Looks like leptin has a new neighbor... [Forum Archive]

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Looks like leptin has a new neighbor...

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Posted by: Monolith

I posted this over at Lyle's forum, but it's pretty slow over there... thought someone here might have some comments

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Musclin, a novel skeletal muscle-derived secretory factor.

Nishizawa H, Matsuda M, Yamada Y, Kawai K, Suzuki E, Makishima M, Kitamura T, Shimomura I.

Department of Medicine and Pathophysiology, Graduate School of Frontier Bioscience, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0871.

Skeletal muscle is involved in the homeostasis of glucose and lipid metabolism. We hypothesized that the skeletal muscle produces and secretes bioactive factor(s), similar to adipocytokines secreted by fat tissue. Here, we report the identification of a novel secretory factor, musclin, by signal sequence trap of mouse skeletal muscle cDNAs. Musclin cDNA encoded 130 amino acids, including NH(2)-terminal 30-amino acid signal sequence. Musclin protein contained a region homologous to natriuretic peptide family, and KKKR, a putative serine protease cleavage site, similar to the natriuretic peptide family. Full-length musclin protein and KKKR-dependent cleaved form were secreted in media of musclin cDNA-transfected mammalian cell cultures. Musclin mRNA was expressed almost exclusively in the skeletal muscle of mice. Musclin mRNA levels in skeletal muscle were markedly low in fasted, increased upon re-feeding, and were low in streptozotocin-treated insulin-deficient mice. Musclin mRNA expression was induced at late stage in the differentiation of C2C12 myocytes. In myocytes, insulin increased, while epinephrine, isoproterenol, and forskolin reduced musclin mRNA, all of which are known to increase the cellular content of cyclic AMP, a counter-regulator to insulin. Pathologically, overexpression of musclin mRNA was noted in the muscles of obese insulin-resistant KKAy mice. Functionally, recombinant musclin significantly attenuated insulin-stimulated glucose uptake and glycogen synthesis in myocytes. In conclusion, we identified musclin, a novel skeletal muscle-derived secretory factor. Musclin expression level is tightly regulated by nutritional changes and its physiological role could be linked to glucose metabolism.

http://www.ncbi.nlm.nih.gov/entrez/q..._uids=15044443

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A few interesting tidbits from the article:

Obese insulin-resistant mice also have abnormally high levels of musclin.

"Muscle-specific insulin receptor knockout mice exhibited adipose hyperplasia and increased mass, suggesting insulin-mediated production of muscle-derived secretory factor that decreases adiposity."

"In preliminary experiments, we noted that adenovirus-mediated production of musclin protein in plasma significantly decreased fat mass in mice."

Posted by: P-funk

Interesting.

Lyles site has a lot of great info. (especially the nerd forum...lol)

Posted by: Monolith

lol. Well, either im missing something or someone already posted something about this... because im the only one who seems to be giddy over this.

Posted by: Paynne

Did Avant come out with Musclingen yet?

Posted by: TaPo31

Very interesting, thanks for posting that, I found it quite interesting. But hell, I am a scientist, what do I know?

Posted by: Monolith

Quote:

Originally Posted by TaPo31

Very interesting, thanks for posting that, I found it quite interesting. But hell, I am a scientist, what do I know?

No shit? What field?

Posted by: TaPo31

I am working on my Ph.D. in Pharmacology and Toxicology.

Posted by: Monolith

Quote:

Originally Posted by TaPo31

I am working on my Ph.D. in Pharmacology and Toxicology.

Awesome!!

Where are you going to school? Got much longer? What kind of work are you looking to do? Research?

Posted by: topolo

I would like to hear TP's take on this

Posted by: TaPo31

I go to the U of Arizona. I have another 3 years or so probably. Right now I am doing a couple projects, one on breast cancer and one on arsenic toxicity. When I get done I hope to find a good job in some sort of industry, whether it be a biotech company, or even better a good supplement company

Posted by: topolo

Quote:

Originally Posted by TaPo31

I go to the U of Arizona. I have another 3 years or so probably. Right now I am doing a couple projects, one on breast cancer and one on arsenic toxicity. When I get done I hope to find a good job in some sort of industry, whether it be a biotech company, or even better a good supplement company

Well good luck to you.........even though you go to U of A

Posted by: TaPo31

Ha ha...thanks...ASU fan I take it?

Posted by: Monolith

Quote:

Originally Posted by TaPo31

Cool.

Sort of an odd question... but, how intense is the math at that level? A friend of mine wanted to go into a similar field (pharm.D) but got turned off by the prospect of shitloads of math courses. He was getting me interested too, until he scared me off with all this math garbage.

Posted by: topolo

Quote:

Originally Posted by TaPo31

Ha ha...thanks...ASU fan I take it?

yes a fan and an alum..........I played ball there years ago when I wore a younger man's clothes

Posted by: Twin Peak

Perhaps I am dense (and I am) but this is potentially a great explanation of what happens physiologically. Until someone learns how to manipulate it, though, its not very relevant to the pursuit of body composition.

Or am I missing something (many things)?

Posted by: TaPo31

Quote:

Originally Posted by Monolith

Cool.

The math varies from field to field, much more on the Pharm D side, but still some on my side. Its not overly difficult math, some basic calculus when looking at pharmacokinetics, but other than that its just simple addition and multiplication

Posted by: TaPo31

Quote:

Originally Posted by Twin Peak

Perhaps I am dense (and I am) but this is potentially a great explanation of what happens physiologically. Until someone learns how to manipulate it, though, its not very relevant to the pursuit of body composition.

Or am I missing something (many things)?

Yes, and the manipulation part is the difficult part. At this point any type of pharmacologically-induced changes in genetic transcripts is still very inefficient

Posted by: aggies1ut

Quote:

Originally Posted by TaPo31

Well what the hell happened to me then? LOL, before my mom passed away when I was young, she had a pharm.D and my dad is a cardiologist. My bro is really good at math and science. As for me, calculus and all the bio I took didn't go well. I strangely did like and do well in ochem with a lab though. Go figure. lol

Posted by: KataMaStEr

Okay, now; can anyone translate this to dumb people English?

Posted by: Twin Peak

Aggie -- that's why you are going to law scholl

Posted by: Monolith

Quote:

Originally Posted by Twin Peak

this is potentially a great explanation of what happens physiologically. Until someone learns how to manipulate it, though, its not very relevant to the pursuit of body composition.

Yeah, i think that about sums it up. How about you lock Spook in a room and tell him he cant come out until he thinks of a way to manipulate musclin?

Anyway, what i concluded from the article is just a few relevant things:

Refeeds for fattys are inefficient and rather pointless... but everyone knows that already.

If you have a shit-ton of insulin and no musclin, you get fat really fast. i.e. adipose hyperplasia.

If you have a shit-ton of musclin and no insulin, you get lean really fast.

If your levels of both are at homeostasis, youre normal.

All of that is, of course, assuming youre a mouse... and we know re: leptin how misleading that can be.

Posted by: Monolith

Quote:

Originally Posted by TaPo31

Ugh. Who the hell needs to know math when we have calculators and computers? Math shouldnt be a required course anymore... just leave it to the hobbyists.

Posted by: aggies1ut

Quote:

Originally Posted by Twin Peak

Aggie -- that's why you are going to law scholl

True true, but if I had more aptitude towards science, I would become an orthapedic surgeon like I originally wanted to be. Damn sports law, you need connections. I'm thinking corporate, business, or tax (along with being a CPA).

Posted by: Monolith

Quote:

Originally Posted by aggies1ut

I dont know how it is out in Cali... but in MA there's a huge demand for lawyers with the balls/skills to aggressively pursue owed taxes. Municipal law, i suppose. There's something like $2 billion in uncollected tax titles in this state alone, and attorneys are being contracted to take care of it for a percentage.

Posted by: Paynne

Quote:

Originally Posted by Monolith

Ugh. Who the hell needs to know math when we have calculators and computers? Math shouldnt be a required course anymore... just leave it to the hobbyists.

Being as my undergrad is in mathematics this sounds great to me. We mathematicians who are programming the calculators and computers could charge whatever we want since no one else understands it. Well, that's why the lawyers and docs are making so much cash.

Posted by: aggies1ut

Quote:

Originally Posted by Monolith

Oh hell ya. You make big bucks doing tax law. If I was also a CPA, I'd be raking in the dough.

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Looks like leptin has a new neighbor...

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