UVB light and 17-beta-estradiol have different effects on the mRNA expression of Ro/SSA and La/SSB autoantigens in HaCaT cells

Antibodies produced against the Ro/SSA and La/SSB autoantigens are not only of diagnostic value but they may even play a role in the pathogenesis of s everal autoimmune diseases (Sjogren's syndrome, subacute cutaneous lupus er ythematosus, neonatal lupus erythematosus and systemic lupus eryrthematosus ). Among other factors, ultraviolet (UV) radiation and also the hormonal mi lieu are well-known cofactors in the pathogenesis of these autoimmune disea ses. The goal of our research was to study the possible alterations in mRNA levels of three different Ro antigens and that of two La species produced by alternative splicing in transformed human keratinocytes (HaCaT cells) af ter UVB irradiation and after 17-beta -estradiol treatment, The polymerase chain reaction technique was used to determine the mRNA levels of the Ro an d La species after 24, 48, and 72 h of irradiation. The mRNA levels of calr eticulin increased as a function of time after UV irradiation but the mRNA levels of 52 kDa and 60 kDa Ro mRNAs were unaltered. After treating the cel ls with 17-beta -estradiol, there was no change observed in the levels of R o mRNAs or La exon 1 mRNA, but a gradual decrease was noted in the mRNA lev els of La exon 1', The importance of alterations in the ratio of La exon 1 to exon 1' is supported by the observations in patients with Sjogren's synd rome, and our results strengthen the notion that the Ro and La antigens par ticipate in the pathogenesis of different autoimmune diseases.