Knock-down of JAK2 and PTEN on pain behavior in rat model of trigeminal neuropathic pain.

Trigeminal neuropathic pain is seen as a huge clinical challenge. Although numerous drugs have been developed to treat the condition, some patients have shown intolerance to the drugs and thus continue to suffer. In the present study, a rat model of trigeminal neuropathic pain was established using incorrectly positioned dental implants, which had various manifestations that were similar to human trigeminal neuropathic pain. Using this model, we investigated the differential regulation of JAK2 and PTEN. Firstly, we examined the expression of JAK2 and PTEN in the medullary dorsal horn. After inhibiting JAK2/PTEN, we evaluated nociception-related behavioral alterations. The rat models were established by replacing the left lower second molar with a mini dental implant. Immunoblot assay and immunofluorescence experiments indicated high expression of JAK2 and PTEN in medullary dorsal horn after the nerve injury, which attained plateau levels on post-operative day (POD) 5-10 and 10-20. Administration of adenovirus-shRNA-JAK2 on POD 1 reduced mechanical allodynia and downstream STAT activation. Meanwhile, the administration of adenovirus-shRNA-PTEN on POD 1 attenuated mechanical allodynia while upregulating AKT. In addition to postoperative JAK2 and PTEN activation, dexmedetomidine treatment (10 mg/kg) also modulated the downstream sensors of these signaling molecules. These data suggest that JAK2 and PTEN are pivotal to the development of trigeminal neuropathic pain, and that JAK2 and PTEN suppression alleviates the neuropathic pain.

YAP-mediated regulation of the chondrogenic phenotype in response to matrix elasticity.

Matrix elasticity exerts considerable influence on the phenotype of terminally differentiated chondrocytes via physical cues. The Yes-associated protein (YAP) transcription co-activator is recognized as a key mediator that may be involved in the nuclear transduction of physical cues controlling cellular behavior and function. However, whether substrate elasticity in the regulation of the chondrocyte phenotype is associated with YAP remains unclear. In this work, we developed micropatterned substrates with varying stiffnesses to investigate the function of YAP and its related Hippo pathway kinases in the regulation of chondrocyte phenotype on soft and stiff substrates. We found that the phenotypic variation of chondrocytes in response to substrate stiffness is concomitant with the changes in YAP localization. The downregulation of YAP expression helps to maintain the chondrogenic phenotype while inhibiting chondrocyte proliferation. Furthermore, the change in the chondrocyte phenotype response to LATS1 kinase inactivation in the Hippo pathway varies significantly between soft and stiff substrates. We also found that LATS1 kinase inactivation promotes chondrocyte dedifferentiation only on stiff substrate. Collectively, these findings reveal that YAP may be involved in the changes that occur in chondrocytes cultured on substrates with different stiffnesses and that these changes do not entirely depend on the Hippo pathway kinase LATS1. Importantly, our findings indicate that YAP inactivation is conducive to the maintenance of the chondrogenic phenotype, thereby providing new insight into articular cartilage repair and regeneration mechanisms.