Protein Kinase C δ (δPKC)-Annexin V Interaction A REQUIRED STEP IN δPKC TRANSLOCATION AND FUNCTION

Aberrant cardiomyocyte microtubule growth is a feature of pressure overload induced cardiac hypertrophy believed to contribute to left ventricular (LV) dysfunction Microtubule Actin Cross-linking Factor 1 (MACF1/Acf7) is a 600 kd spectraplakin that stabilizes and guides microtubule growth along actin filaments MACF1 is expressed in the heart, but its impact on cardiac microtubules, and how this influences cardiac structure, function, and adaptation to hemodynamic overload is unknown Here we used inducible cardiac-specific MACF1 knockout mice (MACF1 KO) to determine the impact of MACF1 on cardiac microtubules and adaptation to pressure overload (transverse aortic constriction (TAC)In adult mouse hearts, MACF1 expression was low under basal conditions, but increased significantly in response to TAC While MACF1 KO had no observable effect on heart size or function under basal conditions, MACF1 KO exacerbated TAC induced LV hypertrophy, LV dilation and contractile dysfunction Interestingly, subcellular fractionation of ventricular lysates revealed that MACF1 KO altered microtubule distribution in response to TAC, so that more tubulin was associated with the cell membrane fraction Moreover, TAC induced microtubule redistribution into this cell membrane fraction in both WT and MACF1 KO mice correlated strikingly with the level of contractile dysfunction (r2 = 0786, p<001) MACF1 disruption also resulted in reduction of membrane caveolin 3 levels, and increased levels of membrane PKCα and β1 integrin after TAC, suggesting MACF1 function is important for spatial regulation of several physiologically relevant signaling proteins during hypertrophy Together, these data identify for the first time, a role for MACF1 in cardiomyocyte microtubule distribution and in adaptation to hemodynamic overload

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Microtubule Actin Cross-linking Factor 1 regulates cardiomyocyte microtubule distribution and adaptation to hemodynamic overload.

We have previously shown that protein kinase C (PKC) ζ and/or PKCδ are necessary for endothelin-1 (ET-1)-induced human myometrial contraction at the end of pregnancy (Eude I, Paris P, Cabrol D, Fer...

https://www.physiology.org/doi/pdf/10.1152/ajpcell.00040.2003

A critical role for PKCζ in endothelin-1-induced uterine contractions at the end of pregnancy

The aims of the study were to meet the demand of new tubulin antagonists with fewer side effects by characterizing the antiangiogenic properties of the experimental compound spongistatin 1, and to elucidate nonmitotic mechanisms by which tubulin antagonists inhibit angiogenesis. Although tubulin-inhibiting drugs and their antiangiogenic properties have been investigated for a long time, surprisingly little is known about their underlying mechanisms of action. Antiangiogenic effects of spongistatin 1 were investigated in endothelial cells in vitro, including functional cell-based assays, live-cell imaging, and a kinome array, and in the mouse cornea pocket assay in vivo. Spongistatin 1 inhibited angiogenesis at nanomolar concentrations (IC50: cytotoxicity>50 nM, proliferation 100 pM, migration 1.0 nM, tube formation 1.0 nM, chemotaxis 1.0 nM, aortic ring sprouting 500 pM, neovascularization in vivo 10 μg/kg). Further, a kinome array and validating data showed that spongistatin 1 inhibits the phosphorylatio...

/pdf/investigation-of-the-marine-compound-spongistatin-1-links-27lathppdg.pdf

Investigation of the marine compound spongistatin 1 links the inhibition of PKCα translocation to nonmitotic effects of tubulin antagonism in angiogenesis

Using laser scanning confocal, fluorescence resonance energy transfer (FRET), and atomic force (AFM) microscopy, we investigated association of protein kinase C (PKC)-α with microtubules during sti...

Microtubule-dependent PKC-α localization in A7r5 smooth muscle cells

The translocation of protein kinase C (PKC) isozymes from their inactive cell locus to a variety of cytoskeletal, organelle, and plasmalemmal sites is thought to play an important role in their activation and substrate specificity. We have utilized confocal microscopy to compare phorbol 12, 13 dibutyrate (PDB) - stimulated translocation of PKCalpha in cultured cells derived from rat vascular smooth muscle. In enzymatically dispersed, passaged smooth muscle cells, PKCalpha was uniformly distributed throughout the unstimulated cell. PDB stimulation resulted in extensive association of the PKCalpha into filamentous strands with subsequent accumulation of the isoform in the peri-nuclear region of the cell. Dual immunostaining indicated that PKCalpha was extensively colocalized with microtubules in the interval immediately following PDB stimulation but was largely disassociated from microtubules at 10 min, at which time the translocation of PKCalpha to the peri-nucleus/nucleus was nearly complete. It was further found that the use of colchicine to disrupt the microtubules caused the loss of PKCalpha translocation to the peri-nuclear region. By comparison, cytochalasin B disruption of actin microfilaments had no significant effect on this parameter. The data suggest that PDB stimulation results in a transient association of PKCalpha with cell microtubules and that the microtubules play an important role in the translocation of PKCalpha from the cytosol in passaged cells derived from rat aortic smooth muscle.

A.S. Battistella-Patterson

Papers

PKCα translocation is microtubule‐dependent in passaged smooth muscle cells