Disease relevance of Marcks

• Recent studies using gene disruption in vivo have demonstrated the importance of both MARCKS and MLP to the development of the central nervous system; specifically, mice lacking either protein exhibit a high frequency of neural tube defects [1].
• In this report we show that macrophage extracts contain a protease which specifically cleaves human MARCKS, expressed in a cell-free system or in E. coli, between Lys-6 and Thr-7 [2].
• On a 129B6(N3) background, the Macs mutation produced IP-MF hyperplasia, a significant increase in hippocampal PKCepsilon expression, and proficient spatial learning relative to wild-type controls [3].
• Phosphorylation of the MARCKS family of protein kinase C substrates in human B chronic lymphocytic leukemia cells [4].
• We isolated a phage clone from a mouse genomic library that spanned the entire coding sequence of the mouse MARCKS protein [5].

Psychiatry related information on Marcks

• We have previously demonstrated that 50% reductions in MARCKS expression in heterozygous Marcks mutant mice produce robust deficits in spatial reversal learning, but not contextual fear conditioning, suggesting that only specific aspects of hippocampal function are impaired by reduction in MARCKS expression [6].

High impact information on Marcks

• We report here on MacMARCKS, a MARCKS homolog, whose synthesis is dramatically increased in macrophages when these cells are exposed to bacterial lipopolysaccharide [7].
• MARCKS is a specific protein kinase C (PKC) substrate that binds both calmodulin and actin and is phosphorylated during phagocyte activation, neurosecretion, and growth factor-dependent mitogenesis [7].
• MacMARCKS and MARCKS also share a second, highly conserved region also found in the internalization domain of the mannose-6-phosphate receptor [7].
• Recently, we showed that the myristoylated, alanine-rich C-kinase substrate (MARCKS) protein is required for mucus secretion by human bronchial epithelial cells in culture [8].
• At these points, MARCKS co-localizes with vinculin and talin [9].

Chemical compound and disease context of Marcks

• Amounts of MARCKS protein, measured by [3H]myristate labeling and western blotting, were severalfold higher in rat C6 glioma and human HTB-11 (SK-N-SH) neuroblastoma cells than in HTB-10 (SK-N-MC) or mouse N1E-115 neuroblastoma cells [10].
• Pretreating the glioma cells with ionomycin prevented TPA-stimulated PKCs from phosphorylating the MARCKS protein [11].

Biological context of Marcks

• Two targets, Akap12 and Marcks, are downregulated in transformed cells and are known tumor suppressor genes [12].
• A novel aspect of the MARCKS-deficient phenotype was also noted, absence of the pontine nuclei; this was also largely reversed in Marcks(-/-) animals expressing the mutant transgene [13].
• Members of the myristoylated alanine-rich protein kinase C substrate (MARCKS) family are involved in several cellular processes such as secretion, motility, mitosis, and transformation [14].
• As targets for both protein kinase C (PKC) and calmodulin (CaM), MARCKS proteins are thought to mediate cross-talk between these two signal transduction pathways [15].
• Our results suggest that MARCKS proteins and actin could be targets of the poly(ADP-ribose) DNA damage signal pathway [15].

Anatomical context of Marcks

• Disruption of Marcks in mice leads to a number of developmental defects within the central nervous system that are completely prevented by expression of an epitope-tagged wild-type human MARCKS transgene [13].
• Interestingly, the affinity of MRP for acidic lipid membranes is 20-30-fold smaller than reported for murine MARCKS (Kim, J., Shishido, T., Jiang, X., Aderem, A. A., and McLaughlin, S. (1994) J. Biol. Chem. 269, 28214-28219) [14].
• MARCKS proteins are myristoylated proteins associated with membranes and the actin cytoskeleton [15].
• We investigated alterations of cellular distribution and phosphorylation of MARCKS in the hippocampus following kainic acid (KA)-induced seizures [16].
• Moreover, immunoreactivities of phosphorylated MARCKS were co-localized in the activated microglia with those of the above isoforms of PKC [16].

Associations of Marcks with chemical compounds

• Binding of MARCKS (myristoylated alanine-rich C kinase substrate)-related protein (MRP) to vesicular phospholipid membranes [17].
• Recently, a peptide derived from the myristoylated alanine-rich C kinase substrate protein NH(2)-terminal sequence (MANS) was shown to inhibit methacholine (MCh)-induced mucin secretion from airway mucous cells by >90% [18].
• This product can be remyristoylated in the presence of myristoyl-CoA and N-myristoyl transferase, demonstrating that cycles of myristoylation/demyristoylation of MARCKS can be achieved in vitro [2].
• Macrophage-enriched myristoylated alanine-rich C kinase substrate and its phosphorylation is required for the phorbol ester-stimulated diffusion of beta 2 integrin molecules [19].
• The PKC-specific inhibitor GF 109203X (bisindolylmaleimide I) reduced MARCKS phosphorylation in intact cells at a similar dose-response as enzymatic activity of recombinant isoenzymes cPKC-alpha, nPKC-epsilon, and nPKC-theta in vitro [20].

Physical interactions of Marcks

• MARCKS-related protein binds to actin without significantly affecting actin polymerization or network structure. Myristoylated alanine-rich C kinase substrate [21].

Enzymatic interactions of Marcks

• p42 MAPK phosphorylates 80 kDa MARCKS at Ser-113 [22].
• We have previously shown that calpain promotes myoblast fusion by acting on protein kinase C-alpha and the cytosolic phosphorylated form of MARCKS [23].

Regulatory relationships of Marcks

• Consistently, phorbol 12,13-dibutyrate-dependent MARCKS phosphorylation was significantly reduced in cell lines expressing dominant negative mutants of either PKC-alpha K368R or (dominant negative) PKC-epsilon K436R [20].
• Depletion or inhibition of PKC activity abolished the 80-kDa MARCKS translocation induced by either bombesin or PDGF [24].
• A concentration of 60 microM doxorubicin did not inhibit MARCKS phosphorylation but completely inhibited c-fos expression [25].
• Bombesin, endothelin and platelet-derived growth factor induce rapid translocation of the myristoylated alanine-rich C-kinase substrate in Swiss 3T3 cells [24].

Other interactions of Marcks

• Cell type-specific upregulation of myristoylated alanine-rich C kinase substrate and protein kinase C-alpha, -beta I, -beta II, and -delta in microglia following kainic acid-induced seizures [16].
• Like pericentrin, p-MARCKS staining at the MI spindle poles was asymmetric [26].
• The mouse equivalent maps to chromosome 10, distal to the c-myb gene, close to the Macs gene [27].
• Our results suggest that MARCKS and MRP may play important roles in microglia activated by amyloid peptides [28].
• We conclude that under physiological conditions, conventional cPKC-alpha and novel nPKC-epsilon, but not atypical aPKC-lambda are responsible for MARCKS phosphorylation in intact NIH 3T3 fibroblasts [20].

Analytical, diagnostic and therapeutic context of Marcks

• Using double-labeling immunofluorescence analysis, we demonstrated that the expression and phosphorylation of MARCKS was dramatically upregulated specifically in microglial cells after KA-induced seizures, but not in other types of glial cells [16].
• Although MARCKS was extensively examined in various cell culture systems, the physiological function of MARCKS in the central nervous system has not been clearly understood [16].
• Genomic Southern blot analysis suggested a single MARCKS gene per haploid genome [29].
• Peptide mapping studies indicated that MARCKS produced by the transfected gene was indistinguishable from the endogenous murine macrophage protein [29].
• In the present study, we assessed the expression (mRNA and protein) and subcellular distribution (membrane and cytolsol) of MARCKS in the hippocampus and frontal cortex of C57BL/6 and DBA/2 mice using quantitative western blotting [30].

References