Co-expression of C/EBPγ and ATF5 in mouse vomeronasal sensory neurons during early postnatal development.

The differentiation of sensory neurons involves gene expression changes induced by specific transcription factors. Vomeronasal sensory neurons (VSNs) in the mouse vomeronasal organ (VNO) consist of two major subpopulations of neurons expressing vomeronasal 1 receptor (V1r)/Gαi2 or vomeronasal 2 receptor (V2r)/Gαo, which differentiate from a common neural progenitor. We previously demonstrated that the differentiation and survival of VSNs were inhibited in ATF5 transcription factor-deficient mice (Nakano et al. Cell Tissue Res 363:621-633, 2016). These defects were more prominent in V2r/Gαo-type than in V1r/Gαi2-type VSNs; however, the molecular mechanisms responsible for the differentiation of V2r/Gαo-type VSNs by ATF5 remain unclear. To identify a cofactor involved in ATF5-regulated VSN differentiation, we investigated the expression and function of CCAAT/enhancer-binding protein gamma (C/EBPγ, Cebpg), which is a major C/EBP family member expressed in the mouse VNO and dimerizes with ATF5. The results obtained showed that C/EBPγ mRNAs and proteins were broadly expressed in the postmitotic VSNs of the neonatal VNO, and their expression decreased by the second postnatal week. The C/EBPγ protein was expressed in the nuclei of approximately 70% of VSNs in the neonatal VNO, and 20% of the total VSNs co-expressed C/EBPγ and ATF5 proteins. We examined the trans-acting effects of C/EBPγ and ATF5 on V2r transcription and found that the co-expression of C/EBPγ and ATF5, but not C/EBPγ or ATF5 alone, increased Vmn2r66 promoter reporter activity via the C/EBP:ATF response element (CARE) in Neuro2a cells. These results suggest the role of C/EBPγ on ATF5-regulated VSN differentiation in early postnatal development.

Activating transcription factor 5 (ATF5) is essential for the maturation and survival of mouse basal vomeronasal sensory neurons.

Activating transcription factor 5 (ATF5) is a member of the CREB/ATF family of transcription factors, which is highly expressed in olfactory chemosensory tissues, the main olfactory epithelium and vomeronasal epithelium (VNE) in mice. The vomeronasal sensory neurons in the VNE detect pheromones in order to regulate social behaviors such as mating and aggression; however, the physiological role of ATF5 in the vomeronasal sensory system remains unknown. In this study, we found that the differentiation of mature vomeronasal sensory neurons, assessed by olfactory marker protein expression, was inhibited in ATF5-deficient VNE. In addition, many apoptotic vomeronasal sensory neurons were evident in ATF5-deficient VNE. The vomeronasal sensory neurons consist of two major types of neuron expressing either vomeronasal 1 receptor (V1r)/Gαi2 or vomeronasal 2 receptor (V2r)/Gαo. We demonstrated that the differentiation, survival and axonal projection of V2r/Gαo-type rather than V1r/Gαi2-type vomeronasal sensory neurons were severely inhibited in ATF5-deficient VNE. These results suggest that ATF5 is one of the transcription factors crucial for the vomeronasal sensory formation.

Analysis of long-term internal stress and film structure of SiO2 optical thin films.

Recently, the demand for durability of optical thin films, which have long been used, has been growing as the performance of optical components improves. The stress of a film is an important parameter that is related to its adhesion. The electron beam (EB) and ion-assisted deposition (IAD) methods are widely used to fabricate optical thin films. However, there are few reports on long-term internal stress, despite the importance of this issue. Here we discuss the time dependence of the stress of SiO2 optical thin films in terms of optical characteristics in the infrared region. It was found that SiO2 thin films prepared by the EB and IAD methods exhibited compression stress. The Si-OH molecular bond was observed at around 930 cm(-1) in the Fourier transform infrared spectroscopy spectrum of the sample prepared by the EB method, which exhibited a large change in internal stress after an elapsed time. It is considered that this change in bonding was related to the decrease in the stress of the films.