Rimmed vacuoleを有する筋線維の蛋白質に関する研究

ELECTROPHORETIC ANALYSIS OF PROTEINS OF THE MUSCLE FIBERS WITH RIMMED VACUOLES

　抄録　筋生検でrimmed vacuoieのみられる患者4名と対照2名で，筋線維の蛋白質について検討した。患者のrimmed vacuoleをもっている筋線維と，もっていない筋線維の両者で，分子量上55,000の蛋白質が増加しており，vacuoleをもっている筋線維で顕著であった。ての蛋白質は，二次元電気泳動の結果からdesminと考えられた。この研究で，染色標本と連続凍結乾燥切片を対比して特定の筋線維をとり出し電気泳動を行う方法を考案し用いたが，きわめて有用であった。

This is the first report on the analysis of the proteins in the single muscle fibers with rimmed vacuoles. A new method was developed to analyse single muscle fibers which had been histologically characterized in the freeze-dried sections of muscles.

Muscle biopsy was performed in three patients with distal myopathy and one patient with Kearns-Sayre-like syndrome associated with rimmed vacuoles (Table 1). Ten (30μm thick) frozen serial sections were dried according to Lowry and Pas-sonneau, and further five consecutive sections were cut and stained with usual histochemical methods including Gomori trichrome and NADH-TR stain-ing. Each muscle fiber in the freeze-dried sections could be identified with the corresponding one in the stained sections, and it was possible to deter-mine whether the fiber had rimmed vacuoles or not (Fig. 2). Particular fibers were identified in the consecutive freeze-dried sections and cut out from three sections with no contamination of the interstitial tissue, and they were subjected to SDS gel electrophoresis. Resultant gel patterns showed substantial increase of 55k dalton band, the extent of which was much more larger in that of the fiber with rimmed vacuoles than that without vacuoles (Fig. 3). This feature was common to all of the gels from four patients.

A portion containing a number of muscle fibers of a freeze-dried section from each of the four patients and the two controls was subjected to two-dimensional gel electrophoresis (2-D). Of 55 k dalton proteins, three spots around the isoelectric point of α-actin were found to be increased (Fig. 4). These spots would correspond to desmin. In addition, basic proteins were examined using non-equilibrated 2-D, and no increase of 55 k dalton proteins was observed.

Further, two-dimensional gels of the muscle fibers with rimmed vacuoles were compared with those of the fibers without rimmed vacuoles (Fig. 5). A faint spot was observed in only one gel of the fiber with rimmed vacuoles and so far could not be identified. The increase of desmin in muscle fibers from the patients, which was observed in both of the fibers with and without rimmed vacuoles, suggests that desmin is related to the degenerative process in distal myopathy.