Fn Pu,Ning Chen,Shenghui Xue,?

    a La Jolla Institute of Allergy&Immunology,La Jolla,CA 92037,USA

    b Hubei Exercise Training and Monitoring Key Laboratory,Hubei Provincial Collaborative Innovation Center for Exercise and Health Promotion,College of Health Science,Wuhan Sports University,Wuhan 430079,China

    Abstract

    Keywords:Calcium;Homeostasis;Calcium sensing receptor;Dietary calcium;Vitamin D

    1.Introduction

    Calcium is the 5th of the most abundant elements in the earth crust and is also the most abundant mineral in human body.The human body contains approximately 1 kg of calcium with more than 99% deposit in the bone in the form of calcium phosphate[1].Through interacting with numerous proteins distributed in different cellular compartments,calcium is involved in a large amount of aspects of life,such as muscle contraction,enzyme activation,cell differentiation,immune response,programmed cell death and neuronal activity[1–11].Such broad functions are maintained by tightly controlled calcium concentration in extracellular fluid and cellular compartments.The concentrations of calcium in blood and extracellular fluid are usually maintained at 1–2 mmol/L,while the concentration of intracellular calcium at resting state is maintained at 100 nmol/L or less by calcium ATPase,channels,and exchangers located in plasma membrane and endoplasmic reticulum(ER)membrane[2,12].During the signaling process of calcium,the concentration of intracellular calcium is increased to approximately 100μM,which triggers calcium signaling through the activation or deactivation of an array of calcium-binding proteins.In addition,pathogens,such as bacteria and viruses,can hijack calcium signaling to benefit their own life cycles including invasion,replication and proliferation[13,14]. ......