{"type": "root", "children": [{"type": "p", "children": [{"type": "t", "text": "\nFRG1HP acts as a pivotal enzyme in fructose metabolism, catalyzing the rapid phosphorylation of fructose that helps drive downstream metabolic processes. The enzyme exists in distinct isoforms – one with high affinity and tissue‐restricted expression that predominates in the liver, intestine, and kidney, and another more ubiquitously expressed form with lower affinity. This duality governs how dietary fructose is processed and has major implications for metabolic health. In experimental models, enhanced FRG1HP activity has been linked to fructose‐induced hepatic steatosis, visceral adipose inflammation, and features of metabolic syndrome, whereas genetic deletion or selective inhibition interrupts these deleterious pathways."}, {"type": "fg", "children": [{"type": "fg_fs", "start_ref": "1", "end_ref": "9"}]}, {"type": "t", "text": "\n"}]}, {"type": "t", "text": "\n\n"}, {"type": "p", "children": [{"type": "t", "text": "\nIn the kidney, FRG1HP–mediated metabolism plays a crucial role in the development of injury under various pathological conditions. Activation of the polyol pathway leads to increased endogenous fructose production, which, when metabolized by FRG1HP, can deplete cellular ATP, induce proinflammatory cytokine expression, and promote renal fibrosis. These processes underlie the progression of diabetic nephropathy, injury due to recurrent dehydration, and even age-associated renal damage. In multiple experimental models, FRG1HP deficiency confers significant protection from such renal insults, positioning it as a promising target for therapeutic intervention in renal diseases."}, {"type": "fg", "children": [{"type": "fg_fs", "start_ref": "10", "end_ref": "13"}]}, {"type": "t", "text": "\n"}]}, {"type": "t", "text": "\n\n"}, {"type": "p", "children": [{"type": "t", "text": "\nBeyond its roles in the liver and kidney, FRG1HP influences fructose handling in other tissues and under unique physiological challenges. Under myocardial hypoxia, hypoxia-inducible factor 1α induces splice switching that enhances FRG1HP activity, contributing to pathological cardiac hypertrophy. In the intestine, FRG1HP works in concert with the fructose transporter GLUT5 and Rab11a-dependent membrane trafficking to regulate fructose uptake and enzymatic capacity. Moreover, in the hypothalamus, FRG1HP’s activity modulates vasopressin secretion in response to dehydration, linking fructose metabolism with neuroendocrine regulation. Structural studies and improved gene annotation have further refined our understanding of FRG1HP isoform-specific functions, underscoring its central role in maintaining fructose homeostasis across diverse tissues."}, {"type": "fg", "children": [{"type": "fg_fs", "start_ref": "14", "end_ref": "18"}]}, {"type": "t", "text": "\n"}]}, {"type": "rg", "children": [{"type": "r", "ref": 1, "children": [{"type": "t", "text": "C P Diggle, M Shires, C McRae, et al. 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