Señalización de la insulina [Transporte de glucosa por GLUT4]

Insulin Signaling Pathway Overview

In this section, the video discusses the insulin signaling pathway and how insulin affects specific cells to facilitate glucose uptake.

Insulin Receptor Structure and Activation

• The insulin receptor consists of two chains, Alpha and Beta, forming dimers. Each cell has insulin receptors on its membrane.

• Insulin binds to the receptor, leading to activation. This binding triggers kinase activity within the receptor, phosphorylating tyrosine residues.

• Phosphorylation of these tyrosine residues initiates a cascade of events involving proteins like IRS1 (insulin receptor substrate 1) that detect and bind to the phosphorylated regions.

Intracellular Signaling Cascade

• IRS1 activates PI3K (phosphatidylinositol 3-kinase), which further activates PDK1 (3-phosphoinositide-dependent protein kinase-1) and subsequently PKB/Akt (protein kinase B).

• Akt activation leads to translocation of vesicles containing GLUT4 transporters to the cell membrane in adipocytes and skeletal muscle cells.

Glucose Uptake Mechanism

This part delves into how insulin-mediated signaling facilitates glucose uptake by promoting GLUT4 translocation.

Vesicle Translocation Process

• Upon Akt activation, vesicles containing GLUT4 transporters move towards the cell membrane through translocation.

• The fusion of these vesicles with the membrane allows GLUT4 transporters to be inserted into the membrane for glucose entry into cells.

Role of GLUT4 Transporter

Exploring the significance of GLUT4 transporter in facilitating glucose entry into cells under insulin influence.

Glucose Entry Facilitation

• The translocated GLUT4 transporter aids in glucose entry into cells by allowing polar glucose molecules across hydrophobic membranes.

• Insulin's role in activating this process highlights the dependency of GLUT4 on insulin for facilitating efficient glucose uptake by cells.

Insulin Signaling Pathway Overview

In this section, the speaker discusses the role of insulin in promoting the positioning of glucose transporters on cell membranes and its significance in glucose uptake.

Insulin's Role in Glucose Uptake

• Insulin promotes the placement of glucose transporters, such as Glut 4, on cell membranes, facilitating glucose entry into cells.

• Without insulin, Glut 4 would not be positioned correctly on the membrane, leading to glucose remaining outside the cell.

• In a fed state with elevated blood glucose levels, glucose enters cells for energy production through processes like glycolysis or glycogen synthesis.

• Skeletal muscle can synthesize glycogen using an important enzyme called glycogen synthase.

• Insulin activates signaling pathways that inhibit GSK3, allowing glycogen synthesis by linking glucose molecules together.

Impact of Insulin Resistance

The discussion shifts to insulin resistance and its implications on cellular processes and glucose uptake.

Consequences of Insulin Resistance

• Insulin resistance occurs when cells lose sensitivity to insulin signaling, affecting processes like protein synthesis and intracellular events.

• Impaired insulin signaling leads to improper positioning of Glut 4 transporters on cell membranes, hindering glucose uptake into cells.

• Chronic carbohydrate intake causing high insulin release can lead to receptor insensitivity and eventually type 2 diabetes due to reduced glucose uptake.

• Insulin resistance may result in hyperglycemia and potential pancreatic dysfunction similar to type 1 diabetes but stemming from different mechanisms.

Insulin as a Hormone Regulator

The role of insulin as a hormone regulator impacting various cellular functions is explored.

Functions of Insulin

• Insulin is considered a key hormone regulator that stimulates glucogenesis (glucose synthesis), crucial for maintaining blood sugar balance.