Date Approved


Document Type


Degree Name

PhD in Cell & Molecular Biology


Cell Biology and Neuroscience


Graduate School of Biomedical Sciences

First Advisor

Venkataswar Venkatamaran, PhD

Committee Member 1

Gary Goldberg, PhD

Committee Member 2

Robert Nagele, PhD

Committee Member 3

Joseph Martin, PhD

Committee Member 4

Bradford Fischer, PhD


Circadian Rhythm, Periodicity, Neuronal Calcium-Sensor Proteins, Neurocalcin, Molecular Chaperones


Cell Biology | Cellular and Molecular Physiology | Laboratory and Basic Science Research | Medicine and Health Sciences | Molecular and Cellular Neuroscience | Molecular Biology | Molecular Genetics


All organisms have an internal clock with a defined period between repetitions of activities. The period for circadian clock in human is 24.5 hours, while in mouse and rat, it is 23.5 hours. However, all organisms are forced to be in synchronization with their environment. A major environmental force that resets the internal clock to 24 hours is light. This phenomenon is defined as “light entrainment” or “phase-setting”. It is unclear how this entrainment process occurs. Studies from this laboratory indicate a role for two neuronal calcium sensor proteins: Neurocalcin  (NCALD) and S100B. For these two genes, mRNA as well as protein levels exhibit a light-dependent variation, which is observed both in a cell line (derived from SCN progenitors) as well as selected tissues in rats and mice. We hypothesize that the two proteins interact with each other and their ability to translocate upon a spike in intracellular calcium is critical for their function. Here, we demonstrate that NCALD and S100B interact with each other both in vivo and in vitro. The interaction is likely modulated by free calcium concentrations under both conditions. We also demonstrate that the NCALD-S100B complex translocates to a peri-nuclear, vesicle-rich location upon histamine addition in COS7 cell line, whereas the S100B-S100B complex does not. The results suggest that NCALD serves as a calcium-dependent chaperone for S100B, enabling targeting of the complex to certain intracellular locations to accomplish different tasks.