爲什麼有些地方長毛髮有些地方卻不長?大綱

Why can millions of hairs grow from our heads, and yet our palms and the soles of our feet are as bare as anything? It all comes down to a special molecule in our bodies, according to the scientists who have found it.

爲什麼數以百萬計的頭髮可以從我們的頭上長出來，而我們的手掌和腳底卻是光禿禿的？據發現這一問題的科學家表示，一切都歸結於我們體內的一種特殊分子。

The hairless regions of our skin secrete a special type of molecule known as an inhibitor. This particular one is a protein named Dickkopf 2 (DKK2). These effectively brick-up the WNT pathway, which is in charge of triggering hair growth in our bodies.

我們皮膚的無毛區域分泌一種特殊的分子，稱爲抑制劑。這種特殊的蛋白質叫做Dickkopf 2(DKK2)。這些物質有效地堵塞了WNT通路，而WNT通路負責刺激我們體內的毛髮生長。

Scientists at the University of Pennsylvania School of Medicine believe certain animals have evolved to produce DKK2 in certain parts of their bodies, depending on what will best help different creatures to survive.

賓夕法尼亞大學醫學院的科學家們認爲，某些動物已經進化到在身體的某些部位產生DKK2，這取決於哪種物質最有助於不同的生物生存。

"In this study, we've shown the skin in hairless regions naturally produces an inhibitor that stops WNT from doing its job," Professor Sarah E. Millar, an author of the study published in the journal Cell Reports, commented.

這項研究的作者薩拉·E·米勒教授評論說：“在這項研究中，我們已經表明，無毛區域的皮膚自然會產生一種阻止WNT發揮作用的抑制劑。”

Millar, who is a professor in dermatology at the University of Pennsylvania School of Medicine, continued: "We know that WNT signaling is critical for the development of hair follicles; blocking it causes hairless skin, and switching it on causes formation of more hair."

米勒是賓夕法尼亞大學醫學院皮膚學教授，他接着說：“我們知道WNT信號對毛囊的發育至關重要；阻斷它會導致無毛的皮膚，而開啓它會導致更多毛髮的形成。”

For their study, the researchers analyzed mouse skin similar to that on a human wrist. Their work showed the protein DKK2 was expressed highly in this part of the mammal compared to hairy areas.

在他們的研究中，研究人員分析了老鼠與人類手腕相似的皮膚。他們的工作表明，與毛髮區相比，這部分哺乳動物體內的DKK2蛋白表達量較高。

As with mice, humans don't grow hair in their wrist area, whereas other mammals, like rabbits and polar bears, do, the authors highlighted. When they compared DKK2 expression in mouse wrist skin with rabbit, they found it in lower levels in the latter.

研究人員強調，與老鼠一樣，人類手腕部位的毛髮不會生長，而兔子和北極熊等其他哺乳動物會。他們將小鼠腕部皮膚的DKK2表達與兔腕部皮膚的DKK2表達進行比較，發現兔腕部皮膚的DKK2表達較低。

"WNT is still present in hairless regions, it's just being blocked," explained Millar.

米勒解釋說：“WNT仍然存在於無毛地區，只是被阻擋了。”

The team hopes its findings could help prompt further research into hair growth. This could, in turn, lead to treatments in those where the body has stopped producing hair in particular areas, for instance those with deep wounds or burns, Millar said.

研究小組希望這一發現能有助於進一步研究頭髮的生長。米勒稱，這進而可能導致在身體某些特定部位停止長頭髮的人，比如那些有深度傷口或燒傷的人，得到治療。

"We hope that these lines of investigation will reveal new ways to improve wound healing and hair growth, and we plan to continue to pursue these goals moving forward," Millar said.

米勒表示：“我們希望這些研究將揭示改善傷口癒合和頭髮生長的新方法，我們計劃繼續追求這些目標。”