Septin 8 is an interaction partner and in vitro substrate of MK5

Abstract

AIM:To identify novel substrates for the mitogen-activated protein kinase-activated protein kinase 5 (MK5). METHODS:Yeast two-hybrid screening with MK5 as bait was used to identify novel possible interaction partners. The binding of putative partner was further examined by glutathione S-transferase (GST) pull-down, co-immunoprecipitation and fluorescence resonance energy transfer (FRET) analysis. In vitro kinase and peptide array assays were used to map MK5 phosphoacceptor sites on the new partner. Confocal microscopy was performed to study the subcellular localization of MK5 and its partners. RESULTS:Septin 8 was identified as a novel interaction partner for MK5 by yeast two-hybrid screening. This interaction was confirmed by GST pull-down, coimmunoprecipitation and FRET analysis. Septin 5, which can form a complex with septin 8, did not interact with MK5. Serine residues 242 and 271 on septin 8 were identified as in vitro MK5 phosphorylation sites. MK5and septin 8 co-localized in the perinuclear area and in cell protrusions. Moreover, both proteins co-localized with vesicle marker synaptophysin. CONCLUSION:Septin 8 is a bona fide interaction partner and in vitro substrate for MK5. This interaction may be implicated in vesicle trafficking.

MK5: A novel regulator of cardiac fibroblast function?

“…As with MK2 and MK3, MK5 phosphorylates hsp27 at Ser‐15, Ser‐78, and Ser‐82 in vivo and in vitro . Septin 8, a member of the septin family of filament‐forming GTP‐binding proteins , was identified as interacting with MK5 by yeast two‐hybrid screening of mouse and human brain cDNA libraries , coimmunoprecipitation, and GST pull‐down assays . In vitro kinase assays reveal that MK5 phosphorylates septin 8 at Ser‐242 and Ser‐271 .…”

“…Septin 8, a member of the septin family of filament‐forming GTP‐binding proteins , was identified as interacting with MK5 by yeast two‐hybrid screening of mouse and human brain cDNA libraries , coimmunoprecipitation, and GST pull‐down assays . In vitro kinase assays reveal that MK5 phosphorylates septin 8 at Ser‐242 and Ser‐271 . Yeast two‐hybrid screening also identified septin 7 and kalirin‐7, a neuron‐specific guanine nucleotide exchange factor for the Rho GTPase family, as potential MK5‐binding proteins and substrates .…”

The novel RAGE interactor PRAK is associated with autophagy signaling in Alzheimer’s disease pathogenesis

“…PRAK can be activated by cellular stress and inflammatory cytokines [ 18 ]. PRAK is known to phosphorylate Heat shock protein 27 (HSP27) [ 17 ], cytosolic phospholipase A2 (cPLA2) [ 19 ], tyrosine hydroxylase [ 20 ], FOXO3a [ 21 ], FAK [ 22 ], septin8 [ 23 ] and p53 [ 24 ]. Thus, PRAK plays a crucial role in cellular signaling phenomena such as the cell cycle, angiogenesis, and neuronal plasticity [ 25 ].…”

Phosphorylation of Pnut in the Early Stages ofDrosophilaEmbryo Development Affects Association of the Septin Complex with the Membrane and Is Important for Viability

“…Little is known about the phosphorylation of septins in higher eukaryotes compared to fungi. Mammalian SEPT8, SEPT4, SEPT5, SEPT9, SEPT2, and SEPT3 are found to be phosphorylated in different tissues ( Estey et al 2013 ; Koch et al 2015 ; Amin et al 2008 ; Sitz et al 2008 ; Shiryaev et al 2012 ; Xue et al 2004 ; Taniguchi et al 2007 ; Yu et al 2009 ; Scholz et al 2015 ); however, in many cases, the functional significance of these modifications remains unclear.…”