positive regulation of calcidiol 1-monooxygenase activity

Definition

Target type: biologicalprocess

Any process that increases the rate, frequency or extent of calcidiol 1-monooxygenase activity. Calcidiol 1-monooxygenase activity is the catalysis of the reaction: calcidiol + NADPH + H+ + O2 = calcitriol + NADP+ + H2O. [GOC:BHF, GOC:dph, GOC:tb]

Positive regulation of calcidiol 1-monooxygenase activity refers to the biological processes that enhance the activity of the enzyme calcidiol 1-monooxygenase (also known as 25-hydroxyvitamin D3 1α-hydroxylase). This enzyme plays a critical role in the synthesis of calcitriol, the active form of vitamin D. Calcitriol is a steroid hormone that regulates calcium homeostasis, bone metabolism, and immune function.

The process of positive regulation of calcidiol 1-monooxygenase activity can be influenced by various factors, including:

**1. Parathyroid hormone (PTH):** PTH is a hormone secreted by the parathyroid glands in response to low blood calcium levels. It stimulates the production of calcitriol by increasing the expression and activity of calcidiol 1-monooxygenase in the kidneys.

**2. Low blood calcium levels:** Low calcium levels directly stimulate the parathyroid glands to release PTH, initiating the regulatory cascade.

**3. Hypophosphatemia:** Low phosphate levels can also stimulate PTH secretion, contributing to the upregulation of calcidiol 1-monooxygenase activity.

**4. Vitamin D deficiency:** Low levels of vitamin D can lead to a decrease in calcitriol production, triggering a compensatory increase in calcidiol 1-monooxygenase activity to maximize the production of active vitamin D from available precursors.

**5. Other factors:** Certain hormones like estrogen and growth hormone can also influence calcidiol 1-monooxygenase activity, although their specific roles in positive regulation are still under investigation.

**The molecular mechanisms involved in positive regulation of calcidiol 1-monooxygenase activity include:**

**1. Transcriptional regulation:** PTH and other regulatory factors can bind to specific DNA sequences upstream of the calcidiol 1-monooxygenase gene, activating its transcription and leading to increased enzyme synthesis.

**2. Post-translational modifications:** PTH can also activate signaling pathways that lead to phosphorylation and other post-translational modifications of the calcidiol 1-monooxygenase protein, enhancing its catalytic activity.

**3. Increased enzyme stability:** Some regulatory factors may stabilize the calcidiol 1-monooxygenase protein, preventing its degradation and prolonging its active lifespan.

In summary, positive regulation of calcidiol 1-monooxygenase activity is a complex process involving multiple factors that modulate the expression, activity, and stability of the enzyme, ultimately ensuring adequate calcitriol levels for maintaining calcium homeostasis and other vital functions.'
"

Proteins (2)

Compounds (20)