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Jakob Valdbjørn Kanne:
Somatic cell reprogramming in Physcomitrium patens

Date: 14-07-2021    Supervisor: Morten Petersen and John Mundy




The reprogramming of somatic cells is a complicated process which requires many either temporary or permanent changes. Here we report that autophagy plays an essential role during temporary reprogramming and permanent reprograming initiated by wounding.

We show that autophagy is activated by a plethora of signals, from growth hormones to immune responses and abiotic stress, and that autophagy removes proteins from the old program and tweak the protein levels of the new program.

We thus tested the role of autophagy during somatic cells reprogramming to stem cells in the moss Physcomitrium patens. Here we show that autophagy mutants have difficulties during somatic cell reprogramming, and that autophagic flux is elevated during the first 48 hours, when the transition from somatic cells to stem cells occur, for the then to be turned off in and around the new stem cells. And by elevating the expression of ATG8 the reprogramming becomes more efficient.

The reprogramming of P. patens is initiated by wounding the mature gametophores and in Arabidopsis it has been shown that wounding activates MAP Kinases. We show that wounding activates 3 MAP kinases in P. patens: MPK4A & B and the Rosetta Acetyltransferase MAPK (RAK1), and that MPK4B and RAK1 facilitates the reprogramming of somatic cell to stem cells after wounding.

These results are presented in four parts, two finished manuscripts about autophagy during reprogramming, one published in EMBO “Autophagy mediates temporary reprogramming and dedifferentiation in plant somatic cells” and one Accepted in Autophagy “Overexpression of ATG8/LC3 enhances wound induced somatic reprogramming in Physcomitrium patens” and two draft manuscripts summarizing our data regarding the role of wound induced MAP kinases during reprogramming in P. patens.