Salivary Histatin 1 and 2 Are Targeted to Mitochondria and Endoplasmic Reticulum in Human Cells.

Dandan Ma,Dandan Ma,Dandan Ma,Richard T Jaspers,Floris J Bikker,Floris J Bikker,Floris J Bikker,Wei Sun,Wei Sun,Wei Sun,Gang Wu,Gang Wu,Gang Wu,Jan G M Bolscher,Jan G M Bolscher,Jan G M Bolscher,Kamran Nazmi,Kamran Nazmi,Kamran Nazmi,Enno C I Veerman

doi:10.3390/cells9040795

Dandan Ma, Dandan Ma + Show 18 more

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https://doi.org/10.3390/cells9040795

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Abstract

Human salivary histatin 1 (Hst1) and Hst2 exhibit a series of cell-activating properties (e.g., promoting adhesion, spreading, migration and metabolic activity of mammalian cells). In contrast, Hst5 shows an anti-fungal property but no cell-activating properties. Previous findings suggest that their uptake and association with subcellular targets may play a determinant role in their functions. In this study, we studied the uptake dynamics and subcellular targets of Hst1, Hst2 and Hst5 in epithelial cells (HO1N1 human buccal carcinoma epithelial cell line). Confocal laser scanning microscopy (CLSM) revealed that fluorescently labeled Hst1 (F-Hst1) was taken up into the intracellular space of epithelial cells. Then, 60 min post-incubation, the total fluorescence of cell-associated F-Hst1, as measured using flow cytometry, was significantly higher compared to those of F-Hst2 and F-Hst5. In contrast, virtually no association occurred using the negative control—scrambled F-Hst1 (F-Hstscr). CLSM images revealed that F-Hst1, 2 and 5 co-localized with mitotrackerTM-labeled mitochondria. In addition, F-Hst1 and F-Hst2 but neither F-Hst5 nor F-Hst1scr co-localized with the ER-trackerTM-labeled endoplasmic reticulum. No co-localization of Hst1, 2 and 5 with lysosomes or the Golgi apparatus was observed. Furthermore, Hst1 and Hst2 but not Hst5 or Hst1scr significantly promoted the metabolic activity of both human epithelial cell lines, HaCaT human keratinocytes and primary human gingival fibroblasts.

Highlights

The histatin (Hst) peptide family, which comprises at least 12 low molecular weight histidine-rich peptides, is mainly found in saliva of higher primates [1]
Fluorescence microscopy revealed that a detectable association of F-histatin 1 (Hst1) with HO1N1 epithelial cells was found as early as 5 min after starting the incubation (Figure 1A)
Previous studies have suggested that the uptake and subcellular targets were critical for the biological functions of both cell-activating Hst1, Hst2 [2,7] and anti-fungal Hst5 [10,22,23]

Summary

Introduction

The histatin (Hst) peptide family, which comprises at least 12 low molecular weight histidine-rich peptides, is mainly found in saliva of higher primates [1]. According to their biological functions Hsts can be divided into two major groups: (1) cell-activating Hsts (Hst and Hst2) [2,3,4,5,6,7] and (2) anti-fungal. Hst and Hst are internalized in epithelial cells [2,7] in contrast to the D-enantiomer of Hst (D-Hst2), which can not promote the migration of epithelial cells and neither is internalized by the cells [3]

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