Discrete Control of TRPV4 Channel Function in the Distal Nephron by Protein Kinases A and C
Year: 2013
Type: article
Abstract: We have recently documented that the Ca 2+ -permeable TRPV4 channel, which is abundantly expressed in distal nephron cells, mediates cellular Ca 2+ responses to elevated luminal flow. In this study, we combined Fura-2-based [Ca 2+ ] i imaging with immunofluorescence microscopy in isolated split-opened distal nephrons of C57BL/6 mice to probe the molecular determinants of TRPV4 activity and subcellular distribution. We found that activation of the PKC pathway with phorbol 12-myristate 13-acetate significantly increased [Ca 2+ ] i responses to flow without affecting the subcellular distribution of TRPV4. Inhibition of PKC with bisindolylmaleimide I diminished cellular responses to elevated flow. In contrast, activation of the PKA pathway with forskolin did not affect TRPV4-mediated [Ca 2+ ] i responses to flow but markedly shifted the subcellular distribution of the channel toward the apical membrane. These actions were blocked with the specific PKA inhibitor H-89. Concomitant activation of the PKA and PKC cascades additively enhanced the amplitude of flow-induced [Ca 2+ ] i responses and greatly increased basal [Ca 2+ ] i levels, indicating constitutive TRPV4 activation. This effect was precluded by the selective TRPV4 antagonist HC-067047. Therefore, the functional status of the TRPV4 channel in the distal nephron is regulated by two distinct signaling pathways. Although the PKA-dependent cascade promotes TRPV4 trafficking and translocation to the apical membrane, the PKC-dependent pathway increases the activity of the channel on the plasma membrane. Background: TRPV4 mediates flow-induced [Ca 2+ ] i responses in distal nephron cells. Results: Activation of PKC augments TRPV4-mediated responses to flow. Activation of PKA promotes TRPV4 translocation to the apical membrane. Conclusion: TRPV4 activity and TRPV4 trafficking are under discrete but synergistic control of PKC- and PKA-dependent pathways. Significance: Systemic physiological stimuli may affect TRPV4-mediated mechanosensitivity in the distal nephron via PKA- and PKC-dependent mechanisms.
Source: Journal of Biological Chemistry
Language: English
Topic: Ion Channels and Receptors
Subfield: Sensory Systems
Field: Neuroscience
Domain: Life Sciences
Open Access status: hybrid
Estimated APC paid: $3,430
OpenAlex ID: W2068159421