Young H E, Carrino D A, Caplan A I
Department of Biology, Case Western Reserve University, Cleveland, Ohio 44106.
Mech Ageing Dev. 1990 Apr 9;53(2):179-93. doi: 10.1016/0047-6374(90)90069-r.
Previous biochemical and morphological studies have demonstrated a change in the synthetic pattern of sulfated proteoglycans during skeletal musculogenesis in the embryonic chick. These studies revealed that a transition occurs in both composition and deposition of sulfated glycoconjugates that parallels the developmental state of the tissue. The current study was undertaken to ascertain whether this transition in the embryonic chick is a conserved developmental process during musculogenesis in the mouse. Leg musculature from embryonic, newborn, juvenile, adolescent, young adult, mature adult and senescent mice, radiolabeled in vivo with [35S]sulfate, was analyzed for relative size and composition of newly synthesized sulfated macromolecules. The data reveal a transition in the synthesis of sulfated proteoglycans and glycoproteins that parallels the myogenic differentiative state of the mouse leg muscle. Embryonic mouse leg musculature synthesizes relatively large proteoglycans consisting of large chondroitin sulfate glycosaminoglycan chains. Subsequently, these major newly synthesized proteoglycans are replaced synthetically by smaller molecules composed of mixtures of dermatan sulfate, chondroitin sulfate and heparan sulfate glycosaminoglycans (newborn through 2 weeks); dermatan sulfate, heparan sulfate and chondroitin sulfate glycosaminoglycans (13 months) and heparan sulfate and dermatan sulfate glycosaminoglycans (25-26 months). The sulfated glycoproteins demonstrate a reciprocal synthetic pattern. Early in development sulfated glycoproteins form a small proportion of the newly synthesized sulfated material. With increasing developmental and maturational age, the proportion of sulfated glycoproteins increases. This continues until they become the predominant sulfated moieties synthesized by senescent mouse muscle. The results from this study thus extend observations initially made in chick to muscle development in the mouse and, therefore, suggest that the transition in synthesis of sulfated glycoconjugates is a conserved developmental process during musculogenesis.
先前的生物化学和形态学研究表明，在胚胎期小鸡的骨骼肌生成过程中，硫酸化蛋白聚糖的合成模式发生了变化。这些研究显示，硫酸化糖缀合物在组成和沉积方面均发生了转变，这与组织的发育状态平行。当前的研究旨在确定小鸡胚胎期的这种转变在小鼠肌肉生成过程中是否为保守的发育过程。对胚胎期、新生期、幼年期、青春期、青年期、成年期和衰老期小鼠的腿部肌肉组织进行体内[35S]硫酸盐放射性标记，分析新合成的硫酸化大分子的相对大小和组成。数据显示，硫酸化蛋白聚糖和糖蛋白的合成发生了转变，这与小鼠腿部肌肉的生肌分化状态平行。胚胎期小鼠腿部肌肉组织合成相对较大的蛋白聚糖，其由大的硫酸软骨素糖胺聚糖链组成。随后，这些主要新合成的蛋白聚糖在合成上被较小的分子取代，这些小分子由硫酸皮肤素、硫酸软骨素和硫酸乙酰肝素糖胺聚糖的混合物组成（新生期至2周）；硫酸皮肤素、硫酸乙酰肝素和硫酸软骨素糖胺聚糖（1至3个月）以及硫酸乙酰肝素和硫酸皮肤素糖胺聚糖（25至26个月）。硫酸化糖蛋白呈现出相反的合成模式。在发育早期，硫酸化糖蛋白占新合成硫酸化物质的比例较小。随着发育和成熟年龄的增加，硫酸化糖蛋白的比例增加。这种情况持续下去，直到它们成为衰老期小鼠肌肉合成的主要硫酸化部分。因此，本研究的结果将最初在小鸡中观察到的结果扩展到了小鼠的肌肉发育，进而表明硫酸化糖缀合物合成的转变是肌肉生成过程中保守的发育过程。
