Effect of serine on growth performance and adipose-muscle metabolism in miR-143-deficient mice in low-protein diet

<bold>Objective</bold> This study aims to investigate the effects of serine on growth performance and fat-muscle metabolism in miR-143-deficient mice under low-protein diet conditions，thus providing new scientific evidence for revealing the interaction between serine and miR-143. <bold>Method</bold> Twenty 4-week-old wild-type（WT）mice and 20 miR-143 knockout（KO）mice with similar body weights were randomly selected.Each type of mouse was further randomly divided into 2 groups，receiving normal drinking water or drinking water supplemented with 1% serine respectively.The effects of serine on growth performance，body composition，grip strength，weights of fat and muscle tissues，and hemoglobin content in miR-143-deficient mice were determined and analyzed. <bold>Result</bold> Under the low-protein diet conditions：（1）compared with WT mice，miR-143 deficiency significantly decreased feed intake and body weight of mice（<italic>P</italic>&lt;0.05）；compared with the normal drinking water group，supplementation of 1% serine in drinking water significantly reduced the body weight of WT mice（<italic>P</italic>&lt;0.05）but had no significant effect on miR-143-deficient mice.（2）Compared with WT mice，miR-143-deficient mice showed an extremely significant decreases in lean meat weight，fat weight，and fat content（<italic>P</italic>&lt;0.01），and a significant increase in lean meat content（<italic>P</italic>&lt;0.05）；compared with the normal drinking water group，1% serine supplementation showed an extremely significant fat weight and content decrease（<italic>P</italic>&lt;0.01）and significantly increased lean meat content（<italic>P</italic>&lt;0.05）in WT mice，but had no significant effect on fat content in miR-143-deficient mice.（3）Compared with WT mice，the deletion of miR-143 extremely significantly reduced the grip strength of mice（<italic>P&lt;</italic>0.01）；while compared with the normal drinking water group，the addition of 1% serine showed a tendency to decrease the grip strength of WT mice（<italic>P</italic>=0.125），and had no significant effect on the grip strength of miR-143-deficient mice.（4）Compared with WT mice，miR-143-deficient mice exhibited extremely significant decreases in the weights of liver，subcutaneous fat，epididymal fat，and brown fat，as well as the contents of subcutaneous fat，epididymal fat，and brown fat（<italic>P</italic>&lt;0.01）；compared with the normal drinking water group，1% serine supplementation significantly reduced the liver and subcutaneous fat weights，and the contents of subcutaneous fat，epididymal fat，and brown fat in WT mice（<italic>P</italic>&lt;0.05），but had no significant effect on these indices in miR-143-deficient mice.（5）Compared with WT mice，miR-143-deficient mice had an extremely significant increase in gastrocnemius muscle content（<italic>P</italic>&lt;0.01），significant increases in soleus muscle，tibialis anterior muscle，and extensor digitorum longus muscle contents（<italic>P&lt;</italic>0.05），and a significant decrease in tibialis anterior muscle weight（<italic>P</italic>&lt;0.05）；compared with the normal drinking water group，1% serine supplementation extremely and significantly increased gastrocnemius muscle content（<italic>P</italic>&lt;0.01）and significantly increased soleus muscle content（<italic>P</italic>&lt;0.05）in WT mice，with tendencies to increase tibialis anterior muscle（<italic>P</italic>=0.108）and extensor digitorum longus muscle contents（<italic>P</italic>=0.106）；however，in miR-143-deficient mice，it extremely and significantly reduced the weights of gastrocnemius muscle，soleus muscle，and tibialis anterior muscle（<italic>P</italic>&lt;0.01）and significantly increased gastrocnemius muscle content（<italic>P</italic>&lt;0.05）.（6）miR-143 deficiency extremely and significantly increased the hemoglobin content of mice（<italic>P</italic>&lt;0.01），while 1% serine supplementation had no significant effect on hemoglobin content（<italic>P</italic>&gt;0.05）. <bold>Conclusion</bold> Both 1% serine supplementation and miR-143 deficiency reduce mouse body weight，fat weight，fat content，and grip strength，and increase the contents of gastrocnemius muscle，soleus muscle，tibialis anterior muscle，and extensor digitorum longus muscle.However，after miR-143 deficiency，serine had no significant effect，indicating a preliminary interaction between serine and miR-143.