title: Rod outer segment membrane guanylate cyclase type 1-linked stimulatory and inhibitory calcium signaling systems in the pineal gland: biochemical, molecular, and immunohistochemical evidence.
abstract: Recent evidence indicates the presence of a novel alpha(2D/A)-adrenergic receptor (alpha(2D/A)-AR) linked membrane guanylate cyclase signal transduction system in the pineal gland. This system operates via a Ca(2+)-driven rod outer segment membrane guanylate cyclase (ROS-GC). In the present study, this transduction system has been characterized via molecular, immunohistochemical, and biochemical approaches. The two main components of the system are ROS-GC1 and its Ca(2+) regulator, S100B. Both components coexist in pinealocytes where the signaling component alpha(2D/A)-AR also resides. The presence of ROS-GC2 was not detected in the pineal gland. Thus, transduction components involved in processing alpha(2D/A)-AR-mediated signals are Ca(2+), S100B, and ROS-GC1. During this investigation, an intriguing observation was made. In certain pinealocytes, ROS-GC1 coexisted with its other Ca(2+) modulator, guanylate cyclase activating protein type 1 (GCAP1). In these pinealocytes, S100B was not present. The other GCAP protein, GCAP2, which is also a known modulator of ROS-GC in photoreceptors, was not present in the pineal gland. The results establish the identity of an alpha(2D/A)-AR-linked ROS-GC1 transduction system in pinealocytes. Furthermore, the findings show that ROS-GC1, in a separate subpopulation of pinealocytes, is associated with an opposite Ca(2+) signaling pathway, which is similar to phototransduction in retina. Thus, like photoreceptors, pinealocytes sense both positive and negative Ca(2+) signals, where ROS-GC1 plays a pivotal role; however, unlike photoreceptors, the pinealocyte is devoid of the ROS-GC2/GCAP2 signal transduction system.
authors.affiliation: The Unit of Regulatory and Molecular Biology, Departments of Cell Biology and Ophthalmology, University of Medicine and Dentistry of New Jersey, Stratford, New Jersey 08084, USA.
authors.forename: V
authors.initials: V
authors.lastname: Venkataraman
authors.forename: R
authors.initials: R
authors.lastname: Nagele
authors.forename: T
authors.initials: T
authors.lastname: Duda
authors.forename: R K
authors.initials: RK
authors.lastname: Sharma
mesh_terms: D000818:Animals; D020013:Calcium Signaling / Q000235:genetics; D002135:Calcium-Binding Proteins / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology; D002417:Cattle; D004789:Enzyme Activation / Q000235:genetics; D004795:Enzyme Stability; D006162:Guanylate Cyclase / Q000037:antagonists & inhibitors* / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D051604:Guanylate Cyclase-Activating Proteins; D006358:Hot Temperature; D007150:Immunohistochemistry; D008565:Membrane Proteins / Q000037:antagonists & inhibitors / Q000096:biosynthesis / Q000737:chemistry / Q000502:physiology*; D009414:Nerve Growth Factors / Q000096:biosynthesis / Q000235:genetics / Q000502:physiology; D009419:Nerve Tissue Proteins / Q000502:physiology; D020419:Photoreceptor Cells, Vertebrate / Q000502:physiology; D010870:Pineal Gland / Q000737:chemistry / Q000166:cytology / Q000201:enzymology* / Q000378:metabolism; D018341:Receptors, Adrenergic, alpha-2 / Q000096:biosynthesis / Q000235:genetics; D011956:Receptors, Cell Surface; D012374:Rod Cell Outer Segment / Q000201:enzymology* / Q000378:metabolism / Q000502:physiology; D064568:S100 Calcium Binding Protein beta Subunit; D009418:S100 Proteins
chemical_list: D002135:Calcium-Binding Proteins; D051604:Guanylate Cyclase-Activating Proteins; D008565:Membrane Proteins; D009414:Nerve Growth Factors; D009419:Nerve Tissue Proteins; D018341:Receptors, Adrenergic, alpha-2; D011956:Receptors, Cell Surface; D064568:S100 Calcium Binding Protein beta Subunit; D009418:S100 Proteins; C110715:guanylate cyclase 1; D006162:Guanylate Cyclase