The forced expression of Yamanaka factors (Oct3/4, Sox2, Klf4, and c-Myc) reprograms cells into induced pluripotent stem cells (iPSCs) through a series of sequential cell fate conversions. The order and robustness of gene expression changes are highly depended on the Yamanaka factor stoichiometry. We specifically focused on two different reprogramming paths induced by high- and low-Klf4 stoichiometry, which were accomplished by introducing OK+9MS or OKMS polycistronic cassettes, respectively, into mouse embryonic fibroblasts. By comparing these reprograming intermediates with embryonic stem cells (ESCs) and primary keratinocytes, we identified high-Klf4 specific, transiently up-regulated epithelial genes. We found that expression of these epithelial genes was enriched in a TROP2-positive cell population. Moreover, we identified a set of transcription factors which are candidates for the regulation of transiently expressed epithelial genes, and revealed their connection to high-Klf4-specific reprogramming hallmarks.
OVOL1 Influences the Determination and Expansion of iPSC Reprogramming Intermediates.
Specimen part, Treatment
View SamplesOct3/4, Sox2, Klf4, and c-Myc re-wire somatic cells to achieve induced pluripotency (iPS cells). However, subtle differences in reprogramming methodology may confound comparative studies of reprogramming-induced gene expression changes. We specifically focused on the design of polycistronic reprogramming constructs, which encode all four factors linked with 2A peptides. Notably, publically available cassettes were found to employ one of two Klf4 variants (Klf4S and Klf4L; GenBank Accession Nos: AAC52939.1 and AAC04892.1), differing only by nine N-terminal amino acids. In a polycistronic context, these two variants generated dissimilar protein stoichiometry, where Klf4L vectors produced more Klf4 protein than those encoding Klf4S.
KLF4 N-terminal variance modulates induced reprogramming to pluripotency.
Sex, Specimen part
View SamplesThe heart responds to pathological overload through myocyte hypertrophy. In our study, we found that this response is regulated by cardiac fibroblasts via a novel paracrine mechanism involving plasma membrane calcium ATPase 4 (PMCA4). PMCA4 deletion in mice, both systemically and specifically in fibroblasts, reduces the hypertrophic response to pressure overload; however, knocking out PMCA4 specifically in cardiomyocytes does not produce this effect. Mechanistically, our microarray data on fibroblasts isolated from PMCA4 WT and PMCA4 knockout animals showed that cardiac fibroblasts lacking PMCA4 produce higher levels of secreted frizzled related protein 2 (sFRP2), which inhibits the hypertrophic response in neighbouring cardiomyocytes.
The plasma membrane calcium ATPase 4 signalling in cardiac fibroblasts mediates cardiomyocyte hypertrophy.
Sex, Age, Specimen part
View SamplesPancreatic cancers (PCs) are highly metastatic with poor prognosis, mainly due to delayed detection. We hypothesized that intercellular communication is critical for metastatic progression. Here, we show that PC-derived exosomes induce liver pre-metastatic niche formation in naïve mice and consequently increase liver metastatic burden. Uptake of PC-derived exosomes by Kupffer cells caused transforming growth factor ß secretion and upregulation of fibronectin production by hepatic stellate cells. This fibrotic microenvironment enhanced recruitment of bone marrow-derived macrophages. We found that macrophage migration inhibitory factor (MIF) was highly expressed in PC-derived exosomes, and its blockade prevented liver pre-metastatic niche formation and metastasis. Compared to patients whose pancreatic tumors did not progress, MIF was markedly higher in exosomes from stage I PC patients who later developed liver metastasis. These findings suggest that exosomal MIF primes the liver for metastasis and may be a prognostic marker for the development of PC liver metastasis. Overall design: Normal pancreas and Pancreatic cancer exosomes education of human von Kupffer cells in vitro
Pancreatic cancer exosomes initiate pre-metastatic niche formation in the liver.
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