coalescence of the fibers. It is suggested that talin may function as a cross-linking protein in the convergence of actin filaments at the membrane, while other actin-bundling proteins participate in the inward coalescence of the filaments to form fibers. The F-actin core of the precursor could provide a structural framework against which differences at the external surface of the membrane develop prior to contact formation.
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PMID:A precursor of the focal contact in cultured fibroblasts. 314 Oct 68

To date, protrusion of pseudopodia has been considered to be primarily responsible for translocation of free-living amoebae and leukocytes of higher organisms. Although there is little question that the pseudopodium plays an important role, little attention has been given to the cortical structures that are responsible for cell-substratum anchorage in amoeboid movement. Here, we report on a new knobby foot-like structure in amoebae of a cellullar slime mold, Dictyostelium discoideum. These feet, each about 1 micron in diameter, appear transiently in multiple units at the base of certain pseudopodia where the amoeba contacts a partially deformable substrate. The feet were discovered, and their spatial and temporal behavior relative to pseudopodial anchorage and invasive locomotion were observed, by examining Dictyostelium amoebae using a DIC video microscope providing an 0.3 micron depth of field. Key evidence for the anchoring role of the knobby feet was obtained by investigating amoebae, flattened in a specially devised observation chamber, and attracted by chemotaxis towards 3',5' cyclic-adenosine monophosphate (cAMP). The cAMP was released by highly localized, pulsed UV-microbeam irradiation of caged cAMP. We show by indirect immunofluorescence that the knobby feet contain a high concentration of filamentous (F-) actin, myoB (a member of Dictyostelium myosin-I family), and alpha-actinin (an actin-binding protein). Interestingly, myoB exhibits a circular disposition around each foot. Neither myosin-II (conventional myosin) nor the 269 kD protein, which has been recently identified as a talin homologue of Dictyostelium [Kreitmeier et al., 1995: J. Cell Biol. 129:179-188], are concentrated at the feet. We propose that the knobby feet provide anchorage to the substratum needed by lamellipodia to exert projectile forces for invading narrow spaces or otherwise for a flattened amoeba to secure itself to the deformable substratum. Some forms of adhesion plaques in higher organisms such as "podosomes" or "invadopodia" may perform functions similar to the knobby feet, but appear to differ in life time, cytoskeletal organization and composition. We have named the knobby foot "eupodium."
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PMID:Amoeboid movement anchored by eupodia, new actin-rich knobby feet in Dictyostelium. 909 56