Intraflagellar-transport A dysfunction causes hyperphagia-induced systemic insulin resistance in a pre-obese state.

Abstract

Deletion of murine Thm1, an intraflagellar transport A (IFT-A) component that mediates ciliary protein trafficking, causes hyperphagia, obesity, and metabolic syndrome. The role of Thm1 or IFT-A in adipogenesis and insulin sensitivity is unknown. Here, we report that Thm1 knockdown in 3T3-L1 pre-adipocytes promotes adipogenesis and enhances insulin sensitivity in vitro. Yet, pre-obese Thm1 conditional knockout mice show systemic insulin resistance. While insulin-induced AKT activation in Thm1 mutant adipose depots and skeletal muscle are similar to those of control littermates, an attenuated insulin response arises in the mutant liver. Insulin treatment of control and Thm1 mutant primary hepatocytes results in similar AKT activation. Moreover, pair-feeding Thm1 conditional knockout mice produces a normal insulin response, both in the liver and systemically. Thus, hyperphagia caused by a cilia defect, induces hepatic insulin resistance via a non-cell autonomous mechanism. In turn, hepatic insulin resistance drives systemic insulin resistance prior to an obese phenotype. These data demonstrate that insulin signaling across cell types is regulated differentially, and that the liver is particularly susceptible to hyperphagia-induced insulin resistance and a critical determinant of systemic insulin resistance.

• Authors: Damon T Jacobs, Bailey A Allard, Tana S Pottorf, Luciane M Silva, Wei Wang, Aisha Al-Naamani, Ewud Agborbesong, Tao Wang, Dajanae A Carr, Pamela V Tran
• Journal: FASEB journal : official publication of the Federation of American Societies for Experimental Biology (FASEB J) Vol. 34 Issue 1 Pg. 148-160 (01 2020) ISSN: 1530-6860 [Electronic] United States
• PMID: 31914634 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, U.S. Gov't, Non-P.H.S.)
• Copyright: © 2019 Federation of American Societies for Experimental Biology.

Chemical References

• Adaptor Proteins, Signal Transducing
• Cytoskeletal Proteins
• Insulin
• Ttc21b protein, mouse
• Proto-Oncogene Proteins c-akt

Topics

• 3T3-L1 Cells
• Adaptor Proteins, Signal Transducing (genetics, metabolism)
• Adipocytes
• Adipogenesis
• Animals
• Cytoskeletal Proteins (genetics, metabolism)
• Genetic Predisposition to Disease
• Hepatocytes (metabolism)
• Hyperphagia (metabolism)
• Insulin (metabolism, pharmacology)
• Insulin Resistance (physiology)
• Mice
• Mice, Knockout
• Obesity (genetics, metabolism)
• Proto-Oncogene Proteins c-akt (genetics, metabolism)