Investigation of the effect of estrogen on DUX4/ β-kateni̇n/ PAX3-7 protein levels and their interaction in facioscapulohumeral muscular dystrophy

Objective: In Facioscapulohumeral Dystrophy(FSHD) it is noteworthy that the findings progressed at an earlier age in men, and the disease worsens in postmenopausal women. Depending on these observations; the role of estrogen was investigated in the pathophysiology of FSHD. Method: Primary FSHD myoblast cell lines prepared from biopsies of four individuals(63 and 71 years old(63yE/71yE) two males; 47 and 58 years old(47yK/58yK) two females) were used. Three different groups i) estradiol untreated control group, ii) 10nM 30-minutes and iii) 10nM 4-hours estradiol treatment were generated. Cell lysates from FSHD myoblasts in these groups were examined by western blot for the presence-amount of DUX4, PAX3/7 and β-catenin transcription factors. Results: After estradiol treatment DUX4 protein level reduced to zero in 71yE, it wasn't detected in 63yE and 47yK. Because of ineffective attachment in 58yK, proteins weren't obtained. The level of β-catenin protein increased with estradiol in 71yE, 63yE and 47yK samples. Three different protein bands of 80 kDa, 56 kDa and 45 kDa were determined for PAX3/7 proteins. Of these, 80 kDa and 56 kDa forms were observed only in 71yE; after estradiol 80-kDa PAX3/7 form reduced; 56-kDa PAX3/7 form was expressed at the 4th hour. The 45 kDa form was determined in all samples; with estradiol treatment this form decreased in 71yE-47yK and increased in 63yE. Conclusion: The decrease in DUX4, the increase in β-catenin, stimulation in the expression of 56 kDa form of PAX3/7 protein family after 4 hours of estradiol treatment support the protective role of estrogen in FSHD pathophysiology. To understand the effect of estradiol on pathophysiology better and to develop treatment alternatives; extensive studies are needed with each transcription factor and related target genes; both at mRNA-protein levels. Key words: estradiol, DUX4, β-catenin, PAX3/7, FSHD (facioscapulohumeral muscular dystrophy)