Spermatogenesis-associated protein 16 is a mammalian

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respo ...

encoded by the SPATA16 gene. SPATA16, also known as NYD-SP12, is a developmental protein that aids in differentiation of germ cells for

spermatogenesis Spermatogenesis is the process by which haploid spermatozoa develop from germ cells in the seminiferous tubules of the testis. This process starts with the mitotic division of the stem cells located close to the basement membrane of the tubule ...

and participates in

acrosome The acrosome is an organelle that develops over the anterior (front) half of the head in the spermatozoa (sperm cells) of many animals including humans. It is a cap-like structure derived from the Golgi apparatus. In placental mammals the acrosome ...

formation for appropriate

sperm Sperm is the male reproductive cell, or gamete, in anisogamous forms of sexual reproduction (forms in which there is a larger, female reproductive cell and a smaller, male one). Animals produce motile sperm with a tail known as a flagellum, whi ...

-egg fusion. SPATA16 is located on

chromosome A chromosome is a long DNA molecule with part or all of the genetic material of an organism. In most chromosomes the very long thin DNA fibers are coated with packaging proteins; in eukaryotic cells the most important of these proteins are ...

3 at position 26.31 (reverse strand) and is a member of the

tetratricopeptide The tetratricopeptide repeat (TPR) is a structural motif. It consists of a Degeneracy (biology), degenerate 34 amino acid protein tandem repeats, tandem repeat identified in a wide variety of proteins. It is found in tandem arrays of 3–16 motif ...

repeat-like superfamily, which facilitate interactions and assemblies between proteins and protein complexes.

Identification

SPATA16 (NYD-SP12) was first identified by a research lab in 2002, led by Dr. Jiahao Sha, at

Nanjing Medical University Nanjing Medical University (NMU; ) is a university in Nanjing, Jiangsu Province, China. It was established in 1934 in Zhenjiang, but subsequently relocated to Nanjing in 1957. The university has two main campuses: Wutai and Jiangning, both of which ...

in Nanjing, China. The research team used cDNA

microarrays A microarray is a multiplex lab-on-a-chip. Its purpose is to simultaneously detect the expression of thousands of genes from a sample (e.g. from a tissue). It is a two-dimensional array on a solid substrate—usually a glass slide or silicon t ...

to compare expression levels of genes between adult and fetal human testes. It was discovered that the expression levels of SPATA16 were higher in adult

testes A testicle or testis (plural testes) is the male reproductive gland or gonad in all bilaterians, including humans. It is homologous to the female ovary. The functions of the testes are to produce both sperm and androgens, primarily testoster ...

than fetal testes, which signified that the gene is required for complete spermatogenesis once a male reaches puberty. Expression of SPATA16 is the highest in testicular tissue; however, SPATA16 is also expressed in several other tissue types including skeletal muscle, nervous tissue, and

integumentary system The integumentary system is the set of organs forming the outermost layer of an animal's body. It comprises the skin and its appendages, which act as a physical barrier between the external environment and the internal environment that it serves ...

tissue. SPATA16 accumulates around the

Golgi apparatus The Golgi apparatus (), also known as the Golgi complex, Golgi body, or simply the Golgi, is an organelle found in most eukaryotic cells. Part of the endomembrane system in the cytoplasm, it packages proteins into membrane-bound vesicles ins ...

that is perinuclear in the cytoplasm of

Sertoli cells Sertoli cells are a type of sustentacular "nurse" cell found in human testes which contribute to the process of spermatogenesis (the production of sperm) as a structural component of the seminiferous tubules. They are activated by follicle-stimula ...

; however, the gene is not present in the interstitial cells of

Leydig Leydig cells, also known as interstitial cells of the testes and interstitial cells of Leydig, are found adjacent to the seminiferous tubules in the testicle and produce testosterone in the presence of luteinizing hormone (LH). They are polyhedral ...

in the testes. Mutations in the SPATA16

gene In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a ba ...

are associated with male

infertility Infertility is the inability of a person, animal or plant to reproduce by natural means. It is usually not the natural state of a healthy adult, except notably among certain eusocial species (mostly haplodiploid insects). It is the normal state ...

in humans and can cause

globozoospermia Globozoospermia is a rare and severe form of monomorphic teratozoospermia. This means that the spermatozoa show the same abnormality, and over 85% of spermatozoa in sperm have this abnormality. Globozoospermia is responsible for less than 0.1% of m ...

, which are round-headed sperm without acrosomes. Sperm with incorrect head

morphology Morphology, from the Greek and meaning "study of shape", may refer to: Disciplines * Morphology (archaeology), study of the shapes or forms of artifacts * Morphology (astronomy), study of the shape of astronomical objects such as nebulae, galaxies ...

and absent acrosome are unable to bind to an

oocyte An oocyte (, ), oöcyte, or ovocyte is a female gametocyte or germ cell involved in reproduction. In other words, it is an immature ovum, or egg cell. An oocyte is produced in a female fetus in the ovary during female gametogenesis. The female ...

for

fertilization Fertilisation or fertilization (see spelling differences), also known as generative fertilisation, syngamy and impregnation, is the fusion of gametes to give rise to a new individual organism or offspring and initiate its development. Proce ...

. Studies involving knockout SPATA16 male mice indicate a slight functional difference of the SPATA16 gene between mice and humans. SPATA16

knockout mice A knockout mouse, or knock-out mouse, is a genetically modified mouse (''Mus musculus'') in which researchers have inactivated, or "knocked out", an existing gene by replacing it or disrupting it with an artificial piece of DNA. They are importan ...

are completely infertile, and it is characterized by spermatogenesis arrest and

azoospermia Azoospermia is the medical condition of a man whose semen contains no sperm. It is associated with male infertility, but many forms are amenable to medical treatment. In humans, azoospermia affects about 1% of the male population and may be seen ...

. This is where the differentiation process is obstructed during spermatogenesis and creates immotile sperm. In contrast, infertility caused by SPATA16 mutations in male humans develop spermatozoa that are motile, but their sperm exhibit head and acrosome abnormalities.

References

{{Reflist Genes on human chromosome 3