A Lin28 homologue reprograms differentiated cells to stem cells in the moss Physcomitrella patens

Abstract

Both land plants and metazoa have the capacity to reprogram differentiated cells to stem cells. Here we show that the moss Physcomitrella patens Cold-Shock Domain Protein 1 (PpCSP1) regulates reprogramming of differentiated leaf cells to chloronema apical stem cells and shares conserved domains with the induced pluripotent stem cell factor Lin28 in mammals. PpCSP1 accumulates in the reprogramming cells and is maintained throughout the reprogramming process and in the resultant stem cells. Expression of PpCSP1 is negatively regulated by its 3′-untranslated region (3′-UTR). Removal of the 3′-UTR stabilizes PpCSP1 transcripts, results in accumulation of PpCSP1 protein and enhances reprogramming. A quadruple deletion mutant of PpCSP1 and three closely related PpCSP genes exhibits attenuated reprogramming indicating that the PpCSP genes function redundantly in cellular reprogramming. Taken together, these data demonstrate a positive role of PpCSP1 in reprogramming, which is similar to the function of mammalian Lin28.

Autophagy mediates temporary reprogramming and dedifferentiation in plant somatic cells

“…Unlike mammals and flowering plants, bryophytes can naturally form PSCs without the need for exogenous hormone treatment or overexpression of transcription factors. In particular, the moss Physcomitrella patens is able to dedifferentiate somatic cells into chloronema stem cells to repair damaged tissue upon wounding (Ishikawa et al , ; Kofuji & Hasebe, ; Li et al , ). Using this system, we compared reprogramming efficiency in WT, atg5, and atg7 lines upon wounding.…”

“…Somatic cells can also undergo directional reprogramming through dedifferentiation and can form pluripotent cells. This allows somatic cells to redifferentiate into other cell types, organs, and even whole organisms in plants (Takahashi & Yamanaka, ; Papp & Plath, ; Ikeuchi et al , ; Li & Belmonte, ; Li et al , ). Similar to temporary reprogramming, reprogramming into other cell types is orchestrated by evolutionarily conserved processes and involves major changes in the transcriptome and epigenetic landscape (Roche et al , ; Sang et al , ; Iwafuchi‐Doi, ).…”

Single-cell transcriptome analysis of Physcomitrella leaf cells during reprogramming using microcapillary manipulation

“… PpCSP1 and PpCSP2 , genes encoding cold-shock protein 1 and 2 [20]; PpCYCD;1 : gene encoding cyclin D;1 [18]. These were calculated and plotted using the monocle package [43].…”

“…The WUSCHEL-related homeobox 13 ( PpWOX13 ) genes are upregulated during reprogramming and required for the tip growth characteristic of the chloronema apical stem cells [19]. The Cold-Shock Domain Protein 1 (PpCSP1) and PpCSP2, orthologous to the mammalian reprogramming factor Lin28A, also positively regulate reprogramming in Physcomitrella [20]. Furthermore, a transcriptome analysis of whole excised leaves during reprogramming revealed that the expression levels of more than 3,900 genes were altered within 24 hours after excision [21].…”

RNA melting and RNA chaperone activities of plant cold shock domain proteins are not correlated

“…Lin-28 has been suggested to be a translational enhancer, which can perform chaperone-like functions in cells, inducing the expression of genes involved in the activation of cellular metabolism, cell growth, and proliferation [17,25]. PpCSP1 from Physcomitrella patens was shown to have functions similar to those of lin-28 [26]. Taken together, these observations suggest that plant CSDPs are involved in the activation of cell growth and division, and that these functions may be, at least partially, determined by their RNA chaperone activity.…”