Expression and distribution of connexin 32 in rat liver with experimentally induced fibrosis

Abstract

RESUMO.-[Expressão e distribuição da conexina 32 em fígados de ratos com fibrose induzida experimentalmente.] A conexina 32 (Cx32) é uma proteína que constitui os canais que promovem as comunicações intercelulares via junções comunicantes (CIJC) no fígado, permitindo difusão de pequenas moléculas citoplasmáticas de uma célula à outra. A fibrose hepática caracteriza-se pela alteração da arquitetura normal do fígado e podem alterar as CIJCs. O objetivo deste trabalho foi estudar a expressão e distribuição de Cx32 na fibrose hepática. O objetivo do presente trabalho foi estudar a expressão e distribuição da Cx32 em fígados com fibrose induzida pela administração oral de dimetilnitrosamina em fêmeas de ratos Wistar. A necropsia foi realizada após cinco semanas da última administração da droga e observou-se um quadro de fibrose hepática. Amostras dos fígados com fibrose e de animais controle foram submetidas à análise imunoistoquímica, por Real Time-PCR e por Western-Blot verificando-se a presença de Cx32 difusa e dispersa no citoplasma dos fígados com fibrose. No grupo controle a Cx32 localizou-se na membrana citoplasmática com a formação de placas juncionais. O fígado com fibrose também revelou diminuição da expressão gênica de Cx32, embora sem a redução da quantidade do produto protéico, quando comparado ao grupo controle. Estes resultados suge- (Cx32) is a protein that forms the channels that promote the gap junction intercellular communication (GJIC) in the liver, allowing the diffusion of small molecules through cytosol from cell-to-cell. Hepatic fibrosis is characterized by a disruption of normal tissue architeture by cellular lesions, and may alter the GJIC. This work aimed to study the expression and distribution of Cx32 in liver fibrosis induced by the oral administration of dimethylnitrosamine in female Wistar rats. The necropsy of the rats was carried out after five weeks of drug administration. They presented a hepatic fibrosis state. Sections from livers with fibrosis and from control livers were submitted to immunohistochemical, Real Time-PCR and Western-Blot analysis to Cx32. In fibrotic livers the Cxs were diffusely scattered in the cytoplasm, contrasting with the control livers, where the Cx32 formed junction plaques at the cell membrane. Also it was found a decrease in the gene expression of Cx32 without reduction in the protein quantity when compared with controls. These results suggest that there the mechanism of intercellular communication between hepatocytes was reduced by the fibrotic process, which may predispose to the occurrence of a neoplastic process, taken in account that connexins are considered tumor suppressing genes. rem que o mecanismo de comunicação intercelular entre os hepatócitos reduziu-se durante o processo fibrótico, o que pode predispor a ocorrência de processos neoplási-cos, uma vez que as conexinas são consideradas genes supressores de tumores.

Morphological and molecular pathology of CCL4‐induced hepatic fibrosis in connexin43‐deficient mice

“…Connexins expression is highly related to cellular proliferation, wound healing, angiogenesis, and carcinogenesis process (Chanson et al, 2004; Mesnil et al, 2005; Yamasaki and Naus, 1996; Zaidan‐Dagli and Hernandez‐Blazquez, 2007). Several studies analyzed Cx32 or Cx26 expression in chronic liver diseases (Ma et al, 2000; Nakashima et al, 2004; Nakata et al, 1996; Santos‐Rodrigues et al, 2009; Yamaoka et al, 1995, 2000), but there are only a few reports of Cx43 expression (Ma et al, 2000; Oloris et al, 2007). Therefore, the role of Cx43 in chronic liver disease and its correlation with the process of liver fibrogenesis are unknown.…”

Connexin‐Based Channels in the Liver

“…Immunohistochemical analysis demonstrates that Cx32 proteins form gap junctions on the cell plasma membrane surface of hepatocytes in control animals. This expression pattern is disrupted in liver fibrosis as a shift in localization of Cx32 proteins towards the cytoplasm is seen in animals treated with dimethylnitrosamine (139). Cx32 deficiency increases liver fibrosis and hepatocellular damage after CCl4-induced liver injury.…”