Cell Signalling

Figure source: uk/teaching/courses/mo dules/Ercs.html Figure source: uk/teaching/courses/mo dules/Ercs.html

Signal transduction refers to how the presence of an extracellular signal can produce a change in the intracellular state of the cell without the initial signal crossing the membrane. Signaling is about communication between different groups of cells and tissues…how one group of cells informs another group of cells what to do.

Signal transduction systems Ca 2+ /calmodulin adenylate cyclase/cAMP NO PLC/PKC PI/IP 3 /DAG membrane receptors G proteins steroid hormones Signal transduction systems Ca 2+ /calmodulin adenylate cyclase/cAMP NO PLC/PKC PI/IP 3 /DAG membrane receptors G proteins steroid hormones

Cell Signaling Case Study: Secretion of insulin from pancreas  cells Insulin is secreted in response to elevated blood concentrations of glucose.

Glucose metabolism produces cellular ATP, which closes the ATP-sensitive potassium channel; then the voltage-dependent L-type Ca 2+ channels open. Ca 2+ from the extracellular space (and intercelluar stores) leads to the exocytosis of insulin. Glucose metabolism produces cellular ATP, which closes the ATP-sensitive potassium channel; then the voltage-dependent L-type Ca 2+ channels open. Ca 2+ from the extracellular space (and intercelluar stores) leads to the exocytosis of insulin.

How does glucose stimulate insulin secretion from  cells of the pancreas?

Exocytosis Case Study: Secretion of insulin from pancreas  cells Exocytosis Case Study: Secretion of insulin from pancreas  cells In diabetes mellitus, insulin secretion by ß-cells of islets of Langerhans is deficient or absent. Cultured Mouse Pancreatic Islets (10x magnification). Provided by David Zhiyong Gao, Ph.D. Insulin is a peptide hormone that regulates glucose uptake and metabolism.

Mistletoe extract (Viscum album) has a long history as a traditional treatment for diabetes. Mistletoe exerts its antidiabetic effect by stimulating insulin secretion.

Mistletoe extract (Viscum album) has long been used as a traditional treatment for diabetes. Mistletoe Exerts Its Antidiabetic Effect by Stimulating Insulin Secretion

The phospholipase C (PLC)/ protein kinase C (PKC) signal transduction system. The phospholipase C (PLC)/ protein kinase C (PKC) signal transduction system.

1.Compare and contrast the structures of preproinsulin, proinsulin and insulin. 2.Delineate the sequence of events from transcription of the preproinsulin gene to exocytosis of insulin. 3.List the five steps associated with the synthesis of preproinsulin and its conversion to proinsulin. 4.Describe the mechanisms by which glucose promotes insulin secretion and biosynthesis via ATP closing K+ channels and via diacylglycerol (DAG). 5.Discuss the mechanism by which DAG mediates the ability of muscarinic agonists to promote insulin secretion and biosynthesis. 6.Compare and contrast the effects and mechanism of action of glucagon and epinephrine on insulin secretion. 7.Identify the components of insulin release that are defective in types I and II diabetes mellitus.