※ CAMKL family introduction

    CAMKL family consists of several subfamily including SNRK, QIK, BRSK, AMPK, MARK, NuaK, NIM1, HUNK, LKB, PASK, MELK and CHK1. They are classified into CAMKL family for the high similarity kinase catalytic domain. AMPK subfamily (AMP-activated protein kinase) consists of three subunits, a catalytic subunit (α) and two regulatory subunits (β and γ). Two catalytic subunits have been identified in mammals. Activation of AMPK is involved in two steps; first, AMP binds to γ-subunit, and second the phosphorylation of threonine 172 by LKB1. Activated AMPK targets a variety of substrates and participates different cellular processes including mTORC1 signaling, phosphorylation of p53 or other tumor suppressors (1). MARK subfamily (microtubule-affinity regulating kinases) consists of four members (MARK1-MARK4) in mammals cells. All isoforms contain a N-terminal header, a catalytic kinase domain, a ubiquitin-associated domain, a spacer domain and a C-terminal KA1 domain. MARKs are discovered for its ability to regulate the stability of microtubules. Studies also show that MARK has some relation with disease, such as Alzheimer's disease (2). Nuak subfamilies are AMPK related kinases. NuaK1 are stress-activated kinase which is involved in tolerance to glucose starvation. NuaK1 can induce cell-cell detachment by increasing F-actin conversion to G-actin. NuaK1 can protect cells from CD95-mediated apoptosis and is required for the increased motility and invasiveness of CD95- activated tumor cells (3).

Reference
1. Luo, Z., Zang, M. and Guo, W. (2010) AMPK as a metabolic tumor suppressor: control of metabolism and cell growth. Future Oncol, 6, 457-470. PMID: 20222801
2. Matenia, D. and Mandelkow, E.M. (2009) The tau of MARK: a polarized view of the cytoskeleton. Trends Biochem Sci, 34, 332-342. PMID: 19559622
3. Suzuki, A., Kusakai, G., Kishimoto, A., Minegichi, Y., Ogura, T. and Esumi, H. (2003) Induction of cell-cell detachment during glucose starvation through F-actin conversion by SNARK, the fourth member of the AMP-activated protein kinase catalytic subunit family. Biochem Biophys Res Commun, 311, 156-161. PMID: 14575707