Endocrine Abstracts

Introduction: Aryl hydrocarbon receptor interacting protein (AIP) is a multifunctional co-chaperone protein with wide-ranging effects. It acts as a tumour suppressor in the pituitary, but may have other roles including oncogenic function in other tissues. To explore the molecular mechanisms, we have performed transcriptomic and phosphoproteomic analysis of Aip-knockout mouse embryonic fibroblasts (Aip-KO MEFs) cells and integrated these data sets.

Method: RNAseq was performed using Illumina NovaSeq 6000 and phosphoproteomics analysis performed by mass spectrometry (MS). Ingenuity Pathway Analysis (IPA), gene set enrichment analysis (GSEA) and Kinase-Substrate Enrichment Analysis (KSEA) were used.

Results: We identified 6,747 transcripts and 2,156 phosphopeptides altered in Aip-KO MEFs. GSEA analysis revealed enrichment of adherens junction, tight junction and cytoskeleton. KSEA revealed multiple kinases (significantly altered at the transcript levels), involved in the adherens junction, tight junction, cytoskeleton and vesicle trafficking. The top hyperphosphorylated peptide is Heart of glass (HEG1, Ser486, 12 log fold) corresponding to 3.3 log fold increased mRNA expression. HEG1, involved in Wnt/β-catenin signaling pathway. TJP2/tight junction protein 2 (Ser898, 3.5 fold), a member of the membrane-associated guanylate kinase homolog family, crucial for tight junction’s assembly and involved in cell adhesion pathway. CAMKK2/calcium/calmodulin dependent protein kinase 2 (Ser495, 2 fold), a novel modulator of Golgi vesicle trafficking. GOLGA5/golgin A5 (Ser155, -10.28 fold), a coiled-coil membrane protein with potential role in vesicle tethering and docking. Both CAMKK2 and GOLGAA5 are involved in vesicle trafficking. NME1/nucleoside diphosphate kinase A (T94, 2 fold), a known AIP interacting partner, a tumor suppressor that negatively regulates cell motility.

Conclusions: Integration of multi-omics data of transcriptional and post-translational events in Aip-Ko cells has revealed the potential role of AIP in remodelling of the adherens junction, tight junction, vesicle trafficking and cell migration. This study has broaden our understanding of AIP-mediated tumorigenesis.