Obtaining freshly isolated and cultured mesenchymal stem cells from human adipose tissue

De novo annotation of lncRNA HOTAIR transcripts by long-read RNA capture-seq reveals a differentiation-driven isoform switch

Background

LncRNAs are tissue-specific and emerge as important regulators of various biological processes and as disease biomarkers. HOTAIR is a well-established pro-oncogenic lncRNA which has been attributed a variety of functions in cancer and native contexts. However, a lack of an exhaustive, cell type-specific annotation questions whether HOTAIR functions are supported by the expression of multiple isoforms.

Results

Using a capture long-read sequencing approach, we characterize HOTAIR isoforms expressed in human primary adipose stem cells. We find HOTAIR isoforms population displays varied splicing patterns, frequently leading to the exclusion or truncation of canonical LSD1 and PRC2 binding domains. We identify a highly cell type-specific HOTAIR isoform pool regulated by distinct promoter usage, and uncover a shift in the HOTAIR TSS usage that modulates the balance of HOTAIR isoforms at differentiation onset.

Conclusion

Our results highlight the complexity and cell type-specificity of HOTAIR isoforms and open perspectives on functional implications of these variants and their balance to key cellular processes.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-022-08887-w.

Successful Immediate Staged Breast Reconstruction with Intermediary Autologous Lipotransfer in Irradiated Patients

As indications for radiotherapy in mastectomized patients grow, the need for greater reconstructive options is critical. Preliminary research suggests an ameliorating impact of lipotransfer on irradiated patients with expander-to-implant reconstruction. Herein, we present our technique using lipotransfer during the expansion stage to facilitate implant placement.

miR-146a-mediated suppression of the inflammatory response in human adipocytes

The obesity-associated inflammation of white adipose tissue (WAT) is one of the factors leading to the development of related diseases such as insulin resistance and liver steatosis. Recently, microRNAs (miRNAs) were identified as important regulators of WAT functions. Herein, we cultured human Simpson-Golabi-Behmel syndrome (SGBS) adipocytes with macrophage-conditioned medium (MacCM) and performed an Affimetrix miRNA array to identify miRNAs differentially expressed under inflammatory conditions. We identified 24 miRNAs differentially expressed upon inflammation in human adipocytes and miR-146a was the most up-regulated miRNA species. In subcutaneous WAT, miR-146a was elevated in both human and murine obesity. Transfection of miR-146a mimics prevented the MacCM-induced inflammatory response in SGBS adipocytes as seen by reduced levels of IL-8 and MCP-1 mRNA and protein. We identified IRAK1 and TRAF6 as targets of miR-146a in human adipocytes and detected a reduced inflammation-induced activation of JNK and p38 upon miR-146a transfection. Taken together, we could show that miR-146a reduces the inflammatory response in human adipocytes. In a negative feedback loop miR-146a might contribute to the regulation of inflammatory processes in WAT and possibly prevent an overwhelming inflammatory response.

Stem cells in the skin and their role in oncogenesis

Stem cells generate great interest because they hold the promise for treatment of various incurable diseases. Several distinct stem cell populations have been identified in each organ, including the skin. As the skin is the largest organ in the body and is easily accessible, cutaneous stem cells have raised significant hopes for being a rich source of easily available multipotent stem cells. Genetic alterations and mutations in stem cells are being proposed as initiation step in multiple cancers. Small populations of oncogenic stem cells termed as cancer stem cells or tumour-initiating cells have been identified in multiple tumours, including squamous cell carcinomas, and melanomas that can sustain tumour growth, underlie its malignant behaviour and initiate distant metastases. These cells are controlled and regulated by the same pathways that are also responsible for maintenance and differentiation of normal stem cells. Developing a targeted therapy against the oncogenic stem cells and dysregulated members of the signalling pathways may be the key to understanding and treating skin cancers like melanomas, for which we still do not have an effective treatment.

Epigenetic regulation of nestin expression during neurogenic differentiation of adipose tissue stem cells

Adipose-tissue-derived stem cells (ASCs) have received considerable attention due to their easy access, expansion potential, and differentiation capacity. ASCs are believed to have the potential to differentiate into neurons. However, the mechanisms by which this may occur remain largely unknown. Here, we show that culturing ASCs under active proliferation conditions greatly improves their propensity to differentiate toward osteogenic, adipogenic, and neurogenic lineages. Neurogenic-induced ASCs express early neurogenic genes as well as markers of mature neurons, including voltage-gated ion channels. Nestin, highly expressed in neural progenitors, is upregulated by mitogenic stimulation of ASCs, and as in neural progenitors, then repressed during neurogenic differentiation. Nestin gene (NES) expression under these conditions appears to be regulated by epigenetic mechanisms. The neural-specific, but not muscle-specific, enhancer regions of NES are DNA demethylated by mitogenic stimulation, and remethylated upon neurogenic differentiation. We observe dynamic changes in histone H3K4, H3K9, and H3K27 methylation on the NES locus before and during neurogenic differentiation that are consistent with epigenetic processes involved in the regulation of NES expression. We suggest that ASCs are epigenetically prepatterned to differentiate toward a neural lineage and that this prepatterning is enhanced by demethylation of critical NES enhancer elements upon mitogenic stimulation preceding neurogenic differentiation. Our findings provide molecular evidence that the differentiation repertoire of ASCs may extend beyond mesodermal lineages.