Septins in Stem Cells

Abstract

Septins were first described in yeast. Due to extensive research in non-yeast cells, Septins are now recognized across all species as important players in the regulation of the cytoskeleton, in the establishment of polarity, for migration, vesicular trafficking and scaffolding. Stem cells are primarily quiescent cells, and this actively maintained quiescent state is critical for proper stem cell function. Equally important though, stem cells undergo symmetric or asymmetric division, which is likely linked to the level of symmetry found in the mother stem cell. Due to the ability to organize barriers and be able to break symmetry in cells, Septins are thought to have a significant impact on organizing quiescence as well as the mode (symmetric vs asymmetric) of stem cell division to affect self-renewal versus differentiation. Mechanisms of regulating mammalian quiescence and symmetry breaking by Septins are though still somewhat elusive. Within this overview article, we summarize current knowledge on the role of Septins in stem cells ranging from yeast to mice especially with respect to quiescence and asymmetric division, with a special focus on hematopoietic stem cells.

Titanium dioxide nanoparticles affect osteoblast-derived exosome cargos and impair osteogenic differentiation of human mesenchymal stem cells

“…As biotransformation enzymes, they play an important role in cellular antioxidant defence mechanisms by catalyzing the reduction of potentially harmful peroxides. 72 They can lead to chondrogenic or adpogenic differentiation of mesenchymal cells. In addition, microfibrillar-associated protein 2 and Fascin have previously been associated with the activation and inhibition of osteogenic differentiation of HMSCs.…”

“…In MG63-derived ExosNPs, we identified 8 different proteins, and interestingly, most have already been described as having osteogenic activity on HMSCs. [70][71][72][73][74][75][76] Among these proteins, we highlight alpha N-acetylglucosaminidase, which has already been described as modulating the negative effect of several transcription effectors including methylation of the transcription factor Runx2. 75,76 Runx2 is the master switch controlling osteoblast differentiation and mineralized skeleton formation.…”

Quantitative determination of changes in the spatial distribution of components in single cells with CellDetail

“…It is known that Cdc42 activity is connected to polarity but how the spatial rearrangements in HSCs upon aging occur remains under investigation. As there are changes in the Cdc42-Borg4-Septin7 axis upon aging [21] and Septin7 belongs to a group of cytoskeletal proteins known for polarity regulation and maintenance (Septins) [27] we hypothesized spatial changes in the 13 distinct Septin proteins of mice which form a network that is critical for the compartmentalization of cell content and thus polarity [30]. CellDetail, analyzing data from a novel six Septin IF staining in single cells, revealed a less focused overall organization of the Septin network within aged HSCs.…”

“…Septins interact with Actin and Tubulin. They compartmentalize cells by forming hetero-oligomeric complexes and filaments which serve as scaffolds for protein recruitment or as diffusion barriers [27,30]. There are 13 Septins in mammals, which are classified into four SEPT groups based on homology: SEPT2 (Septin1, Septin2, Septin4, Septin5), SEPT3 (Septin3, Septin9, Septin12), SEPT6 (Septin6, Septin8, Septin10, Septin11, Septin14) and SEPT7 (Septin7).…”

Stem Cell Theory of Cancer: Clinical Implications of Epigenomic versus Genomic Biomarkers in Cancer Care

“…For example, Mo et al [56] demonstrated that changes in ctDNA may enable us to detect residual disease, guide chemotherapy, stratify risk, and monitor recurrence of stage I to III colorectal cancer. They performed multiplex ctDNA methylation and quantitative polymerase chain reaction assay to detect the ctDNA of six biomarkers (SEPTIN9 locus 1, BCAT1, IKZF1, SEPTIN9 locus 2, VAV3, and BCAN), which in one way or another implicated stem-like or stemness properties, i.e., pluripotency, self-renewal, and differentiation of progenitor stem cells in various tissues [57][58][59][60][61][62].…”