Proteomic responses to progressive dehydration and rehydration in Xenopus laevis

Amphibians, notably Xenopus laevis, exhibit remarkable dehydration tolerance, yet the tissue-specific proteomic adaptations remain poorly understood. Here, we used data-independent acquisition-based proteomics to analyze molecular responses in five organs and tissues (heart, kidney, liver, lung, skeletal muscle) of X. laevis during graded dehydration (15 %, 30 %) and rehydration. We identified 844 differentially expressed proteins (DEPs) in heart, 334 in kidney, 1057 in liver, 560 in lung, and 374 in muscle, respectively. DEPs in heart, liver, and kidney were significantly enriched in energy metabolism pathways, highlighting metabolic remodeling in response to dehydration and rehydration stresses. Progressively down-regulated proteins in heart during dehydration were enriched in NAD/NADH and ATP metabolic processes as well as glycolysis, aligning with metabolic rate depression to conserve energy and reduce oxidative stress. Conversely, lung and skeletal muscle prioritized cytoskeletal integrity (actin-myosin reorganization) over metabolic adjustments. Heart tissue exhibited activation of p38-MAPK signaling and up-regulation of MAPKAPK2, which is important in implementing the response to dehydration. Tissue-specific antioxidant responses showed that kidney and muscle catalase were up-regulated during 15 % dehydration, whereas lung delayed induction until rehydration to mitigate ischemia-reperfusion damage. Chaperone dynamics varied, with HSP27 up-regulated in heart and lung during dehydration and HSP60 sustained in liver, which contribute to maintaining the structural integrity of mitochondrial proteins. Moreover, X. laevis up-regulates proteins involved in oxygen transport, blood circulation and blood coagulation in order to counteract dehydration-induced hemoconcentration and hypovolemia. Five conserved DEPs shared in all examined tissues displayed dynamic expression, including Na⁺/K⁺-ATPase, plectin, annexin, electron transfer flavoprotein, and aconitate hydratase, indicating systemic adjustments in ion homeostasis, cytoskeletal stability, and mitochondrial metabolism. Overall, these findings highlight tissue-specific and conserved responses to dehydration stress, elucidate the importance of inhibiting metabolic pathways and eliciting protective mechanisms, and provide valuable insights for future studies exploring animal adaptation to stressful environments.