Blockade of β1 Integrin–Laminin-5 Interaction Affects Spreading and Insulin Secretion of Rat β-Cells Attached on Extracellular Matrix

  1. Geraldine Parnaud1,
  2. Eva Hammar1,
  3. Dominique G. Rouiller1,
  4. Mathieu Armanet2,
  5. Philippe A. Halban1 and
  6. Domenico Bosco2
  1. 1Department of Genetic Medicine and Development, University Medical Center, Geneva, Switzerland
  2. 2Cell Isolation and Transplantation Center, Division of Surgical Research, Department of Surgery, University Hospital, Geneva, Switzerland
  1. Address correspondence and reprint requests to Geraldine Parnaud, Department of Genetic Medicine and Development, University Medical Center, 1 rue Michel-Servet, 1211 Geneva-4, Switzerland. E-mail: geraldine.parnaud{at}medecine.unige.ch

Abstract

When attached on a matrix produced by a rat bladder carcinoma cell line (804G matrix), rat pancreatic β-cells spread in response to glucose and secrete more insulin compared with cells attached on poly-l-lysine. The aim of this study was to determine whether laminin-5 and its corresponding cell receptor β1 integrin are implicated in these phenomena. By using specific blocking antibodies, we demonstrated that laminin-5 is the component present in 804G matrix responsible for the effect of 804G matrix on β-cell function and spreading. When expression of two well-known laminin-5 ligands, β1 and β4 integrin, was assessed by Western blot and RT-PCR, only the β1 integrin was detected in β-cells. Anti–β1 integrin antibody reduced the spreading of β-cells on 804G matrix. Blockade of the interaction between β1 integrins and laminin-5 resulted in a reduction in glucose-stimulated insulin secretion. Blocking anti–β1 integrin antibody also inhibited focal adhesion kinase phosphorylation induced by 804G matrix. In conclusion, anti–β1 integrin and –laminin-5 antibodies interfere with spreading of β-cells, resulting in decreased insulin secretion in response to glucose. Our findings indicate that outside-in signaling via engagement of β1 integrins by laminin-5 is an important component of normal β-cell function.

Footnotes

  • The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

    • Accepted February 6, 2006.
    • Received October 25, 2005.
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