The Ras-like GTPase Rem2 is a potent inhibitor of calcium/calmodulin-dependent kinase II activity

Abstract

Ca/calmodulin-dependent protein kinase II (CaMKII) is a well-characterized, abundant protein kinase that regulates a diverse set of functions in a tissue-specific manner. For example, in heart muscle, CaMKII regulates Ca homeostasis, whereas in neurons, CaMKII regulates activity-dependent dendritic remodeling and long-term potentiation (LTP), a neurobiological correlate of learning and memory. Previously, we identified the GTPase Rem2 as a critical regulator of dendrite branching and homeostatic plasticity in the vertebrate nervous system. Here, we report that Rem2 directly interacts with CaMKII and potently inhibits the activity of the intact holoenzyme, a previously unknown Rem2 function. Our results suggest that Rem2 inhibition involves interaction with both the CaMKII hub domain and substrate recognition domain. Moreover, we found that Rem2-mediated inhibition of CaMKII regulates dendritic branching in cultured hippocampal neurons. Lastly, we report that substitution of two key amino acid residues in the Rem2 N terminus (Arg-79 and Arg-80) completely abolishes its ability to inhibit CaMKII. We propose that our biochemical findings will enable further studies unraveling the functional significance of Rem2 inhibition of CaMKII in cells.

Experience-dependent development of dendritic arbors in mouse visual cortex

“…This is consistent with the many alterations we observe in our past and current studies of Rem2 deletion [51, 54, 55, 67, 76–79]. Compellingly, the ability for Rem2 to inhibit CaMKII catalytic activity has already been linked to regulation of dendritic complexity [79]. We propose a model in which direct inhibition of CaMKII by Rem2 promotes morphological stability, the loss of which results in cascading instability of the dendritic arbor.…”

“…Likewise, loss of such inhibition leading to increased CaMKII catalytic activity, such as by Rem2 deletion, could lead to widespread changes in cellular structure and function. This is consistent with the many alterations we observe in our past and current studies of Rem2 deletion [51, 54, 55, 67, 76–79]. Compellingly, the ability for Rem2 to inhibit CaMKII catalytic activity has already been linked to regulation of dendritic complexity [79].…”

“…Furthermore, we show that Rem2 is a cell-autonomous regulator of basal arbor stability and directionality, a new function for this molecule. We hypothesize that these functions of Rem2 depend on a recently-described [79] direct inhibition of CaMKII by Rem2, the loss of which leads to numerous downstream effects dependent on both network activity and age.…”

“…One possible explanation comes from recent data showing that Rem2 is a potent inhibitor of Ca 2+ /calmodulin-dependent protein kinase II (CaMKII) [79]. CaMKII is perhaps one of the most intensely studied proteins in excitable cells, such as neurons and cardiomyocytes, and is a key regulator of Ca 2+ signaling and homeostasis in these cells.…”

The Metastasis Suppressor Protein Nme1 Is a Concentration-Dependent Modulator of Ca2+/Calmodulin-Dependent Protein Kinase II

“…The assay has been used previously by us and other groups to monitor the activity of purified CaMKII in vitro. 6,12 We found that addition of CaMKIIα to the reaction mixture led to a fast consumption of ATP due to the phosphorylation of the 15 amino acid peptide substrate syntide-2 by CaMKII ( Figure 1B,C). When the experiment was repeated in the presence of 500 nM wtNme1, a strong increase in total ATP consumption was detected.…”