Owing to the wide application of miniature pigs in biomedicine, the formation mechanism of its short stature must be elucidated. The insulin-like growth factor 1 receptor (IGF-1R), which receives signals through the extracellular domain (ECD) binding with ligands, is crucial in regulating cell growth and bone matrix mineralization. In this study, two haplotypes of Igf1r with four synonymous mutations in the coding sequences of IGF-1R ECD between large pigs (LP) and Bama pigs (BM) were stably expressed in the Igf1r-knockout MC3T3-E1 cells and named as MC3T3-LP cells (LP group) and MC3T3-BM cells (BM group), respectively. IGF-1R expression was lower in the BM group than in the LP group both in terms of transcription and translation levels, and IGF-1R expression inhibited cell proliferation. In addition, IGF-1R expression in the BM group promoted early-stage differentiation but delayed late-stage differentiation, which not only suppressed the expression of bone-related factors but also reduced alkaline phosphatase activity and calcium deposition. Moreover, different haplotypes of Igf1r changed the stability and conformation of the protein, further affecting the binding with IGF-1. Our data indicated that the four synonymous mutations of IGF1R ECD encoded by affect gene transcription and translation, thereby further leading to differences in the downstream pathways and functional changes of osteoblasts.

由于小型猪在生物医学中的广泛应用，必须阐明其矮小身形的形成机理。胰岛素样生长因子1受体（IGF-1R）通过与配体结合的细胞外域（ECD）接收信号，对调节细胞生长和骨基质矿化至关重要。在这项研究中，两种单倍型的Igf1r 在大猪（LP）和巴马猪（BM）之间的IGF-1R ECD编码序列中出现四个同义突变 Igf1r-敲除MC3T3-E1细胞，分别命名为MC3T3-LP细胞（LP组）和MC3T3-BM细胞（BM组）。在转录和翻译水平上，BM组的IGF-1R表达均低于LP组，并且IGF-1R表达抑制细胞增殖。另外，BM组中IGF-1R的表达促进了早期分化，但延迟了晚期分化，这不仅抑制了骨相关因子的表达，而且降低了碱性磷酸酶活性和钙沉积。而且，不同的单倍型Igf1r改变了蛋白质的稳定性和构象，进一步影响了与IGF-1的结合。我们的数据表明，IGF1R ECD编码的四个同义突变影响基因的转录和翻译，从而进一步导致成骨细胞下游途径和功能变化的差异。