Epigenetic regulation of cardiac progenitor cells marker c-kit by stromal cell derived factor-1α
Authors: Genshan Ma
Xiaodong Pan
Fengdi Yan
Yuyu Yao
Long Chen
Zhongpu Chen
Rong Huang
Journal: PLoS ONE (2013)
Discipline: Multidisciplinary
Keywords: Cardiac progenitor cells; c-kit; stem cell factor; SDF-1α; CXCR4
Affiliations: Department of Cardiology, Zhongda Hospital, Medical School of Southeast University, Nanjing, Jiangsu, China.

Abstract:  Background: Cardiac progenitor cells (CPCs) have been proven suitable for stem cell therapy after myocardial infarction, especially c-kit(+)CPCs. CPCs marker c-kit and its ligand, the stem cell factor (SCF), are linked as c-kit/SCF axis, which is associated with the functions of proliferation and differentiation. In our previous study, we found that stromal cell-derived factor-1α (SDF-1α) could enhance the expression of c-kit. However, the mechanism is unknown. Methods and results: CPCs were isolated from adult mouse hearts, c-kit(+) and c-kit(-) CPCs were separated by magnetic beads. The cells were cultured with SDF-1α and CXCR4-selective antagonist AMD3100, and c-kit expression was measured by qPCR and Western blotting. Results showed that SDF-1α could enhance c-kit expression of c-kit(+)CPCs, made c-kit(-)CPCs expressing c-kit, and AMD3100 could inhibit the function of SDF-1α. After the intervention of SDF-1α and AMD3100, proliferation and migration of CPCs were measured by CCK-8 and transwell assay. Results showed that SDF-1α could enhance the proliferation and migration of both c-kit(+) and c-kit(-) CPCs, and AMD3100 could inhibit these functions. DNA methyltransferase (DNMT) mRNA were measured by qPCR, DNMT activity was measured using the DNMT activity assay kit, and DNA methylation was analyzed using Sequenom's MassARRAY platform, after the CPCs were cultured with SDF-1α. The results showed that SDF-1α stimulation inhibited the expression of DNMT1 and DNMT3β, which are critical for the maintenance of regional DNA methylation. Global DNMT activity was also inhibited by SDF-1α. Lastly, SDF-1α treatment led to significant demethylation in both c-kit(+) and c-kit(-) CPCs. Conclusions: SDF-1α combined with CXCR4 could up-regulate c-kit expression of c-kit(+)CPCs and make c-kit(-)CPCs expressing c-kit, which result in the CPCs proliferation and migration ability improvement, through the inhibition of DNMT1 and DNMT3β expression and global DNMT activity, as well as the subsequent demethylation of the c-kit gene. 

Retracted: Yes

PubPeer comments:
 Figure 3C. * Red boxes: Two panels appear to show an overlap. Reported to the journal in October 2015, but no action as of today. ![file] , 
 February 12 retraction. The Retraction Notice reads:  Following the publication of this article [1], concerns were raised regarding similarity between panels presented in Fig 3C, as well as similarity between figures presented in this article [1] and figures presented in a publication accepted in the journal Heart, Lung and Circulation [2] prior to the acceptance of this article [1] in PLOS ONE. In addition, concerns were raised regarding substantial overlap with the work reported in both articles [1, 2]. Specifically, * The panels in Fig 1A and 1B [1] appear similar to the panels in Fig 1B and 1C [2] respectively. * The c-kit(+)CPCs control panel in Fig 3C [1] partially overlaps with the c-kit(+)CPCs SDF-1+AMD3100 panel in Fig 3C [1], the normal panel of Fig 3C [2], and the SDF-1+AMD3100 panel of Fig 3C [2]. * There is overlap in the experimental design, results and analyses between the PLOS ONE article [1] and those reported in [2]. The related paper is not cited in the PLOS ONE article and was not disclosed at the time of submission. The authors have provided underlying data for the results presented in Fig 3 and indicated that the two Fig 3C panels [1] appear similar because the wrong image was included in the figure. The authors indicate that the experimental data in this article [1] appears similar to the data presented in [2] because several experiments were repeated, and they state that experimental data was not reused for both articles. However, the authorsu2019 statement that the experimental data was not reused does not sufficiently address concerns regarding the similarity between multiple panels presented in these articles. In light of the concerns about redundancy of this work, the PLOS ONE Editors retract this article. The panels of Figs 1A, 1B and 3C listed above appear visually similar to copyright protected material which is not offered under a CC-BY licence. The indicated panels therefore are excluded from the PLOS ONE articleu2019s [1] licence. At the time of retraction, the article [1] was republished to note this exclusion in the Figs 1 and 3 legends and the articleu2019s copyright statement. ZC agreed with the retraction and apologises for the issues with the published article. XP, YY, FY, LC, RH, and GM either did not respond directly or could not be reached. I thank the authors and journal staff for their time investigating this paper. , 
 Here is an illustration of the similarities between Figures 1 of both papers: ![file] And the similarities between Figures 3 of both papers: ![file] ,