Figure 4.

This figure illustrates the ways in which activity from the mTOR signaling pathway contributes to epidermis (a), gut (b) and liver regeneration (c): (a) mTORC1 activity is necessary for wound closure and can be enhanced by insulin/insulin-like growth factor signaling (IIS). S6K1/2 is a TOR target which helps wound closure. mTOR inhibitory signals like rapamycin or an overexpressed PRAS40 delay wound closure and promote autophagy. (b) For gut regeneration, mTORC1 activity is required for initial cell proliferation but chronic activation leads to intestinal stem cell exhaustion. (c) For liver regeneration, mTORC1 activity leads to cell cycle reentry and functional recovery. eIF4E (Eukaryotic Initiation Factor 4E) dependent translation is activated with mTORC1 activity and leads to Cyclin D expression. Cyclin D amplifies cell proliferation and leads to functional liver recovery.