  Thermogenesis is a physiological activity of releasing heat that originates
from intracellular biochemical reactions. Recent experimental studies
discovered that externally applied heat changes intracellular signaling
locally, resulting in global changes in cell morphology and signaling.
Therefore, we hypothesize an inevitable contribution of thermogenesis in
modulating biological system functions throughout the spatial scales from
molecules to individual organisms. One key issue examining the hypothesis,
namely, the "trans-scale thermal signaling," resides at the molecular scale on
the amount of heat released via individual reactions and by which mechanism the
heat is employed for cellular function operations. This review introduces
atomistic simulation tool kits for studying the mechanisms of thermal signaling
processes at the molecular scale that even state-of-the-art experimental
methodologies of today are hardly accessible. We consider biological processes
and biomolecules as potential heat sources in cells, such as ATP/GTP hydrolysis
and multiple biopolymer complex formation and disassembly. Microscopic heat
release could be related to mesoscopic processes via thermal conductivity and
thermal conductance. Additionally, theoretical simulations to estimate these
thermal properties in biological membranes and proteins are introduced.
Finally, we envisage the future direction of this research field.
