Anti-Inflammatory Action of Insulin via Induction of Gadd45-β Transcription by the mTOR Signaling Pathway

• Published in: Hepatic medicine: evidence and research Vol. 2001; no. 2; pp. 79 - 85
• Main Authors: Bortoff, Katherine D, Keeton, Adam B, Franklin, J Lee, Messina, Joseph L
• Format: Journal Article
• Language: English
• Published: New Zealand 01.06.2010
• ISSN: 1179-1535; 1179-1535

Insulin regulates a large number of genes in a tissue-specific manner. We have identified genes modulated by insulin in the liver and in liver-derived cells that had not yet been characterized as insulin regulated, and these previous studies indicate that numerous genes are induced by insulin via the MEK-ERK pathway. We now describe new studies indicating that Gadd45-β can be induced by acute insulin treatment. Although other regulators of Gadd45-β expression may utilize the MEK-ERK pathway, the data indicate that insulin utilizes signaling pathways separate from either MEK-ERK, PI3-K or p38 signaling pathways in the regulation of Gadd45-β transcription. Our findings show that activation of a downstream effector of multiple signaling pathways, mTOR, was required for insulin-induction of Gadd45-β gene transcription. Increased expression of Gadd45-β can inhibit c-Jun N-terminal kinase (JNK) activity. Since TNFα is increased during inflammation, and acts, at least in part, via the JNK signaling pathway, insulin induction of Gadd45-β suggests a mechanism for the anti-inflammatory actions of insulin.