Defining the minimal factors required for erythropoiesis through direct lineage conversion

Abstract

SUMMARYErythroid cell commitment and differentiation proceed through activation of a lineage-restricted transcriptional network orchestrated by a group of well characterized genes. However, the minimal set of factors necessary for instructing red blood cell (RBC) development remains undefined. We employed a screen for transcription factors allowing direct lineage reprograming from fibroblasts to induced erythroid progenitors/precursors (iEPs). We show that Gata1, Tal1, Lmo2, and c-Myc (GTLM) can rapidly convert murine and human fibroblasts directly to iEPs. The transcriptional signature of murine iEPs resembled mainly that of primitive erythroid progenitors in the yolk sac, whereas addition of Klf1 or Myb to the GTLM cocktail resulted in iEPs with a more adult-type globin expression pattern. Our results demonstrate that direct lineage conversion is a suitable platform for defining and studying the core factors inducing the different waves of erythroid development.

Activation of KLF1 Enhances the Differentiation and Maturation of Red Blood Cells from Human Pluripotent Stem Cells

“…Interestingly that study also demonstrated that lentiviral transduction of BCL11A alone was sufficient to induce the expression of b2globin in the immortalized iPSCderived HiDEP-1 cell line because that cell lines had adult-like levels of KLF1 [52]. A recent study that added KLF1 to iEP cells showed adult-like globin [17]. The erythroid cells derived from the SFCi55 iPSC cell line used in this study have lower levels of KLF1 compared to differentiated adult CD34 1 cells (Fig.…”

“…Current protocols to produce RBCs from hPSC have limitations because they generate a relatively low proportion of enucleated cells and express embryonic/foetal but not adult globin [6]. Forward programming using lineage specific transcription factors has been used to enhance the production of a number cell types from hPSCs including hematopoietic lineages [16,17,40].…”

“…This study is the first to demonstrate enhanced erythropoiesis from hPSCs using a forward programming approach by activation of a single transcription factor, KLF1 at levels that are comparable to physiological level. However, the successful production of adult-like erythroid cells in sufficient quantities from iPSCs will undoubtedly require the use of multiple transcription factors in a combinatorial forward programming approach as recently described for the production of platelets form hPSCs [40] and primitive erythroid cells from fibroblasts [17]. The key to this strategy is to define the complex cocktail of transcription factors that define the development and maintenance of adult erythroid cells and to induce their expression at defined timepoints in a reproducible manner.…”

“…Transcription factor programming has been used to direct hESC/iPSC differentiation into distinct cell types such as cardiomyocytes and neurons [9,10]. Enhanced expression of transcription factors known to be involved in the development and maintenance of the hematopoietic system such as SCL/TAL1, RUNX1, HOXA9, or HOXB4 have been used to increase the production of hematopoietic stem/progenitor cells from hESCs/iPSCs [11][12][13][14][15][16] and four transcription factors (GATA1, LMO2, SCL/TAL1, and cMYC) directly converted fibroblast into primitive erythroid progenitors [17].…”

Variational Infinite Heterogeneous Mixture Model for Semi-supervised Clustering of Heart Enhancers

“…Experimental validation is required to determine if the motifs uniquely enriched in specific classes control different enhancer states and whether multiple binding events are required for enhancers to transition from an inactive state to a functional state. However, there are examples of multiple TF binding events driving expression of the Hbb gene to facilitate cell fate transitions (Capellera-Garcia et al, 2016;Mitchell et al, 2012).…”