The basic helix-loop-helix(bHLH)transcription factor,DEC1,provides neuroprotection from apoptosis induced by MPP^+ through PI3K/Akt pathway in SHSY5Y cells

OBJECTIVE To determine the role of the basic helix-loop-helix(b HLH)transcription factor,differentiated embryonic chondrocyte gene 1(DEC1),in the apoptosis induced by 1-methyl-4-phenylpyridiniumion(MPP+)in SH-SY5Y cells.METHODS SH-SY5Y cells were treated with different concentrations of MPP+for 24or 48 h.The cell inhibition and apoptosis were measured by MTT and DAPI staining.DEC1,the apoptosis-related proteins and PI3K/Akt/GSK3β/β-catenin signaling were determined by Western blotting.The expression of DEC1was regulated by overexpression and sh RNA.RESULTS MPP+induces apoptosis along with decreasing of DEC1expression in SH-SY5Y cells.Overexpression or knockdown of DEC1 can alleviate or enhance the cell inhibition induced by MPP+.And overexpression of DEC1 can alleviate the increased cleaved caspase 3/caspase 3 but not alleviate Bax/Bcl-2 induced by MPP+.Meanwhile,MPP+represses PI3Kp110α,p-Akt/Akt,p-GSK-3β/GSK-3βandβ-catenin expression,which is accompanied by decreasing DEC1 expressions.It is confirmed that the activator or inhibitor of PI3K/Akt/GSK-3βpathway can alleviate or enhance the repression of PI3K/Akt/GSK3β/β-catenin signaling cascade induced by MPP+.Further study,we find that overexpression of DEC1 alone can increase PI3Kp110α,p-Akt/Akt,p-GSK-3β/GSK-3β,andβ-catenin expression.More importantly,overexpression of DEC1 significantly alleviates the decreased levels of PI3Kp110α,p-Akt/Akt,p-GSK-3β/GSK-3β,andβ-catenin induced by MPP+.CONCLUSION DEC1 provides neuroprotection from apoptosis induced by MPP+through PI3K/Akt pathway in SH-SY5Y cells.Promisingly,DEC1 is a candidate gene that may provide a novel therapeutic approach for the treatment of Parkinson disease.

Directing the osteoblastic and chondrocytic differentiations of mesenchymal stem cells:matrix vs.induction media

While both induction culture media and matrix have been reported to regulate the stem cell fate,little is known about which factor plays a more decisive role in directing the MSC differentiation lineage as well as the underlying mechanisms.To this aim,we seeded MSCs on HA-collagen and HA-synthetic hydrogel matrixes,which had demonstrated highly different potentials toward osteoblastic and chondrocytic differentiation lineages,respectively,and cultured them with osteogenic,chondrogenic and normal culture media,respectively.A systematic comparison has been carried out on the effects of induction media and matrix on MSC adhesion,cytoskeleton organization,proliferation,and in particular differentiation into the osteoblastic and chondrocytic lineages.The results demonstrated that the matrix selection had a much more profound effect on directing the differentiation lineage than the induction media did.The strong modulation effect on the transcription activities might be the critical factor contributing to the above observations in our study,where canonical Wnt-b-Catenin signal pathway was directly involved in the matrix-driven osteoblastic differentiation.Such findings not only provide a critical insight on natural cellular events leading to the osteoblastic and chondrocytic differentiations,but also have important implications in biomaterial design for tissue engineering applications.

Control of MSC Differentiation by Tuning the Alkyl Chain Length of Phe- nylboroinc Acid Based Low-molecular-weight Gelators

The physical environment plays a critical role in modulating stem cell differentiation into specific lineages. In this study, we designed and synthesized a series of low-molecular-weight gels （LMWGs） with different moduli based on phenylboronic acid derivatives. The moduli of the LMWGs were readily tuned by varying the alkyl chain without any chemical crosslinker. The cell responses to the gels were evaluated with mesenchymal stem cell （MSCs）, in respect of cell morphology, proliferation and differentiation. The prepared gels were non-toxic to MSCs, suggesting good biocompatibility. The hydrogel stiffness exerted a striking modulation effect on MSC fate decisions, where MSCs were inclined to differentiate into osteoblasts in stiff LMWGs and into chondrocytes in soft LMWGs. The pivotal elastic modulus of the LMWGs to drive MSC differentiation into osteoblastic lineage and chondrocytic lineage were approximately 20 kPa - 40 kPa and 1 kPa - 10 kPa, respectively. Overall, our results demonstrated that the modification ofhydrogel stiffness via tuning the alkyl chain was a simple but effective approach to regulate MSC differentiation into specific lineage, which might have important implications in the design of LMWGs for tissue engineering applications.