Cell Biology & Molecular Genetics
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Item Impaired LEF1 Activation Accelerates iPSC-Derived Keratinocytes Differentiation in Hutchinson-Gilford Progeria Syndrome(MDPI, 2022-05-14) Mao, Xiaojing; Xiong, Zheng-Mei; Xue, Huijing; Brown, Markus A.; Gete, Yantenew G.; Yu, Reynold; Sun, Linlin; Cao, KanHutchinson–Gilford progeria syndrome (HGPS) is a detrimental premature aging disease caused by a point mutation in the human LMNA gene. This mutation results in the abnormal accumulation of a truncated pre-lamin A protein called progerin. Among the drastically accelerated signs of aging in HGPS patients, severe skin phenotypes such as alopecia and sclerotic skins always develop with the disease progression. Here, we studied the HGPS molecular mechanisms focusing on early skin development by differentiating patient-derived induced pluripotent stem cells (iPSCs) to a keratinocyte lineage. Interestingly, HGPS iPSCs showed an accelerated commitment to the keratinocyte lineage than the normal control. To study potential signaling pathways that accelerated skin development in HGPS, we investigated the WNT pathway components during HGPS iPSCs-keratinocytes induction. Surprisingly, despite the unaffected β-catenin activity, the expression of a critical WNT transcription factor LEF1 was diminished from an early stage in HGPS iPSCs-keratinocytes differentiation. A chromatin immunoprecipitation (ChIP) experiment further revealed strong bindings of LEF1 to the early-stage epithelial developmental markers K8 and K18 and that the LEF1 silencing by siRNA down-regulates the K8/K18 transcription. During the iPSCs-keratinocytes differentiation, correction of HGPS mutation by Adenine base editing (ABE), while in a partial level, rescued the phenotypes for accelerated keratinocyte lineage-commitment. ABE also reduced the cell death in HGPS iPSCs-derived keratinocytes. These findings brought new insight into the molecular basis and therapeutic application for the skin abnormalities in HGPS.Item Investigation of progerin expression in non-Hutchinson-Gilford Progeria Syndrome individuals(2023) Yu, Reynold; Cao, Kan; Mount, Steve; Molecular and Cell Biology; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Hutchinson-Gilford Progerin Syndrome (HGPS) is a premature aging disease caused by a point mutation in the LMNA gene, which encodes A-type lamins. This mutation activates a cryptic splice donor in exon 11 and leads to the production of a toxic lamin variant called progerin. Interestingly, small amounts of progerin have also been found in cells and tissues of normal individuals. Here we examine the expression of progerin in publicly available RNA-seq data from normal individuals of the GTEx project. Among the 30 available tissues, progerin expression in normal individuals is highest in sun-exposed skin samples, and its expression in different tissues of the same donor is correlated. In addition, telomere shortening is significantly correlated with progerin expression. Transcriptome-wide correlation analyses suggest that the level of progerin expression is highly correlated with switches in gene isoform expression patterns, perhaps reflecting widespread isoform shifts in these samples. Differential expression analyses show that progerin expression is correlated with significant changes in the level of transcripts from genes involved in splicing regulation and a significant reduction of mitochondrial transcripts. Interestingly, 5’ splice sites whose use is correlated (either positively or negatively) with progerin expression have significantly altered frequencies of consensus trinucleotides within the core 5’ splice site. Furthermore, introns whose alternative splicing is correlated with progerin have reduced GC content. Together, our study suggests that progerin expression in normal individuals is part of a global shift in splicing patterns and provides insight into the mechanism behind these changes.