Fbxo45 Inhibits Calcium-sensitive Proteolysis of N-cadherin and Promotes Neuronal Differentiation

Fbxo45 is an atypical E3 ubiquitin ligase, which specifically targets proteins for ubiquitin-mediated degradation. Fbxo45 ablation results in defective neuronal differentiation and abnormal formation of neural connections; however, the mechanisms underlying these defects are poorly understood. Using...

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Veröffentlicht in:The Journal of biological chemistry 2014-10, Vol.289 (41), p.28448-28459
Hauptverfasser: Chung, Fu-Zon, Sahasrabuddhe, Anagh A., Ma, Kaiyu, Chen, Xiaofei, Basrur, Venkatesha, Lim, Megan S., Elenitoba-Johnson, Kojo S.J.
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Sprache:eng
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Zusammenfassung:Fbxo45 is an atypical E3 ubiquitin ligase, which specifically targets proteins for ubiquitin-mediated degradation. Fbxo45 ablation results in defective neuronal differentiation and abnormal formation of neural connections; however, the mechanisms underlying these defects are poorly understood. Using an unbiased mass spectrometry-based proteomic screen, we show here that N-cadherin is a novel interactor of Fbxo45. N-cadherin specifically interacts with Fbxo45 through two consensus motifs overlapping the site of calcium-binding and dimerization of the cadherin molecule. N-cadherin interaction with Fbxo45 is significantly abrogated by calcium treatment. Surprisingly, Fbxo45 depletion by RNAi-mediated silencing results in enhanced proteolysis of N-cadherin. Conversely, ectopic expression of Fbxo45 results in decreased proteolysis of N-cadherin. Fbxo45 depletion results in dramatic reduction in N-cadherin expression, impaired neuronal differentiation, and diminished formation of neuronal processes. Our studies reveal an unanticipated role for an F-box protein that inhibits proteolysis in the regulation of a critical biological process.
ISSN:0021-9258
1083-351X
DOI:10.1074/jbc.M114.561241