Increased Apoptosis after Autoimmune Regulator Expression in Epithelial Cells Revealed by a Combined Quantitative Proteomics Approach

Abstract

Autoimmune polyendocrinopathy-candidiasis-ectodermal dystrophy (APECED) is a rare autosomal recessive autoimmune disease, affecting many endocrine tissues. APECED is associated to the lack of function of a single gene called AutoImmune REgulator (AIRE). Aire knockout mice develop various autoimmune disorders affecting different organs, indicating that Aire is a key gene in the control of organ-specific autoimmune diseases. AIRE is mainly expressed by medullary thymic epithelial cells (mTECs), and its absence results in the loss of tolerance against tissue restricted antigens (TRAs). Aire induces the transcription of genes encoding for TRAs in mTECs. In this report, the analysis of AIRE's effect on the cellular proteome was approached by the combination of two quantitative proteomics techniques, 2D-DIGE and ICPL, using an AIRE-transfected and nontransfected epithelial cell line. The results showed increased levels of several chaperones, (HSC70, HSP27 and tubulin-specific chaperone A) in AIRE-expressing cells, while various cytoskeleton interacting proteins, that is, transgelin, caldesmon, tropomyosin alpha-1 chain, myosin regulatory light polypeptide 9, and myosin-9, were decreased. Furthermore, some apoptosis-related proteins were differentially expressed. Data were confirmed by Western blot and flow cytometry analysis. Apoptosis assays with annexin V and etoposide demonstrated that AIRE-positive cells suffer more spontaneous apoptosis and are less resistant to apoptosis induction.

Expression and prognostic significance of the autoimmune regulator gene in breast cancer cells

“…10 Accordingly, loss of AIRE was observed in both human and murine thymomas. 23,24 Other studies indicated a role of AIRE in increasing apoptosis when expressed in thymic and thyroid epithelial models [8][9] , suggesting that overproduction of TSAs rather than induction of an apoptotic program might indirectly induce cellular stress leading to death. Such a role does not conflict with the nature of AIRE as a transcription factor, since it favors a continuous turnover of antigen-presenting mTECs and promote cross-presentation of tissue-specific antigens to developing thymocytes.…”

“…Since individual mTECs transcribe TSA genes stochastically to favor a continuous turnover of presented antigen peptides, AIRE supports mTEC apoptosis. [8][9][10] Moreover, AIRE acts in the tolerance process by favoring the development of regulatory T cells. 11,12 Not only is AIRE highly expressed in mTECs, but there is evidence of AIRE expression in murine peripheral lymphoid organs.…”

Autoimmune Regulator (AIRE) Is Expressed in Spermatogenic Cells, and It Altered the Expression of Several Nucleic-Acid-Binding and Cytoskeletal Proteins in Germ Cell 1 Spermatogonial (GC1-spg) Cells

“…Our data also showed an up-regulation of a number of chaperones (Hspe1, Hspa1a, and Hspb1). In the study carried out by Colome et al (27), 2D difference gel electrophoresis (DIGE) and Isotope coded pro- tein labeling (ICPL) were used to analyze the effect of AIRE on the cellular proteome of the AIRE-transfected and nontransfected epithelial cell line. They showed a similar increase in the levels of several chaperones (HSC70, HSP27, and tubulinspecific chaperone A) in AIRE-expressing cells, while various cytoskeleton-interacting proteins (transgelin, caldesmon, tropomyosin alpha-1 chain, myosin regulatory light polypeptide 9, and myosin-9) were decreased.…”

“…They showed a similar increase in the levels of several chaperones (HSC70, HSP27, and tubulinspecific chaperone A) in AIRE-expressing cells, while various cytoskeleton-interacting proteins (transgelin, caldesmon, tropomyosin alpha-1 chain, myosin regulatory light polypeptide 9, and myosin-9) were decreased. We could identify at least five proteins in our proteomics data (heat shock protein beta 1 (Hspb1), Post synaptic density protein (PSD95), Drosophila disc large tumor suppressor (Dlg1), and zonula occludens-1 protein (zo-1) (PDZ) and Lin11, Isl-1 & Mec-3 (LIM) domain protein, trp/asp (WD) repeat containing protein 1, tubulinspecific chaperone A, and keratin type I cytoskeletal 18) that were shown to be modulated in the study carried out by Colome et al (27). Their studies suggest that AIRE-positive cells were more likely to undergo spontaneous apoptosis and that they were less resistant to apoptosis inducers.…”

“…Studies have pointed toward a possible role of AIRE in regulating germ cell apoptosis (6). Recent studies suggested that AIRE-positive cells were likely to undergo spontaneous apoptosis and that they were less resistant to apoptosis inducers (27).…”