Characteristics of Shisa Family Genes in Zebrafish.

Shisa represents a type of single-transmembrane adaptor protein containing an N-terminal cysteine-rich domain and a proline-rich C-terminal region. Nine shisa subfamily genes have been proposed in most vertebrates; however, some might be species-specific. The number of shisa genes present in zebrafish remains unclear. This study aimed to investigate the evolutionary relationships among shisa family genes in zebrafish (TU strain) using phylogenetic and syntenic analyses. The function of shisa-2 was preliminarily examined via CRISPR/Cas13d-mediated knockdown. Following identification in zebrafish, 10 shisa family genes, namely shisa-1, 2, 3, 4, 5, 6, 7, 8, 9a, and 9b, were classified into three main clades and six subclades. Their encoding proteins contained a cysteine-rich N-terminal domain and a proline-rich C-terminal region containing different motifs. A specific syntenic block containing atp8a2 and shisa-2 was observed to be conserved across all species. Furthermore, all these genes were expressed during embryogenesis. Shisa-2 was expressed in the presomitic mesoderm, somites, and so on. Shisa-2 was identified as a regulator of the expression of the somite formation marker mesp-ab. Overall, our study provides new insights into the evolution of shisa family genes and the control of shisa-2 over the convergent extension cells of somitic precursors in zebrafish.

Sonic Hedgehog switches on Wnt/planar cell polarity signaling in commissural axon growth cones by reducing levels of Shisa2.

Commissural axons switch on responsiveness to Wnt attraction during midline crossing and turn anteriorly only after exiting the floor plate. We report here that Sonic Hedgehog (Shh)-Smoothened signaling downregulates Shisa2, which inhibits the glycosylation and cell surface presentation of Frizzled3 in rodent commissural axon growth cones. Constitutive Shisa2 expression causes randomized turning of post-crossing commissural axons along the anterior-posterior (A-P) axis. Loss of Shisa2 led to precocious anterior turning of commissural axons before or during midline crossing. Post-crossing commissural axon turning is completely randomized along the A-P axis when Wntless, which is essential for Wnt secretion, is conditionally knocked out in the floor plate. This regulatory link between Shh and planar cell polarity (PCP) signaling may also occur in other developmental processes.

SHISA2 enhances the aggressive phenotype in prostate cancer through the regulation of WNT5A expression.

The present study aimed at identifying novel molecular cancer drug targets and biomarkers by analyzing the gene expression profiles of high-grade prostate cancer (PC), using a cDNA microarray combined with laser microbeam microdissection. A number of genes were identified that were transactivated in high-grade PC. First, a novel molecular target and diagnostic biomarker, shisa family member 2 (SHISA2), was identified as an overexpressed gene in high-grade PC cells. The reverse transcription-semi-quantitative polymerase chain reaction and immunohistochemical analysis validated the overexpression of SHISA2 (295 amino acids in length), specifically in high-grade PC cells with Gleason scores of between 8 and 10, relative to normal prostate epithelium. Knockdown of SHISA2 expression by short interfering RNA resulted in the marked suppression of PC cell viability. By contrast, exogenous SHISA2 expression in transfected cells promoted PC cell proliferation, indicating its oncogenic effects. Notably, as a result of cDNA microarray analysis, protein Wnt-5a (WNT5A) was focused upon and the expression of WNT5A was identified to be downregulated in SHISA2-knockdown. Western blot analysis validated significant downregulation of WNT5A by SHISA2-knockdown and upregulation of WNT5A by SHISA2 overexpression. The results of the present study indicated that SHISA2 may affect WNT5A synthesis. Furthermore, the secreted SHISA2 protein was determined in the culture medium of PC cells. We hypothesize that SHISA2 is involved in the regulation of WNT5A and in the aggressiveness of PC via the Wnt signaling pathway through WNT5A. Furthermore, SHISA2 may be a molecular target for cancer drugs, and a useful diagnostic biomarker for the prognosis and therapeutic effect in cancer.