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Association of HAP1 isoforms with a unique cytoplasmic structure.

Authors: Li, SH  Gutekunst, CA  Hersch, SM  Li, XJ 
Citation: Li SH, etal., J Neurochem. 1998 Nov;71(5):2178-85.
Pubmed: (View Article at PubMed) PMID:9798945

HAP1 is a neural protein and interacts with the Huntington's disease protein huntingtin. There are at least two HAP1 isoforms, HAP1-A and HAP1-B, which have different C-terminal amino acid sequences. Here we report that both HAP1 isoforms associate with a unique cytoplasmic structure in neurons of rat brain. The HAP1-immunoreactive structure appears as an inclusion that is an oval mass of electron-dense material, 0.5-3 microm in diameter, containing many curvilinear or ring-shaped segments, and often containing electron-lucent cores. This structure is very similar to those previously termed the stigmoid body, nematosome, or botrysome. Transfection of cell lines with cDNA encoding HAP1-A, but not HAP1-B, resulted in similar HAP1-immunoreactive inclusions in the cytoplasm, suggesting that HAP1-A is essential to the formation of this structure. Yeast two-hybrid and transfection studies show that both HAP1-A and HAP1-B can self-associate, implying that native HAP1 in the cytoplasmic inclusion may be a heteromultimer of HAP1-A and HAP1-B. Coexpression of HAP1-A and HAP1-B in human embryonic kidney 293 cells demonstrates that the ratio of the expressed HAP1-A to HAP1-B regulates the formation of HAP1-associated inclusions. We propose that HAP1 isoforms are involved in the formation of HAP1-immunoreactive inclusions in the neuronal cytoplasm.


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CRRD Object Information
CRRD ID: 10047369
Created: 2015-07-11
Species: All species
Last Modified: 2015-07-11
Status: ACTIVE


RGD is funded by grant HL64541 from the National Heart, Lung, and Blood Institute on behalf of the NIH.