Department of Biosciences, University of Oslo, Oslo, Norway.
Center for Integrative Neuroplasticity, Department of Biosciences, University of Oslo, Oslo, Norway.
Nat Commun. 2020 Dec 8;11(1):6288. doi: 10.1038/s41467-020-20057-8.
Muscle fibers are the largest cells in the body, and one of its few syncytia. Individual cell sizes are variable and adaptable, but what governs cell size has been unclear. We find that muscle fibers are DNA scarce compared to other cells, and that the nuclear number (N) adheres to the relationship N = aV where V is the cytoplasmic volume. N invariably scales sublinearly to V (b < 1), making larger cells even more DNA scarce. N scales linearly to cell surface in adult humans, in adult and developing mice, and in mice with genetically reduced N, but in the latter the relationship eventually fails when they reach adulthood with extremely large myonuclear domains. Another exception is denervation-atrophy where nuclei are not eliminated. In conclusion, scaling exponents are remarkably similar across species, developmental stages and experimental conditions, suggesting an underlying scaling law where DNA-content functions as a limiter of muscle cell size.
肌纤维是人体中最大的细胞之一，也是少数几个合胞体之一。单个细胞的大小是可变的和可适应的，但是什么控制着细胞的大小还不清楚。我们发现，与其他细胞相比，肌纤维的 DNA 含量很少，而且核数 (N) 遵循 N = aV 的关系，其中 V 是细胞质体积。N 总是以亚线性的方式缩放至 V (b < 1)，使得更大的细胞甚至更缺乏 DNA。在成年人类、成年和发育中的老鼠以及遗传上减少 N 的老鼠中，N 与细胞表面积呈线性关系，但当它们进入成年期并具有非常大的肌核域时，这种关系最终会失效。另一个例外是去神经萎缩，其中核不会被消除。总之，缩放指数在不同物种、发育阶段和实验条件下非常相似，这表明存在一种潜在的缩放规律，其中 DNA 含量作为肌肉细胞大小的限制因素。
