Structural prediction of two novel human atypical SLC transporters, MFSD4A and MFSD9, and their neuroanatomical distribution in mice

Abstract

Out of the 430 known solute carriers (SLC) in humans, 30% are still orphan transporters regarding structure, distribution or function. Approximately one third of all SLCs belong to the evolutionary conserved and functionally diverse Major Facilitator Superfamily (MFS). Here, we studied the orphan proteins, MFSD4A and MFSD9, which are atypical SLCs of MFS type. Hidden Markov Models were used to identify orthologues in several vertebrates, and human MFSD4A and MFSD9 share high sequence identity with their identified orthologues. MFSD4A and MFSD9 also shared more than 20% sequence identity with other phylogenetically related SLC and MFSD proteins, allowing new family clustering. Homology models displayed 12 transmembrane segments for both proteins, which were predicted to fold into a transporter-shaped structure. Furthermore, we analysed the location of MFSD4A and MFSD9 in adult mouse brain using immunohistochemistry, showing abundant neuronal protein staining. As MFSD4A and MFSD9 are plausible transporters expressed in food regulatory brain areas, we monitored transcriptional changes in several mouse brain areas after 24 hours food-deprivation and eight weeks of high-fat diet, showing that both genes were affected by altered food intake in vivo. In conclusion, we propose MFSD4A and MFSD9 to be novel transporters, belonging to disparate SLC families. Both proteins were located to neurons in mouse brain, and their mRNA expression levels were affected by the diet.

Glucose Availability Alters Gene and Protein Expression of Several Newly Classified and Putative Solute Carriers in Mice Cortex Cell Culture and D. melanogaster

“…The newly identified SLC and putative transporters that were included here have been found to be mostly neuronal (Perland et al, 2016(Perland et al, , 2017cCeder et al, 2017;Lekholm et al, 2017), and the staining found here was also localized to neurons in the mixed cultures used. Glucose is mainly used to provide the neurons with one highly important product, energy in the form of ATP, a task performed in the cytosol and within the mitochondria (Jonckheere et al, 2012).…”

“…Immunocytochemistry (ICC) was performed with a set of antibodies against putative SLCs that have been verified elsewhere and that provided similar immunostaining patterns between the published ICCs ( Perland et al, 2017c ) and the ICCs performed in this study. Immunocytochemistry was performed as described in Lekholm et al (2017) with antibodies for MFSD1 [SAB3500575, Sigma, ( Perland et al, 2017b )] diluted 1:50 in Supermix blocking solution, SLC60A1 [SAB1305276, Sigma, ( Perland et al, 2017c )] diluted 1:100, MFSD11 [Sc-243473, Santa-Cruz, ( Perland et al, 2016 )] diluted 1:80, MFSD14A [Ab103836, Abcam, ( Lekholm et al, 2017 )] diluted 1:100, MFSD14B [SAB2107506, Sigma, ( Lekholm et al, 2017 )] diluted 1:100, UNC93A [Ab69443, Abcam, ( Ceder et al, 2017 )] diluted 1:100 also in Supermix together with PAN diluted 1:200 (Millipore), GFAP diluted 1:200 (Abcam) and DAPI (Sigma Aldrich) diluted in PBS 1:15,000. For fluorescent quantification, images were taken using the same exposure settings for all pictures using an Olympus microscope BX53 with an Olympus DP73 camera and CellSens Dimension software.…”

“…The cells were then washed 3 × 10 min with DPBS and stored in DPBS at 4 • C until analysis. Immunocytochemistry (ICC) was performed with a set of antibodies against putative SLCs that have been verified elsewhere and that provided similar immunostaining patterns between the published ICCs (Perland et al, 2017c) and the ICCs performed in this study. Immunocytochemistry was performed as described in Lekholm et al 2017 (Ceder et al, 2017)] diluted 1:100 also in Supermix together with PAN diluted 1:200 (Millipore), GFAP diluted 1:200 (Abcam) and DAPI (Sigma Aldrich) diluted in PBS 1:15,000.…”

Genome-wide association study for milk production traits in a Brazilian Holstein population

“…On BTA16, a window from 3.07 to 3.42 Mbp was associated with C18:0, where MFSD4A, SLC41A1, and SLC45A3, all solute carrier family members, are located. The MFSD4A gene was identified as a transporter expressed in food regulatory brain areas in mice (Perland et al, 2017). Those authors also suggested MFSD4A can be a sugar transporter for sharing 20% of the AA with MFSD4B, a sodium-dependent sugar transporter (Horiba et al, 2003).…”

CG4928 Is Vital for Renal Function in Fruit Flies and Membrane Potential in Cells: A First In-Depth Characterization of the Putative Solute Carrier UNC93A

“…Lately, several orphan transporters suggested to be putative SLCs ( Perland and Fredriksson, 2017 ; Perland et al, 2017a ) have begun to be characterized with focus on evolutionary relationship, protein structure prediction, and expression profile ( Perland et al, 2016 , 2017b , c ; Ceder et al, 2017 ; Lekholm et al, 2017 ). Previous phylogenetic analyses predicted UNC93A to be evolutionary preserved ( Ceder et al, 2017 ; Perland and Fredriksson, 2017 ; Perland et al, 2017a ), which we also confirmed.…”