auditory-brainstem-response-outer-hair-cell-whole-cell-patch-clamp

Auditory Brainstem Response and Outer Hair Cell Whole-cell Patch Clamp Recording in Postnatal Rats

The outer hair cell is one of the two types of sensory hair cells in the mammalian cochlea. They alter their cell length with the receptor potential to ...

Southern Medical University

Prestin is the motor protein expressed in the cochlear outer hair cells (OHCs) of mammalian inner ear. The electromotility of OHCs driven by prestin is responsible for the cochlear amplification which is required for normal hearing in adult animals. Postnatal expression of prestin and activity of OHCs may contribute to the maturation of hearing in rodents. However, the temporal and spatial expression of prestin in cochlea during the development is not well characterized. In the present study, we examined the expression and function of prestin from the OHCs in apical, middle, and basal turns of the cochleae of postnatal rats. Prestin first appeared at postnatal day 6 (P6) for basal turn, P7 in middle turn, and P9 for apical turn of cochlea. The expression level increased progressively over the next few days and by P14 reached the mature level for all three segments. By comparison with the time course of the development of auditory brainstem response for different frequencies, our data reveal that prestin expression synchronized with the hearing development. The present study suggests that the onset time of hearing may require the expression of prestin and is determined by the mature function of OHCs.

Synchronized Progression of Prestin Expression and Auditory Brainstem Response during Postnatal Development in Rats.

Malignant gliomas (MGs) are one of the most common primary brain cancers in adults with a high mortality rate and relapse rate. Thus, finding better effective approaches to treat MGs has become very urgent. Here, we studied the effects of cryptotanshinone (CTS) on MGs in vitro and in vivo, and explored the underlying mechanisms. Effects of CTS in vitro on cell proliferation, cycle, migration and invasion were evaluated. The activation of JAK/STATs signaling was detected by western blot and immunofluorescenc staining. SHP-2 inhibitor or SiRNA were used to determine the involvement of SHP-2. The in vivo anti-MGs activity of CTS was studied with nude mice bearing intracerebral U87 xenografts. Our results revealed that CTS significantly inhibited the proliferation of MGs in vitro via inhibiting STAT3 signal pathway. The cell cycle was arrested at G0/G1 phase. Although CTS did not change the expression of total SHP-2 protein, the tyrosine phosphatase activity of SHP-2 protein was increased by CTS treatment in a dose-dependent manner in vivo and in vitro. SHP-2 inhibitor or SiRNA could reverse the inhibitory effect of CTS on phosphorylation of STAT3 Tyr705. In vivo study also showed that CTS inhibited the intracranial tumor growth and extended survival of nude mice bearing intracerebral U87 xenografts, confirming an inhibitory effect of CTS on MGs. Our results indicated CTS may be a potential therapeutic agent for MGs. The inhibitory action of CTS is largely attributed to the inhibition of STAT3 Tyr705 phosphorylation with a novel mechanism of upregulating the tyrosine phosphatase activity of SHP-2 protein.

Cryptotanshinone inhibits human glioma cell proliferation in vitro and in vivo through SHP-2-dependent inhibition of STAT3 activation.

Matrix metalloproteinases (MMPs) plays a critical role in the degradation of extracellular matrix (ECM). Sorting nexin (SNX) 10 is a member of the SNX family, which functions in regulation of endosomal sorting and osteoclast activation, has been implicated to play an important role in the bone erosion of rheumatoid arthritis. In this study, we aimed to investigate the possible role of SNX10 on MMP9 secretion and the potential mechanism. By immunostaining and co-immunoprecipitation, we found that SNX10 was extensively co-localized with MMP9, indicating that SNX10 might participate in MMP9 trafficking. After knocking down SNX10 via siRNA, the secretion and activity of MMP9 was significantly reduced, but the amount of protein was increased. By contraries, over-expression of SNX10 could increase the secretion and activity levels. Deficiency of SNX10 impaired the differentiation and bone resorption function of osteoclast, with a low activity of MMP9 compared to WT one. In SNX10 knockout osteoclast, the phosphorylation levels of JNK, p38, and ERK were obviously down-regulated. Our results first identified the role of SNX10 in MMP9 trafficking and secretion, and provided an evidence for SNX10 as a possible therapeutic target for bone destructing disease. J. Cell. Biochem. 118: 4664-4671, 2017. © 2017 Wiley Periodicals, Inc.

Cuixian Li

Department of Physiology,
School of Basic Medical Sciences,
Department of Physiology, School of Basic Medical Sciences

Southern Medical University

Auditory Brainstem Response and Outer Hair Cell Whole-cell Patch Clamp Recording in Postnatal Rats

Cuixian Li

.css-o250i3{font-size:18px;font-family:Open Sans,sans-serif;line-height:21.6px;}Department of Physiology,School of Basic Medical Sciences,Department of Physiology, School of Basic Medical Sciences

Southern Medical University

Auditory Brainstem Response and Outer Hair Cell Whole-cell Patch Clamp Recording in Postnatal Rats

Department of Physiology,
School of Basic Medical Sciences,
Department of Physiology, School of Basic Medical Sciences