UP-REGULATION OF FERRITIN HEAVY-CHAIN MESSENGER-RNA EXPRESSION IN THERAT SKELETAL-MUSCLE AFTER DENERVATION - DETECTED BY MEANS OF DIFFERENTIAL DISPLAY

The differential display method was applied to identify gene expressio n, which is especially up-regulated in denervated skeletal muscle. Tot al RNA from normal and denervated rat facial muscles (muscles zygomati cus, levator nasolabialis and caninus) was isolated, amplified by poly merase chain reaction (PCR) using certain primers and separated by ele ctrophoresis on a polyacrylamide gel. PCR products, the amounts of whi ch were significantly higher in the operated side than in the control side, were cut out from the gel and sequenced. One of the cDNA fragmen ts obtained in the present study showed 100% identity in nucleotide se quence to the rat ferritin heavy chain (FHC) mRNA. Northern blot analy sis and in situ hybridization histochemistry confirmed that FHC mRNA e xpression was up-regulated after denervation and was distributed throu ghout whole muscle cell bodies. The biological damage attributed to su peroxide and hydrogen peroxide is dependent on the presence of intrace llular free iron. Intracellularly, most of the iron that is not metabo lized is sequestered in ferritin as a crystalline core of ferric irons (Fe3+). These findings suggest that alterations in the ferritin subun it composition after denervation play an important role in iron metabo lism in skeletal muscle cells, resulting in restriction of the biologi cal tissue damage caused by reactive oxygen species.