Since 3D printed hard materials could match the shape of bone,cell survival and fate determination towards osteoblasts in such materials have become a popular research target.In this study,a scaffold of hardmaterial f...Since 3D printed hard materials could match the shape of bone,cell survival and fate determination towards osteoblasts in such materials have become a popular research target.In this study,a scaffold of hardmaterial for 3D fabrication was designed to regulate developmental signal(Notch)transduction guiding osteoblast differentiation.We established a polycaprolactone(PCL)and cell-integrated 3D printing system(PCI3D)to reciprocally print the beams of PCL and cell-laden hydrogel for a module.This PCI3D module holds good cell viability of over 87%,whereas cells show about sixfold proliferation in a 7-day culture.The osteocytic MLO-Y4 was engineered to overexpress Notch ligand Dll4,making up 25%after mixing with 75%stromal cells in the PCI3D module.Osteocytic Dll4,unlike other delta-like family members such as Dll1 or Dll3,promotes osteoblast differentiation and themineralization of primary mouse and a cell line of bone marrow stromal cells when cultured in a PCI3D module for up to 28 days.Mechanistically,osteocytic Dll4 could not promote osteogenic differentiation of the primary bone marrow stromal cells(BMSCs)after conditional deletion of the Notch transcription factor RBPjκby Cre recombinase.These data indicate that osteocytic Dll4 activates RBPjκ-dependent canonical Notch signaling in BMSCs for their oriented differentiation towards osteoblasts.Additionally,osteocytic Dll4 holds a great potential for angiogenesis in human umbilical vein endothelial cells within modules.Our study reveals that osteocytic Dll4 could be the osteogenic niche determining cell fate towards osteoblasts.This will open a new avenue to overcome the current limitation of poor cell viability and low bioactivity of traditional orthopedic implants.展开更多
Intracellular Notch (ICN) initiates DNA transcription in cooperation with CSL that acts as repressor in the absence of ICN. The ICN mediates recruitment of MAML protein, leading to the formation of minimal transcripti...Intracellular Notch (ICN) initiates DNA transcription in cooperation with CSL that acts as repressor in the absence of ICN. The ICN mediates recruitment of MAML protein, leading to the formation of minimal transcriptional complex, MAML/ICN/CSL/DNA. Crystal structure reveals that different conformations exist between the free (CSL/DNA) and bound (ICN/MAML/CSL/DNA) forms. The significance of this modulation of the CSL/DNA molecular complex can be better understood by experimental approaches that aim to elucidate the cause and timing of these events. There are four orthologues of human ICN (ICN1-4). We studied interactions between human full-length ICN1 and CSL/DNA without involvement of MAML, in vitro, and found that 1) the EMSA profile of CSL/DNA is altered in the presence of ICN1 as a consequence of an intrinsic change(s) in CSL/DNA, and not due to the formation of an ICN/CSL/DNA molecular complex;2) ICN1 destabilizes CSL/DNA. These findings indicate that human ICN1 functions to modulate the CSL/DNA molecular complex for subsequent recruitment of MAML, and that modulated CSL/DNA cannot accommodate ICN1 in the absence of MAML. The latter in turn, implies that the formation of the MAML/ICN1/CSL/DNA is likely to be a collective event, wherein preassembly of MAML and ICN1 as a binary complex co-localizes at the CSL/DNA promoter site, or the MAML/ICN1/CSL complex is pre-assembled prior to binding to the promoter, rather than ICN1 arriving at CSL/DNA ahead of MAML and/or other associated transcription factors. The novel finding that ICN1 destabilizes the CSL/DNA complex opens new possibilities of transcriptional regulation by Notch.展开更多
文摘多能发育相关因子2和4(developmental pluripotency-associated 2 and 4,DPPA2/DPPA4)是激活类2细胞期胚胎干细胞(2-cell-like embryonic stem cells,2CL ESCs)基因组的重要调控因子,同时调控胚胎干细胞的增殖。DPPA2/DPPA4在牛早期胚胎发育过程中的功能和机制尚不清楚。本研究利用RNA干扰技术结合胚胎显微注射技术敲低牛胚胎中的DPPA2/DPPA4后发现,与阴性对照组相比,敲低组中牛胚胎的8—16细胞阶段卵裂率和囊胚阶段囊胚率无显著差异,但是囊胚总细胞数、滋养层细胞数和内细胞团细胞数均显著减少(P<0.001、P<0.05、P<0.01)。进一步通过RNA测序(RNA-sequencing,RNA-Seq)分析发现,与阴性对照组相比,敲低组的晚期桑葚胚中,NOTCH信号通路的核心转录因子RBPJ(recombination signal binding protein gene for immunoglobulin kappa J region)的表达量显著下调(P<0.05),而本课题组前期实验证明,RBPJ敲低会导致牛早期胚胎的囊胚质量严重受损。本研究结果揭示了DPPA2/DPPA4在牛着床前胚胎发育中可能通过调节RBPJ的表达来影响细胞增殖。
基金the National Natural Science Foundation of China(Nos.U1601220,82072450,and 81672118)Chongqing Science and Technology Commission-Basic Science and Frontier Technology Key Project(No.cstc2015jcyjBX0119)Chongqing Medical University Intelligent Medicine Research Project(No.ZHYX202115).
文摘Since 3D printed hard materials could match the shape of bone,cell survival and fate determination towards osteoblasts in such materials have become a popular research target.In this study,a scaffold of hardmaterial for 3D fabrication was designed to regulate developmental signal(Notch)transduction guiding osteoblast differentiation.We established a polycaprolactone(PCL)and cell-integrated 3D printing system(PCI3D)to reciprocally print the beams of PCL and cell-laden hydrogel for a module.This PCI3D module holds good cell viability of over 87%,whereas cells show about sixfold proliferation in a 7-day culture.The osteocytic MLO-Y4 was engineered to overexpress Notch ligand Dll4,making up 25%after mixing with 75%stromal cells in the PCI3D module.Osteocytic Dll4,unlike other delta-like family members such as Dll1 or Dll3,promotes osteoblast differentiation and themineralization of primary mouse and a cell line of bone marrow stromal cells when cultured in a PCI3D module for up to 28 days.Mechanistically,osteocytic Dll4 could not promote osteogenic differentiation of the primary bone marrow stromal cells(BMSCs)after conditional deletion of the Notch transcription factor RBPjκby Cre recombinase.These data indicate that osteocytic Dll4 activates RBPjκ-dependent canonical Notch signaling in BMSCs for their oriented differentiation towards osteoblasts.Additionally,osteocytic Dll4 holds a great potential for angiogenesis in human umbilical vein endothelial cells within modules.Our study reveals that osteocytic Dll4 could be the osteogenic niche determining cell fate towards osteoblasts.This will open a new avenue to overcome the current limitation of poor cell viability and low bioactivity of traditional orthopedic implants.
文摘Intracellular Notch (ICN) initiates DNA transcription in cooperation with CSL that acts as repressor in the absence of ICN. The ICN mediates recruitment of MAML protein, leading to the formation of minimal transcriptional complex, MAML/ICN/CSL/DNA. Crystal structure reveals that different conformations exist between the free (CSL/DNA) and bound (ICN/MAML/CSL/DNA) forms. The significance of this modulation of the CSL/DNA molecular complex can be better understood by experimental approaches that aim to elucidate the cause and timing of these events. There are four orthologues of human ICN (ICN1-4). We studied interactions between human full-length ICN1 and CSL/DNA without involvement of MAML, in vitro, and found that 1) the EMSA profile of CSL/DNA is altered in the presence of ICN1 as a consequence of an intrinsic change(s) in CSL/DNA, and not due to the formation of an ICN/CSL/DNA molecular complex;2) ICN1 destabilizes CSL/DNA. These findings indicate that human ICN1 functions to modulate the CSL/DNA molecular complex for subsequent recruitment of MAML, and that modulated CSL/DNA cannot accommodate ICN1 in the absence of MAML. The latter in turn, implies that the formation of the MAML/ICN1/CSL/DNA is likely to be a collective event, wherein preassembly of MAML and ICN1 as a binary complex co-localizes at the CSL/DNA promoter site, or the MAML/ICN1/CSL complex is pre-assembled prior to binding to the promoter, rather than ICN1 arriving at CSL/DNA ahead of MAML and/or other associated transcription factors. The novel finding that ICN1 destabilizes the CSL/DNA complex opens new possibilities of transcriptional regulation by Notch.
