The role of the Siglec-G ITIM domain during bacterial infection

The Novel Role of GDI2: A Mini-Review

GDP Dissociation Inhibitor 2 (GDI2) plays a crucial role in maintaining cellular homeostasis by regulating Rab GTPases involved in vesicular transport. This review highlights the importance of GDI2 in various biological processes, particularly embryonic development, apoptosis regulation, cancer, and immune responses. GDI2's essential function in embryonic development is evidenced by the embryonic lethality observed in GDI2 knockout mice. In apoptosis, GDI2 is implicated in the caspase pathway, influencing cell survival and death. In cancer, dysregulation of GDI2 contributes to altered tumor cell-macrophage interactions, promoting inflammation and metastasis, with GDI2 acting as a metastasis suppressor in certain cancers. Furthermore, GDI2's role in immune responses, particularly during bacterial infections, and its potential therapeutic implications in conditions like Alzheimer's disease are explored. This review emphasizes the need for further research to elucidate the molecular mechanisms of GDI2 and its potential as a therapeutic target in developmental disorders, cancer, and immune-related diseases.

Membrane Trafficking-Related Genes Predict Tumor Immune Microenvironment and Prognosis in Colorectal Cancer

Colorectal cancer (CRC) is a heterogeneous disease with varying clinical outcomes. The identification of distinct subgroups of CRC patients based on molecular profiling can aid in better understanding the disease and improving patient outcomes. This study aimed to investigate the potential of membrane trafficking-related genes (MTRGs) in sub-grouping colorectal cancer patients based on their overall survival and immune microenvironments. Consensus clustering analysis identified two distinct clusters with different expression profiles of membrane trafficking-related genes. The patients in cluster 1 had a significantly better overall survival than those in cluster 2. Furthermore, the immune microenvironments in the two clusters were also found to be significantly different, with cluster 1 having a higher immune score and more immune cells present. Functional analysis of differentially expressed genes between the two clusters revealed that MTRGs were involved in immune response and metabolic processes, and a risk signature model based on MTRGs was established to predict the prognosis of CRC patients. These findings suggest that MTRGs play a crucial role in the immune microenvironment and overall survival of CRC patients and may provide a potential target for personalized therapy.

Targeted disruption of Gdi2 causes early embryonic lethality

INTRODUCTION

GDI2 regulates the GDP/GTP exchange reaction of Rab proteins by inhibiting the dissociation of GDP and the subsequent binding of GTP, dysregulation of GDI2 has been reported in many different cancers. Recently, we found that GDI2 bound to the ITIM domain of Siglec-G under normal homeostasis, whereas Rab1a was recruited to the ITIM domain during bacterial infection. Therefore, GDI2 and Rab1a may regulate the immune response through interaction with the ITIM domain during bacterial infection. However, the regulation of the inflammatory response by GDI2 in vivo and its regulatory mechanism remain unknown.

METHODS

We generated a Gdi2 null mutant mouse with a trapped Gdi2 gene and examined the expression by X-gal and immunohistochemistry staining. TUNEL staining was used to determine the apoptosis cells.

RESULTS

Here we show that Gdi2 is essential for embryonic development. One functional Gdi2 allele is sufficient for murine embryo development, but complete loss of Gdi2 leads to embryonic lethality. Developmental retardation of Gdi2-/- mice is apparent at E10.5 to E14.5, with no viable Gdi2-/- embryos detected after E14.5. Histological analysis revealed extensive cell death and cell loss in Gdi2-/- embryos. Apoptosis was confirmed by staining with cleaved caspase-3, suggesting that Gdi2 maintain homeostasis by regulating the apoptosis of the cells. There was no significant difference in cytokine production and survival between wild-type and Gdi2+/- mice after LPS challenge.

DISCUSSION

These findings suggest that one Gdi2 allele is sufficient to maintain function. However, the detailed molecular mechanism underlying Gdi2 in regulating the embryonic development needs further identification.

Targeted disruption of Rab1a causes early embryonic lethality

Guanosine nucleotide diphosphate (GDP) dissociation inhibitor 2 (GDI2) regulates the GDP/guanosine triphosphate (GTP) exchange reaction of Rab proteins by inhibiting the dissociation of GDP and the subsequent binding of GTP. The present study aimed to determine the function of Rab1a in vivo, and thus generated mice with a trapped Rab1a gene. It was demonstrated that Rab1a is essential for embryonic development. It was also found that one functional Rab1a allele was sufficient for development in a heterozygous murine embryo, whereas a double mutant led to embryonic lethality. The dissection of uteri on embryonic day (E)10.5‑14.5 yielded no homozygous embryos, indicating that homozygotes die between E10.5 to E11.5. The gene trap construct contains a β‑galactosidase/neomycin reporter gene, allowing for heterozygotes to be stained for β‑galactosidase to determine the tissue‑specific expression of Rab1a. Rab1a was found to be highly expressed in the small intestine of both adult mice and embryos, although its expression levels were low in the brains of embryos. Moreover, there was no significant change in cytokine production and survival in wild‑type and heterozygous Rab1a+/‑ mice following a challenge with lipopolysaccharide. On the whole, the present study demonstrates that the disruption of the Rab1a gene causes embryonic lethality and homozygotes die between E10.5 and E11.5, suggesting that Rab1a is essential for the early development of mouse embryos.