The Role of Potassium Channels in Stripe Pattern Formation
Shigeru Kondo1,○Masafumi Inaba1, Ken-ichiro Ida2, Koichi Kawakami3
1)Osaka University, Suita, Japan, 2)Nagoya University, Nagoya, Japan,3)Institute of Genetics, Mishima, Japan
Understanding the mechanisms that generate complex patterns seen in animals is one of the goals of
developmental biology. To address this issue at the molecular level, we have analyzed stripe pattern mutant
of zebrafish. Our previous study about jaguar/obelix mutant revealed that dysfunction of inwardly rectifying
potassium channel 7.1 (Kir7.1) caused the change of stripe width resulting in broad stripes on fish body. The role
of Kir7.1 channel in stripe pattern formation remains unclear, because (1) little is known about the physiological
functions of this channel; (2) molecular functions of the channel differ from those of other Kir subfamilies.
Here, we used transgenic approaches to examine how Kir7.1 channels form the stripe pattern on zebrafish.
We first generated transgenic jaguar fish that expresses WT-kir7.1 only in melanophores. The transgenic
mutant fish showed normal stripe pattern like wild-type fish, suggesting that expression of kir7.1 only in
melanophores is enough for stripe pattern formation. We then generated transgenic jaguar fish that expresses
kir4.1, kir2.1 (Kir subfamilies) or kv1.2 (voltage gated potassium channel) only in melanophores instead of
kir7.1. As a result, both kir4.1 and kir2.1 could rescue the jaguar phenotype, whereas kv1.2 failed to rescue.
These results suggest that common features of Kir channels are required for stripe pattern formation, rather
than some unique properties of kir7.1. Taken together, our results suggest that resting membrane potential
(Eres) of melanophores is a key factor in stripe pattern formation, because all of Kir channels we tested
play a role in maintenance of Eres, whereas Kv1.2 does not. We are currently using voltage sensitive dye to
investigate the Eres of melanophores, and the results will be discussed in this meeting.