Hormones

Key Biological Properties: HCG is essential for maintaining early pregnancy. It promotes the production of progesterone by the corpus luteum, which is crucial for sustaining the uterine lining and supporting embryo implantation .

Expression Patterns and Tissue Distribution: HCG is primarily produced by the syncytiotrophoblast cells of the placenta. It can also be detected in the blood and urine of pregnant women as early as 7-9 days after fertilization .

Primary Biological Functions: HCG supports the corpus luteum, ensuring the continued production of progesterone during early pregnancy. It also promotes angiogenesis in the uterine vasculature and suppresses maternal immune responses against the developing embryo .

Role in Immune Responses and Pathogen Recognition: HCG modulates the maternal immune system to prevent rejection of the embryo. It also has roles in promoting the growth and differentiation of fetal organs .

Mechanisms with Other Molecules and Cells: HCG interacts with the luteinizing hormone/chorionic gonadotropin receptor (LHCGR) on ovarian cells, stimulating the production of progesterone. It can also activate various signaling pathways, including protein kinase C (PKC) and protein kinase A (PKA) .

Binding Partners and Downstream Signaling Cascades: HCG binds to LHCGR, leading to the activation of downstream signaling cascades that promote progesterone production and support pregnancy .

Control of Expression and Activity: The expression of HCG is regulated by several hormones, growth factors, and cytokines, including corticosteroids, progesterone, GnRH, placental growth hormone, and vascular endothelial growth factor (VEGF) .

Transcriptional Regulation and Post-Translational Modifications: HCG gene expression is influenced by transcription factors and post-translational modifications that ensure its proper function and stability .

Biomedical Research: HCG is used in research to study pregnancy and reproductive health. It is also a marker for certain types of cancer .

Diagnostic Tools: HCG is widely used in pregnancy tests and as a biomarker for pregnancy-related disorders and certain cancers .

Therapeutic Strategies: HCG injections are used in assisted reproduction treatments to induce ovulation and support early pregnancy. It is also used in the treatment of male hypogonadism and cryptorchidism .

From Development to Aging and Disease: HCG plays a crucial role in early pregnancy by supporting the corpus luteum and promoting progesterone production. Its levels peak during the first trimester and then decline. Abnormal levels of HCG can indicate pregnancy-related disorders or certain cancers .