Zhanfeng Jia

M/K_v7 potassium channels play a key role in regulation of neuronal excitability. Modulation of neuronal excitability of primary sensory neurons determines the itch sensation induced by a variety of itch-causing substances including chloroquine (CQ). In the present study, we demonstrate that suppression of M/K_v7 channel activity contributes to generation of itch in mice. CQ enhances excitability of the primary sensory neurons through inhibiting M/K_v7 potassium currents in a Ca²⁺ influx-dependent manner. Specific M/K_v7 channel opener retigabine (RTG) or tannic acid (TA) not only reverses the CQ-induced enhancement of neuronal excitability but also suppresses the CQ-induced itch behavior. Systemic application of RTG or TA also significantly inhibits the itch behavior induced by a variety of pruritogens. Taken together, our findings provide novel insight into the molecular basis of CQ-induced itch sensation in mammals that can be applied to the development of strategies to mitigate itch behavior.

The transient receptor potential cation channel, vanilloid type (TRPV) 3, is a member of the TRPV subfamily that is expressed predominantly in the skin, hair follicles, and gastrointestinal tract. It is also distributed in the organ of Corti of the inner ear and colocalizes with TRPV1 or TRPV4, but its role in auditory function is unknown. In the present study, we demonstrate that TRPV3 is expressed in inner hair cells (HCs) but mainly in cochlear outer HCs in mice, with expression limited to the cytoplasm and not detected in stereocilia. We compared the number of HCs as well as distortion product otoacoustic emissions (DPOAE) and auditory brainstem response (ABR) thresholds between TRPV3 knockout (V3KO) and wild-type (V3WT) mice and found that although most mutants (72.3%) had normal hearing, a significant proportion (27.7%) showed impaired hearing associated with loss of cochlear HCs. Compensatory upregulation of TRPV4 in HCs prevented HC damage and kanamycin-induced hearing loss and preserved normal auditory function in most of these mice. Thus, TRPV4 and TRPV3 in cochlear HCs protect hearing in mice; moreover, the results suggest some functional redundancy in the functions of TRPV family members. Our findings provide novel insight into the molecular basis of auditory function in mammals that can be applied to the development of strategies to mitigate hearing loss.

Prostate cancer is one of the most common types of cancer affecting men worldwide; however, its etiology and pathological mechanisms remain poorly understood. Mechanical stimulation plays a key role in prostate cancer development. Piezo type mechanosensitive ion channel component 1 (Piezo1), which functions as a cell sensor and transducer of mechanical stimuli, may have a crucial role in the development of prostate cancer. In the present study, the expression of the Piezo1 channel was demonstrated to be significantly elevated in prostate cancer cell lines and in human prostate malignant tumor tissues. Downregulation of Piezo1 significantly suppressed the viability, proliferation and migration of prostate cancer cells in vitro, and inhibited prostate tumor growth in vivo. The activation of the Akt/mTOR pathway or acceleration of cell cycle progression from G0/G1 to S phase may downstream consequences of Piezo 1 signal pathway activation. Downregulation of Piezo1 considerably suppressed Ca2+ signal increments, inhibited the phosphorylation of Akt and mTOR and arrested the cell cycle of prostate cancer cells at G0/G1 phase in while inhibiting the activation of CDK4 and cyclin D1. Taken together, these findings suggest that Piezo1 channels have a crucial role in prostate cancer development and may, therefore, be a novel therapeutic target in the treatment of prostate cancer.