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Toxin injury‐dependent switched expression between EF‐1α and its sister, S1, in rat skeletal muscle
Author(s) -
Khalyfa Abdelnaby,
Carlson Bruce M.,
Carlson Jean A.,
Wang Eugenia
Publication year - 1999
Publication title -
developmental dynamics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.634
H-Index - 141
eISSN - 1097-0177
pISSN - 1058-8388
DOI - 10.1002/(sici)1097-0177(199911)216:3<267::aid-dvdy5>3.0.co;2-v
Subject(s) - biology , myocyte , skeletal muscle , alpha (finance) , eukaryotic translation elongation factor 1 alpha 1 , microbiology and biotechnology , messenger rna , blot , gene , endocrinology , biochemistry , rna , medicine , ribosome , construct validity , nursing , patient satisfaction
Elongation factor‐1α, (EF‐1α), a translation factor involved in peptide chain elongation, is found ubiquitously in all cells. Previously, we identified a highly homologous EF‐1α sister gene, S1, whose transcript is found in only three tissues: brain, heart, and muscle, where the tissue‐specific expression of S1 is caused by its exclusive presence in cells such as neurons and myocytes. Using sequence‐specific synthetic peptides, we have recently produced polyclonal antibodies that can distinguish the protein product of EF‐1α from that of its sister, S1. Results of Western blotting show that these two proteins appear in S1‐positive muscle tissue in inverse relationship, i.e., when S1 protein is in abundance, EF‐1α protein is in contrast in low quantity, and vice versa. During early embryonic stages, EF‐1α is the predominant protein species, whereas S1 is hardly detectable. This high EF‐1α versus low S1 protein presence undergoes a switch in that by postnatal day 14, EF‐1α is scarce whereas S1 is abundant; thus, there is a development‐dependent shift of EF‐1α/S1 ratio from high to low, and the low EF‐1α/S1 ratio is maintained in adulthood. In this report, we describe the reversal of the EF‐1α/S1 ratio from low to high during muscle injury (experimentally induced by Marcaine injection), and a return to the original low ratio once the injury is repaired by regeneration. In this injury condition, EF‐1α is rapidly upregulated immediately after the Marcaine treatment, possibly reflecting an injury‐dependent response of regeneration. The increase of EF‐1α corresponds with a decrease of S1 protein presence, thus resulting in a change of EF‐1α/S1 ratio from low to high. However, the high EF‐1α/S1 ratio eventually reverts to low, when regeneration‐associated proliferation ceases, and fully differentiated myotubes are reestablished in the injured cells. This result shows that: (1) a high EF‐1α/S1 ratio is an early molecular diagnostic marker for injury‐elicited regeneration; and (2) when injury repair is accomplished, there is a reversion to the low EF‐1α/S1 ratio, reflecting the restoration of the muscle fiber to the preinjury functional status. Results presented here not only show that a high EF‐1α/S1 ratio is a molecular marker for injured muscle, but also reveal the underpinning translational regulation in muscle during injury. Dev Dyn 1999;216:267–273. ©1999 Wiley‐Liss, Inc.