OSKMOpen-Source Knowledge Management
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In addition, mimics of pluripotency-related miR-302b and/or miR372 in combination with OSKM factors yielded more efficient reprogramming (Subramanyam et al., 2011).
Pluripotency is determined by analysis of gene and protein expression of pluripotency-related factors (still under discussion) by qPCR, immunofluorescence staining (e.g., TRA-1-160, SSEA-3, OSKM, Nanog), or by detailed transcriptional profiling using the PluriTest (Muller et al., 2011).
For example, micro/nanotopography can regulate cell and nucleus shape, modulate the epigenetic state, and replace biochemical factors (i.e., VPA and TCP) to enhance cell reprogramming into iPSCs.[30] Interestingly, cell reprogramming with OSKM factors can be performed in suspension culture under adherence- and matrix-free conditions, which suggests that OSKM factors are sufficient to reprogram cells without the input of cell adhesion-induced signaling.
As mentioned briefly above, many studies have shown the possibility of obtaining iPSCs using molecules other than Yamanaka OSKM [4] or Thomson OS-LIN28-NANOG factors [5].
Interestingly, some studies have shown the potential of small molecules as a substitute for OSKM factors by reprogramming in NSCs, although most researchers prefer to combine transcription factors with small molecules to increase the efficiency of obtaining neural clones from somatic cells [114].
In this case, the team set up a library of about 100 million distinct antibodies and used it to find any that could substitute for OSKM transcription factors.
However, another study established that this impairment could be reversed, augmenting OSKM expression, and that the essential pathway was Atg5-independent, relied on Rab9 and sintaxin 7, and included AMP-kinase (AMPK) activation, endoplasmic reticulum autophagy, and mitophagy [36, 37].
This is highly preferable to the traditional OSKM cocktail, which produces a large number of colonies but the majority of which fail the pluripotcncy test.
By comparison, only 2030 percent of high quality OSKM passed the same test.
In 2006, the Yamanaka group showed that mouse fibroblast cells can be reprogrammed into iPSCs by overexpression of OCT4, SOX2, KLF4, and cMyc (OSKM) TFs [1].
Typically, the four genes introduced are Oct4, Sox2, Klf4 and c-Myc, a combination known as OSKM.
Somatic cells can be reprogrammed to a pluripotent state similar to that of ES cells by ectopic expression of Oct4, Sox2, Klf4, and c-Myc (OSKM hereinafter) [81]; chemical treatment [82]; or nuclear transfer [83-85].