Browsing by Author "Affolter, Kajsa E."

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    Cardiolipin deficiency disrupts CoQ redox state and induces steatohepatitis
    (bioRxiv, 2024-10-10) Brothwell, Marisa J.; Cao, Guoshen; Maschek, J. Alan; Poss, Annelise M.; Peterlin, Alek D.; Wang, Liping; Baker, Talia B.; Shahtout, Justin L.; Siripoksup, Piyarat; Pearce, Quentinn J.; Johnson, Jordan M.; Finger, Fabian M.; Prola, Alexandre; Pellizzari, Sarah A.; Hale, Gillian L.; Manuel, Allison M.; Watanabe, Shinya; Miranda, Edwin R.; Affolter, Kajsa E.; Tippetts, Trevor S.; Nikolova, Linda S.; Choi, Ran Hee; Decker, Stephen T.; Patil, Mallikarjun; Catrow, J. Leon; Holland, William L.; Nowinski, Sara M.; Lark, Daniel S.; Fisher-Wellman, Kelsey H.; Mimche, Patrice N.; Evason, Kimberley J.; Cox, James E.; Summers, Scott A.; Gerhart-Hines, Zach; Funai, Katsuhiko; Dermatology, School of Medicine
    Metabolic dysfunction-associated steatotic liver disease (MASLD) is a progressive disorder marked by lipid accumulation, leading to steatohepatitis (MASH). A key feature of the transition to MASH involves oxidative stress resulting from defects in mitochondrial oxidative phosphorylation (OXPHOS). Here, we show that pathological alterations in the lipid composition of the inner mitochondrial membrane (IMM) directly instigate electron transfer inefficiency to promote oxidative stress. Specifically, cardiolipin (CL) was downregulated across four mouse models of MASLD. Hepatocyte-specific CL synthase knockout (CLS-LKO) led to spontaneous MASH with elevated mitochondrial electron leak. Loss of CL interfered with the ability of coenzyme Q (CoQ) to transfer electrons, promoting leak primarily at sites IIF and IIIQ0. Data from human liver biopsies revealed a highly robust correlation between mitochondrial CL and CoQ, co-downregulated with MASH. Thus, reduction in mitochondrial CL promotes oxidative stress and contributes to pathogenesis of MASH.
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    Integrated Molecular Characterization of Intraductal Papillary Mucinous Neoplasms: An NCI Cancer Moonshot Precancer Atlas Pilot Project
    (American Association for Cancer Research, 2023) Semaan, Alexander; Bernard, Vincent; Wong, Justin; Makino, Yuki; Swartzlander, Daniel B.; Rajapakshe, Kimal I.; Lee, Jaewon J.; Officer, Adam; Schmidt, Christian Max; Wu, Howard H.; Scaife, Courtney L.; Affolter, Kajsa E.; Nachmanson, Daniela; Firpo, Matthew A.; Yip-Schneider, Michele; Lowy, Andrew M.; Harismendy, Olivier; Sen, Subrata; Maitra, Anirban; Jakubek, Yasminka A.; Guerrero, Paola A.; Surgery, School of Medicine
    Intraductal papillary mucinous neoplasms (IPMN) are cystic precursor lesions to pancreatic ductal adenocarcinoma (PDAC). IPMNs undergo multistep progression from low-grade (LG) to high-grade (HG) dysplasia, culminating in invasive neoplasia. While patterns of IPMN progression have been analyzed using multiregion sequencing for somatic mutations, there is no integrated assessment of molecular events, including copy-number alterations (CNA) and transcriptional changes that accompany IPMN progression. We performed laser capture microdissection on surgically resected IPMNs of varying grades of histologic dysplasia obtained from 23 patients, followed by whole-exome and whole-transcriptome sequencing. Overall, HG IPMNs displayed a significantly greater aneuploidy score than LG lesions, with chromosome 1q amplification being associated with HG progression and with cases that harbored co-occurring PDAC. Furthermore, the combined assessment of single-nucleotide variants (SNV) and CNAs identified both linear and branched evolutionary trajectories, underscoring the heterogeneity in the progression of LG lesions to HG and PDAC. At the transcriptome level, upregulation of MYC-regulated targets and downregulation of transcripts associated with the MHC class I antigen presentation machinery as well as pathways related to glycosylation were a common feature of progression to HG. In addition, the established PDAC transcriptional subtypes (basal-like and classical) were readily apparent within IPMNs. Taken together, this work emphasizes the role of 1q copy-number amplification as a putative biomarker of high-risk IPMNs, underscores the importance of immune evasion even in noninvasive precursor lesions, and reinforces that evolutionary pathways in IPMNs are heterogenous, comprised of both SNV and CNA-driven events. Significance: Integrated molecular analysis of genomic and transcriptomic alterations in the multistep progression of IPMNs, which are bona fide precursors of pancreatic cancer, identifies features associated with progression of low-risk lesions to high-risk lesions and cancer, which might enable patient stratification and cancer interception strategies.