Proteomic approach to investigate the expression, localization, and functions of the protein product of the <i>SOWAHD</i> gene during granulocytic differentiation

Abstract

Cataloging human proteins, determining their level of content, cellular localization, function performed, and potential medical significance are important tasks facing the global proteomic community. At present, the localization and functions of protein products for almost half of the protein-coding genes are unknown or poorly understood. The study of the organelle proteome is a promising approach to reveal the localization and functions of human proteins. The nuclear proteome is of particular interest because many nuclear-localized proteins, such as transcription factors, perform regulatory functions that determine cell fate. According to the results of a meta-analysis of the nuclear proteome, or nucleome, of HL-60 cells treated by all-trans-retinoic acid (ATRA), it was revealed that the function and localization of the protein product of the SOWAHD gene is poorly understood, in addition, there is no comprehensive information on the expression of SOWAHD at the protein level. In HL-60 cells for the protein-coding gene SOWAHD, mRNA expression was determined at the level of 6.4 ± 0.7 transcripts per million molecules. Using targeted mass spectrometry, the content of SOWAHD protein was measured in the range of 0.27-1.25 fmol/µg of total protein. Using stable isotope pulse-chase labeling, the half-life for the protein product of the SOWAHD gene was determined to be approximately 19 h. Proteomic profiling of the nuclear fraction of HL-60 cells showed that the SOWAHD protein content increased during ATRA-induced granulocytic differentiation, peaking at 9 h after the addition of the inductor and followed by a decrease at later time points. The results of the study indicate for the first time the nuclear localization and involvement of the protein product of the SOWAHD gene in induced granulocytic differentiation.