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( r: C; ~6 Z, F( O H0 dNaked mole rats are remarkable in
4 [; f: _% q. A- fcombining extreme longevity with virtually complete resistance to cancer. Now a
! Y( j! o; A$ {/ @( N2 d) |9 a# }novel glycosaminoglycan variant that may have evolved to provide the creatures ( v/ X& @; {- {. H
with the tough, flexible skin needed for a subterranean lifestyle has been
" T8 p/ e. g8 d; \' g0 x' ~identified as a key contributor to their cancer resistance. Hyaluronan, or / G+ Y; S! G6 z; ~" z& E& a6 ~
hyaluronic acid, is a ubiquitous component of the extracellular matrix. Xiao * o. k& Q+ ^' d5 U! q
Tian et al. observed that the culture media of naked mole-rat 8 U5 w, S+ A) C; l( x# }$ c* n6 A( L
fibroblasts becomes viscous owing to the accumulation of a thick ‘gooey’
1 c) T6 K( S9 S5 Lsubstance and identified it as a high-molecular-mass hyaluronan (HMM-HA), more , e& v& Z( F/ o: P
than five times larger than mouse and human equivalents. It accumulates in naked
. @4 }1 O$ g& Y2 [; q7 umole-rat tissues owing to low hyaluronidase activity and a unique form of " _6 ]+ u0 N) v, x4 q3 z
hyaluronan synthase 2. HMM-HA acts through the CD44 receptor and removal of # B% X* ]. o$ o7 D, \7 V& i! \4 U
HMM-HA makes naked mole-rat cells more susceptible to transformation. This 7 Y+ R, h: K: u; [+ S" `8 \6 l
unusual model of cancer protection suggests potential new avenues of research
9 B8 n, M1 ^" x0 |. l1 o9 zinto anticancer and life-extension strategies. Cover: Joel Sartore/National
; M1 r& C! Z3 u$ o }Geographic Image Collection/Alamy8 f9 P4 `7 ?3 T3 I: G
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发表于 2013-7-19 19:33
