SOX Family

SOX proteins make up a family of high-mobility group (HMG) domain transcription factors implicated in a variety of physiological and pathological processes, including development, cell reprogramming and tumorigenesis. So far, 20 different SOX genes have been discovered (see Schepers et al., 2002). Based on the HMG domain homology, SOX proteins are divided into different groups termed A to H (Figure 1). Within each group, individual SOX proteins share biochemical properties and have overlapping functions. In contrast, SOX factors from different groups have distinct biological functions despite recognizing the same DNA consensus motif (Wegner, 2010). The action of SOX proteins is often dependent on homo- or dimerization or interaction with other transcription factors.

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Figure 1: Tissue expression of various SOX factors belonging to SOXB1-SOXH groups visualized using fluorescence or chromogenic immunohistochemistry:
(A) SOX2 in mouse embryo E11 neural tube (AMAb91307),
(B) SOX21 in mouse brain (AMAb91311),
(C) SOX4 in mouse brain rostral migratory stream (AMAb91378),
(D) SOX6 in human testis (HPA001923),
(E) SOX9 in mouse embryo E14 cartilage,
(F) SOX17 in human endometrium (HPA068399), (G) SOX15 in human esophagus (HPA067196),
(H) SOX30 in human testis (HPA006159).

Nervous system

Many SOX factors are involved in the de- velopment of the nervous system. For ex- ample SOXB1 proteins are important for the early embryonal CNS development and are also expressed in adult neural stem cells. SOX2 is one of the essential transcription factors contributing to the embryonic stem cell state and further de- velopment of the central nervous system.

Figure 2: SOX factors in nervous system development. (A) SOX2 expression in the developing forebrain, eye and trigeminal ganglion of mouse embryo E11 visualized by Anti-SOX2 antibody AMAb91307.
(B) Western Blot with AMAb91307 displays a band of expected size in NTERA-2 cell lysate. (C) ICC-IF with AMAb91307 in U-251 MG cell line shows nuclear localization of the protein. (D) SOX10 expression in the developing trigeminal ganglion and sensory placodes of mouse embryo E11 visualized by Anti- SOX10 antibody AMAb91297.

Figure 2 shows SOX2 immunoreactivity in the developing brain of the mouse embryo E11 (A) using PrecisA Monoclonal antibody AMAb91307. The specificity of the antibody used for the staining was confirmed by WB (B) and ICC-IF (C) experiments. B

SOXE proteins are involved in CNS gliogenesis, where for example SOX10 is essential for terminal oligodendrocyte dif- ferentiation in the CNS. In the peripheral nervous system, SOX10 is required for specification of all PNS glia.

Figure 2D shows SOX10 immunoreactivity in mouse embryo E11 (A) using Pre- cisA Monoclonal antibody AMAb91297. Note that at this stage SOX10 is mainly expressed in the peripheral nervous system, e.g. trigeminal ganglion and sensory placodes.

Reproductive system

Another example of involvement of SOX factors in development is the reproductive system. SOX9 is expressed initially in the neural crest-competent cell population present in the dorsal neural tube (Cheung and Briscoe, 2003) (Figure 3A). Later in development, SOX9 is expressed in both male and female genital ridges up until the onset of Sry expression. Following this event, SOX9 expression becomes restricted to the male gonad, where it functions as a critical Sertoli cell differentiation factor (Figure 3B). Whereas SOX9 is restricted to somatic cells of the gonad, there is a second set of SOX proteins expressed in germ cells. Thus, group D proteins SOX5 and SOX6 are expressed in post-meiotic germ cells, with the highest levels in spermatids, as illustrated for SOX6 in Figure 3C.

Figure 3:(A) SOX9 expression in the developing dorsal neural tube of mouse embryo E11 shown by IHC-IF with Anti-SOX9 AMAb90795.

Figure 3B/C:
(B) SOX9 expression in adult human testis shown C by IHC with Anti-SOX9 antibody HPA001758.
(C) SOX6 expression in human testis visualized
by Anti-SOX6 antibody HPA001923.

Tumorigenesis

Several SOX factors are also involved in tumorigenesis. For example upregulation of SOXD (SOX5, SOX6) proteins is ob- served in glioma (Figure 4A, SOX6), while mantle cell lymphoma can be diagnosed by overexpression of SOX11 protein (Figure 4B, C).

Figure 4: (A) IHC staining of human high grade glioma with Anti- SOX6 antibody HPA001923 shows strong nuclear im- munoreactivity in tumor cells. (B) IHC staining of hu- man mantle cell lymphoma with Anti-SOX11 antibody HPA000536 shows nuclear positivity in tumor cells. Compare to the absence of nuclear positivity in a con- trol chronic lymphocytic leukemia shown in C.

SOXB1 Products

Anti-SOX 2 Antibody AMAB91307

Validated Application: IHC, WB*, ICC-IF

Sequence Identity Mouse/Rat: 99/99%

Involved in: Early embryonic development. Neural stem cells.

SOX Family

Nervous system

Reproductive system

Tumorigenesis

SOXB1 Products

Anti-SOX 2 Antibody AMAB91307

Anti-SOX2 Antibody HPA045725

Anti-SOX3 Antibody AMAb91312

Anti--SOX3 Antibody HPA054720

Anti-SOX3 Antibody HPA075003

SOXB2 Products

Anti-SOX21 Antibody AMAb91309

Anti-SOX21 Antibody AMAb91311

Anti-SOX21 Antibody HPA064084

SOXC Products

Anti-SOX4 Antibody HPA029901

Anti-SOX4 Antibody AMAb91378

Anti-SOX4 Antibody AMAb91380

Anti-SOX11 Antibody AMAb90501

SOXD Products

Anti-SOX5 Antibody HPA060499

Anti-SOX6 Antibody HPA001923

Anti-SOX13 Antibody HPA054843

SOXE Products

Anti-SOX8 Antibody HPA058665

Anti-SOX9 Antibody AMAb90795

Anti-SOX10 Antibody HPA068898

SOXF Products

Anti-SOX7 Antibody HPA009065

Anti-SOX17 Antibody HPA068399

Anti-SOX18 Antibody HPA073703

SOXG Products

Anti-SOX15 Antibody HPA067196

Anti-SOX15 Antibody HPA074049

SOXH Products

Anti-SOX30 Antibody HPA006159