NAIP (gene)

NAIP, or Neuronal Apoptosis Inhibitory Protein, is a human gene that encodes a protein belonging to the Inhibitor of Apoptosis Protein (IAP) family. IAPs are a group of structurally and functionally related proteins involved in regulating apoptosis, or programmed cell death.

Function:

The NAIP protein functions as an anti-apoptotic factor, meaning it helps prevent cells from undergoing apoptosis. It achieves this by binding to and inhibiting the activity of caspases, a family of cysteine proteases that play a central role in the execution phase of apoptosis. Specifically, NAIP is thought to inhibit caspase-9, an initiator caspase, and caspase-3, an effector caspase, preventing the apoptotic cascade from proceeding. NAIP also interacts with other proteins involved in cell survival and death pathways.

Location:

In humans, the NAIP gene is located on chromosome 5q13.2, a region frequently deleted in individuals with Spinal Muscular Atrophy (SMA).

Role in Spinal Muscular Atrophy (SMA):

NAIP is one of the survival motor neuron (SMN) regulator genes, and its deletion or mutation is associated with a more severe form of SMA, particularly SMA Type I, the most severe and common form. While the primary cause of SMA is mutations or deletions in the SMN1 gene, the absence of functional NAIP protein can exacerbate the severity of the disease. It is believed that the loss of NAIP contributes to the increased neuronal cell death observed in SMA patients, particularly motor neurons in the spinal cord, leading to muscle weakness and atrophy. The number of copies of the NAIP gene present in an individual can influence the disease phenotype, with fewer copies correlating with a more severe prognosis.

Other Functions:

Beyond its role in SMA, NAIP may have other functions in neuronal development, maintenance, and protection. Research suggests it could also play a role in other neurodegenerative diseases, cancer, and immune responses.