Lack of bombesin receptor–activated protein attenuates bleomycin-induced pulmonary fibrosis in mice

Abstract

Bombesin receptor–activated protein (BRAP) was found to express in the interstitial cells of human fibrotic lungs with unknown function. Its homologous protein, encoded by BC004004 gene, was also present in mouse lung tissues. We used BC004004−/− mice which lack BRAP homologous protein expression to establish a bleomycin-induced lung fibrotic model. After bleomycin treatment, BC004004−/− mice exhibited attenuation of pulmonary injury and less pulmonary fibrosis. Fibroblasts from BC004004−/− mice proliferated at a lower rate and produced less collagen. Autophagy-related gene 5 (ATG5) was identified as a partner interacting with human BRAP. Lacking BRAP homologous protein led to enhanced autophagy activity in mouse lung tissues as well as in isolated lung fibroblasts, indicating a negative regulatory role of this protein in autophagy via interaction with ATG5. Enhanced autophagy process in fibroblasts due to lack of BRAP homologous protein might contribute to the resistance of BC004004−/− mice to pulmonary fibrosis.

Knockout of the BRAP homolog in mice leads to abnormal tracheal cilia

“…1, BRAP was present in bronchial epithelial cells within lung tissue samples from patients with interstitial lung disease, pulmonary tuberculosis, pulmonary fibrosis, and lung squamous cell carcinoma. We have generated BC004004 −/− mice using CRISPR/Cas9‐mediated genome engineering method to investigate the role of BRAP homologous protein as described previously [11]. The trachea tissues were isolated from BC004004 −/− mice and their isogenic wild‐type control BC004004 +/+ mice in order to examine whether BRAP homolog was involved in maintaining the morphology of airway cilia.…”

“…Total RNA was extracted from lung tissues or isolated cells using RNAiso Plus (Takara, Beijing, China, cat: 9108) according to the manufacturer's instructions as described previously [11]. Next, 1.0 lg of total RNA was reversely transcribed into complementary DNA (cDNA) using the Prime Script TM RT reagent Kit with gDNA Eraser (Takara, cat: RR047B), and quantitative real-time PCR analyses were conducted using SYBRÒ Premix Ex Taq TM II system (Takara, cat: RR420A) on a deep well Real-Time PCR Detection System (CFX96 Touch TM ; Bio-Rad, Hercules, CA, USA) as described previously [11]. Each sample was analyzed in triplicate.…”

Bombesin receptor-activated protein homolog deficiency altered the pattern of pathological changes of psoriasis - like skin lesion in mice

“…All clinical samples were obtained from the department of pathology at the second xiangya hospital, and human experiments were conducted in accordance with the standard operating guidelines of the Institutional Animal Care and Research Advisory Committee of Central South University, Changsha, China (No: 2022-KT118). Seven weeks old female BC004004 -/- mice, in which BC004004 gene was disrupted by CRISPR/Cas9-mediated genome engineering technique 12 , and their isogenic control C57BL/6 mice ( BC004004 +/+ ) were used in the study.…”

“…The mouse homolog of BRAP, which is encoded by BC004004 gene and shares 83% similarity to the human BRAP, was also expressed in mouse skin. In our previous study, we investigated the function of BRAP and its mouse homolog by utilizing a gene knockout mouse model BC004004 -/- , which led to several distinct phenotypes 12 - 14 . Compared with their isogenic wild type control, BC004004 -/- mice exhibited attenuation of injury induced fibrosis in both lungs 12 and kidneys (data not published), exacerbation of stress induced behavioral changes 13 and abnormal cilia formation in trachea epithelial cells 14 .…”

“…In our previous study, we investigated the function of BRAP and its mouse homolog by utilizing a gene knockout mouse model BC004004 -/- , which led to several distinct phenotypes 12 - 14 . Compared with their isogenic wild type control, BC004004 -/- mice exhibited attenuation of injury induced fibrosis in both lungs 12 and kidneys (data not published), exacerbation of stress induced behavioral changes 13 and abnormal cilia formation in trachea epithelial cells 14 . The underlying cellular and molecular mechanisms remain largely unknown, but our studies provide evidence for altered behaviors of several cell types including lung fibroblasts, tubular epithelial cells and neurons due to lack of BRAP expression.…”