A member of the Six gene family promotes the specification of P cell fates in the O/P equivalence group of the leech Helobdella

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• 作者：Ian K. Quigley ; Matthew W. Schmerer ; Marty Shankl
• 关键词：Annelid ; Six gene ; Equivalence group ; Induction ; Gene duplication
• 刊名：Developmental Biology
• 出版年：2010
• 出版时间：1 August 2010
• 年：2010
• 卷：344
• 期：1
• 页码：319-330
• 全文大小：1585 K

文摘

The lateral ectoderm of the leech embryo arises from the o and p bandlets, two parallel columns of blast cells that collectively constitute the O/P equivalence group. Individual blast cells within this equivalence group become committed to alternative O or P developmental pathways in accordance with their respectively ventrolateral or dorsolateral position (Weisblat and Blair, 1984). We here describe a novel member of the Six gene transcription factor family, Hau-Six1/2A, which contributes to the patterning of these cell fates in the leech Helobdella sp. (Austin). During embryogenesis Hau-Six1/2A expression is restricted to the dorsolateral column of p blast cells, and thus correlates with P cell fate over most of the body's length. Experimental manipulations showed that Hau-Six1/2A expression is induced in p blast cells by the interaction with the adjoining q bandlet. In addition, misexpression of Hau-Six1/2A in the ventrolateral o blast cells by injection of an expression plasmid elicited the dorsolateral P cell fates ectopically. These data imply that Hau-Six1/2A is a component of the molecular pathway that normally distinguishes O and P cell fates within this equivalence group. Genomic analysis revealed that the Six1/2 subfamily has expanded to a total of six genes in Helobdella. The pattern of Hau-Six1/2A expression during later embryogenesis suggested that this gene may have lost ancestral function(s) and/or acquired novel roles in association with the gene duplications that produced this expansion.