paracrine signaling

Examples of paracrine signaling in the following topics:

• Forms of Signaling

  • The major types of signaling mechanisms that occur in multicellular organisms are paracrine, endocrine, autocrine, and direct signaling.
  • There are four categories of chemical signaling found in multicellular organisms: paracrine signaling, endocrine signaling, autocrine signaling, and direct signaling across gap junctions .
  • Signals that act locally between cells that are close together are called paracrine signals.
  • Paracrine signals move by diffusion through the extracellular matrix.
  • One example of paracrine signaling is the transfer of signals across synapses between nerve cells.

• Bone Remodeling

  • Osteoblasts and osteoclasts, coupled together via paracrine cell signaling, are referred to as bone remodeling units.
  • The cells also use paracrine signalling to control the activity of each other.
  • Both processes utilize cytokine (TGF-β, IGF) signalling.

• Chemistry of Hormones

  • In essence, it is a chemical messenger that transports a signal from one cell to another.
  • The hormone binds to the receptor protein, resulting in the activation of a signal transduction mechanism that ultimately leads to cell type-specific responses.
  • Endocrine hormone molecules are secreted (released) directly into the bloodstream, or simply diffuse through the interstitial spaces to nearby target tissues (paracrine signalling).

• Glandular Epithelia

  • It secretes its essential product without the use of a duct directly into the bloodstream or else by diffusion into its surrounding tissue (paracrine signaling) where it often affects only target cells near the release site.

• Stages of Bone Development

  • Osteoblasts and osteoclasts, coupled together via paracrine cell signalling, are referred to as bone remodeling unit.
  • Both processes utilize cytokine (TGF-β, IGF) signalling.

• Eicosanoids

  • The eicosanoids are signaling molecules that exert complex control over many bodily systems, mainly in inflammation or immunity.
  • In biochemistry, eicosanoids (preferred IUPAC name: icosanoids) are signaling molecules made by oxidation of 20 carbon essential fatty acids, EFAs.
  • In humans, eicosanoids are local hormones that are released by most cells, act on that same cell or nearby cells (i.e., they are autocrine and paracrine mediators), and then are rapidly inactivated.

• Target Cell Specificity

  • In essence, it is a chemical messenger that transports a signal from one cell to another.
  • Receptors are protein molecules to which one or more specific kinds of signaling molecules may attach.
  • Paracrine action: the hormone acts locally by diffusing from its source to target cells in the neighborhood.

• Mammary Glands

  • In this stage, mammary gland development depends on systemic (and maternal) hormones, but is also under the local regulation of paracrine communication between neighboring epithelial and mesenchymal cells by parathyroid hormone-related protein.
  • In gestation, serum progesterone remains at a stably high concentration so signaling through its receptor is continuously activated.
  • As one of the transcribed genes, Wnts secreted from mammary epithelial cells act paracrinely to induce more neighboring cells branching.

• Types of Cells in the Pancreas

  • The islets of Langerhans can influence each other through paracrine and autocrine communication.
  • The paracrine feedback system is based on the following correlations: the insulin hormone activates beta cells and inhibits alpha cells.

• Termination of the Signal Cascade

  • Signal cascades convey signals to the cell through the phosphorylation of molecules by kinases.
  • Ligand binding to the receptor allows for signal transduction through the cell.
  • The chain of events that conveys the signal through the cell is called a signaling pathway or cascade.
  • The aberrant signaling often seen in tumor cells is proof that the termination of a signal at the appropriate time can be just as important as the initiation of a signal.
  • Describe the process by which the signal cascade in cell communication is terminated