Publications (12)120.34 Total impact
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Article: Expression of beta 1 integrins in sensory neurons of the dorsal root ganglion and their functions in neurite outgrowth on two laminin isoforms.
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ABSTRACT: Integrins are heterodimeric receptors that mediate responses of neurons and many other cell types to components of the extracellular matrix. In the present article, we examine the roles of individual integrin receptors expressed by spinal sensory neurons of the dorsal root ganglion (DRG) in mediating interactions with laminin, an extracellular matrix glycoprotein that promotes neurite outgrowth. DRG neurons were shown to express three beta 1 integrins that have been shown in other cell types to function as laminin receptors--high levels of alpha 1 beta 1 and alpha 3 beta 1 and low levels of alpha 6 beta 1. In addition, DRG neurons were shown to express a known fibronectin receptor, alpha 5 beta 1, and an integrin with undefined ligands, alpha 6 beta 4. Function-inhibitory monoclonal antibodies specific for the alpha 1, alpha 2, alpha 3, alpha 5, and alpha 6 integrin subunits were used to determine the roles of individual integrins in mediating neurite outgrowth by DRG neurons on laminin. The results demonstrate that alpha 1 beta 1 and alpha 3 beta 1 function as laminin receptors on these neurons. As many as 18 distinct isoforms of laminin may exist, assembled as heterotrimers containing one each of the different A, B1, or B2 subunit homologs. In the present study, we characterize neurite outgrowth in response to two of these isoforms, the AeB1eB2e isoform and the AmB1eB2e isoform. Results utilizing DRG neurons and a pheochromocytoma cell line (PC12) indicate that these two isoforms exhibit differential selectivities for the alpha 1 beta 1 and alpha 3 beta 1 integrins.(ABSTRACT TRUNCATED AT 250 WORDS)Journal of Neuroscience 12/1993; 13(11):4880-8. · 7.11 Impact Factor -
Article: 2001 interactions? An extracellular space odyssey.
Current Opinion in Neurobiology 11/1991; 1(3):364-9. · 7.44 Impact Factor -
Article: Extracellular matrix molecules and their receptors: functions in neural development.
Annual Review of Neuroscience 02/1991; 14:531-70. · 25.74 Impact Factor -
Article: Beta 1-integrin-mediated neuronal responses to extracellular matrix proteins.
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ABSTRACT: Immunologic and biochemical studies demonstrate that beta 1-class integrin heterodimers mediate attachment and neurite outgrowth by primary neurons and neuronal cell lines in response to neurite-promoting ECM molecules. Individual cells are likely to express several alpha beta 1 integrins, each possessing unique ligand specificities. In some cases, a cell may express two beta 1 integrins that recognize different binding domains in a single ECM ligand, as appears to be the case for the alpha 3 beta 1 and alpha 1 beta 1 integrins on PC12 cells. Thus, the responses of a neuron to even a single ligand may be regulated by the combined action of several receptors. Finally, preliminary studies suggest that neurons can regulate the ligand specificity of individual integrin heterodimers (e.g., alpha 1 beta 1). Given the tremendous diversity in the extracellular matrix surrounding them, it is not surprising that neurons possess intrinsic factors that dictate if and how they respond to a particular ECM component.Annals of the New York Academy of Sciences 02/1991; 633:100-4. · 3.15 Impact Factor -
Article: A neuronal cell line (PC12) expresses two beta 1-class integrins-alpha 1 beta 1 and alpha 3 beta 1-that recognize different neurite outgrowth-promoting domains in laminin.
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ABSTRACT: Integrins mediate neuronal process outgrowth on components of the ECM. Integrin alpha subunit-specific antibodies have been used to examine the roles of individual beta 1 integrins in attachment and neurite outgrowth by the neuronal cell line, PC12, in response to laminin and collagen. alpha 1 beta 1 and alpha 3 beta 1 were identified as the major beta 1 integrins expressed by PC12 cells. In functional assays, both alpha 1 beta 1 and alpha 3 beta 1 mediated PC12 cell interactions with laminin, whereas alpha 1 beta 1 alone mediated responses to collagen types I and IV. alpha 1 beta 1 and alpha 3 beta 1 were shown to recognize two different neurite-promoting sites in laminin: alpha 1 beta 1 interacted with the cross-region of laminin present in proteolytic fragments E1-4 and E1; alpha 3 beta 1 recognized a site in the long arm contained in laminin fragment E8. Thus, PC12 cells express two beta 1 integrins, which together function in attachment and neurite outgrowth on laminin and collagen. These integrins are candidates for mediating neurite outgrowth of sympathetic and other neurons in response to these ECM components.Neuron 12/1990; 5(5):651-62. · 14.74 Impact Factor -
Article: Integrins and cell adhesion molecules: neuronal receptors that regulate axon growth on extracellular matrices and cell surfaces.
Developmental Neuroscience 02/1989; 11(4-5):332-47. · 3.63 Impact Factor -
Article: N-cadherin, NCAM, and integrins promote retinal neurite outgrowth on astrocytes in vitro.
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ABSTRACT: Retinal ganglion neurons extend axons that grow along astroglial cell surfaces in the developing optic pathway. To identify the molecules that may mediate axon extension in vivo, antibodies to neuronal cell surface proteins were tested for their effects on neurite outgrowth by embryonic chick retinal neurons cultured on astrocyte monolayers. Neurite outgrowth by retinal neurons from embryonic day 7 (E7) and E11 chick embryos depended on the function of a calcium-dependent cell adhesion molecule (N-cadherin) and beta 1-class integrin extracellular matrix receptors. The inhibitory effects of either antibody on process extension could not be accounted for by a reduction in the attachment of neurons to astrocytes. The role of a third cell adhesion molecule, NCAM, changed during development. Anti-NCAM had no detectable inhibitory effects on neurite outgrowth by E7 retinal neurons. In contrast, E11 retinal neurite outgrowth was strongly dependent on NCAM function. Thus, N-cadherin, integrins, and NCAM are likely to regulate axon extension in the optic pathway, and their relative importance varies with developmental age.The Journal of Cell Biology 10/1988; 107(3):1177-87. · 10.26 Impact Factor -
Article: Purification and characterization of mammalian integrins expressed by a rat neuronal cell line (PC12): evidence that they function as alpha/beta heterodimeric receptors for laminin and type IV collagen.
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ABSTRACT: Cells of the rat neuronal line, PC12, adhere well to substrates coated with laminin and type IV collagen, but attach poorly to fibronectin. Adhesion and neurite extension in response to these extracellular matrix proteins are inhibited by Fab fragments of an antiserum (anti-ECMR) that recognizes PC12 cell surface integrin subunits of Mr 120,000, 140,000, and 180,000 (Tomaselli, K. J., C. H. Damsky, and L. F. Reichardt. 1987. J. Cell Biol. 105:2347-2358). Here we extend our study of integrin structure and function in PC12 cells using integrin subunit-specific antibodies prepared against synthetic peptides corresponding to the cytoplasmic domains of the human integrin beta 1 and the fibronectin receptor alpha (alpha FN) subunits. Anti-integrin beta 1 immunoprecipitated a 120-kD beta 1 subunit and two noncovalently associated integrin alpha subunits of 140 and 180 kD from detergent extracts of surface-labeled PC12 cells. Immunodepletion studies using anti-integrin beta 1 demonstrated that these two putative alpha/beta heterodimers are identical to those recognized by the adhesion-perturbing ECMR antiserum. Anti-alpha FN immunoprecipitated fibronectin receptor heterodimers in human and rat fibroblastic cells, but not in PC12 cells. Thus, low levels of expression of the integrin alpha FN subunit can explain the poor attachment of PC12 cells to FN. The PC12 cell integrins were purified using a combination of lectin and ECMR antibody affinity chromatography. The purified integrins: (a) completely neutralize the ability of the anti-ECMR serum to inhibit PC12 cell adhesion to laminin and collagen IV; (b) have hydrodynamic properties that are very similar to those of previously characterized integrin alpha/beta heterodimeric receptors for ECM proteins; and (c) can be incorporated into phosphatidylcholine vesicles that then bind specifically to substrates coated with laminin or collagen IV but not fibronectin. Thus, the ligand-binding specificity of the liposomes containing the purified PC12 integrins closely parallels the substrate-binding preference of intact PC12 cells. These results demonstrate that mammalian integrins purified from a neuronal cell line can, when incorporated into lipid vesicles, function as receptors for laminin and type IV collagen.The Journal of Cell Biology 10/1988; 107(3):1241-52. · 10.26 Impact Factor -
Article: N-cadherin and integrins: two receptor systems that mediate neuronal process outgrowth on astrocyte surfaces.
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ABSTRACT: Receptor-mediated interactions between neurons and astroglia are likely to play a crucial role in the growth and guidance of CNS axons. Using antibodies to neuronal cell surface proteins, we identified two receptor systems mediating neurite outgrowth on cultured astrocytes. N-cadherin, a Ca2(+)-dependent cell adhesion molecule, functions prominently in the outgrowth of neurites on astrocytes by E8 and E14 chick ciliary ganglion (CG) neurons. beta 1-class integrin ECM receptor heterodimers function less prominently in E8 and not at all in E14 neurite outgrowth on astrocytes. The lack of effect of integrin beta 1 antibodies on E14 neurite outgrowth reflects an apparent loss of integrin function, as assayed by E14 neuronal attachment and process outgrowth on laminin. N-CAM appeared not to be required for neurite outgrowth by either E8 or E14 neurons. Since N-cadherin and integrin beta 1 antibodies together virtually eliminated E8 CG neurite outgrowth on cultured astrocytes, these two neuronal receptors are probably important in regulating axon growth on astroglia in vivo.Neuron 04/1988; 1(1):33-43. · 14.74 Impact Factor -
Article: Interactions of a neuronal cell line (PC12) with laminin, collagen IV, and fibronectin: identification of integrin-related glycoproteins involved in attachment and process outgrowth.
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ABSTRACT: Neuronal responses to extracellular matrix (ECM) constituents are likely to play an important role in nervous system development and regeneration. We have studied the interactions of a neuron-like rat pheochromocytoma cell line, PC12, with ECM protein-coated substrates. Using a quantitative cell attachment assay, PC12 cells were shown to adhere readily to laminin (LN) or collagen IV (Col IV) but poorly to fibronectin (FN). The specificity of attachment to these ECM proteins was demonstrated using ligand-specific antibodies and synthetic peptides. To identify PC12 cell surface proteins that mediate interactions with LN, Col IV, and FN, two different antisera to putative ECM receptors purified from mammalian cells were tested for their effects on PC12 cell adhesion and neuritic process outgrowth. Antibodies to a 140-kD FN receptor heterodimer purified from Chinese hamster ovarian cells (anti-FNR; Brown, P. J., and R. L. Juliano, 1986, J. Cell Biol., 103:1595-1603) inhibited attachment to LN and FN but not to Col IV. Antibodies to an ECM receptor preparation purified from baby hamster kidney fibroblastic cells (anti-ECMR; Knudsen, K. A., P. E. Rao, C. H. Damsky, and C. A. Buck, 1981, Proc. Natl. Acad. Sci. USA., 78:6071-6075) inhibited attachment to LN, FN, and Col IV, but did not prevent attachment to other adhesive substrates. In addition to its effects on adhesion, the anti-ECMR serum inhibited both PC12 cell and sympathetic neuronal process outgrowth on LN substrates. Immunoprecipitation of surface-iodinated or [3H]glucosamine-labeled PC12 cells with either the anti-FNR or anti-ECMR serum identified three prominent cell surface glycoproteins of 120, 140, and 180 kD under nonreducing conditions. The 120-kD glycoprotein, which could be labeled with 32P-orthophosphate and appeared to be noncovalently associated with the 140- and 180-kD proteins, cross reacted with antibodies to the beta-subunit (band 3) of the avian integrin complex, itself a receptor or receptors for the ECM constituents LN, FN, and some collagens.The Journal of Cell Biology 12/1987; 105(5):2347-58. · 10.26 Impact Factor -
Article: Distinct molecular interactions mediate neuronal process outgrowth on non-neuronal cell surfaces and extracellular matrices.
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ABSTRACT: We have compared neurite outgrowth on extracellular matrix (ECM) constituents to outgrowth on glial and muscle cell surfaces. Embryonic chick ciliary ganglion (CG) neurons regenerate neurites rapidly on surfaces coated with laminin (LN), fibronectin (FN), conditioned media (CM) from several non-neuronal cell types that secrete LN, and on intact extracellular matrices. Neurite outgrowth on all of these substrates is blocked by two monoclonal antibodies, CSAT and JG22, that prevent the adhesion of many cells, including neurons, to the ECM constituents LN, FN, and collagen. Neurite outgrowth is inhibited even on mixed LN/poly-D-lysine substrates where neuronal attachment is independent of LN. Therefore, neuronal process outgrowth on extracellular matrices requires the function of neuronal cell surface molecules recognized by these antibodies. The surfaces of cultured astrocytes, Schwann cells, and skeletal myotubes also promote rapid process outgrowth from CG neurons. Neurite outgrowth on these surfaces, though, is not prevented by CSAT or JG22 antibodies. In addition, antibodies to a LN/proteoglycan complex that block neurite outgrowth on several LN-containing CM factors and on an ECM extract failed to inhibit cell surface-stimulated neurite outgrowth. After extraction with a nonionic detergent, Schwann cells and myotubes continue to support rapid neurite outgrowth. However, the activity associated with the detergent insoluble residue is blocked by CSAT and JG22 antibodies. Detergent extraction of astrocytes, in contrast, removes all neurite-promoting activity. These results provide evidence for at least two types of neuronal interactions with cells that promote neurite outgrowth. One involves adhesive proteins present in the ECM and ECM receptors on neurons. The second is mediated through detergent-extractable macromolecules present on non-neuronal cell surfaces and different, uncharacterized receptor(s) on neurons. Schwann cells and skeletal myotubes appear to promote neurite outgrowth by both mechanisms.The Journal of Cell Biology 01/1987; 103(6 Pt 2):2659-72. · 10.26 Impact Factor -
Article: Peripheral motoneuron interactions with laminin and Schwann cell-derived neurite-promoting molecules: developmental regulation of laminin receptor function.
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ABSTRACT: Schwann cells synthesize several neurite outgrowth-promoting molecules and localize them in either the extracellular matrix (ECM; e.g., laminin) or on the plasma membrane (e.g., L1/NgCAM and N-cadherin). Neurite outgrowth by embryonic chick ciliary ganglion (CG) neurons in response to these Schwann cell molecules largely depends on several specific neuronal cell surface receptors: integrin beta 1-class ECM receptors, L1/NgCAM, and N-cadherin (Bixby et al.: Journal of Cell Biology 107:353-361 1988). To address whether neuronal ECM receptors are regulated independently of cell surface adhesion molecules, we studied the ability of dissociated CG neurons from different developmental ages to extend neurites rapidly on 1) substrates coated with the ECM glycoprotein laminin (either from Schwann cell-conditioned medium or purified from the Engelbreth-Holm-Swarm sarcoma) or 2) the surfaces of Schwann cells or Schwannoma (RN22) cells. CG neurons gradually lost the ability between embryonic day 8 (E8) and E14 to attach to and extend neurites in an integrin-dependent fashion on purified laminin or Schwann cell-derived laminin. The inability of E14 CG neurons to respond to laminin was partially reversed after explantation for 2.5 days in vitro, which increased the percentage of responsive neurons approximately ten-fold. E14 neurons remained capable of extending neurites rapidly on the surfaces of Schwann and Schwannoma cells. Thus, the inability of E14 neurons to respond to laminin reflects a specific loss of laminin receptor function, while other receptors, most likely N-cadherin and L1/NgCAM, remain capable of promoting neurite outgrowth on Schwann cell surfaces. Since integrin beta 1-class heterodimers have been shown to function directly as receptors mediating neuronal attachment and process outgrowth on laminin, our results imply that the expression or function of laminin-binding integrin heterodimers is regulated during the development of CG neurons. The apparent loss of integrin receptor function occurs during the period when the axons of CG neurons innervate their targets. Substantial integrin receptor function is recovered when target contact is disrupted by explantation. Thus, the functions of integrin-class receptors in CG neurons may be regulated by target contact.Journal of Neuroscience Research 21(2-4):275-85. · 2.74 Impact Factor
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Institutions
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1987–1991
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University of California, San Francisco
- Department of Physiology
San Francisco, CA, USA
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1990
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Howard Hughes Medical Institute
Chevy Chase, MD, USA
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