The unique prodomain of T-cadherin plays a key role in adiponectin binding with the essential extracellular cadherin repeats 1 and 2

Abstract

Adiponectin, an adipocyte-derived circulating protein, accumulates in the heart, vascular endothelium, and skeletal muscles through an interaction with T-cadherin (T-cad), a unique glycosylphosphatidylinositol-anchored cadherin. Recent studies have suggested that this interaction is essential for adiponectin-mediated cardiovascular protection. However, the precise protein-protein interaction between adiponectin and T-cad remains poorly characterized. Using ELISA-based and surface plasmon analyses, we report here that T-cad fused with IgG Fc as a fusion tag by replacing its glycosylphosphatidylinositol-anchor specifically bound both hexameric and larger multimeric adiponectin with a dissociation constant of ∼1.0 nm and without any contribution from other cellular or serum factors. The extracellular T-cad repeats 1 and 2 were critical for the observed adiponectin binding, which is required for classical cadherin-mediated cell-to-cell adhesion. Moreover, the 130-kDa prodomain-bearing T-cad, uniquely expressed on the cell surface among members of the cadherin family and predominantly increased by adiponectin, contributed significantly to adiponectin binding. Inhibition of prodomain-processing by a prohormone convertase inhibitor increased 130-kDa T-cad levels and also enhanced adiponectin binding to endothelial cells both by more preferential cell-surface localization and by higher adiponectin-binding affinity of 130-kDa T-cad relative to 100-kDa T-cad. The preferential cell-surface localization of 130-kDa T-cad relative to 100-kDa T-cad was also observed in normal mice aorta In conclusion, our study shows that a unique key feature of the T-cad prodomain is its involvement in binding of the T-cad repeats 1 and 2 to adiponectin and also demonstrates that adiponectin positively regulates T-cad abundance.

Adiponectin/T-cadherin system enhances exosome biogenesis and decreases cellular ceramides by exosomal release

“…Adiponectin purification. Adiponectin purification was performed as reported previously (35). Briefly, serum from AKO mice treated with Ad-APN was applied onto T-cadherin-Fc conjugated with Protein G sepharose (GE healthcare).…”

“…To specify the effect of adiponectin, other than unknown exosome-stimulating factors possibly contained in serum, we purified adiponectin from mouse serum using T-cadherin-conjugated resin (35). Such purified protein consisted of high-and middle-molecular-weight multimers of adiponectin, even in Coomassie brilliant blue staining and in Western blotting ( Figure 4D).…”

Interorgan communication by exosomes, adipose tissue, and adiponectin in metabolic syndrome

“…T-cadherin was discovered as an adiponectin binding partner by evaluating cell binding to coated recombinant adiponectin produced in HEK293 mammalian cells (57). Its unique prodomain gives T-cadherin high-affinity interaction with native HMW adiponectin in serum (19). On the other hand, the majority of exosomes can be phagocytosed by macrophages (48)(49)(50)(51).…”

“…Adipose tissue-derived exosomes affect whole-body glucose metabolism (6,7). Adiponectin secreted from adipocytes stimulates exosome production from T-cadherin-expressing cells in aorta, heart, and muscle and affects systemic exosome levels (17)(18)(19). The adiponectin-mediated production of exosomes also may also affect whole-body glucose metabolism.…”

“…Several recent studies have reported that T-cadherin mediates cardiovascular protection and skeletal muscle regeneration via the clinically important high molecular weight (HMW) multimeric adiponectin (14)(15)(16)(17). T-cadherin facilitates adiponectin accumulation in multivesicular bodies, a subtype of endosome in which exosomes are generated, wherein adiponectin stimulates exosome biogenesis and secretion (17)(18)(19).…”