Duckett S K, Greene M A, Udoka A N S, Powell R R, Bruce T F, Klotz J L
Department of Animal and Veterinary Sciences, Clemson University, Clemson, SC, United States.
Clemson Light Imaging Facility, Clemson University, Clemson, SC, United States.
Front Mol Biosci. 2025 May 16;12:1547182. doi: 10.3389/fmolb.2025.1547182. eCollection 2025.
MicroRNAs (miRNAs) play a crucial role in regulating gene expression and muscle development. Previous research identified miR-22-3p as being differentially regulated during muscle hypertrophy, and experiments found that antagomir-22-3p enhanced satellite cell proliferation. The objective of this study was to evaluate the vascular injection of antagomir-22-3p into the lateral saphenous vein and its effect on miRNA and histone deacetylase (HDAC) family mRNA expression in intrauterine growth restriction (IUGR) lambs.
Pregnant ewes (n = 18) carrying twins were fed either 100% of NRC (CON) or were nutrient-restricted to 60% NRC (NR) from gestational d 86 until parturition. On d 12 of age, NR lambs (n = 8) were randomly selected and given a systemic injection of antagomir-22-3p (440 µg/lamb) into the lateral saphenous vein of the right leg (NR-ANT22) for three consecutive days. CON lambs (n = 8) were also randomly selected and received a sham injection of phosphate-buffered saline (PBS) into the lateral saphenous vein of the right leg (CON-SHAM). Blood samples were collected from each lamb weekly to monitor circulating miR-22-3p expression. Muscle samples were collected 24 days post-injection to assess miR-22-3p levels and mRNA expression of potential miRNA targets.
Cell-free circulating miR-22-3p expression was more downregulated (P < 0.05) in NR-ANT22 lambs compared to that in CON-SHAM on d 14 after injection. On d 21 after injection, miR-22-3p expression in plasma tended to be more downregulated (P = 0.08) in NR-ANT22 compared to CON-SHAM. Lamb body weight and muscle weights at harvest were similar between the NR-ANT and CON- SHAM treatment groups. In the semitendinosus (ST) muscle, miR-22-3p expression was more downregulated (P < 0.05) in NR-ANT22_R ST (treated) lambs compared to that in NR-ANT22_L ST (non-treated) and CON-SHAM ST. In the heart and semimembranosus (SM) muscles, the expression of miR-22-3p was more downregulated (P < 0.05) in NR-ANT22 compared to that in CON-SHAM. In the gastrocnemius muscle, miR-22-3p expression remained unchanged (P > 0.05). The number of types I, IIa, and IIax muscle fibers were greater (P < 0.05) in NR-ANT22 lambs than those in CON-SHAM, whereas the number of type IIx fibers was greater (P < 0.05) in CON-SHAM lambs. NR-ANT22 treatment appears to promote a shift toward more oxidative muscle fiber metabolism. The systemic injection of antagomir-22-3p downregulated miR-22-3p expression in circulation and muscle tissues, which, in turn, altered the expression of HDAC/SIRT genes involved in muscle fiber type conversion and hypertrophy.
微小RNA（miRNA）在调节基因表达和肌肉发育中起着至关重要的作用。先前的研究发现，miR-22-3p在肌肉肥大过程中存在差异调节，并且实验发现抗miR-22-3p可增强卫星细胞增殖。本研究的目的是评估经血管向宫内生长受限（IUGR）羔羊的隐静脉外侧注射抗miR-22-3p及其对miRNA和组蛋白去乙酰化酶（HDAC）家族mRNA表达的影响。
怀有双胞胎的怀孕母羊（n = 18），从妊娠第86天至分娩，一组饲喂100%的美国国家研究委员会（NRC）标准日粮（对照组），另一组营养限制至60% NRC标准日粮（营养限制组）。在出生后第12天，从营养限制组的羔羊（n = 8）中随机选取，连续三天经血管向右侧隐静脉外侧注射抗miR-22-3p（440 μg/只羔羊）（营养限制-抗miR-22-3p组）。对照组的羔羊（n = 8）也随机选取，经血管向右侧隐静脉外侧注射磷酸盐缓冲盐水（PBS）进行假注射（对照组-假注射组）。每周从每只羔羊采集血样，监测循环miR-22-3p的表达。注射后24天采集肌肉样本，评估miR-22-3p水平以及潜在miRNA靶标的mRNA表达。
与对照组-假注射组相比，营养限制-抗miR-22-3p组羔羊在注射后第14天，无细胞循环miR-22-3p的表达下调更明显（P < 0.05）。在注射后第21天，与对照组-假注射组相比，营养限制-抗miR-22-3p组血浆中miR-
