Hepatocyte ALOXE3 is induced during adaptive fasting and enhances insulin sensitivity by activating hepatic PPARγ

Abstract

The hepatic glucose fasting response is gaining traction as a therapeutic pathway to enhance hepatic and whole-host metabolism. However, the mechanisms underlying these metabolic effects remain unclear. Here, we demonstrate the epidermal-type lipoxygenase, eLOX3 (encoded by its gene, Aloxe3), is a potentially novel effector of the therapeutic fasting response. We show that Aloxe3 is activated during fasting, glucose withdrawal, or trehalose/trehalose analogue treatment. Hepatocyte-specific Aloxe3 expression reduced weight gain and hepatic steatosis in diet-induced and genetically obese (db/db) mouse models. Aloxe3 expression, moreover, enhanced basal thermogenesis and abrogated insulin resistance in db/db diabetic mice. Targeted metabolomics demonstrated accumulation of the PPARγ ligand 12-KETE in hepatocytes overexpressing Aloxe3. Strikingly, PPARγ inhibition reversed hepatic Aloxe3–mediated insulin sensitization, suppression of hepatocellular ATP production and oxygen consumption, and gene induction of PPARγ coactivator-1α (PGC1α) expression. Moreover, hepatocyte-specific PPARγ deletion reversed the therapeutic effect of hepatic Aloxe3 expression on diet-induced insulin intolerance. Aloxe3 is, therefore, a potentially novel effector of the hepatocellular fasting response that leverages both PPARγ-mediated and pleiotropic effects to augment hepatic and whole-host metabolism, and it is, thus, a promising target to ameliorate metabolic disease.

Degradation-resistant trehalose analogues block utilization of trehalose by hypervirulent Clostridioides difficile

“…Consistent with this notion, recent data demonstrate that lactotrehalose (3) induces canonical fasting signaling in isolated murine hepatocytes, similar to the effects of native trehalose on hepatocyte metabolism. 17,18 To evaluate whether 2-4 were resistant to enzymatic degradation by trehalase, we tested them using a commercially available model trehalase from porcine kidney. 10 mM of the analogues or native trehalose were incubated in the presence of trehalase or buffer alone, then the reactions were quenched and analyzed by thin-layer chromatography (TLC).…”

miR-18a promotes glioblastoma development by down-regulating ALOXE3-mediated ferroptotic and anti-migration activities

“…1C–D ). Since 12-hydroperoxyeicosatetraenoic acids (12-HpETE) metabolized from arachidonic acid, can be further catalyzed into 12-HETE or 12-ketoeicosatetraenoic acids (12-KETE) in an ALOXE3-dependent manner 25 (Fig. 1E ), we next explored the circulating levels of 12-HETE and 12-KETE in cerebrospinal fluid (CSF) of GBM patients and their controls.…”

“…S9A-B ), indicating that ALOXE3 down-regulation promotes migration of GBM cells. Since 12-HETE can modulate cell metabolism and functions in an autocrine or paracrine manner 17 , 25 , 35 , 36 , we hypothesized that ALOXE3 knockdown in GBM cells promoted secretion of 12-HETE, which in turn enhanced migration of GBM cells in an autocrine manner. To investigate this assumption, we collected conditional medium (CM) from the U87 GBM cells with ALOXE3 silencing, and measured the 12-HETE levels.…”

Lactotrehalose, an Analog of Trehalose, Increases Energy Metabolism Without Promoting Clostridioides difficile Infection in Mice

“…1,4,11,12 These responses improve mitochondrial function and total energy expenditure, reduce diet-induced hepatic steatosis, and enhance insulin sensitivity. 11,13,14 Targeting the hepatocyte is an attractive therapeutic strategy, in light of its primary function of coordinating gluconeogenesis and ketogenesis and up-regulating fatty acid beta oxidation during fasting by mobilizing peripheral fatty acids. 15 Clostridioides difficile causes a common nosocomial infection that is characterized by pseudomembranous colorectal inflammation.…”

“…Histological analysis by Oil Red-O staining in liver frozen sections, serum biochemical analyses, and hepatic gene expression was performed precisely as we have reported previously. 4,13,14,30,31…”