BIK blocking peptide

Rationale: Aberrant regulation of airway epithelial cell numbers in airways leads to increased mucous secretions in chronic lung diseases such as chronic bronchitis. Because the Bcl-2 family of proteins is crucial for airway epithelial homeostasis, identifying the players that reduce cigarette smoke (CS)-induced mucous cell metaplasia can help to develop effective therapies. Objectives: To identify the Bcl-2 family of proteins that play a role in reducing CS-induced mucous cell metaplasia. Methods: We screened for dysregulated expression of the Bcl-2 family members. Measurements and Main Results: We identified Bik to be significantly reduced in bronchial brushings of patients with chronic epithelial cell hyperplasia compared with nondiseased control subjects. Reduced Bik but increased MUC5AC mRNA levels were also detected when normal human airway epithelial cells (HAECs) were exposed to CS or when autopsy tissues from former smokers with and without chronic bronchitis were compared. Similarly, exposure of C57BI/6 mice to CS resulted in increased numbers of epithelial and mucous cells per millimeter of basal lamina, along with reduced Bik but increased Muc5ac expression, and this change was sustained even when mice were allowed to recover in filtered air for 8 weeks. Restoring Bik expression significantly suppressed CS-induced mucous cell metaplasia in differentiated primary HAEC cultures and in airways of mice in vivo. Bik blocked nuclear translocation of phospho-ERK1/2 to induce apoptosis of HAECs. The conserved Leu61 within Bik and ERK1/2 activation were essential to induce cell death in hyperplastic mucous cells. Conclusions: These studies show that CS suppresses Bik expression to block airway epithelia cell death and thereby increases epithelial cell hyperplasia in chronic bronchitis.

Ataxia telangiectasia (AT) is an autosomal recessive multisystem disorder characterized by variable immunodeficiency, progressive neurodegeneration, occulocutaneous telangiectasia, and an increased susceptibility to malignancies. This study was designed to study the role of proapoptotic BAK, BAX, and NBK/BIK genes in a group of patients with AT to elucidate the possible role of these genes in progression of malignancies in this disease. Fifty Iranian patients with AT were investigated in this study. The entire coding regions of the BAK gene (exons 2-6), NBK/BIK gene (exons 2-5), and BAX gene (exons 1-7) were amplified using polymerase chain reaction (PCR). The PCR products were separated by 2% agarose gel electrophoresis, and all positive samples were verified by direct sequencing of PCR products using the same primers used for PCR amplification, BigDye chemistry, and Avent 3100 Genetic Analyzer following the manufacturer's instructions (Applied Biosystems). Eight of fifty Iranian AT patients (16%) exhibited a C > T transition in exon 2 (c342C > T) of the BAK gene, while none of the healthy controls had such alteration (P = 0.0001). Higher frequency of another nucleotide substitution in the noncoding region of exon 7 in BAX gene (6855G > A) was also identified in 68% of the patient group versus 24% in the controls (P < 0.0001). Sequence alteration in intronic region of the NBK/BIK gene IVS4-12delTC was observed in 52% of AT patients, which was significantly higher than 20% in the control group (P = 0.0023). Another variant IVS1146C > T in the intronic region of the BAX gene was found in 78% of patients, which was significantly higher than 10% in the controls (P < 0.0001). Frequency of alteration in intronic region of exon 3 of the BAX gene (IVS3 + 14A > G) was also significantly higher in the AT patients (P < 0.0001). Several alterations in the proapoptotic genes BAK, NBK/BIK, and BAX were found in our study, which could elucidate involvement of the mitochondrial pathway mediated apoptosis in accelerating and developing of cancers and in immunopathogenesis of AT. Such altered apoptosis in AT could play some roles in developing cancers in this group of patients.