背景:Alström综合征(ALMS)是一种罕见的常染色体隐性遗传疾病,与ALMS1基因突变有关。ALMS的主要临床表现为视网膜营养不良,肥胖,2型糖尿病,扩张型心肌病和多器官纤维化,以肾脏和肝脏为特征。ALMS1编码的蛋白质的耗尽与通过初级纤毛调节的不同过程的改变有关,如NOTCH或TGF-β信号通路。然而,在缺乏ALMS1的情况下,这些失调的途径对细胞的影响仍然未知.
方法:在本研究中,我们整合了RNA-seq和蛋白质组学分析以确定TGF-β刺激后hTERT-BJ-5taALMS1敲除成纤维细胞的基因表达谱。此外,我们研究了该细胞系中TGF-β途径和AKT途径之间交叉信号的改变.
结果:我们发现ALMS1耗竭影响TGF-β途径及其与其他途径(如PI3K/AKT)的交叉信号传导,EGFR1或p53。此外,与ALMS1耗竭相关的改变聚集在转录组和蛋白质组中的细胞外基质调节和脂质代谢过程中。通过研究在转录组和蛋白质组中差异表达的常见基因的富集途径,胶原蛋白原纤维组织,脂肪酸的β-氧化和类花生酸代谢是由于缺乏ALMS1而改变的关键过程。最后,在ALMS1缺失的情况下确定了AKT途径的过度激活,这可以通过PTEN基因表达降低来解释.
结论:ALMS1缺乏破坏了TGF-β途径与hTERT-BJ-5ta细胞中其他依赖性途径之间的交叉信号传导。此外,改变的交叉信号影响细胞外基质相关过程和脂肪酸代谢的调节,并导致AKT途径的过度激活。
Alström syndrome (ALMS) is a rare autosomal recessive disease that is associated with mutations in ALMS1 gene. The main clinical manifestations of ALMS are retinal dystrophy, obesity, type 2 diabetes mellitus, dilated cardiomyopathy and multi-organ fibrosis, characteristic in kidneys and liver. Depletion of the protein encoded by ALMS1 has been associated with the alteration of different processes regulated via the primary cilium, such as the NOTCH or TGF-β signalling pathways. However, the cellular impact of these deregulated pathways in the absence of ALMS1 remains unknown.
In this study, we integrated RNA-seq and proteomic analysis to determine the gene expression profile of hTERT-BJ-5ta ALMS1 knockout fibroblasts after TGF-β stimulation. In addition, we studied alterations in cross-signalling between the TGF-β pathway and the AKT pathway in this cell line.
We found that ALMS1 depletion affects the TGF-β pathway and its cross-signalling with other pathways such as PI3K/AKT, EGFR1 or p53. In addition, alterations associated with ALMS1 depletion clustered around the processes of extracellular matrix regulation and lipid metabolism in both the transcriptome and proteome. By studying the enriched pathways of common genes differentially expressed in the transcriptome and proteome, collagen fibril organisation, β-oxidation of fatty acids and eicosanoid metabolism emerged as key processes altered by the absence of ALMS1. Finally, an overactivation of the AKT pathway was determined in the absence of ALMS1 that could be explained by a decrease in PTEN gene expression.
ALMS1 deficiency disrupts cross-signalling between the TGF-β pathway and other dependent pathways in hTERT-BJ-5ta cells. Furthermore, altered cross-signalling impacts the regulation of extracellular matrix-related processes and fatty acid metabolism, and leads to over-activation of the AKT pathway.