Abstract
Cyclic adenosine 3′,5′monophosphate (cAMP) regulated element binding protein (CREB) is a transcription factor involved in many different signaling processes including memory storage and retrieval. The mouse hippocampal neuronal cell line HT22 is widely used as a model system for neuronal cell death and cellular signal pathway investigations. For the present work a variant of HT22 with a stably expressed CRE-luciferase (CRE-luc) reporter (HT22CRE) is introduced, characterized and used to investigate cAMP-dependent and independent CRE-dependent signal processes. Trehalose (Mykose or 1-α-Glucopyranosyl-1-α-glucopyranosid) is a naturally occurring disaccharide consisting of two α,α′,1,1-glycosidic connected glucose molecules in a wide range of organisms but usually not found in mammals. Trehalose has been shown to activate autophagy, a process which regulates the degradation and recycling of proteins and organelles. The exact processes how trehalose application works on mammalian neuronal cells is not yet understood. The present work shows that trehalose application dose-dependently elevates CRE-luc activity in HT22 cells and acts synergistically with cAMP-elevating agents. In this pathway cAMP-dependent protein kinase (PKA) appears to be the most important factor and the stress kinase p38 and protein tyrosine kinases (PTKs) act as modulators.
Highlights
Trehalose, Autophagy and Human TherapyTrehalose (Mykose or 1-α-Glucopyranosyl-1-α-glucopyranoside) is a naturally occurring disaccharide consisting of two α,α,1,1-glycosidic connected glucose molecules in a wide range of organisms but usually not produced in mammals
Trehalose applied in combination with forskolin significantly inhibited CRE-luc activity compared to forskolin application (Figures 2A,B)
Data presented here show that trehalose application to HT22CRE cells leads to: (1) an induction of CRE-luc activity without elevation of cAMP levels; (2) a transient induction of CREB serine 133 phosphorylation; (3) an induction of phospho-p38; (4) a bi-phasic interaction with cAMP-elevating agents where trehalose is inhibitory to the forskolin-effect in the early phase (1–3 h) and synergistically activating the forskolin-effect in the second phase (6–12 h); and (5) a persisting elevation of intracellular cAMP levels and CRE-luc activity if combined with forskolin
Summary
Trehalose (Mykose or 1-α-Glucopyranosyl-1-α-glucopyranoside) is a naturally occurring disaccharide consisting of two α,α ,1,1-glycosidic connected glucose molecules in a wide range of organisms but usually not produced in mammals It plays an important role in hibernation of invertebrates and can be used to preserve deep-frozen mammalian cells (Bailey et al, 2015), tissues and organs (Richards et al, 2002; Iturriaga et al, 2009). Doses of 30 g/patient/day intravenous (which would result in a transient concentration of approximately 20 mM in blood) and 50 g/day per patient are considered safe (Richards et al, 2002) Such doses of trehalose have been utilized in experimental human studies for the treatment of Oculopharyngeal Muscular Dystrophy (OPMD; Argov, 2015). The exact processes how trehalose application works on mammalian cells, including neuronal cells, is not yet understood, but extra- and intracellular action as well as mTor-dependent and -independent mechanisms have been discussed (Sarkar et al, 2007; Iturriaga et al, 2009; Casarejos et al, 2011; Holler et al, 2016; Martano et al, 2017; Lee et al, 2018)
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