Phorbol 12,13-dibutyrate

Ionomycin inhibits Jurkat T cell behaviors in the presence of phorbol-12,13-dibutyrate.[Pubmed:24292536]

Ann Hematol. 2014 May;93(5):735-46.

Ionomycin in conjunction with phorbol-12,13-dibutyrate (PDBu) is conventionally used as a stimulator to activate cells, especially original T cells. But we accidently found it had an entirely opposite action on malignant tumor cells derived from T cells. Thus, influence of ionomycin on human leukemia Jurkat T cell behaviors and its preliminary mechanistic process were explored in the presence of PDBu. Ionomycin could remarkably inhibit colony formation of the cells, and inhibitory rate of the cell proliferation was increased with ionomycin treatment in a dose- or time-related relationship, following the reduction of ERK1/2 and phosphorylated-ERK1/2 levels. However, a high dose of ionomycin might moderately repress mid-stage activation of the cells. It also blocked the cell entry at S-phase and G2/M-phase with the attenuation of transforming growth factor-beta (TGF-beta) level in the cells, and promoted the cell apoptosis following the augment of caspase-3 and cleaved caspase-3 in the cells. The dramatic elevation of [Ca2(+)]i and intracellular pH (pHi) was simultaneously followed by the above alteration of the cell behaviors. These results indicate that ionomycin may strongly inhibit human acute T lymphocyte leukemia progress in the presence of PDBu through the inhibition of ERK1/2 signaling, the activation of caspase-3 and the attenuation of TGF-beta mediated by the [Ca2(+)]i and pHi enhancement, providing a novel insight into function and potential application of both ionomycin and PDBu.

A Comparison Between Phorbol 12 Myristate 13 Acetate and Phorbol 12, 13 Dibutyrate in Human Melanocyte Culture.[Pubmed:26894087]

J Clin Diagn Res. 2016 Jan;10(1):GC01-4.

INTRODUCTION: Melanocyte culture is an integral part of the studies of skin biology and cosmetic applications. After the introduction of selective medium for the culture of human melanocyte using Phorbol 12-myristate13-acetate (PMA) in 1982, a lot of methods of culturing were tried but till date PMA is a preferred mitogen because of its cost effectiveness compared to growth factors. We have tried to preliminarily evaluate the efficacy of another phorbol ester, Phorbol 12, 13-dibutyrate (PDBu) in melanocyte culture because of its less hydrophobic nature compared to PMA. This property minimizes the trace amount of mitogen in cell culture after washing off and hence does not interfere in other biological assays. AIM: To evaluate the differences in the melanocyte survival rate, morphology and mitotic index when grown in media supplemented with PMA and PDBu. MATERIALS AND METHODS: Foreskins were collected from children undergoing circumcision. Epidermal cells were isolated from foreskin and cultured using PMA and PDBu. Melanocytes in culture were monitored for the better establishment and documented. In proliferative assay, melanocytes were treated with PMA and PDBu for 24, 48 and 72 hours and proliferation was measured using 3-(4,5-Dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay method. RESULTS: When cultured, melanocytes acquired proliferative status and bipolar morphology quicker in PDBu medium than in PMA medium. Keratinocytes survived as contamination in PMA medium whereas PDBu medium had minimal keratinocytes. MTT assay showed that PDBu has higher proliferative induction capacity than PMA. In even lower concentration of PDBu in medium, melanocytes survived till 72 hours without significant cell loss in compared to PMA medium. CONCLUSION: PDBu can be a valuable replacement for PMA in human melanocyte culture. Higher proliferation induction, unfavourable to keratinocyte survival and less hydrophobicity make PDBu a promising alternative for quicker establishment of pure human melanocyte cultures especially in cosmetic in vitro experimental dermatology.

Distribution of Spinal Sensitization Evoked by Inflammatory Pain Using Local Spinal Cord Glucose Utilization Combined with (3) H-Phorbol 12,13-Dibutyrate Binding in Rats.[Pubmed:27335874]

ISRN Pain. 2013 Dec 26;2013:340167.

Aims. Hyperalgesia following tissue injury is induced by plasticity in neurotransmission. Few investigators have considered the ascending input which activates the superficial of spinal cord. The aim was to examine neurotransmission and nociceptive processing in the spinal cord after mustard-oil (MO) injection. Both in vitro and in vivo autoradiographs were employed for neuronal activity and transmission in discrete spinal cord regions using the (14)C-2-deoxyglucose method and (3)H-Phorbol 12,13-dibutyrate ((3)H-PDBu) binding sites. Methods. To quantify the hyperalgesia evoked by MO, the flinching was counted for 60 min after MO (20%, 50 muL) injection in Wistar rats. Simultaneous determination of (14)C-2-deoxyglucose and (3)H-PDBu binding was used for a direct observation of neuronal/metabolic changes and intracellular signaling in the spinal cord. Results. MO injection evoked an increase in flinching for 60 min. LSCGU significantly increased in the Rexed I-II with (3)H-PDBu binding in the ipsilateral side of spinal cord. Discussion. We clearly demonstrated that the hyperalgesia is primarily relevant to increased neuronal activation with PKC activation in the Rexed I-II of the spinal cord. In addition, functional changes such as "neuronal plasticity" may result in increased neuronal excitability and a central sensitization.

Electron microscopic examination of podosomes induced by phorbol 12, 13 dibutyrate on the surface of A7r5 cells.[Pubmed:25986486]

J Pharmacol Sci. 2015 Jun;128(2):78-82.

The role of myosin light chain kinase (MLCK) in inducing podosomes was examined by confocal and electron microscopy. Removal of myosin from the actin core of podosomes using blebbistatin, a myosin inhibitor, resulted in the formation of smaller podosomes. Downregulation of MLCK by the transfection of MLCK small interfering RNA (siRNA) led to the failure of podosome formation. However, ML-7, an inhibitor of the kinase activity of MLCK, failed to inhibit podosome formation. Based on our previous report (Thatcher et al. J.Pharm.Sci. 116 116-127, 2011), we outlined the important role of the actin-binding activity of MLCK in producing smaller podosomes.

Augmented PDBu-mediated contraction of bronchial smooth muscle of mice with antigen-induced airway hyperresponsiveness.[Pubmed:21187674]

J Smooth Muscle Res. 2010;46(5):259-66.

To explore the role of protein kinase C (PKC) in the augmented bronchial smooth muscle (BSM) contraction observed in the antigen-induced airway hyperresponsive (AHR) mice, the effects of a PKC activator, phorbol 12,13-dibutylate (PDBu), on BSM contraction were compared between the AHR and control mice. Actively sensitized mice were repeatedly challenged by antigen inhalation. Twenty-four hours after the final antigen challenge the isometrical contractions of the BSMs were measured. The BSM contraction induced by acetylcholine, but not high K(+) depolarization, was significantly augmented in the AHR mice. In BSMs of control mice, PDBu caused a significant increase in tension when the tissues were precontracted with high K(+), although PDBu itself had no effect on basal tone. The PDBu-mediated contraction was markedly augmented in BSMs of the AHR mice. These findings suggest that an increase in the PKC-mediated signaling is involved in the augmented contraction of BSMs in the antigen-induced AHR mice.

Presynaptic mechanism for phorbol ester-induced synaptic potentiation.[Pubmed:10460232]

J Neurosci. 1999 Sep 1;19(17):7262-7.

Phorbol ester facilitates transmitter release at a variety of synapses, and the phorbol ester-induced synaptic potentiation (PESP) is a model for presynaptic facilitation. To address the mechanism underlying PESP, we have made paired whole-cell recordings from the giant presynaptic terminal, the calyx of Held, and its postsynaptic target in the medial nucleus of the trapezoid body in rat brainstem slices. Phorbol ester potentiated EPSCs without affecting either presynaptic calcium currents or potassium currents. Protein kinase C inhibitors applied from outside or injected directly into the presynaptic terminal attenuated the PESP. Furthermore, presynaptic loading of a synthetic peptide with the sequence of the N-terminal domain of Doc2alpha interacting with Munc13-1 (Mid peptide) significantly attenuated PESP, whereas mutated Mid peptide had no effect. We conclude that the target of the presynaptic facilitatory effect of phorbol ester resides downstream of calcium influx and may involve both protein kinase C and Doc2alpha - Munc13-1 interaction.

Heterogeneity of protein kinase C-mediated rapid regulation of Na/K-ATPase in kidney epithelial cells.[Pubmed:8393456]

J Biol Chem. 1993 Jul 25;268(21):15958-64.

Na/K-ATPase in renal epithelium is expressed at the basolateral surface and thus is critical for vectorial solute transport. One potential mode of regulation of Na/K-ATPase involves the intracellular effector protein kinase C (PKC). In kidney cell lines, activation of PKC by the phorbol ester Phorbol 12,13-dibutyrate (PDBu) (1 microM) inhibited Na/K-ATPase transport activity in OK cells (Vmax decreased 42%; p < 0.02), but not in LLC-PK1 cells. By immunoblot, both cell types expressed detectable levels of PKC alpha and PKC sigma. In response to PDBu, PKC alpha translocated from the cytosol to the membrane fractions of both cell lines. Phorbol ester treatment increased incorporation of 32PO4 in multiple substrates in both cell types, but a approximately 109-kDa substrate with neutral pI was detected only in the OK cell. Anti-LEAVE, directed against a highly conserved sequence in the H4-H5 loop of all known alpha isoforms of Na/K-ATPase, recognized a approximately 109-kDa membrane protein from both cell lines. Anti-LEAVE also identified a protein that comigrated with the large phosphoprotein which was only present in OK cells. Following 32PO4 loading and PDBu treatment, anti-LEAVE immunoprecipitated a approximately 109-kDa phosphoprotein in OK but not LLC-PK1 cells. These data support the notion that PKC is capable of phosphorylating the alpha subunit and inhibiting Na/K-ATPase transport activity in intact renal cells. Furthermore, they suggest that some forms of Na/K-ATPase in the kidney are not susceptible to PKC phosphorylation and that this heterogeneity may contribute to response diversity.