Browsing pathways

Corticotropin is a polypeptide tropic hormone produced and secreted by the anterior pituitary gland. It is produced from the cleavage of pre-pro-opiomelanocortin by various endopeptidases, along with other physiologically active peptide fragments such as β-lipotropin, γ-lipotropin, Melanocyte Stimulating Hormone (MSH) and β-endorphin. It is an important component of the hypothalamic-pituitary-adrenal axis and is often produced in response to biological stress. Its principal effects are increased production of androgens and cortisol from the adrenal cortex. The ACTHR receptor activates G(s) proteins which lead to the activation of Adenylyl cyclase which produces the secondary messenger cAMP. cAMP activates PKA (Protein Kinase A) which phosphorylates down stream effectors that lead to androgen and cortisol production.

The 5-HT4 receptor is primarily found in the CNS, GI tract and PNS. Peripheral receptors have important roles in the function of many organ responses (alimentary tract, urinary bladder, heart and adrenal gland). Alimentary tract receptors have a role in smooth muscle tone, mucosal electrolyte secretion, and the peristaltic reflex. Urinary Bladder receptors control cholinergic/purinergic transmission. Atrial heart receptors produce positive inotropy and tachycardia that can precipitate arrhythmias. This receptor is also thought to have roles in Anxiety, Appetite, GI Motility, Learning, Memory, Mood, and Respiration. The 5-HT4 receptor activates G(s) proteins which lead to the activation of Adenylyl cyclase which produces the secondary messenger cAMP. cAMP activates PKA (Protein Kinase A) which phosphorylates down stream effectors that lead to a specific cellular response.

The 5-HT6 receptor is primarily expressed in the brain and is involved in glutamatergic and cholinergic neuronal activity. The 5-HT6 receptor activates G(s) proteins which lead to the activation of Adenylyl cyclase which produces the secondary messenger cAMP. cAMP activates PKA (Protein Kinase A) which phosphorylates down stream effectors that lead to a specific cellular response.

The 5-HT7 receptor is primarily found in the CNS, GI tract and Blood Vessels. It is involved in thermoregulation, circadian rhythm, learning and memory, and sleep. It is also speculated that this receptor may be involved in mood regulation. The 5-HT7 receptor activates G(s) proteins which lead to the activation of Adenylyl cyclase which produces the secondary messenger cAMP. cAMP activates PKA (Protein Kinase A) which phosphorylates down stream effectors that lead to a specific cellular response.

Insulin is responsible for the regulation of glucose levels in the body. It stimulates the storage of energy and inhibits the breakdown of high energy metabolites. Glycogen and lipid biosynthesis is unregulated and conversely glycogen and Fatty acid metabolism is down regulated. Insulin also modulates transcription and translation. Binding of Insulin to the Insulin receptor (IR) results in the activation of its tryrosine kinase activity leading to IR autophosphorylation. IR then phosphorylates several substrates that lead to the activation of an intracellular signaling cascade. IR activation leads to the activation of H-Ras, MAPK1-3 and PI3-kinase pathways. The activation of these pathways leads to modulation of key proteins in glycogen metabolism / lipid metabolism and transcription / translation.

The A2A receptor is responsible for regulating myocardial blood flow by vasodilating the coronary arteries, which increases blood flow to the myocardium, but may lead to hypotension. The A2A receptor is also expressed in the brain, where it has important roles in the regulation of glutamate and dopamine release. The Adenosine receptor A2a activates G(s) proteins which lead to the activation of Adenylyl cyclase which produces the secondary messenger cAMP. cAMP activates PKA (Protein Kinase A) which phosphorylates down stream effectors that lead to a specific cellular response. This occurs though activation of the MAPK/ERK signaling cascade.

Adenosine is thought to play a role in the pathophysiology of asthma. Stimulation of A2B can induce production of interleukin-8 Mast cells. The Adenosine receptor A2b activates G(s) proteins which lead to the activation of Adenylyl cyclase which produces the secondary messenger cAMP. cAMP activates PKA (Protein Kinase A) which phosphorylates down stream effectors that lead to a specific cellular response. This occurs though activation of the MAPK/ERK signaling cascade.

In the ovary, the FSH receptor is necessary for follicular development and is expressed on the granulosa cells. In the male the FSH receptor has been identified on the Sertoli cells that are critical for spermatogenesis. The FSH receptor activates G(s) proteins which lead to the activation of Adenylyl cyclase which produces the secondary messenger cAMP. cAMP activates PKA (Protein Kinase A) which phosphorylates down stream effectors that lead to a specific cellular response.

Histamine is a ubiquitous messenger molecule released from mast cells, enterochromaffin-like cells, and neurons. Its various actions are mediated by histamine receptors H1, H2, H3 and H4. Histamine receptor H2 belongs to the family 1 of G protein-coupled receptors. It is an integral membrane protein and stimulates gastric acid secretion. It also regulates gastrointestinal motility and intestinal secretion and is thought to be involved in regulating cell growth and differentiation. The H2 receptor activates G(s) proteins which lead to the activation of Adenylyl cyclase which produces the secondary messenger cAMP. cAMP activates PKA (Protein Kinase A) which phosphorylates down stream effectors that lead to a specific cellular response.

Its activation is necessary for the hormonal functioning during reproduction. LHCGRs are found in the ovary, testis, and many extragonadal tissues.In the ovary, the LHCG receptor is necessary for follicular maturation and ovulation, as well as luteal function. In the male the LHCGR has been identified on the Leydig cells that are critical for testosterone production, and support spermatogenesis. The LHCGRs receptor activates G(s) proteins which lead to the activation of Adenylyl cyclase which produces the secondary messenger cAMP. cAMP activates PKA (Protein Kinase A) which phosphorylates down stream effectors that lead to a specific cellular response.