Developmental dynamics of neurotensin binding sites in the human hypothalamus during the first postnatal year

Olfactory marker protein elevates basal cAMP concentration

Olfactory marker protein (OMP), which is expressed abundantly in mature olfactory receptor neurons, operates as a cAMP-binding protein. OMP captures phasic cAMP surges induced by sensory stimuli and punctuates the downstream signalling in the cilia. On the other hand, OMP is also abundant in the soma. At equilibrium, OMP should exhibit association/dissociation reactions with cAMP. To examine the steady-state function of OMP, we expressed OMP in an HEK293 heterologous expression system and measured the activity of cAMP-dependent protein kinase (PKA) using a cAMP response element/luciferase reporter assay. In the presence of OMP, the basal activity level of PKA was elevated to approximately twice as much as that in the absence of OMP. Upon tonic stimulation by membrane-permeable cAMP, the PKA activity increased in a dose-dependent manner and was greater in the presence of OMP at all doses until saturation. These results indicate that OMP, a cytosolic cAMP-binding protein, operates as a cAMP reservoir by increases the basal cAMP concentration and enhances tonic cAMP actions. Together with the previous finding that OMP acutely sequesters cAMP-related responses, these results indicate that OMP can buffer acute surges in cAMP and tonic production, which stabilizes the basal cAMP pool in the long run.

Faraday-Cage-Type Electrochemiluminescence Immunoassay: A Rise of Advanced Biosensing Strategy

Electrochemiluminescence immunoassays are usually carried out through "on-electrode" strategy, i.e., sandwich-type immunoassay format, the sensitivity of which is restricted by two key bottlenecks: (1) the number of signal labels is limited and (2) only a part of signal labels could participate in the electrode reaction. In this Perspective, we discuss the development of an "in-electrode" Faraday-cage-type concept-based immunocomplex immobilization strategy. The biggest difference from the traditional sandwich-type one is that the designed "in-electrode" Faraday-cage-type immunoassay uses a conductive two-dimensional (2-D) nanomaterial simultaneously coated with signal labels and a recognition component as the detection unit, which could directly overlap on the electrode surface. In such a case, electrons could flow freely from the electrode to the detection unit, the outer Helmholtz plane (OHP) of the electrode is extended, and thousands of signal labels coated on the 2-D nanomaterial are all electrochemically "effective." Thus, then, the above-mentioned bottlenecks obstructing the improvement of the sensitivity in sandwich-type immunoassay are eliminated, and as a result a much higher sensitivity of the Faraday-cage-type immunoassay can be obtained. And, the applications of the proposed versatile "in-electrode" Faraday-cage-type immunoassay have been explored in the detection of target polypeptide, protein, pathogen, and microRNA, with the detection sensitivity improved tens to hundreds of times. Finally, the outlook and challenges in the field are summarized. The rise of Faraday-cage-type electrochemiluminescence immunoassay (FCT-ECLIA)-based biosensing strategies opens new horizons for a wide range of early clinical identification and diagnostic applications.