Heterogeneous nuclear ribonucleoprotein (HNRNP) A1 and A2 are the most abundant HNRNPs with nearly identical functions, and play important roles in regulating gene expression at multiple levels (. transcription, posttranscription, and translation). However, the expression and regulation mechanism of HNRNPA1 and A2 themselves remain unclear. In this study, the amino acid sequences of HNRNPA1 and HNRNPA2 were compared and found to have 78% and 86% homology in key functional domains. Transfection of HEK293 cells with small interfering RNA and overexpression vectors of HNRNPA1 and HNRNPA2 demonstrated that HNRNPA1 and HNRNPA2 paralogs regulate each other’s expression in a compensatory manner at both the RNA and protein levels. Multiprimer reverse transcription-polymerase chain reaction showed that HNRNPA1 and HNRNPA2 did not affect splicing of the HNRNPA2 and HNRNPA1 gene. | Turkish Journal of Biology Turk J Biol 2021 45 187-195 http biology TÜBİTAK Research Article doi biy-2010-29 Compensatory expression regulation of highly homologous proteins HNRNPA1 and HNRNPA2 1 1 1 2 Yan CHANG Xiaofeng LU Jiaying QIU 1 School of Life Sciences Nantong University Nantong Jiangsu China 2 Department of Prenatal Screening and Diagnosis Center Affiliated Maternity and Child Health Care Hospital of Nantong University Nantong Jiangsu China Received Accepted Published Online Final Version Abstract Heterogeneous nuclear ribonucleoprotein HNRNP A1 and A2 are the most abundant HNRNPs with nearly identical functions and play important roles in regulating gene expression at multiple levels . transcription posttranscription and translation . However the expression and regulation mechanism of HNRNPA1 and A2 themselves remain unclear. In this study the amino acid sequences of HNRNPA1 and HNRNPA2 were compared and found to have 78 and 86 homology in key functional domains. Transfection of HEK293 cells with small interfering RNA and overexpression vectors of HNRNPA1 and HNRNPA2 demonstrated that HNRNPA1 and HNRNPA2 paralogs regulate each other s expression in a compensatory manner at both the RNA and protein levels. Multiprimer reverse transcription-polymerase chain reaction showed that HNRNPA1 and HNRNPA2 did not affect splicing of the HNRNPA2 and HNRNPA1 gene. Using luciferase reporting system we found that compensatory degradation was mediated by the 3 UTR of the two genes rather than by the promoter. Moreover treatment with cycloheximide inhibited the compensatory regulation. Our results indicate a novel regulation mechanism of HNRNPA1 and A2 expression. Through compensatory regulation the expression levels of HNRNPA1 and HNRNPA2 are strictly controlled within a certain range to maintain normal cellular activities under different physiological conditions. Key words HNRNPA1 HNRNPA2 .
