Cloning and characterization of PAK5, a novel member of mammalianp21-activated kinase-II subfamily that is predominantly expressed in brain

Abstract

The p21-activated kinase (PAK) family of protein kinases has recently attracted considerable attention as an eector of Rho family of small G proteins and as an upstream regulator of MAPK signalling pathways during cellular events such as re-arrangement of the cytoskeleton and apoptosis. We have cloned a novel human PAK family kinase that has been designated as PAK5. PAK5 contains a CDC42/Rac1 interactive binding (CRIB) motif at the N-terminus and a Ste20-like kinase domain at the C-terminus. PAK5 is structurally most related to PAK4 and PAK6 to make up the PAK-II subfamily. We have shown that PAK5 preferentially binds to CDC42 in the presence of GTP and that CRIB motif is essential for this interaction. PAK5 is a functional protein kinase but unlike PAK-I family kinases (PAK1, 2, and 3), the kinase activity of PAK5 does not seem to require the binding of CDC42. Overexpression of PAK5 activates the JNK kinase pathway but not p38 or ERK pathways. PAK5 transcript is predominantly expressed in brain as revealed by Northern blot and in situ hybridization. The expression pattern of PAK5 is distinct from that of PAK4 and PAK6, suggesting a functional division among PAK-II subfamily kinases based on dierential tissue distribution.

PAK5 Kinase Is an Inhibitor of MARK/Par-1, Which Leads to Stable Microtubules and Dynamic Actin

“…For example, MARK isoforms are involved not only in regulating microtubule dynamics and the Par cell polarity determinants but also in Wnt signaling (Sun et al, 2001), and the upstream kinase MARKK/TAO-1 activates the p38 stress pathway by phosphorylating MEK3 and MEK6 (Hutchison et al, 1998). On the other hand, PAK5 is not only involved in remodelling the actin cytoskeleton, but also in inducing the JNK stress pathway Pandey et al, 2002) and in the apoptotic pathway (Cotteret et al, 2003). It is interesting to note that the two kinases whose interaction we have studied in the context of the cytoskeleton also have a relationship to the cell's stress response.…”

“…Nucleotide sequence analysis revealed 10 positive clones encoding the cytosolic scaffold proteins 14-3-3 , 14-3-3␤ and a fragment of the catalytic domain of the protein kinase PAK5 (residues 502-719). This kinase is a member of the mammalian p21-activated kinase-II subfamily and is predominantly expressed in brain Pandey et al, 2002;). For further experiments the full-length PAK5-cDNA was cloned from the human fetal brain library by PCR.…”

“…In neuroblastoma cells, PAK5 induces filopodia, neurite outgrowth, and dendritic spines Bryan et al, 2004). It has a mainly cytosolic distribution where it can activate the JNK kinase pathway Pandey et al, 2002). In conjunction with mitochondria, PAK5 can phosphorylate BAD and inhibit apoptosis (Cotteret et al, 2003).…”

“…The PAKs can be subdivided into group I (PAK1, 2, 3) and group II (PAK4, 5, 6). PAK5, the most recently characterized member, contains 719 residues, binds Cdc42, and occurs mainly in the brain Pandey et al, 2002). It contains a CRIB motif around residues 9 -30 and an inhibitory KI motif around residues 120 -133 (Ching et al, 2003).…”

P21‐activated kinase 5 is overexpressed during colorectal cancer progression and regulates colorectal carcinoma cell adhesion and migration

“…PAK4 was found to be overexpressed in 78% of a variety of human cancer cell lines, 12 whereas PAK5 and PAK6 showed restricted tissue-specific expression patterns that both were found to be highly expressed in the brain. [13][14][15][16] Overexpression of PAK5 triggered both filopodium formation and neurite development in N1E-115 cells, while dominant-negative PAK5 mutant inhibited neurite outgrowth. 13 Furthermore, overexpression of PAK5 activated the Jun N-terminal protein kinase pathway which was associated with apoptosis.…”