Primary cilia function as critical sensory organelles that mediate multiple signaling pathways, including the Hedgehog (Hh) pathway, which is essential for organ patterning and morphogenesis. Disruptions in Hh signaling have been implicated in supernumerary tooth formation and molar fusion in mutant mice. Cilk1, a highly conserved serine/threonine-protein kinase localized within primary cilia, plays a critical role in ciliary transport. Loss of Cilk1 results in severe ciliopathy phenotypes, including polydactyly, edema, and cleft palate. However, the role of Cilk1 in tooth development remains unexplored. In this study, we investigated the role of Cilk1 in tooth development. Cilk1 was found to be expressed in both the epithelial and mesenchymal compartments of developing molars. Cilk1 deficiency resulted in altered ciliary dynamics, characterized by reduced frequency and increased length, accompanied by downregulation of Hh target genes, such as Ptch1 and Sostdc1, leading to the formation of diastemal supernumerary teeth. Furthermore, in Cilk1^-/-;PCS1-MRCS1^△/△ mice, which exhibit a compounded suppression of Hh signaling, we uncovered a novel phenomenon: diastemal supernumerary teeth can be larger than first molars. Based on these findings, we propose a progressive model linking Hh signaling levels to sequential changes in tooth patterning: initially inducing diastemal supernumerary teeth, then enlarging them, and ultimately leading to molar fusion. This study reveals a previously unrecognized role of Cilk1 in controlling tooth morphology via Hh signaling and highlights how Hh signaling levels shape tooth patterning in a gradient-dependent manner.
Animals ; Hedgehog Proteins/physiology* ; Mice ; Signal Transduction/physiology* ; Tooth, Supernumerary ; Molar ; Cilia/physiology* ; Odontogenesis/physiology* ; Patched-1 Receptor ; Protein Serine-Threonine Kinases/physiology* ; Mice, Knockout ; Adaptor Proteins, Signal Transducing

Effective axon regeneration is essential for the successful restoration of nerve functions in patients suffering from axon injury-associated neurological diseases. Certain self-regeneration occurs in injured peripheral axonal branches of dorsal root ganglion (DRG) neurons but does not occur in their central axonal branches. By performing rat sciatic nerve or dorsal root axotomy, we determined the expression of the dysbindin domain containing 2 (DBNDD2) in the DRGs after the regenerative peripheral axon injury or the non-regenerative central axon injury, respectively, and found that DBNDD2 is down-regulated in the DRGs after peripheral axon injury but up-regulated after central axon injury. Furthermore, we found that DBNDD2 expression differs in neonatal and adult rat DRGs and is gradually increased during development. Functional analysis through DBNDD2 knockdown revealed that silencing DBNDD2 promotes the outgrowth of neurites in both neonatal and adult rat DRG neurons and stimulates robust axon regeneration in adult rats after sciatic nerve crush injury. Bioinformatic analysis data showed that transcription factor estrogen receptor 1 (ESR1) interacts with DBNDD2, exhibits a similar expression trend as DBNDD2 after axon injury, and may targets DBDNN2. These studies indicate that reduced level of DBNDD2 after peripheral axon injury and low abundance of DBNDD2 in neonates contribute to axon regeneration and thus suggest the manipulation of DBNDD2 expression as a promising therapeutic approach for improving recovery after axon damage.
Animals ; Ganglia, Spinal/metabolism* ; Nerve Regeneration/genetics* ; Rats ; Axons/metabolism* ; Sciatic Nerve/injuries* ; Rats, Sprague-Dawley ; Male

Multiple morphological abnormalities of the flagella (MMAF) represent a severe form of sperm defects leading to asthenozoospermia and male infertility. In this study, we identified a novel homozygous splicing mutation (c.871-4 ACA>A) in the adenylate kinase 7 (AK7) gene by whole-exome sequencing in infertile individuals. Spermatozoa from affected individuals exhibited typical MMAF characteristics, including coiled, bent, short, absent, and irregular flagella. Transmission electron microscopy analysis showed disorganized axonemal structure and abnormal mitochondrial sheets in sperm flagella. Immunofluorescence staining confirmed the absence of AK7 protein from the patients' spermatozoa, validating the pathogenic nature of the mutation. This study provides direct evidence linking the AK7 gene to MMAF-associated asthenozoospermia in humans, expanding the mutational spectrum of AK7 and enhancing our understanding of the genetic basis of male infertility.
Humans ; Male ; Sperm Tail/ultrastructure* ; Homozygote ; Consanguinity ; Asthenozoospermia/pathology* ; Infertility, Male/genetics* ; Mutation ; Pakistan ; Adenylate Kinase/genetics* ; Adult ; Pedigree ; RNA Splicing ; Exome Sequencing ; Spermatozoa

Male infertility can result from impaired sperm motility caused by multiple morphological abnormalities of the flagella (MMAF). Distinct projections encircling the central microtubules of the spermatozoal axoneme play pivotal roles in flagellar bending and spermatozoal movement. Mammalian sperm-associated antigen 17 ( SPAG17 ) encodes a conserved axonemal protein of cilia and flagella, forming part of the C1a projection of the central apparatus, with functions related to ciliary/flagellar motility, skeletal growth, and male fertility. This study investigated two novel homozygous SPAG17 mutations (M1: NM_206996.2, c.829+1G>T, p.Asp212_Glu276del; and M2: c.2120del, p.Leu707*) identified in four infertile patients from two consanguineous Pakistani families. These patients displayed the MMAF phenotype confirmed by Papanicolaou staining and scanning electron microscopy assays of spermatozoa. Quantitative real-time polymerase chain reaction (PCR) of patients' spermatozoa also revealed a significant decrease in SPAG17 mRNA expression, and immunofluorescence staining showed the absence of SPAG17 protein signals along the flagella. However, no apparent ciliary-related symptoms or skeletal malformations were observed in the chest X-rays of any of the patients. Transmission electron microscopy of axoneme cross-sections from the patients showed incomplete C1a projection and a higher frequency of missing microtubule doublets 1 and 9 compared with those from fertile controls. Immunofluorescence staining and Western blot analyses of spermatogenesis-associated protein 17 (SPATA17), a component of the C1a projection, and sperm-associated antigen 6 (SPAG6), a marker of the spring layer, revealed disrupted expression of both proteins in the patients' spermatozoa. Altogether, these findings demonstrated that SPAG17 maintains the integrity of spermatozoal flagellar axoneme, expanding the phenotypic spectrum of SPAG17 mutations in humans.
Humans ; Male ; Infertility, Male/pathology* ; Sperm Tail/ultrastructure* ; Homozygote ; Microtubule-Associated Proteins/genetics* ; Axoneme/genetics* ; Spermatozoa/ultrastructure* ; Adult ; Mutation ; Sperm Motility/genetics* ; Pedigree ; Microtubules ; Microtubule Proteins/genetics*

Multiple morphological abnormalities of sperm flagella (MMAF) is a severe form of asthenoteratozoospermia, characterized by morphological abnormalities and reduced motility of sperm, causing male infertility. Although approximately 60% of MMAF cases can be explained genetically, the etiology of the remaining cases is unclear. Here, we identified two novel compound heterozygous variants in the gene, dynein axonemal heavy chain 10 ( DNAH10 ), in three patients from two unrelated Pakistani families using whole-exome sequencing (WES), including one compound heterozygous mutation ( DNAH10 : c.9409C>A [p.P3137T]; c.12946G>C [p.D4316H]) in family 1 and another compound heterozygous mutation ( DNAH10 : c.8849G>A [p.G2950D]; c.11509C>T [p.R3687W]) in family 2. All the identified variants are absent or rare in public genome databases and are predicted to have deleterious effects according to multiple bioinformatic tools. Sanger sequencing revealed that these variants follow an autosomal recessive mode of inheritance. Hematoxylin and eosin (H&E) staining revealed MMAF, including sperm head abnormalities, in the patients. In addition, immunofluorescence staining revealed loss of DNAH10 protein signals along sperm flagella. These findings broaden the spectrum of DNAH10 variants and expand understanding of the genetic basis of male infertility associated with the MMAF phenotype.
Adult ; Humans ; Male ; Alleles ; Asthenozoospermia/pathology* ; Axonemal Dyneins/genetics* ; Dyneins/genetics* ; Exome Sequencing ; Infertility, Male/pathology* ; Mutation ; Pakistan ; Pedigree ; Sperm Tail/pathology*

The syndrome of multiple morphological abnormalities of the sperm flagella (MMAF) is one of the most serious kinds of sperm defects, leading to asthenoteratozoospermia and male infertility. In this study, we use whole-exome sequencing to identify genetic factors that account for male infertility in a patient born from a consanguineous Pakistani couple. A homozygous frameshift mutation (c.1399_1402del; p.Gln468ArgfsTer2) in axonemal dynein light chain domain containing 1 ( AXDND1 ) was identified in the patient. Sanger sequencing data showed that the mutation was cosegregated recessively with male infertility in this family. Papanicolaou staining and scanning electron microscopy analysis of the sperm revealed severely abnormal flagellar morphology in the patient. Immunofluorescence and western blot showed undetectable AXDND1 expression in the sperm of the patient. Transmission electron microscopy analysis showed disorganized sperm axonemal structure in the patient, particularly missing the central pair of microtubules. Immunofluorescence staining showed the absence of sperm-associated antigen 6 (SPAG6) and dynein axonemal light intermediate chain 1 (DNALI1) signals in the sperm flagella of the patient. These findings indicate that AXDND1 is essential for the organization of flagellar axoneme and provide direct evidence that AXDND1 is a MMAF gene in humans, thus expanding the phenotypic spectrum of AXDND1 frameshift mutations.
Humans ; Male ; Sperm Tail/ultrastructure* ; Frameshift Mutation ; Infertility, Male/pathology* ; Pakistan ; Pedigree ; Consanguinity ; Axonemal Dyneins/genetics* ; Adult ; Spermatozoa ; Exome Sequencing

Primary ciliary dyskinesia (PCD) is a genetically heterogeneous disorder characterized by impaired motility of cilia and flagella. Mutations in cilia- and flagella-associated protein 300 ( CFAP300 ) are associated with human PCD and male infertility; however, the underlying pathogenic mechanisms remain poorly understood. In a consanguineous Chinese family, we identified a homozygous CFAP300 loss-of-function variant (c.304delC) in a proband presenting with classical PCD symptoms and severe sperm abnormalities, including dynein arm deficiency and acrosomal malformation, as confirmed by transmission electron microscopy (TEM). Histological analysis revealed multiple morphological abnormalities of the sperm flagella in CFAP300 -mutant individual, whereas immunofluorescence demonstrated markedly reduced CFAP300 expression in the spermatozoa of the proband. Furthermore, tandem mass tag (TMT)-based quantitative proteomics showed that the CFAP300 mutation reduced key spermatogenesis proteins (e.g., sperm flagellar 2 [SPEF2], solute carrier family 25 member 31 [SLC25A31], and A-kinase anchoring protein 3 [AKAP3]) and mitochondrial ATP synthesis factors (e.g., SLC25A31, cation channel sperm-associated 3 [CATSPER3]). It also triggered abnormal increases in autophagy-related proteins and signaling mediator phosphorylation. These molecular alterations are likely to contribute to progressive deterioration of sperm ultrastructure and function. Notably, successful pregnancy was achieved via intracytoplasmic sperm injection (ICSI) using the proband's sperm. Overall, this study expands the known CFAP300 mutational spectrum and offers novel mechanistic insights into its role in spermatogenesis.
Humans ; Male ; Infertility, Male/pathology* ; Acrosome/pathology* ; Sperm Tail/pathology* ; Pedigree ; Spermatozoa ; Adult ; Loss of Function Mutation ; Ciliary Motility Disorders/genetics* ; Spermatogenesis/genetics* ; Female

White matter injury (WMI) is a major form of brain injury in preterm infants. Its characteristic pathological features primarily involve impaired development of oligodendrocyte precursor cells and structural damage to axons, which can lead to the neurological sequelae such as motor, behavioral, and cognitive dysfunctions. Chondroitin sulfate proteoglycans (CSPGs), as the important components of extracellular matrix, can participate in neuroinflammatory response mediated by microglial cells and dynamically balance glial scar reconstruction and axon growth by regulating specific receptors and signaling pathways. This article reviews the relationship between CSPGs and WMI, as well as the mechanisms by which CSPGs inhibit axon growth, focusing on the role of multi-target regulation of CSPGs in promoting axon plasticity and functional brain recovery, thereby providing a theoretical basis for improving the prognosis of preterm infants with WMI.
Humans ; Chondroitin Sulfate Proteoglycans/physiology* ; White Matter/pathology* ; Axons/physiology* ; Infant, Premature ; Infant, Newborn ; Animals

OBJECTIVE: The aim of this study is to analyze the clinical features and genetic etiology of a patient with multiple morphological abnormalities of the sperm flagella (MMAF) retrospectively. METHODS: A severely oligospermic patient from the Reproductive Center of the First Affiliated Hospital of Ningbo University was selected as the study subject. Clinical data and examination results were collected. High-throughput sequencing and bioinformatics were used to analyze the genetic etiology. And Sanger sequencing was employed to validate findings in the family. Transmission electron microscopy (TEM) was used to observe the sperm ultrastructure, and immunofluorescence analysis was performed to examine the localization of FSIP2 protein in the sperm. RESULTS: The patient presented with severe oligospermia, and sperm morphology displayed MMAF. TEM revealed fibrous sheath and 9+2 microtubule structural disruptions in the sperm. Sequencing identified compound heterozygous variants in the FSIP2 gene (c.17798C > T, c.5927T > G), inherited from the father and mother, respectively. According to the guidelines of the American College of Medical Genetics and Genomics, the variants were classified as pathogenic. The patient's spouse underwent intracytoplasmic single sperm injection, resulting in one embryo, but no clinical pregnancy occurred after embryo transfer. CONCLUSION This study reported the mutation of FSIP2 gene c.17798C > T, c.5927T > G in a patient with MMAF. These findings expand the mutational spectrum of the FSIP2 gene and provide insights for genetic and assisted reproductive counseling for patients with MMAF.
Humans ; Male ; Sperm Tail/pathology* ; Heterozygote ; Oligospermia/genetics* ; Spermatozoa ; Mutation ; Infertility, Male/genetics* ; Adult ; Pedigree ; Retrospective Studies ; Sperm Injections, Intracytoplasmic

Tubal ciliary movement is one of the essential transport mechanisms for female fertility, playing a key role in facilitating oocyte pickup and transporting the fertilized ovum. This movement is mediated by multiciliated cells and regulated by specific proteins and hormones that modulate ciliary number, length, polarity, beat frequency, and amplitude to ensure proper function. Genetic mutations, inflammatory stimuli, and hormonal fluctuations can impair ciliary activity or induce ciliary apoptosis, leading to ciliary dysfunction. Disorders of tubal ciliary movement are frequently observed in primary ciliary dyskinesia, pelvic inflammatory disease, polycystic ovary syndrome, and endometriosis, conditions commonly associated with female infertility. These disorders manifest as structural abnormalities of cilia, disrupted polarity, shortened ciliary length, reduced ciliary count, and decreased beat frequency and amplitude. Understanding the role of tubal ciliary movement in female infertility-related diseases, through immunohistochemistry and ultrastructural analysis, helps clarify underlying infertility mechanisms. Identifying abnormal inflammatory factors, hormonal environments, and gene expression, combined with advanced techniques for measuring ciliary protein and beat frequency, may offer novel clinical targets for early prevention and treatment of female infertility.
Humans ; Female ; Infertility, Female/etiology* ; Cilia/physiology* ; Polycystic Ovary Syndrome/physiopathology* ; Fallopian Tubes/physiopathology* ; Endometriosis/complications* ; Pelvic Inflammatory Disease/complications*