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Connexins protect mouse pancreatic β cells against apoptosis
Philippe Klee, … , Jacques-Antoine Haefliger, Paolo Meda
Philippe Klee, … , Jacques-Antoine Haefliger, Paolo Meda
Published November 7, 2011
Citation Information: J Clin Invest. 2011;121(12):4870-4879. https://doi.org/10.1172/JCI40509.
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Research Article Metabolism

Connexins protect mouse pancreatic β cells against apoptosis

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Abstract

Type 1 diabetes develops when most insulin-producing β cells of the pancreas are killed by an autoimmune attack. The in vivo conditions modulating the sensitivity and resistance of β cells to this attack remain largely obscure. Here, we show that connexin 36 (Cx36), a trans-membrane protein that forms gap junctions between β cells in the pancreatic islets, protects mouse β cells against both cytotoxic drugs and cytokines that prevail in the islet environment at the onset of type 1 diabetes. We documented that this protection was at least partially dependent on intercellular communication, which Cx36 and other types of connexin channels establish within pancreatic islets. We further found that proinflammatory cytokines decreased expression of Cx36 and that experimental reduction or augmentation of Cx36 levels increased or decreased β cell apoptosis, respectively. Thus, we conclude that Cx36 is central to β cell protection from toxic insults.

Authors

Philippe Klee, Florent Allagnat, Helena Pontes, Manon Cederroth, Anne Charollais, Dorothée Caille, Aurore Britan, Jacques-Antoine Haefliger, Paolo Meda

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Figure 5

β cell protection requires cell contact and Cx expression.

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β cell protection requires cell contact and Cx expression.
(A) The propo...
(A) The proportion of dead cells was similar in all control islet cell suspensions. STZ similarly increased this proportion in all groups. n as indicated. (B) Islet cells of control and homozygous mice of both Cx36 and RIP-Cx36 lines showed increased apoptosis (white) and necrosis (gray) after exposure to the cytokine mix of IL-1β, IFN-γ, and TNF-α. (C) The cytokine mix increased apoptosis of INS1E cells and control C57BL/6 islets. (D) The cytokine mix decreased Cx36 mRNA in mouse islets and in MIN6 and INS-1E cells. Values are expressed relative to L27 gene level. (E) The cytokine mix also decreased Cx36 in extracts of INS1E and MIN6 cells. Values are shown relative to the tubulin signal, normalized to control. Cx36 and actin Western blot immunolabeling, from which the quantitative data were generated, is also shown (inset). **P < 0.01, ***P < 0.001 versus corresponding control. (F) STZ injection induced hyperglycemia in RIP-Cx32–/– mice, but not in RIP-Cx32+/– and RIP-Cx32+/+ littermates. (G) RIP-Cx43–/– mice also became hyperglycemic after STZ injection, whereas RIP-Cx43+/– and RIP-Cx43+/+ littermates did not. Data are mean ± SEM of 4–6 experiments (A), of 3–5 experiments (B–E), or of 3–12 mice (F and G).

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