Characterization of the microRNA transcriptomes and proteomics of cochlear tissue-derived small extracellular vesicles from mice of different ages after birth.

The cochlea is an important sensory organ for both balance and sound perception, and the formation of the cochlea is a complex developmental process. The development of the mouse cochlea begins on embryonic day (E)9 and continues until postnatal day (P)21 when the hearing system is considered mature. Small extracellular vesicles (sEVs), with a diameter ranging from 30 to 200 nm, have been considered a significant medium for information communication in both physiological and pathological processes. However, there are no studies exploring the role of sEVs in the development of the cochlea. Here, we isolated tissue-derived sEVs from the cochleae of FVB mice at P3, P7, P14, and P21 by ultracentrifugation. These sEVs were first characterized by transmission electron microscopy, nanoparticle tracking analysis, and western blotting. Next, we used small RNA-seq and mass spectrometry to characterize the microRNA transcriptomes and proteomes of cochlear sEVs from mice at different ages. Many microRNAs and proteins were discovered to be related to inner ear development, anatomical structure development, and auditory nervous system development. These results all suggest that sEVs exist in the cochlea and are likely to be essential for the normal development of the auditory system. Our findings provide many sEV microRNA and protein targets for future studies of the roles of cochlear sEVs.

Self-Driven Infrared Electrochromic Device with Tunable Optical and Thermal Management.

Electrochromic devices (ECDs) exhibiting tunable optical and thermal modulation in the infrared (IR) region have attracted extensive attention in recent years due to their attractive application prospects in both military and civilian settings. However, considering the continuous energy supply needed for driving the device operation, it is desired to develop advanced IR-ECDs with low energy consumption. Herein, a flexible self-driven IR-ECD is constructed for achieving variable optical and thermal management in a low-energy mode. In this device, a built-in potential difference of 1.36 V exists between the EC polyaniline cathode and the aluminum foil anode. Consequently, there is a rapid and obvious increase in the IR reflectance of the device after connecting the two electrodes. Such a self-driven reflectance contrast is over 20% at the wavelength of 1500 nm, and the coloration efficiency of the device reaches up to 93.6 cm2 C-1. Meanwhile, the maximum apparent temperature modulation on the surface of the device reaches up to 5.6 °C. Then, the self-driven IR-ECD could recover to its original state driven by a solar cell, indicating good reversibility and stability. We anticipate that this work may provide a new insight into developing advanced self-driven IR-ECDs for applications in dynamic military camouflage and commercial thermal control.

The Expression and Roles of the Super Elongation Complex in Mouse Cochlear Lgr5+ Progenitor Cells.

The super elongation complex (SEC) has been reported to play a key role in the proliferation and differentiation of mouse embryonic stem cells. However, the expression pattern and function of the SEC in the inner ear has not been investigated. Here, we studied the inner ear expression pattern of three key SEC components, AFF1, AFF4, and ELL3, and found that these three proteins are all expressed in both cochlear hair cells (HCs)and supporting cells (SCs). We also cultured Lgr5+ inner ear progenitors in vitro for sphere-forming assays and differentiation assays in the presence of the SEC inhibitor flavopiridol. We found that flavopiridol treatment decreased the proliferation ability of Lgr5+ progenitors, while the differentiation ability of Lgr5+ progenitors was not affected. Our results suggest that the SEC might play important roles in regulating inner ear progenitors and thus regulating HC regeneration. Therefore, it will be very meaningful to further investigate the detailed roles of the SEC signaling pathway in the inner ear in vivo in order to develop effective treatments for sensorineural hearing loss.

Characterization of Strip1 Expression in Mouse Cochlear Hair Cells.

Striatin-interacting protein 1 (Strip1) is a core component of the striatin interacting phosphatase and kinase (STRIPAK) complex, which is involved in embryogenesis and development, circadian rhythms, type 2 diabetes, and cancer progression. However, the expression and role of Strip1 in the mammalian cochlea remains unclear. Here we studied the expression and function of Strip1 in the mouse cochlea by using Strip1 knockout mice. We first found that the mRNA and protein expression of Strip1 increases as mice age starting from postnatal day (P) 3 and reaches its highest expression level at P30 and that the expression of Strip1 can be detected by immunofluorescent staining starting from P14 only in cochlear HCs, and not in supporting cells (SCs). Next, we crossed Strip1 heterozygous knockout (Strip +/-) mice to obtain Strip1 homozygous knockout (Strip1-/-) mice for studying the role of Strip1 in cochlear HCs. However, no Strip1-/- mice were obtained and the ratio of Strip +/- to Strip1+/+ mice per litter was about 2:1, which suggested that homozygous Strip1 knockout is embryonic lethal. We measured hearing function and counted the HC number in P30 and P60 Strip +/- mice and found that they had normal hearing ability and HC numbers compared to Strip1+/+ mice. Our study suggested that Strip1 probably play important roles in HC development and maturation, which needs further study in the future.