https://twitter.com/chydorina/status/1648795519492448256 Time will tell about mast cells: Circadian control of mast cell activation
Fig 2. The circadian clock system in mammals. The mammalian circadian clock con- sists of the central oscillator, located in the suprachiasmatic nucleus (SCN) of the hy- pothalamus called “central clock”, and peripheral oscillators present in virtually all cell types, including mast cells, called “peripheral clock”. The SCN receives innervation from the retina, allowing it to be entrained by solar light/dark cycles. In turn, the SCN transmits time-of-day information to peripheral clocks via the hormonal and/or the autonomic nervous pathways. Recently, diet timing, in particular breakfast, is also shown to have ability to reset peripheral clock. This system keeps the central and peripheral clocks (e.g. a huge number of mast cells) in phase with each other and synchronizes temporal programs of physiology across many tissues.
Fig. 3. Clock-controlled genes (CCGs) in mast cells. CLOCK temporally regulates the expression of Fc?RI?, ST2, and OCT-3 through its binding to the E-box sequence in the promoter of these genes. As a result, expressions of these receptors exhibit time-of-day-dependent variation in mast cells. Specifically, Fc?RI, ST2, and OCT-3 show increased expressions in the resting phase compared with in the active phase. Consequently, in the cases of Fc?RI and ST2, high-intensity Fc?RI or ST2 signaling occurs in the resting phase whereas low-intensity Fc?RI or ST2 signaling occurs in the active phase, upon IgE or IL-33 stimulation.
Fig. 4. De-synchronization of the mast cell clockworks can affect net response of mast cell activation. De-synchronization of the mast cell clockworks by genetic and/or environmental factors such as corticosterone insufficiency in mice can dampen the rhythmicity of the circadian clockworks in mast cells at the population levels. As a net result, the intensity and temporal profiles of mast cell activation could be altered. A. When mast cell clockworks are synchronized at the population levels, expression of CCGs and mast cell activation show clear circadian rhythms as a net. B. When mast cell clockworks are de-synchronized, expression of CCGs and mast cell activation lose circadian rhythms as a net.
