Sir2B, A Sirtuin Family Protein, Involves in Cell Adhesion Molecule Expression During Early &amp;lt;i&amp;gt;Dictyostelium&amp;lt;/i&amp;gt; Development Upon Starvation

Hideo Taniura,Shuhei Soeda,Yui Sano,Minori Nakamura,Mio Morioka,Ai Fujii

doi:10.11648/j.cb.20210901.11

Abstract

Sirtuin involves in cellular processes to adapt to starvation in the endocrine and metabolic systems. We examined Sir2B function during early Dictyostelium development upon starvation. GFP-tagged Sir2B was expressed and the immunoreactivity was detected a punctate pattern near cell surface. Sir2B mRNA was expressed in vegetative cells and peaked at 2 h after starvation. Ectopic expression of Sir2B enhanced aggregate formation with increased expressions of cell adhesion molecules such as cadA, csaA, TgrB1, and TgrC1 at 8h compared to those in control cells. Sir2B null-mutant cells (Sir2B KO cells) were generated and they formed aggregates smaller than those of wild-type cells after 24 h. Because cell-cell adhesion affects aggregation size, cell cohesion assay of Sir2B KO cells showed cell-cell adhesion impairment at 8 and 10 h during development, and the expressions of four cell adhesion molecules were reduced in Sir2B KO cells compared to wild-type cells until 8 h after starvation. When RNAi-mediated cadA or csaA knockdown cells (cadA KD or csaA KD cells) were generated, csaA KD cells formed smaller aggregates and affected the expressions of other cell adhesion molecules to reduce, but cadA KD cells did not show to affect aggregation size and cell adhesion molecules expressions apparently. These results suggest that Sir2B is involved in csaA expression and affects other cell adhesion molecules during early development upon starvation.

Highlights

Sirtuin is originally discovered in Saccharomyces cerevisiae as Sir2, and Sir2 orthologs are highly conserved throughout evolution from archaebacteria to eukaryote.Sirtuin exhibits various enzymatic activities such as protein deacetylase and ADP ribosyltransferase
We have previously reported that Sirtuin activator resveratrol and inhibitor nicotinamide affect early development [5] and Sir2D regulates adenylate cyclase expression through interaction with a putative transcription factor MybB [6]
We examined roles of Sir2B during early development and found that Sir2B was involved in cell-cell adhesion molecules expression during early Dictyostelium development upon starvation

Summary

Introduction

Sirtuin exhibits various enzymatic activities such as protein deacetylase and ADP ribosyltransferase. These enzymatic activities are generally activated in response to calorie restriction by the utilization of nicotine adenine dinucleotide (NAD+) as the co-substrate. Dictyostelium cells is a eukaryote and grow vegetatively. Upon starvation, they start to gather with neighboring cells to form aggregates consisting of up to 105 cells. Because Dictyostelium cells start development in response to starvation, Sirtuin activation may be important for developmental process. We have previously reported that Sirtuin activator resveratrol and inhibitor nicotinamide affect early development [5] and Sir2D regulates adenylate cyclase (aca) expression through interaction with a putative transcription factor MybB [6]. Katayama et al have reported that Sir2A null mutant is less

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Conclusion