Knockdown expression of a MYB-related transcription factor gene, OsMYBS2, enhances production of recombinant proteins in rice suspension cells

Abstract

Background Transgenic plant suspension cells show economic potential for the production of valuable bioproducts. The sugar starvation-inducible rice αAmy3 promoter, together with its signal peptide, is widely applied to produce recombinant proteins in rice suspension cells. The OsMYBS2 transcription factor was shown recently to reduce activation of the αAmy3 promoter by competing for the binding site of the TA box of the αAmy3 promoter with the potent OsMYBS1 activator. In this study, rice suspension cells were genetically engineered to silence OsMYBS2 to enhance the production of recombinant proteins. Results The mouse granulocyte–macrophage colony-stimulating factor (mGM-CSF) gene was controlled by the αAmy3 promoter and expressed in OsMYBS2-silenced transgenic rice suspension cells. Transcript levels of the endogenous αAmy3 and the transgene mGM-CSF were increased in the OsMYBS2-silenced suspension cells. The highest yield of recombinant mGM-CSF protein attained in the OsMYBS2-silenced transgenic suspension cells was 69.8 µg/mL, which is 2.5-fold that of non-silenced control cells. The yield of recombinant mGM-CSF was further increased to 118.8 µg/mL in cultured cells derived from homozygous F5 seeds, which was 5.1 times higher than that of the control suspension cell line. Conclusions Our results demonstrate that knockdown of the transcription factor gene OsMYBS2 increased the activity of the αAmy3 promoter and improved the yield of recombinant proteins secreted in rice cell suspension cultures.

Comparative analysis of the MYB gene family in seven Ipomoea species

“…The MYB transcription factor gene family is one of plants’ most prominent transcription factor families. It is involved in various essential life processes, including plant growth ( Zhao et al., 2019 ), development ( Liu et al., 2021 ; Yu et al., 2021 ), biosynthesis ( Sinaga et al., 2021 ), and defense responses ( Dubos et al., 2010 ; Lv et al., 2021 ; Hawku et al., 2022 ). Therefore, this gene family attracted more and more attention from various plant researchers and has been extensively investigated in many plant species, such as Arabidopsis ( Chen et al., 2006 ), rice ( Chen et al., 2006 ), soybean ( Du et al., 2012b ), maize ( Du et al., 2012a ), and potato ( Li et al., 2021c ).…”

“…Based on the highly conserved motif, the MYB-related TFs can be divided into subgroups ( Liu et al., 2020b ; Arce-Rodríguez et al., 2021 ; Yan et al., 2022 ). The MYB-related TFs play essential roles in plant seed germination and root growth ( Zhao et al., 2019 ), leaf senescence and epidermal cell patterning ( Lee and Schiefelbein, 1999 ; Machado et al., 2009 ; Park et al., 2018 ), biosynthesis ( Sinaga et al., 2021 ), the regulation of circadian rhythms ( Alabadí et al., 2001 ; Mizoguchi et al., 2002 ; Okada et al., 2009 ; Kamioka et al., 2016 ), and stress responses ( Dubos et al., 2010 ; Park et al., 2018 ; Zhao et al., 2019 ; Hoseinpour et al., 2021 ).…”

Maximizing the Production of Recombinant Proteins in Plants: From Transcription to Protein Stability

“…Accumulation of high levels of recombinant proteins in these lines was stable in multiple vegetative propagations. In rice, the sugar starvation-inducible αAmy3 promoter and its signal peptide has been widely used for production of recombinant proteins in rice suspension cells [ 69 ]. Rice MYBS1 is a transcription factor that recognizes specific cis-acting elements in the αAmy3 promoter to activate the inducible expression of the endogenous αAmy3 gene.…”

“…Rice MYBS1 is a transcription factor that recognizes specific cis-acting elements in the αAmy3 promoter to activate the inducible expression of the endogenous αAmy3 gene. Rice MYBS2, on the other hand, is a negative regulator of αAmy3 expression by competing for binding sites with MYBS1 in the αAmy3 promoter [ 69 ]. By knocking down the expression of MYBS2 expression in rice suspension culture, Sinaga and colleagues were able to increase accumulation of recombinant proteins by 2-5-fold [ 69 ].…”

“…Rice MYBS2, on the other hand, is a negative regulator of αAmy3 expression by competing for binding sites with MYBS1 in the αAmy3 promoter [ 69 ]. By knocking down the expression of MYBS2 expression in rice suspension culture, Sinaga and colleagues were able to increase accumulation of recombinant proteins by 2-5-fold [ 69 ].…”