Oocyte-Specific Homeobox 1, Obox1, Facilitates Reprogramming by Promoting Mesenchymal-to-Epithelial Transition and Mitigating Cell Hyperproliferation
STEM CELL REPORTS
Authors: Wu, Li; Wu, You; Peng, Bing; Hou, Zhenzhen; Dong, Yu; Chen, Kang; Guo, Mingyue; Li, Han; Chen, Xia; Kou, Xiaochen; Zhao, Yanhong; Bi, Yan; Wang, Yixuan; Wang, Hong; Le, Rongrong; Kang, Lan; Gao, Shaorong
Abstract
Mammalian oocytes possess fascinating unknown factors, which can reprogram terminally differentiated germ cells or somatic cells into totipotent embryos. Here, we demonstrate that oocyte-specific homeobox 1 (Obox1), an oocyte-specific factor, can markedly enhance the generation of induced pluripotent stem cells (iPSCs) from mouse fibroblasts in a proliferation-independent manner and can replace Sox2 to achieve pluripotency. Overexpression of Obox1 can greatly promote mesenchymal-to-epithelial transition (MET) at early stage of OSKM-induced reprogramming, and meanwhile, the hyperproliferation of THY1-positive cells can be significantly mitigated. Subsequently, the proportion of THY1-negative cells and Oct4-GFP-positive cells increased dramatically. Further analysis of gene expression and targets of Obox1 during reprogramming indicates that the expression of Obox1 can promote epithelial gene expression and modulate cell-cycle-related gene expression. Taken together, we conclude that the oocyte-specific factor Obox1 serves as a strong activator for somatic cell reprogramming through promoting the MET and mitigating cell hyperproliferation.
A Wireless Headstage for Combined Optogenetics and Multichannel Electrophysiological Recording
IEEE TRANSACTIONS ON BIOMEDICAL CIRCUITS AND SYSTEMS
Authors: Gagnon-Turcotte, Gabriel; LeChasseur, Yoan; Bories, Cyril; Messaddeq, Younes; De Koninck, Yves; Gosselin, Benoit
Abstract
This paper presents a wireless headstage with real-time spike detection and data compression for combined optogenetics and multichannel electrophysiological recording. The proposed headstage, which is intended to perform both optical stimulation and electrophysiological recordings simultaneously in freely moving transgenic rodents, is entirely built with commercial off-the-shelf components, and includes 32 recording channels and 32 optical stimulation channels. It can detect, compress and transmit full action potential waveforms over 32 channels in parallel and in real time using an embedded digital signal processor based on a low-power field programmable gate array and a Microblaze microprocessor softcore. Such a processor implements a complete digital spike detector featuring a novel adaptive threshold based on a Sigma-delta control loop, and a wavelet data compression module using a new dynamic coefficient re-quantization technique achieving large compression ratios with higher signal quality. Simultaneous optical stimulation and recording have been performed in-vivo using an optrode featuring 8 microelectrodes and 1 implantable fiber coupled to a 465-nm LED, in the somatosensory cortex and the Hippocampus of a transgenic mouse expressing ChannelRhodospin (Thy1:: ChR2-YFP line 4) under anesthetized conditions. Experimental results show that the proposed headstage can trigger neuron activity while collecting, detecting and compressing single cell microvolt amplitude activity from multiple channels in parallel while achieving overall compression ratios above 500. This is the first reported high-channel count wireless optogenetic device providing simultaneous optical stimulation and recording. Measured characteristics show that the proposed headstage can achieve up to 100% of true positive detection rate for signal-to-noise ratio (SNR) down to 15 dB, while achieving up to 97.28% at SNR as low as 5 dB. The implemented prototype features a lifespan of up to 105 minutes, and uses a lightweight (2.8 g) and compact (17 x 18 x 10 mm(3)) rigid-flex printed circuit board.