%0 Journal Article
%T Phospholipase C beta 4 in mouse hepatocytes: Rhythmic expression and cellular distribution
%A Brittany M Klein
%A Jane B Andrews
%A Barbra A Bannan
%A Ashley E Nazario-Toole
%A Travis C Jenkins
%A Kimberly D Christensen
%A Sorinel A Oprisan
%A Elizabeth L Meyer-Bernstein
%J Comparative Hepatology
%D 2008
%I BioMed Central
%R 10.1186/1476-5926-7-8
%X We found that in the liver of mice housed on a light:dark cycle, PLC¦Â4 protein underwent a significant circadian rhythm with a peak occurring during the early night. In constant darkness, the protein rhythm was more robust and peaked around dusk. We also observed a significant oscillation in plc¦Â4 gene expression in the livers of mice housed in both photoperiodic and constant dark conditions. The cellular distribution of the protein in hepatocytes varied over the course of the circadian day with PLC¦Â4 primarily cytoplasmic around dusk and nuclear at dawn.Our results indicate that PLC¦Â4 gene and protein expression is regulated by a circadian clock in the mouse liver and is not dependent on the external photoperiod. A light-independent daily translocation of PLC¦Â4 implies that it may play a key role in nuclear signaling in hepatocytes and serve as a daily temporal cue for physiological processes in the liver.The phospholipase C (PLC) enzyme family participates extensively in intracellular signaling processes by catalyzing the breakdown of phosphotidylinositol bis-phosphate to generate the second messengers, inositol trisphosphate (IP3) and diacylglycerol (DAG) [1]. In turn, these signaling molecules regulate the release of intracellular calcium stores and promote the activation of protein kinase C [2]. In one PLC subfamily, the ¦Â class (¦Â1, ¦Â2, ¦Â3, ¦Â4), the enzyme is often activated by the binding of various chemical substrates to their associated G-protein coupled receptors [1]. While the tissue localization of these various PLC¦Â isoforms can be quite extensive, there are distinct differences between their distributions [1]. For example, in liver membranes, the presence of all four PLC¦Â isoforms has been examined, and only PLC¦Â1, 2 and 3 have shown to be present this tissue [3]. As far as we are aware, there has been no study to date that has provided evidence for the expression of PLC¦Â4 in liver tissue as total extracts have not been previously examined.PLC¦Â enzymes
%U http://www.comparative-hepatology.com/content/7/1/8