beta-1 integrin

Examples of beta-1 integrin in the following topics:

• Mammary Glands

  • The binding of laminin and collagen in the myoepithelial basement membrane with beta-1 integrin on the epithelial surface insures correct placement of prolactin receptors on basal lateral side of alveoli cells and directional secretion of milk into lactiferous ducts.
  • Cross-section of the mammary-gland. 1.

• Basement Membranes and Diseases

  • The electron-dense lamina densa membrane is about 30–70 nanometers in thickness, and consists of an underlying network of reticular collagen (type IV) fibrils (fibroblast precursors) which average 30 nanometers in diameter and 0.1–2 micrometers in thickness.
  • This is an inherited connective tissue disease causing blisters in the skin and mucosal membranes, with an incidence of 1/50,000.
  • It is caused by a mutation in the integrin α6β4 cell-adhesion molecule on either the alpha or beta subunit.

• Type 1 Diabetes Mellitus

  • Diabetes mellitus type 1 results from autoimmune destruction of insulin-producing beta cells of the pancreas and is potentially fatal.
  • Diabetes mellitus type 1 (Type 1 diabetes, T1DM, formerly insulin-dependent or juvenile diabetes) is a form of diabetes mellitus that results from autoimmune destruction of insulin-producing beta cells of the pancreas.
  • Most people who develop type 1 are otherwise healthy.
  • The pathophysiology in diabetes type 1 is basically a destruction of beta cells in the pancreas, regardless of which risk factors or causative entities have been present.
  • Type 1 diabetes is not currently preventable.

• Types of Cells in the Pancreas

  • Beta cells that produce insulin and amylin, and make up 65–80% of the total islet cells.
  • Epsilon cells that produce ghrelin, and make up less than 1% of the total islet cells.
  • The hormone glucagon activates alpha cells which then activate beta cells and delta cells.
  • The right image is the same section stained by immunofluorescence against insulin, indicating beta cells.

• Overview of Pancreatic Islets

  • Beta cells that produce insulin and amylin and make up 65–80% of the total islet cells.
  • Epsilon cells that produce ghrelin and make up less than 1% of the total islet cells.
  • Insulin activates beta cells and inhibits alpha cells, while glucagon activates alpha cells, which activates beta cells and delta cells.
  • Somatostatin inhibits the activity of alpha cells and beta cells.
  • The small cells in the middle are beta cells, and the surrounding larger cells are alpha, delta, gamma, and epsilon cells.

• Alzheimer's Disease

  • Alzheimer's is predicted to affect 1 in 85 people globally by 2050.
  • The cause for most Alzheimer's cases is still essentially unknown (except for 1% to 5% of cases where genetic differences have been identified).
  • In 1991, the amyloid hypothesis postulated that amyloid beta (Aβ) deposits are the fundamental cause of the disease.
  • In 2009, this theory was updated, suggesting that a close relative of the beta-amyloid protein, and not necessarily the beta-amyloid itself, may be a major culprit in the disease.
  • In this model, beta-amyloid plays a complementary role, by depressing synaptic function.

• Inflammation

  • Other inflammatory mediators, such as TNF-alpha and IL-1, increase the expression of adhesion molecules on vascular endothelial cells.
  • Then integrins firmly attach to the adhesion molecules on the endothelial cells, which is called adhesion.
  • The next step is for neutrophils to squeeze through the gaps in the endothelium into the tissues through binding with PECAM-1 expressed on the endothelium, a process called extravasion.

• Blood Plasma

  • It is an aqueous solution containing about 90% water, 8% soluble blood plasma proteins, 1% electrolytes, and 1% elements in transit.
  • Globulins are a diverse group of proteins designated into three groups, gamma, alpha, and beta, based on how far they move during electrophoresis tests.
  • For example, the beta globulin transferrin can transport iron.
  • Alpha globulins are notable for inhibiting certain proteases, while beta globulins often function as enzymes in the body.

• Early Pregnancy Tests

  • Most chemical tests for pregnancy look for the presence of the beta subunit of hCG or human chorionic gonadotropin in the blood or urine. hCG can be detected in urine or blood after implantation, which occurs six to 12 days after fertilization.
  • Quantitative blood (serum beta) tests can detect hCG levels as low as 1 mIU/mL, while urine test strips have published detection thresholds of 20 mIU/mL to 100 mIU/mL, depending on the brand.

• Direct Gene Activation and the Second-Messenger System

  • The G-protein is bound to the inner membrane of the cell and consists of three sub-units: alpha, beta, and gamma.
  • Upon binding to the receptor, it releases a GTP molecule, at which point the alpha sub-unit of the G-protein breaks free from the beta and gamma sub-units and is able to move along the inner membrane until it contacts another membrane-bound protein: the primary effector. 
  • General schematic of second messenger generation following activation of membrane bound receptors. 1.