Adipocyte spliced form of X-box-binding protein 1 promotes adiponectin multimerization and systemic glucose homeostasis.
The physiological role of the spliced form of X-box-binding protein 1 (XBP1s), a key transcription factor of the endoplasmic reticulum (ER) stress response, in adipose tissue remains largely unknown. In this study, we show that overexpression of XBP1s promotes adiponectin multimerization in adipocytes, thereby regulating systemic glucose homeostasis. Ectopic expression of XBP1s in adipocytes improves glucose tolerance and insulin sensitivity in both lean and obese (ob/ob) mice. The beneficial effect of adipocyte XBP1s on glucose homeostasis is associated with elevated serum levels of high-molecular-weight adiponectin and, indeed, is adiponectin-dependent. Mechanistically, XBP1s promotes adiponectin multimerization rather than activating its transcription, likely through a direct regulation of the expression of several ER chaperones involved in adiponectin maturation, including glucose-regulated protein 78 kDa, protein disulfide isomerase family A, member 6, ER protein 44, and disulfide bond oxidoreductase A-like protein. Thus, we conclude that XBP1s is an important regulator of adiponectin multimerization, which may lead to a new therapeutic approach for the treatment of type 2 diabetes and hypoadiponectinemia.
Division of Nutritional Sciences, Cornell University, Ithaca, NY.
Haibo
H
Sha
Liu
L
Yang
Meilian
M
Liu
Sheng
S
Xia
Yong
Y
Liu
Feng
F
Liu
Sander
S
Kersten
Ling
L
Qi
D041721:3T3-L1 Cells; D017667:Adipocytes / Q000378:metabolism*; D052242:Adiponectin / Q000097:blood / Q000737:chemistry*; D000818:Animals; D004268:DNA-Binding Proteins / Q000502:physiology*; D059865:Endoplasmic Reticulum Stress; D005786:Gene Expression Regulation; D005947:Glucose / Q000378:metabolism*; D006706:Homeostasis; D051379:Mice; D008810:Mice, Inbred C57BL; D008820:Mice, Obese; D055503:Protein Multimerization; D000071701:Regulatory Factor X Transcription Factors; D014157:Transcription Factors / Q000502:physiology*; D000071717:X-Box Binding Protein 1
D052242:Adiponectin; D004268:DNA-Binding Proteins; D000071701:Regulatory Factor X Transcription Factors; D014157:Transcription Factors; D000071717:X-Box Binding Protein 1; C000605544:Xbp1 protein, mouse; D005947:Glucose