TYPES OF CELL SIGNALING(with specific example of each)

PRESENTED BY-NEHA MAYACH

M.Sc. LIFE SCIENCES(3rd semester)

CENTRAL UNIVERSITY OF GUJARAT DATE- 11.08.2015

CONTENT• Introduction of cell signaling• Its need• Brief history• Types of cell signaling- 1. Autocrine2. Paracrine3. Endocrine• Recapitulation• Review article using types of cell signaling• Reference

CELL SIGNALLING- (Brief History)

• In 1970, Martin Rodbell examined effects of glucagon on rat's liver cell membrane receptor.

• He revealed about guanosine triphosphate and stimulated G-protein role in cell's metabolism.

AUTOCRINEcells respond to substances which they themselves release and thus changes takes place in the cell itself

EXAMPLE:-• Tumour cells

release growth factors for their own survival and proliferation

ENDOCRINE Signaling over long distance

Signal molecules(hormones) secreted by glands

Bloodstream carries hormones far and wide may lie anywhere in the body

EXAMPLE:-Epinephrine-

amino acid derivative(of tyrosine)

hydrophilic signaling molecule (bind to G protein coupled receptor)

Released from Adrenal medulla

FUNCTION-

Acts on LIVER cells to increase

blood glucose

level

Glycogen breakdown

Gluconeogenesis(glucose from pyruvate)

Glycogen breakdown Glycolysis(more ATP) Beta Oxidation(breakdown of fatty acid for energy)

Acts on MUSCLE cells to make ATP-

FIGHT OR FLIGHT(The physiological response to a threatening situation, which readies one either to resist forcibly or to run away)

• Muscle needs energy!

• So liver makes glucose and muscle breaks glucose down to ATP.

• Available for use to fight and flight.

7TM receptor(serpentine receptor)Made up of single polypeptide

PARACRINESignaling molecules released by a secretory cell affectonly those target cells in close proximity

•For paracrine signals to act locally , secreted molecules must not be allowed to diffuse to far.

•Rapidly taken up by neighboring target cells or immobilized by ECM.

EXAMPLES:-• conduction by a neurotransmitter of a signal from one nerve

cell to another or from a nerve cell to a muscle cell

• Mostly studies neurotransmitters-

NEURO-MUSCULAR JUNCTION

Chemically gated receptors or Ion channel receptors

ION GATED CHANNELFundamental task of neuron-to

receive, conduct, transmit signals.

Neurons are excitable cells, have ability to respond to stimulus by producing an electrical signal.

Nerve impulse propagates at speed ranging from 0.5 to 130 ms.

REVIEW ARTICLE Autocrine insulin-like growth factor-I signaling promotes growth survival of human acute myeloid leukemia cells via the phosphoinositide 3-kinase/Akt pathway

• role for autocrine IGF-I signaling in the growth and survival of primary AML cells.

• IGF-IR inhibitors in combination with chemotherapeutic agents may represent a novel approach to target human AML(Acute myeloid leukemia)

RECAPITULATEAUTOCRINE CELL SIGNALING- normal cell ,cancer cell

ENDOCRINE CELL SIGNALING- epinephrine, GPCR, G protein, adenylate cyclase, cAMP fight and flight response

PARACRINE CELL SIGNALING- Neurotransmitter, neuro-muscular transmitter, ion gated channels

REFERENCES:-I. THE CELL- Geoffrey M.Cooper and Robert E.Hausman (5th edition)

II. BIOCHEMISTRY- Lubert Stryer (6th edition)

III. THE CELL- Alberts (5th edition)

IV. Review(Nature) Leukemia (2007) Nature Publishing Group www.nature.com/leu

THANK YOU