title: Aging-related changes and topology of adhesion responses sensitive to cycloheximide on collagen substrata by human dermal fibroblasts.
abstract: Human dermal fibroblasts (both papillary and reticular) were tested during in vivo or in vitro aging for their responses on collagen and/or fibronectin (FN) substrata, as well as on topologically mixed substrata. Cycloheximide treatments were used to evaluate whether receptors to these matrix molecules, mediating F-actin reorganization into stress fibers, are altered during aging processes. Late-passage (but not mid-passage) papillary and reticular cells from both an elderly male and a newborn infant spread effectively on collagen +/- FN but failed to generate stress fibers after lengthy pretreatment of cells with cycloheximide. In contrast, treatment with cycloheximide only when cells were reattaching was not inhibitory. None of the treatments had any effect on stress fiber formation of cells on FN-only substrata, demonstrating that drug sensitivity was specific for collagen responses. The inhibition could be reversed by rinsing cycloheximide out of cultures and could be prevented by prior growth of cells in ascorbate-supplemented medium to stimulate production/maturation of collagen and possibly collagen-specific receptors. Adjacent regions of coverslips were adsorbed with collagen and a proteolytic fragment of plasma FN lacking the collagen-binding domain but retaining other binding domains; cells bridging the interface were of special interest. When fragment F155 containing both the RGDS cell-binding and the heparin II-binding domains was tested in this paradigm, cells generated stress fibers continuous from the collagen-facing side into the F155-facing side of the same cell, consistent with the compatability of both collagen and FN receptors in generating the same stress fiber. However, F110 lacking the heparin II domain was incapable of facilitating stress fiber formation; fibers formed effectively on the collagen side and terminated abruptly at the collagen:F110 interface. These experiments demonstrate stringent regulation of where stress fibers begin, span, and terminate in the cytoplasm by matrix receptors at the cell's undersurface and establish that there are alterations of collagen-specific receptors as a consequence of in vitro aging, but not of in vivo aging, in both papillary and reticular human dermal fibroblasts.
authors: Department of Molecular Biology and Microbiology, Case Western Reserve University, School of Medicine, Cleveland, Ohio 44106.
authors: K S
authors: KS
authors: Flickinger
authors: L A
authors: LA
authors: Culp
mesh_terms: D000375:Aging / Q000473:pathology* / Q000502:physiology; D002448:Cell Adhesion / Q000187:drug effects / Q000502:physiology*; D002478:Cells, Cultured; D003094:Collagen / Q000378:metabolism; D003513:Cycloheximide / Q000494:pharmacology*; D000078404:Epidermal Cells; D004817:Epidermis / Q000378:metabolism / Q000648:ultrastructure; D005347:Fibroblasts / Q000166:cytology* / Q000378:metabolism / Q000648:ultrastructure; D005353:Fibronectins / Q000378:metabolism; D006801:Humans; D011506:Proteins / Q000378:metabolism; D017469:Receptors, Fibronectin; D011971:Receptors, Immunologic / Q000378:metabolism
chemical_list: D005353:Fibronectins; D011506:Proteins; D017469:Receptors, Fibronectin; D011971:Receptors, Immunologic; D003094:Collagen; D003513:Cycloheximide