Dual lipidation of the brain-specific Cdc42 isoform regulates its functional properties.
Cdc42 (cell division cycle 42) is a member of the Rho GTPase family which regulates a variety of cellular activities by controlling actin cytoskeleton and gene expression. Cdc42 is expressed in the form of two splice variants. The canonical Cdc42 isoform is prenylated (Cdc42-prenyl), whereas the brainspecific isoform can be palmitoylated (Cdc42-palm). In the present study we have demonstrated palmitoylation of endogenous Cdc42 in rodent and human brains and identified Cys(188) and Cys(189) as acylation sites of Cdc42-palm. Moreover, we have shown that Cys(188) can also be prenylated. Analysis of acylation-deficient mutants revealed that lipidation of Cys(188) is essential for proper membrane binding of Cdc42-palm as well as for Cdc42-mediated regulation of gene transcription and induction of densely packed filopodia in neuroblastoma cells. We also found that Cdc42-prenyl is a dominant splice variant in a wide range of commonly used cell lines as well as in the cerebellum, whereas Cdc42-palm is the main Cdc42 isoform in hippocampus, where it is critically involved in the formation of dendritic filopodia and spines. Replacement of endogenous Cdc42 by its acylation-deficient mutants revealed the importance of Cdc42-palm lipidation for its morphogenic and synaptogenic effects in neurons. These findings demonstrate that dual lipidation of Cdc42-palm represents an important regulator of morphogenic signalling in hippocampal neurons.
*Cellular Neurophysiology, Hannover Medical School, 30625 Hannover, Germany.
Alexander
A
Wirth
Chen
C
Chen-Wacker
Yao-Wen
YW
Wu
Nataliya
N
Gorinski
Mikhail A
MA
Filippov
Ghanshyam
G
Pandey
Evgeni
E
Ponimaskin
D000818:Animals; D045744:Cell Line, Tumor; D002531:Cerebellum / Q000166:cytology / Q000378:metabolism*; D003545:Cysteine / Q000235:genetics / Q000378:metabolism; D003712:Dendrites / Q000235:genetics / Q000378:metabolism*; D006624:Hippocampus / Q000166:cytology / Q000378:metabolism*; D006801:Humans; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D054878:Lipoylation / Q000502:physiology*; D051379:Mice; D009928:Organ Specificity / Q000502:physiology; D017368:Protein Prenylation / Q000502:physiology; D011554:Pseudopodia / Q000235:genetics / Q000378:metabolism; D014158:Transcription, Genetic / Q000502:physiology; D020764:cdc42 GTP-Binding Protein / Q000235:genetics / Q000378:metabolism*
C581598:Cdc42 protein, mouse; D007527:Isoenzymes; D020764:cdc42 GTP-Binding Protein; D003545:Cysteine