Melatonin promotes self-renewal of nestin-positive pancreatic stem cells through activation of the MT2/ERK/SMAD/nestin axis
Authors: Weijun Guan
Chunyu Bai
Yuhua Gao
Xiangyang Zhang
Wancai Yang
Journal: Artificial Cells Nanomedicine and Biotechnology (2018)
Discipline: BIOLOGY & BIOCHEMISTRY
Keywords: ERK pathway; Pancreatic stem cells; TGF-β1/SMAD pathway; cell proliferation; melatonin
Affiliations: Key Laboratory of Precision Oncology of Shandong Higher Education, Institute of Precision Medicine, Jining Medical University, Jining, Shandong Province, P. R. China;, Institute of Animal Sciences, Chinese Academy of Agricultural Sciences, Beijing, P. R. China;, College of Basic Medicine, Jining Medical University, Jining, Shandong Province, P. R. China;

Abstract:  Although melatonin has been shown to exhibit a wide variety of biological functions, its effects on promotion of self-renewal in pancreatic stem cells remain unknown. In this study, we incubated murine pancreatic stem cells (PSCs) with various concentrations of melatonin (0.01, 0.1, 1, 10 or 100 μM) to screen for the optimum culture medium for increasing cell proliferation. We found that 10 μM melatonin can significantly increase proliferation and enhance expression of a stem cell marker, nestin, in PSCs via melatonin receptor 2 (MT2). Thus, we used 10 μM melatonin to study the melatonin-mediated molecular mechanisms of cell proliferation in PSCs. We applied extracellular signal-regulated kinase (ERK) pathway inhibitor SCH772984 and transforming growth factor beta (TGF-β) pathway inhibitor SB431542, along with interfering RNAs siERK1, siERK2, siSmad2, siSmad3, siSmad4 and siNestin, to melatonin-treated PSCs to research the roles of these genes in self-renewal. The results revealed a novel molecular mechanism by which melatonin promotes self-renewal of PSCs: a chain reaction in the MT2/ERK/SMAD/nestin axis promoted the aforementioned self-renewal as well as inhibited differentiation. In addition, upregulation of nestin created a positive feedback loop in the regulation of the transforming growth factor beta 1 (TGF-β1)/SMADs pathway by promoting expression of Smad4. Conversely, knockdown of nestin significantly suppressed the proliferative effect in melatonin-treated PSCs. These are all novel mechanisms through which the ERK pathway cooperatively crosstalks with the SMAD pathway to regulate nestin expression, thereby enhancing self-renewal in PSCs. 

Retracted: No

PubPeer comments:
 The flow cytometry data presented in this article look artificial, due to the dot plot distribution pattern. Example from Figure 8A show repetitive patterns (red circles) and an unusual distribution in general. In addition, the Western immunoblots are unusual. Examples from Figure 6 and 7 show that all the bands in the panel are diffuse? Why? ![file] ![file] , 
 Thank you for your pointing this out. We have checked this original data of flow cytometry in FCM system (picture taken by a camera), and found the published image of Figure 8A had some distinction relative to original image, as you pointed out, a lot of u201ctailu201d appeared in the pixel behind to result in repetitive patterns. This distinction may have caused in figure assembly, we have contacted the journal and applied for correction using original image.![file] The anamorphose of western immunoblot also caused in figure assembly, the immunoblot bands had adjusted in size for assembly with histogram. We will be more careful for the future papers. ,