AUTHOR=England Samantha J. , Campbell Paul C. , Banerjee Santanu , Swanson Annika J. , Lewis Katharine E. 

TITLE=Identification and Expression Analysis of the Complete Family of Zebrafish pkd Genes

JOURNAL=Frontiers in Cell and Developmental Biology

VOLUME=5

YEAR=2017

URL=https://www.frontiersin.org/journals/cell-and-developmental-biology/articles/10.3389/fcell.2017.00005

DOI=10.3389/fcell.2017.00005

ISSN=2296-634X

ABSTRACT=<p>Polycystic kidney disease (PKD) proteins are trans-membrane proteins that have crucial roles in many aspects of vertebrate development and physiology, including the development of many organs as well as left–right patterning and taste. They can be divided into structurally-distinct PKD1-like and PKD2-like proteins and usually one PKD1-like protein forms a heteromeric polycystin complex with a PKD2-like protein. For example, PKD1 forms a complex with PKD2 and mutations in either of these proteins cause Autosomal Dominant Polycystic Kidney Disease (ADPKD), which is the most frequent potentially-lethal single-gene disorder in humans. Here, we identify the complete family of <italic>pkd</italic> genes in zebrafish and other teleosts. We describe the genomic locations and sequences of all seven genes: <italic>pkd1, pkd1b, pkd1l1, pkd1l2a, pkd1l2b, pkd2</italic>, and <italic>pkd2l1</italic>. <italic>pkd1l2a/pkd1l2b</italic> are likely to be ohnologs of <italic>pkd1l2</italic>, preserved from the whole genome duplication that occurred at the base of the teleosts. However, in contrast to mammals and cartilaginous and holostei fish, teleosts lack <italic>pkd2l2</italic>, and <italic>pkdrej</italic> genes, suggesting that these have been lost in the teleost lineage. In addition, teleost, and holostei fish have only a partial <italic>pkd1l3</italic> sequence, suggesting that this gene may be in the process of being lost in the ray-finned fish lineage. We also provide the first comprehensive description of the expression of zebrafish <italic>pkd</italic> genes during development. In most structures we detect expression of one <italic>pkd1</italic>-like gene and one <italic>pkd2</italic>-like gene, consistent with these genes encoding a heteromeric protein complex. For example, we found that <italic>pkd2</italic> and <italic>pkd1l1</italic> are expressed in Kupffer's vesicle and <italic>pkd1</italic> and <italic>pkd2</italic> are expressed in the developing pronephros. In the spinal cord, we show that <italic>pkd1l2a</italic> and <italic>pkd2l1</italic> are co-expressed in KA cells. We also identify potential co-expression of <italic>pkd1b</italic> and <italic>pkd2</italic> in the floor-plate. Interestingly, and in contrast to mouse, we observe expression of all seven <italic>pkd</italic> genes in regions that may correspond to taste receptors. Taken together, these results provide a crucial catalog of <italic>pkd</italic> genes in an important model system for elucidating cell and developmental processes and modeling human diseases and the most comprehensive analysis of embryonic <italic>pkd</italic> gene expression in any vertebrate.</p>