Ultrastructural localization of myoglobin mRNA in human skeletal muscle.
The intracellular localization of myoglobin mRNA in the skeletal muscles of normal subjects was examined by in situ hybridization using a biotin-labeled cDNA probe. By phase-contrast microscopy, myoglobin mRNA signals were demonstrated to be located preferentially on the A-band. Two different methods of tissue preparation, i.e., pre-embedding method and post-embedding method, were used for the electron microscopic study. With the pre-embedding method, only a few gold particles were found to be associated with cytoskeletal filaments in the intermyofibrillar space. With the post-embedding method, superior preservation of sections and higher signal intensities were obtained. Although most of the gold particles were localized on the A-band, some were seen in other regions; i.e., in the intermyofibrillar space, perinuclear space, or the I-band, where myoglobin is localized. These findings suggest that myoglobin is primarily synthesized on the A-band, where ribosomes predominantly exist, although myoglobin is also localized on the I-band. The predominant localization of myoglobin mRNA on the A-band may aid in the mRNA transcription and may be related to the regulation of myoglobin synthesis in skeletal muscle cells.
Mitsui
T
T
First Department of Internal Medicine, School of Medicine, University of Tokushima, Japan.
Kawai
H
H
Naruo
T
T
Saito
S
S
D000328:Adult; D015342:DNA Probes; D005260:Female; D006801:Humans; D017403:In Situ Hybridization; D008297:Male; D008858:Microscopy, Phase-Contrast; D009132:Muscles / Q000737:chemistry* / Q000648:ultrastructure; D009211:Myoglobin / Q000032:analysis* / Q000096:biosynthesis / Q000235:genetics; D012333:RNA, Messenger / Q000032:analysis*; D016610:Tissue Embedding
D015342:DNA Probes; D009211:Myoglobin; D012333:RNA, Messenger