MHC
MHC Class I
MHC Class I molecules are found on every nucleated cell in the body. They display protein fragments on the side of cells so that T-cells are able to distinguish healthy cells from infected cells. They are best known for their role in mediating adaptive immunity. It has been shown that they regulate activity-dependent refinement of developing visual projections, synaptic plasticity in hippocampal and cerebellar slices, and synaptic transmission in dissociated hippocampal cultures. However, it is still not known how MHC Class I molecules affect cortical development and where they act in the cortex.
One group showed using immunogold electron microscopy that MHC I proteins are found in the rat primary visual cortex throughout development, both in the presynaptic terminal (associated to synaptic vesicles) and on the postsynaptic spine or dendritic shaft, where it associates with PSD. MHCI proteins are expressed during synaptogenesis peak times and during times of activity dependent plasticity. However, there is a significant decrease in expression after P7 into adulthood. If MHC I works by marking synapses for destabilization before elimination, then the results imply that more synapse are eliminated during the initial establishment of connections than during later refinement periods.1
Related Pages
Abnormal Cellular/Synaptic Growth Hypothesis
Citations
1. Needleman LA et. al. MHC class I molecules are present both pre- and postsynaptically in the visual cortex during postnatal development and in adulthood.Proc Natl Acad Sci U S A. 2010 Sep 28;107(39):16999-7004. PMID 20837535
