Hormonal
Obesity-induced insulin resistance is mechanistically driven by the activation of serine/threonine kinases (such as JNK, IKK, and PKC isoforms) which phosphorylate insulin receptor substrates (IRS) on inhibitory serine residues, thereby blocking normal tyrosine phosphorylation and signal transduction.
Insulin resistance in obesity is not just 'bad luck'; it is a specific biological response to stressors like excess lipids and inflammation. These stressors trigger specific enzymes (kinases) that physically block insulin's ability to signal. Understanding this means recognizing that reducing these stressors (via weight loss, exercise, or metabolic health improvements) can reverse the signaling block.
Increased inhibitory Ser/Thr phosphorylation of IR and especially IRS-1 and -2 occurs in response to cytokines, fatty acids, hyperglycemia, mitochondrial dysfunction, and ER stress, and insulin itself via activation of multiple kinases, predominantly by c-Jun amino-terminal kinase (JNK), IKK, conventional and novel PKCs, but also mTORC1/S6K and MAPK.
Why this rating
The paper is a comprehensive review by leading experts (Kahn et al.) citing extensive foundational literature and knockout mouse models.
Source
Insulin Receptor Signaling in Normal and Insulin-Resistant States
Jérémie Boucher et al. · Cold Spring Harbor Perspectives in Biology · 2014
DOI 10.1101/cshperspect.a009191
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