RESUMO
Cerebellar cortices from feline fetuses with estimated gestational ages of 40-66days and from kittens aged 2days to 2months, all negative for feline panleukopenia virus (FPV) infection, were analysed for expression of the transferrin receptor 1 (TrFR1), proliferating cell nuclear antigen (PCNA), p27(Kip1) and calbindin. TrFR1, the receptor used by FPV to enter target cells, was expressed in capillary endothelial cells in the cerebellum at all fetal stages investigated and in Purkinje cells of a 3-week-old kitten, but not in the neuroblasts in the external granule layer (EGL). PCNA was expressed in cells of the superficial layer of the EGL. The cyclin-dependent kinase inhibitor p27(Kip1) was expressed in cells of the deep layer of the EGL. Purkinje cells expressed calbindin from the earliest fetal stage investigated. Co-expression of PCNA and calbindin could not be demonstrated, indicating that feline Purkinje cells are post-mitotic from at least 40days gestation.
Assuntos
Animais Recém-Nascidos/metabolismo , Calbindinas/metabolismo , Gatos/embriologia , Inibidor de Quinase Dependente de Ciclina p27/metabolismo , Regulação da Expressão Gênica no Desenvolvimento/fisiologia , Receptores da Transferrina/metabolismo , Animais , Calbindinas/genética , Cerebelo/citologia , Cerebelo/metabolismo , Inibidor de Quinase Dependente de Ciclina p27/genética , Feto/metabolismo , Células de Purkinje/metabolismo , Receptores da Transferrina/classificação , Receptores da Transferrina/genéticaRESUMO
Parvoviruses depend on initiation of host cell division for their replication. Undefined parvoviral proteins have been detected in Purkinje cells of the cerebellum after experimental feline panleukopenia virus (FPV) infection of neonatal kittens and in naturally occurring cases of feline cerebellar hypoplasia. In this study, a parvoviral protein in the nucleus of Purkinje cells of kittens with cerebellar hypoplasia was shown by immunoprecipitation to be the FPV viral capsid protein VP2. In PCR-confirmed, FPV-associated feline cerebellar hypoplasia, expression of the FPV VP2 protein was demonstrated by immunohistochemistry in Purkinje cell nuclei in 4/10 cases and expression of the FPV non-structural protein NS1 was demonstrated in Purkinje cell nuclei in 5/10 cases. Increased nuclear ERK1 expression was observed in several Purkinje cells in 1/10 kittens. No expression of the G1 and S mitotic phase marker proliferating cell nuclear antigen (PCNA) was evident in Purkinje cell nuclei. These results support the hypothesis that FPV is able to proceed far into its replication cycle in post-mitotic Purkinje cells.