title: Identification of new signaling components in the sensory epithelium of human saccule.
abstract: OBJECTIVE
  To locate components and target proteins of relevance for the cAMP and cGMP signaling networks including cAMP and cGMP phosphodiesterases (PDEs), salt-inducible kinases (SIKs), subunits of Na+, K+-ATPases, and aquaporins (AQPs) in the human saccule.
  
  
  METHODS
  The human saccule was dissected out during the removal of vestibular schwannoma via the translabyrinthine approach and immediately fixed. Immunohistochemistry was performed using PDE, SIK, Na(+), K(+)-ATPase, and AQP antibodies.
  
  
  RESULTS
  PDEs selective for cAMP (PDE4A, PDE4D, and PDE8A) and cGMP (PDE9A) as well a dual specificity PDE (PDE10A) were detected in the sensory epithelium of the saccule. Furthermore, AQP2, 4, and 9, SIK1 and the α-1 subunit of the Na(+), K(+)-ATPase were detected.
  
  
  CONCLUSIONS
  cAMP and cGMP are important regulators of ion and water homeostasis in the inner ear. The identification of PDEs and SIK1 in the vestibular system offers new treatment targets for endolymphatic hydrops. Exactly how the PDEs are connected to SIK1 and the SIK1 substrate Na(+), K(+)-ATPase and to AQPs 2, 4, 9 remains to be elucidated. The dissection of the signaling networks utilizing these components and evaluating their roles will add new basic knowledge regarding inner ear physiology.
authors: Section for Diabetes, Metabolism and Endocrinology, Department of Experimental Medical Sciences, Lund University Lund, Sweden.
authors: Eva
authors: E
authors: Degerman
authors: Uwe
authors: U
authors: Rauch
authors: Olga
authors: O
authors: Göransson
authors: Sven
authors: S
authors: Lindberg
authors: Anna
authors: A
authors: Hultgårdh
authors: Måns
authors: M
authors: Magnusson