SEMA3A

SEMA3A is a member of the semaphorin family of proteins, which are known for their roles in axonal guidance, immune function, and angiogenesis. SEMA3A, specifically, is a secreted protein that acts as a chemorepellent, guiding the growth of axons and influencing the development of the nervous system.

Structure

SEMA3A is a secreted protein that belongs to the class 3 semaphorins. It is characterized by a conserved sema domain, a plexin-semaphorin-integrin (PSI) domain, and an immunoglobulin-like domain. The sema domain is crucial for its interaction with receptors and its biological activity.

Function

SEMA3A plays a critical role in the nervous system by guiding axons during development. It acts as a chemorepellent, meaning it repels axons, helping to direct them to their appropriate targets. This function is essential for the proper wiring of the nervous system.

In addition to its role in axonal guidance, SEMA3A is involved in:

• Immune Function: SEMA3A modulates immune responses by influencing the migration and function of immune cells.
• Angiogenesis: It affects the growth of blood vessels by acting on endothelial cells.
• Cancer: SEMA3A has been implicated in cancer progression, where it can either suppress or promote tumor growth depending on the context.

Receptors

SEMA3A exerts its effects by binding to receptor complexes composed of neuropilins and plexins. Neuropilin-1 (NRP1) is a primary receptor for SEMA3A, and its interaction with plexin-A1 is crucial for signal transduction.

Clinical Significance

Alterations in SEMA3A expression or function have been associated with various diseases, including:

• Neurological Disorders: Abnormal SEMA3A signaling is linked to conditions such as autism and schizophrenia.
• Cancer: Changes in SEMA3A expression can influence tumor growth and metastasis.
• Cardiovascular Diseases: SEMA3A is involved in the regulation of vascular development and function.

Research

Ongoing research is exploring the therapeutic potential of targeting SEMA3A in various diseases. For example, modulating SEMA3A activity could offer new strategies for treating cancer or neurodegenerative diseases.

Also see

• Semaphorin
• Axonal guidance
• Neuropilin
• Plexin
• Angiogenesis