CHANGES IN MESSENGER-RNA LEVELS OF THE SARCOPLASMIC ENDOPLASMIC-RETICULUM CA2+-ATPASE ISOFORMS IN THE RAT SOLEUS MUSCLE REGENERATING FROM NOTEXIN-INDUCED NECROSIS/
E. Zador et al., CHANGES IN MESSENGER-RNA LEVELS OF THE SARCOPLASMIC ENDOPLASMIC-RETICULUM CA2+-ATPASE ISOFORMS IN THE RAT SOLEUS MUSCLE REGENERATING FROM NOTEXIN-INDUCED NECROSIS/, Biochemical journal, 320, 1996, pp. 107-113
The relative mRNA levels corresponding to the different sarcoplasmic/e
ndoplasmic-reticulum Ca2+-ATPase isoforms (SERCA1a, SERCA1b, SERCA2a,
SERCA2b and SERCA3) were measured by reverse transcriptase-PCR in rat
soleus muscles regenerating after notexin-induced necrosis. The succes
sion of appearance of the different types of SERCA mRNA species in reg
enerating muscle largely recapitulates those observed during normal on
togenesis. The mRNA levels of the muscle-specific isoforms SERCA1a and
SERCA2a became very low on the first and third days after injection o
f the snake venom. It was only on the fifth day of regeneration that t
he mRNA of the neonatal variant of the fast-twitch skeletal SERCA1b is
oform began to rise, well before the other SERCA transcripts. At 7 and
10 days, i.e. at a time when the new myofibres normally become reinne
rvated, the mRNA level of SERCA1a and SERCA2a increased markedly, but
the fast-twitch skeletal SERCA1a isoform was still the most prominent.
On day 21, in the advanced stage of regeneration, a switch in the rel
ative expression levels of SERCA1a and SERCA2a mRNA was observed and t
he ratio of both isoforms became similar to that found in the normal s
oleus muscles. This was followed by a decline in the level of all SERC
A mRNA species, so that on day 28 the levels of the sarcoplasmic/endop
lasmatic-reticulum Ca2+-pump RNAs was again lower but their ratio rema
ined similar to that of the untreated control soleus.