Also, they are picking on those poor EAE rats again.
The first article is really old and all I can post is the title. The second article (abstract) is more recent.
Methylthioadenosine, a potent inhibitor of spermine synthase from bovine brain.
Pajula RL, Raina A. FEBS Lett. 1979 Mar 15;99(2):343-5.
Methylthioadenosine Reverses Brain Autoimmune Disease
Beatriz Moreno, PhD, Henar Hevia, PhD, Monica Santamaria, PhD, Jorge Sepulcre, MD, Javier Mun˜oz, BSc, Elena R. Garcı´a-Trevijano, PhD, Carmen Berasain, PhD, Fernando J. Corrales, PhD, Matias A. Avila, PhD, and Pablo Villoslada, MD
Objective: To assess the immunomodulatory activity of methylthioadenosine (MTA) in rodent experimental autoimmune encephalomyelitis (EAE) and in patients with multiple sclerosis.
Methods: We studied the effect of intraperitoneal MTA in the acute and chronic EAE model by quantifying clinical and histological scores and by performing immunohistochemistry stains of the brain. We studied the immunomodulatory effect of MTA in lymphocytes from EAE animals and in peripheral blood mononuclear cells from healthy control subjects and multiple sclerosis patients by assessing cell proliferation and cytokine gene expression, by real-time polymerase chain reaction, and by nuclear factor-κB modulation by Western blot.
Results: We found that MTA prevents acute EAE and, more importantly, reverses chronic-relapsing EAE. MTA treatment markedly inhibited brain inflammation and reduced brain damage. Administration of MTA suppressed T-cell activation in vivo and in vitro, likely through a blockade in T-cell signaling resulting in the prevention of inhibitor of kappa B (IκB-) degradation and in the impaired activation transcription factor nuclear factor-κB. Indeed, MTA suppressed the production of proinflammatory genes and cytokines (interferon-γ, tumor necrosis factor-, and inducible nitric oxide synthase) and increased the production of antiinflammatory cytokines (interleukin-10).
Interpretation: MTA has a remarkable immunomodulatory activity and may be beneficial for multiple sclerosis and other autoimmune diseases.
Ann Neurol 2006;60:323–334
Targeting the polyamine pathway with transition-state analogue inhibitors of 5'-methylthioadenosine phosphorylase.
J Med Chem. 2004 Jun 3;47(12):3275-81.
Evans GB, Furneaux RH, Schramm VL, Singh V, Tyler PC.
Carbohydrate Chemistry, Industrial Research Limited, P.O. Box 31310, Lower Hutt, New Zealand.
The polyamine biosynthetic pathway is a therapeutic target for proliferative diseases because cellular proliferation requires elevated levels of polyamines. A byproduct of the latter stages of polyamine biosynthesis (the synthesis of spermidine and spermine) is 5'-methylthioadenosine (MTA).
In humans, MTA is processed by 5'-methylthioadenosine phosphorylase (MTAP) so that significant amounts of MTA do not accumulate. Potent inhibitors of MTAP might allow the buildup of sufficient levels of MTA to generate feedback inhibition of polyamine biosynthesis.
We have designed and synthesized a family of potential transition-state analogue inhibitors of MTAP on the basis of our knowledge of the transition-state structure of purine nucleoside phosphorylase and the assumption that it is likely the two enzymes share a common catalytic mechanism. Several of the inhibitors display slow-onset tight-binding properties, consistent with them being transition-state analogues, with the most potent having a dissociation constant of 166 pM.
MTA is actually created as a product of polyamine (spermine and spermidine) synthesis. So it is in each cell in low amounts. It is quickly converted to phospho-MTA and then back to methionine to create more S-adenosylmethionine (SAM).
SAM is important for methylation of DNA and histone (and other proteins) to help in gene silencing and packaging. In competition with this use of SAM, SAM is decarboxylated by SAM decarboxylase creating dcSAM for use in polyamine synthesis. For spermidine synthesis by the enzyme spermidine synthase, dcSAM and putrescine are converted to spermidine and MTA. For spermine synthesis by the enzyme spermine synthase, dcSAM and spermidine are converted to spermine and MTA.
So, by providing an abundance of the product MTA, it backs up the polyamine synthesis. Increases in polyamines are necessary in cell proliferation, such as in T-cell expansion in reaction to an antigen.
If you are converted spermidine to spermine faster than you can replenish the spermidine due to extra expression of spermine synthase (as I am suggesting), then you are reducing the cell's spermidine. Spermidine is essential in a cell for a very unique control (I believe it is translation control). Spermidine is ligated to an elongation factor and converted to a rare amino acid hypusine. Without this, the cell will not live. Also, increased spermine (+4) could cause more stabilization of alternate protein and DNA complexes (such as Z-DNA), compared to spermidine (+3). Normal there is a balance in the spermine/spermidine ratio. I have referred previously to the Quaking and Jimpy mouse strains that have progressive neurodegeneration. They were shown to have changes in their spermine/spermidine ratios and amounts relative to control mice.
I don't know if you can buy MTA as a drug. I am in drug discovery and have a potential drug candidate for SAM decarboxylase for cancer therapy. I am hoping to work on spermine synthase for drug discovery but it would be for cancer treatment. As it is, I have about 15 other cancer related targets I am working on, so not much time to work on what interests me most.
Got to get to work now.
Department of Pharmacy, School of Chemical Sciences and Pharmacy, Central University of Rajasthan, Bandar Sindri, Distt., Ajmer, Rajasthan, 305817, India
Oral Delivery of Methylthioadenosine to the Brain Employing Solid Lipid Nanoparticles: Pharmacokinetic, Behavioral, and Histopathological Evidences.
The present study aimed to orally deliver methylthioadenosine (MTA) to the brain employing solid lipid nanoparticles (SLNs) for the management of neurological conditions like multiple sclerosis. The stearic acid-based SLNs were below 100 nm with almost neutral zeta potential and offered higher drug entrapment and drug loading. Cuprizone-induced demyelination model in mice was employed to mimic the multiple sclerosis-like conditions. It was observed that the MTA-loaded SLNs were able to maintain the normal metabolism, locomotor activity, motor coordination, balancing, and grip strength of the rodents in substantially superior ways vis-à-vis plain MTA. Histopathological studies of the corpus callosum and its subsequent staining with myelin staining dye luxol fast blue proved the potential of MTA-loaded SLNs in the remyelination of neurons. The pharmacokinetic studies provided the evidences for improved bioavailability and enhanced bioresidence supporting the pharmacodynamic findings. The studies proved that SLN-encapsulated MTA can be substantially delivered to the brain and can effectively remyelinate the neurons. It can reverse the multiple sclerosis-like symptoms in a safer and effective manner, that too by oral route.
( https://www.researchgate.net/publicatio ... _verrucosa )
I don't exclude the possibility that some remyelination may occur at that point.
This again proves the overall concept on viewtopic.php?f=1&t=15188&start=870#p256596