Thinking outside the liver: Induced pluripotent stem cells for hepatic applications

Table 3 Role of reprogramming factors for induced pluripotent stem cell generation

Reprogramming factors	Description	Function	Ref.
Oct4	Octamer binding transcription factor 4	This transcription factor plays a role in embryonic development, especially during early embryogenesis, and it is necessary for embryonic stem cell pluripotency	[7]
Sox2	SRY box 2	In embryonic stem cells, Sox2 and Oct3/4 often co-occupy target genes, including own promoters. These proteins cooperate regulatory feedback loops to maintain pluripotency	[60]
Klf4	Kruppel-like factor 4	This transcription factor plays a role in upregulation of pluripotency gene Nanog and the modification of chromatin structure to facilitate the binding of Oct3/4 and Sox2 to their sequences. Klf4 itself is an oncogenic factor. This gene is over expressed in a variety of tumor types associated with advanced cancer	[61-63]
c-Myc	Proto oncogene protein	An oncogene that induces global histone acetylation, allowing Oct3/4 and Sox2 to bind to their specific target loci	[60,63]
Nanog	Homeo box transcription factor	A transcription factor critically involved with self-renewal of undifferentiated embryonic stem cells	[64]
Lin28	RNA binding protein Lin28	The Lin28 gene codes for an RNA-binding protein that selectively blocks the processing of microRNAs of the let-7 family, and possibly certain other microRNAs in ESCs, to prevent their differentiation	[65,66]

ESCs: Embryonic stem cells; Oct: Octamer-binding transcription factor; Sox2: SRY box-containing gene 2; Klf4: Kruppel-like factor 4.